POST LOGGING SUCCESSION AND 
VEGETATION MANAGEMENT WITH 
HEXAZINONE HERBICIDE IN Picea 
glauca (Moench) Voss - Populus 
tremuloides Michx. FOREST 
by 
EILEEN M. FORESTELL HARVEY 
A thesis submitted in partial fulfillment for 
requirements of the degree of 
Master of Science in Forestry 
Lakehead University 
School of Forestry 
December 1981 
ProQuest Number: 10611673 
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ACKNOWLEDGEMENTS 
I wish to express my appreciation to Professor R. J. Day for 
his encouragement, guidance and enthusiastic support. I am grateful 
to Dr. W. H. Carmeam, Professor F. R. Clarke and Dr. G. R. Stephenson 
for advice on various aspects of this thesis and to Dr. T. Hazenberg 
for statistical advice. 
I am grateful to Mr. Paul McAlister and Mr. Fred Kreikmann of 
the Ontario Ministry of Natural Resources for helping me locate 
study areas. 
I am thankful to the following students who assisted with 
laboratory and field work: William and Ralph Day, Garry Gilbert, 
Stephen Harvey, Steve Moore, Brian Murray and Iris Weisner. 
I appreciate the time amd patience taken by Mrs. Anne Sutherland, 
Ms. Carey Thomas, and Mrs. Marge Doggett in typing this thesis and I 
wish to thank Ms. Lynn Palmer and Miss R. Strocen for assisting with 
final corrections and compilations. 
Financial support was provided by Dupont of Canada Ltd. and a 
Canadian Forestry Service Grant. 
Finally, I am greatly indebted to my husband Mark Harvey who 
drafted many of the diagrams for this thesis and assisted me many 
times in the field. Without his patience, encouragement, under- 
stcuiding, and support I would not have been able to complete this 
thesis. 
Abstract 
The objectives were: to review the successional behaviour of 
white spruce (Picea glauca (Moench) Voss) - trembling aspen (Populus 
tremuloides Michxt)stands in the literature, to conduct field studies 
of the successional behaviour of planted white spruce in aspen stands, 
and to test hexazinone herbicide as a means of modifying the post- 
logging environment to release white spruce and other conifers. 
Five and 13 year old white spruce plantations were selected 
for study. Fifty square random plots were established in each 
plantation. Total and mean aspen and white spruce volumes per plot 
were calculated. Each plantation was stratified into 3 components 
or "Situation Types" based on aspen density. Five plots were 
established at both plantations in each of these Types. These 
"Situation Plots" were circular and selected so that a white spruce 
tree was located at each plot centre. The central white spruce and 
the mean aspen tree on each "Situation Plot" were cut down for stem 
analysis. The number of frost damaged tips per m^ crown area on 
each central white spruce tree were calculated. 
The mean and total aspen volumes per plot are not related to 
the white spruce volumes per plot in either plantation. The current 
annual increment curves of the paired central white spruce and the 
mean aspen tree from each "Situation Plot" do not show ciny trends 
for the 5 year old plaintation. Current annual volume increment 
curves from the 13 year old plantation show that a rapidly growing 
aspen tree will suppress its white spruce neighbour. The number of 
frost damaged tips per m^ white spruce crown area significantly 
decreases as the number of aspen trees per plot increases at the 5 
year old plantation. This relationship was not strong at the 13 
year old plantation. 
This information is used to make recommendations for releasing 
white spruce from trembling aspen competition with hexazinone 
herbicide. 
Factorial herbicide trials were established in the field and 
greenhouse to evaluate the effect of hexazinone herbicide on white 
spruce and trembling aspen. Trials were also established to evalu- 
ate the effect of hexazinone on black spruce (Picea mariana (Mill.) 
B.S.P.), jack pine (Pinus banksiana Lamb.), willow (Salix spp.) and 
beaked hazel (Corylus cornuta Marsh.) , Various hexazinone rates, 
forms, spacings and spray positions were tested. Hexazinone 
'Gridball' pellets and hexazinone concentrated solution (DPX-LX or 
LE) were the herbicide forms used. 
White spruce, black spruce and jack pine were found to be quite 
tolerant to hexazinone herbicide. Hexazinone did not reduce the 
survival or height growth of the white spruce significantly except 
in the greenhouse trial. Jack pine and black spruce were only 
significantly affected at the highest rates. In the greenhouse 
trial, the high hexazinone rates applied to the foliage and soil 
significantly reduced the survival and the foliage dry weight of 
both white spruce and jack pine. Most rates of hexazinone applied 
caused a significant reduction in height growth, survival and 
foliage dry weight of the aspen, willow and hazel. 
These results suggest that hexazinone can be used effectively 
to control weed species in conifer plantations. 
TABLE OF CONTENTS 
LIST OF TABLES iii 
LIST OF FIGURES v 
LIST OF APPENDICES x 
INTRODUCTION 1 
LITERATURE REVIEW 9 
Autecology of White Spruce 9 
i) Germination and Establishment 9 
ii) rowth and Development 15 
Autecology of Trembling Aspen 17 
i) Germination, Suckering and Establishment 17 
ii) Growth and Development 21 
White Spruce - Trembling Aspen Succession and the 
Influence of Fire 21 
Post Logging Spruce-Aspen Succession 27 
Silviculture in Post~Logged White Spruce - Aspen Forest 29 
i) White Spruce Plantations and their 
Establishment 29 
ii) Stand Conversion 37 
iii) Mech2uiical Release of White Spruce from Aspen 
Competition 38 
iv) Chemical Release of White Spruce from Aspen 
Competition 41 
The Use of Hexazinone Herbicide in Forestry 45 
SECTION I 
The post logging successional behaviour of planted white 
spruce in sucker origin trembling aspen stands 50 
Methods 50 
i. Study Areas 50 
ii. tand Description Plots 51 
iii. ituation Plots 55 
iv. tem Analysis 58 
Results 59 
SECTION II 
Field and greenhouse trials with Hexazinone Herbicide 76 
Methods 78 
1. The Brush Control Trials 78 
2. The Seedling Survival Trials 90 
3. The Crop Tree Trials 92 
4. The Weed Tree and Brush Trials 97 
5. The Mature Aspen Trial 104 
6. The Greenhouse Trials 109 
ii 
Statistical Analysis of the Hexazinone Herbicide 
Trials 116 
Results 119 
1. The Brush Control Trials 119 
2. The Seedling Survival Trials 128 
3. The Crop Tree Trials 132 
4. The Weed Tree and Brush Trials 140 
5. The Mature Aspen Trial 1^9 
6. The Greenhouse Trials 151 
DISCUSSION 165 
SECTION I 
The post logging successional behaviour of planted 
white spruce in sucker origin trembling aspen stands 165 
SECTION II 
Field and greenhouse trials with Hexazinone Herbicide 170 
1. The Brush Control Trials 170 
2. The Seedling Survival Trials 172 
3. The Crop Tree Trials 173 
4. The Weed Tree and Brush Trials 175 
5. The Mature Aspen Trial 177 
6. The Greenhouse Trials 177 
CONCLUSION 180 
THE USE OF HEXAZINONE FOR WEED CONTROL IN SITE PREPARATION, 
PLANTATION ESTABLISHMENT AND PLANTATION TENDING IN THE 
BOREAL FOREST 182 
LITERATURE CITED 187 
Ill 
LIST OF TABLES 
Table 1. The Three Situation Types Defined at Plantations 
1 and 2. 55 
Table 2. Outline of the Hexazinone Herbicide Trials. 77 
Table 3. Stand History and Description of Locations 1, 
2 and 3. 81 
Table 4. Description of the Hexazinone Herbicide Trials 
at Locations 1, 2 and 3. 82 
Table 5. The Hexazinone Herbicide Treatments Applied in 
the Brush Control Trials. 83 
Table 6. The Subjective Condition Code Used to i:>escribe 
the Condition of the Aspen. 90 
Table 7. Species and Height of Trees in the Four Crop 
Tree Hexazinone Herbicide Trials. 93 
Table 8. The Hexazinone Herbicide Treatments Applied in 
the Crop Tree Trials. 94 
Table 9. Species and Height of the Trees in the Two Weed 
Tree and Brush Hexazinone Herbicide Trials. 97 
Table 10. The Hexazinone Herbicide Treatments Applied in 
the Aspen Weed Tree Trial. 99 
Table 11. The Hexazinone Herbicide Treatments Applied in 
the Willow Brush Trial. 101 
Table 12. The Three Diameter Classes in the Mature Aspen 
Trial. 105 
Table 13. The Hexazinone Herbicide Treatments Applied in 
the Mature Aspen Trial. 106 
Table 14. The Subjective Condition Code Used to Evaluate 
the Mature Aspen Trial. 107 
Table 15. The Hexazinone Herbicide Treatments Applied in 
the Jack Pine and White Spruce Crop Tree Greenhouse 
Trials. 110 
IV 
Table 16. The Hexazinone Herbicide Treatments Applied in the 
Aspen and Hazel Weed Tree and Brush Greenhouse 
Trials. 114 
Table 17. The Statistical Analyses Used in the Hexazinone 
Herbicide Trials. 118 
LIST OF FIGURES 
Figure 1. The chemical structure of hexazifione 
(3-Cyclohexyl-6-- (dimethylamino) -methyl- 
1, 3 ,5-triazine-2 ,4 (IH,3H)-dione). 
Figure 2. Schematic description of plots with high, 
medium and low tree density at Plantation 1. 60 
Figure 3. Total volume of spruce per plot vrs. total 
volume of aspen per plot at Plantation 1. 61 
Figvire 4. Mean volume of spruce per plot vrs. mean 
volume of aspen per plot at Plantation 1. 61 
Figure 5. Mean volume of spruce per plot vrs. total 
volume of aspen per plot at Plantation 1. 62 
Figure 6. White spruce frost damaged tips per unit 
crown area vrs. number of aspen trees per 
plot at Plantation 1. 64 
Figure 7. Plantation 1 - The growth curves for white 
spruce on Situation Type I plots. 65 
Figure 8. Plantation 1 - The growth curves for aspen 
on Situation Type I plots. 65 
Figure 9. Plantation 1 - The growth curves for white 
spruce on Situation Type II plots. 65 
Figure 10. Plantation 1 - The growth curves for aspen 
on Situation Type II plots. 65 
Figure 11. Plantation 1 - The growth curves for white 
spruce on Situation Type III plots. 65 
Figure 12. Plantation 1 - The growth curves for aspen 
on Situation Type III plots. 65 
Figure 13. Schematic description of plots with high, 
medium and low tree density at Plantation 2. 68 
Figure 14. Total volume of spruce per plot vrs. total 
volume of aspen per plot at Plantation 2. 70 
Figure 15. Mean volume of spruce per plot vrs. mean 
volume of aspen per plot at Plantation 2. 70 
VI 
Figure 16. Mean volume of spruce per plot vrs. total 
volume of aspen per plot at Plantation 2. 71 
Figure 17. White spruce frost damaged tips per unit 
crown area vrs. number of aspen trees per 
plot at Plantation 2. 72 
Figure 18. Plantation 2 - The growth curves for white 
spruce on Situation Type I plots. 74 
Figure 19. Plantation 2 - The growth- curves for aspen 
on Situation Type I plots. 74 
Figure 20. Plantation 2 - The growth curves for white 
spruce on Situation Type II plots. 74 
Figure 21. Plantation 2 - The growth curves for aspen 
on Situation Type II plots. 74 
Figure 22. Plantation 2 - The growth curves for white 
spruce on Situation Type III plots. 74 
Figure 23. Plantation 2 - The growth curves for aspen 
on Situation Type III plots. 74 
Figure 24. Schematic description of Locations 1, 2 
and 3. 79 
Figure 25. Schematic description of the rate and 
spacing treatments. 84 
Figure 26. Schematic description of the zone of 
effectiveness around a hexazinone "Spot”. 85 
Figure 27. The branch diameter guide. 87 
Figure 28. The plotted points show actual foliage dry 
weight (FDW) and branch di8uneter at point 
of foliation (D). 89 
Figure 29. Planting layout of a single plot in the 
Seedling Survival Trial. 91 
Figure 30. Schematic description of the hexazinone 
spacing treatments. 86 
Figure 31. Schematic description of the hexazinone 
spot placements. 103 
Figure 32. Schematic description of the hexazinone 
spot treatments. 106 
vii 
Figure 33. The relationship between spot and grid 
application rates of hexazinone herbicide. 112 
Figure 34. The predicted foliage dry weights adjusted 
by covariance analysis of the aspen at 
Location 1. 121 
Figure 35. The condition code of the aspen at Location 
1 in 1979. 122 
Figure 36. The predicted foliage dry weights adjusted 
by covariance analysis of the aspen at 
Location 2. 124 
Figure 37. The condition code of the aspen at Location 
2 in 1979. 125 
Figure 38. The predicted foliage dry weights adjusted 
by covariance analysis of the aspen at 
Location 3. 127 
Figure 39. The condition code of the aspen at Location 
3 in 1979. 127 
Figure 40, The height increment of the White Spruce 
Seedling Survival Trial. 129 
Figure 41. The condition code of the White Spruce 
Seedling Survival Trial. 129 
Figure 42. The condition code of the Black Spruce 
Seedling Survival Trial, 131 
Figure 43. The condition code of the White Spruce 
(1.5 Metre) Crop Tree Trial. 133 
Figure 44. The condition code of the White Spruce 
(0.5 Metre) Crop Tree Trial. 134 
Figure 45. The survival (%) of the Black Spruce Crop 
Tree Trial. 136 
Figure 46. The condition code of the Black Spruce 
Crop Tree Trial. 136 
Figure 47. The height growth of the Jack Pine Crop 
Tree Trial adjusted by covariance analysis. 138 
Figure 48. The survival (%) of the Jack Pine Crop Tree 
Trial. 138 
yiii 
Figure 49. The condition code of the Jack Pine Crop 
Tree Trial. 139 
Figure 50. The height growth of the Aspen Weed Tree 
Trial adjusted by covariance analysis. 142 
Figure 51. The survival (%) of the Aspen Weed Tree 
Trial. 142 
Figure 52. The condition code of the Aspen Weed Tree 
Trial. 143 
Figure 53. The total stem growth of the Willow Brush 
Trial adjusted by covariance analysis. 146 
Figure 54. The survival (%) of the Willow Brush Trial. 146 
Figure 55. The condition code of the Willow Brush 
Trial. 147 
Figure 56. The survival (%) of the Mature Aspen Trial. 
The solid and liquid treatments applied at 
the saune rate to trees of the same diameter 
class are combined. 150 
Figure 57. The condition code of the Mature Aspen Trial. 
The solid and liquid treatments applied at 
the same rate to trees of the same diameter 
class are combined. 150 
Figure 58. The survival (%) of the Jack Pine Greenhouse 
Trial. 152 
Figure 59. The actual foliage dry weight of the Jack Pine 
Greenhouse Trial. 152 
Figure 60. The condition code of the Jack Pine Greenhouse 
Trial. 154 ' 
Figure 61. The survival (%) of the White Spruce Greenhouse 
Trial. 156 
Figure 62. The actual foliage dry weight of the White 
Spruce Greenhouse Trial. 156 
Figure 63. The condition code of the White Spruce Green- 
house Trial, 158 
Figure 64. The survival (%) of the Aspen Greenhouse Trial. 160 
ix 
Figure 65. The foliage dry weight of the Aspen Greenhouse 
Trial adjusted by covariance analysis. 160 
Figure 66. The condition code of the Aspen Greenhouse 
Trial. 161 
Figure 67. The survival (%) of the Hazel Greenhouse Trial. 163 
Figure 68. The foliage dry weight of the Hazel Greenhouse 
Trial adjusted by covariance analysis. 163 
Figure 69. The condition code of the Hazel Greenhouse 
Trial. 164 
X 
LIST OF APPENDICES 
APPENDIX A Maps showing exact locations of Plantations 
1 and 2 and the Hexazinone Herbicide Trials. 202 
APPENDIX B Regressions relating diameter above butt 
swell to volume for the aspen and white 
spruce at Plantations 1 and 2. 208 
APPENDIX C Regression curves relating foliage dry 
weight to branch diameter at point of 
foliation. 213 
APPENDIX D Analysis of variance of the regressions 
relating number of frost damaged tips per 
unit white spruce crown area to number of 
aspen trees per plot for Plantations 1 and 2. 220 
APPENDIX E Analysis of variance, analysis of covariance 
and Student-Newman-Keul's test tables for the 
Hexazinone Herbicide Trials. 222 
INTRODUCTION 
The objectives of this thesis are: 
to review the successional behaviour of white spruce 
(Picea g1auca (Moench) Voss)-trembling aspen (Populus 
tremuloides Michx . )sbands in the Great Lakes-St. 
Lawrence and Boreal Forest Regions in tlie literature in 
order to gain an understanding of natural forest 
succession as a basis for plantation management, 
to study the successional behaviour of planted white 
spruce that occurs during the first 13 years after 
logging in sucker origin trembling aspen stands of the 
B9 or Superior Section of the Boreal Forest Region (Rowe 
1972), 
2 
3. to test hexazinone herbicide as a means of modifying the 
post-logging environment and releasing white spruce, 
black spruce fPicea mariana (Mill.) B.S.P.), and jack 
pine (Pinus banksiana Lamb.)from the aspen, willow 
(Sal i X spp,), and beaked liazel (Cor vlus co r nu ta Marsh.) 
competition that occurs after logging. 
The normal post-wildfire succession of the 
spruce-aspen forest is modified in two ways: 1. by forest 
fire suppression and 2. by logging. Naturally, most 
spruce-aspen stands in the boreal forest are subject to 
wild-fire every 60 to 100 years (Day and Harvey 1980a). 
Through forest fire suppression timber that would normally 
be consumed by fire is available for harvesting. 
The boreal forest is subject to the frequent occurrence 
of fire. Usually the tree species that were present before 
the fire return after the fire because of adaptations for 
survival after fire (Methven et al 1975). Logging 
drastically changes the species composition of the majority 
of post-logged forest cover types. 
3 
Commercial clearcutting is the most common logging system 
used in the spruce-aspen forest. Spruce and high quality veneer 
aspen are the more valuable species on today's market. 
Usually these species are logged leaving the unmerchantable 
aspen unutilized. Because of this, the spruce seed source 
is often severely reduced while, in contrast, the aspen seed 
source and suckers remain. Under normal conditions white 
spruce trees can be expected to disperse seed abundantly 
every 4 years for a distance of 100 metres (Fowells 1963) . 
As some clearcuts inspected by the author in northwestern 
Ontario range up to 800 hectares in size, and as cutting is 
an annual event, it is obvious that spruce seed will be 
inadequate to regenerate such large clearcuts. 
Natural regeneration of white spruce is best on bare 
mineral soil (Phelps 1951, LeBarron 1945) or decayed wood 
(Lees 1972, Day 1963a, Phelps 1948). The slash, duff and 
litter that are usually present on recently logged sites 
provide the most unfavorable seedbed for white spruce. 
White spruce is normally tolerant to low levels of light, 
but because of its small size and slow growth during the first 
few years it is not able to compete with the dense growth of 
herbacious vegetation, shrubs and understory trees that remain 
in the absence of fire (Bedell 1948, Row 1955). Such 
dense and rapidly growing competition may be enough 
4 
to completely exclude white spruce from a stand that was 
white spruce-aspen prior to logging. 
After logging, aspen reproduces vegetatively by 
prolific suckering (MacLean 1960). During logging 
operations the forest stand is severely disturbed; surface 
litter is often removed and the dark mineral soil increases 
in temperature; parent aspen trees are often cut and 
therefore the apical dominance effect is lost. All of these 
factors contribute to abundant suckering of aspen (Jarvis 
1968, Maini and Horton 1966 a and b ). 
Aspen grows very quickly and it will rapidly overtop 
and suppress any neighbouring white spruce trees. Aspen 
competes with white spruce in two ways: 1) Physiologically 
by reducing the amount of moisture and light available to 
the spruce and therefore causing diminished white spruce 
growth, and 2) mechanically by whipping the white spruce 
crown. 
Various methods have been used to reduce aspen 
competition in white spruce-trembling aspen stands. 
Mechanical methods such as cutting, breaking or girdling the 
aspen suckers and prescribed burns in advance of planting 
have been attempted. Mechanical release treatments are 
often too expensive to apply in Canada. These treatments 
usually do not last very long as the aspen will rapidly 
5 
re-sucker. Prescribed burning, after logging and before 
planting, may result in increased aspen suckering. It is 
a technique that requires a great deal of expertise. 
Chemical release treatments have generally been used 
with more success than mechanical release treatments in 
spruce-aspen stands. Herbicide treatments tend to be quite 
effective. They are often much faster to apply, require 
less manpower and are therefore more economical and have 
longer lasting results than mechanical release treatments 
(Roe 1953). Chemical treatment prior to mechanical site 
preparation has also been used success!ully. 
Low volatile formulations of the phenoxy acetic 
acids were, until recently, the principal herbicides used 
in forestry (Romancier 1965 and Haagsma 1968). Herbicides 
such as 2,4-D and 2,4,5-T must be applied at quite high rates 
in order to be effective. These rates are often close to the 
detrimental rate for spruce and pine. The herbicide 2,4,5-T 
is no longer available for use in forestry since the Ontario 
Ministry of Natural Resources withdrew it from use in 1980. 
Controversy over the environmental effects of the phenoxy 
acetic acids may also result in 2,4-D being taken off the 
market. 
Studies during the 1960's with fenuron were very 
promising for the control of woody plants (Sutton 1965a and 
b). Work with fenuron was discontinued in the late 1960's 
when the herbicide was no longer available from the Dupont 
6 
Chemical Company. The forestry market was not large enough 
to commercially warrant its production. 
In the 1970's, none of the herbicides available for 
forestry even closely approximated the effectiveness of 
fenuron. Mathews (1970) worked with bromacil and karbutilate 
as possible substitutes for fenuron. These herbicides were 
all quite toxic to both white and black spruce seedlings and 
could not replace fenuron (Mathews 1970). This factor and 
the bleak future of the phenoxy acetic acids has stimulated 
interest in research for new herbicides. 
Hexazinone is a new triazine herbicide, the chemical 
structure of hexazinone is shown in Figure 1. Although its 
mode of action is not clearly understood, it is thought to 
be a photosynthetic inhibitor that affects the dark release 
of oxygen (Weed Science Society of America 1979). Much 
research surrounding hexazinone has taken place in New 
Zealand and in the loblolly pine (Pinus taeda L.) 
plantations of the southern United States. 
7 
N(CH3>2 
Figure 1. The chemical structure of hexazinone (3-Cyc- 
lohexyl- 6- (dimethylamino)-1-methyl-1,3,5- 
triazine-2,4(IH,3H)-dione). 
Hexazinone can be applied as a foliar spray, in 
concentrated solution with a 'Spotton-gun', or in a pellet of 
'Gridball' formulation. These different formulations make it 
possible to apply hexazinone non selectively in a grid 
pattern with 'Gridballs' or concentrated solution or 
broadcast as a foliage spray. It can also be applied 
selectively with 'Gridballs' or concentrated solution 
applied with a *Spotton-gun' to individually release trees. 
8 
Studies using hexazinone herbicide to reduce 
competition with white spruce in the Boreal Forest Region 
were initiated in the Thunder Bay area during 1978 and 1979, 
(Polhill 1978, Dunsford 1979). These studies have shown 
that hexazinone is an effective herbicide for controlling 
aspen and in stands where aspen is providing competition to 
white spruce regeneration. 
This thesis will provide initial information on the 
post logging succession in white spruce plantations. It 
also provides recommendations for vegetation management 
techniques with hexazinone herbicide. In addition to white 
spruce and trembling aspen, hexazinone trials were also 
conducted on black spruce, jack pine, willow, and beaked 
hazel as these species are also important components of the 
mixedwood forest. Knowledge about the release of white 
spruce from trembling aspen in the B9 or Superior Section of 
the Boreal Forest Region (Rowe 1972) should be enhanced by this 
thesis. 
9 
LITERATURE REVIEW 
Autecology of White Spruce: 
i)Germination and Establishment: 
W^hite spruce begins to produce seeds at approximately 
30 years of age. Optimum seed production occurs when the 
trees are 60 years of age or older (Powells 1965). Good 
seed crops are produced every 2 to 6 years, with light seed 
crops in the intervening years (Powells 1965). Seedfall 
begins in late August or early Setember and may continue, to 
a limited extent, through the following winter (Roe 1946). 
If sufficient wind is available, mature trees can be 
expected to disperse seed in excess of 300 metres (Rowe 
1955). Under calmer conditions, seed dispersal has been 
observed to be about 100 metres (Powells 1965). 
White spruce seed normally germinates during June, but 
low air temperature or inadequate moisture may delay 
germination until July or August (Waldron 1966). 
Temperature is of the greatest importance in tiie germination 
of v;hite spruce seed. Holt (1955) found that white spruce 
seed will not germinate belov^; or above certain critical 
temperature limits. White spruce seed will germinate 
10 
between a minimum temperature of 7^C and a maximum 
temperature of 29^C (Mork 1938). Rowe (1953b) found a mean 
. o 
air temperature of 7 C during the week prior to white spruce 
seed germination. Germination began during the first half 
of^ Juln y at a mean air temperature of 14 0 C and i. t stopped,  
0 
when the mean air temperature reached 12 C during the first 
week in September (Rowe 1953b). In overmature spruce stands 
in the foothills of Alberta, low soil temperatures reached 
beneath the organic layer provided an inhospitable rooting 
medium for both mature white spruce trees and seedlings 
(Endean 1972). At low temperatures, root growth is very 
slow. Endean (1972) feels that this is a major factor 
limiting regeneration success. 
Moisture is often a limiting factor in spruce 
germination and survival. (Holt 1955 and Day 1963a). Day 
(1964) found that regeneration after logging is more 
abundant on moisture retentive seedbeds in moist and shaded 
microenvironments. The length of the growing season before 
the onset of drought appears to reduce mortality and this 
remains true as long as the rate of root extension exceeds 
the rate of surface drying (Day 1963). Phelps (1948) found 
that the number of days of drought sufficient to cause 
seedling mortality varied from 7 to 24. Day (1963b) 
suggests that abundant and well distributed precipitation is 
required to ensure good spruce germination on exposed 
seedbeds. 
Insects, fungi, birds and animals may prevent white 
spruce germination by destroying the seed (Holt 1955). 
The presence or absence of a receptive seedbed is a 
major constraint on the germination and establishment of 
white spruce. Bare mineral soil is a much better seedbed 
than the original duff surface of the natural forest floor 
(LeBarron 1945 , Phelps 1951). Wlien the seed makes contact 
with bare mineral soil during drier periods it can take 
advantage of water diffused to the soil surface from more 
moist subsurface soil layers. Duff, litter and moss are 
easily dried out; this could kill the newly germinating 
seedlings. The number of white spruce seedlings tends to 
decrease as litter depth increases (Phelps 1948). Holman 
(1927) found that a duff layer greater than 5 cm 
in depth inhibited spruce germination. A scarified seedbed 
was superior to both a mounded and undisturbed seedbed for 
spruce regeneration in Alberta (Lees 1963). Crossley (1955) 
found that baring the mineral soil to coniferous seedfall 
resulted in increased spruce stocking for 4 years, and the 
scarified seedbed remained more receptive to spruce 
germination than the unscarified control for 3 years. 
Remeasurement of this area in 1961 (Day 1963c) showed that 
although the seedbed treatment was initially promising, it 
12 
was not a success. Spruce reproduction on the scarified 
areas was not significantly different from that on the 
unscarified controls. Day (1963c) suggests that poor 
response and growth of spruce regeneration was due to 
moisture deficiencies and lack of nutrients rather than 
vegetative competition. Phelps (1948) found that areas 
where the litter had been removed, either by raking or 
burning, were more favorable to the establishment and 
survival of white spruce seedlings than those where the 
litter had been undisturbed. Fifteen years after logging, 
regeneration on deep untreated moss was inadequate whereas 
all of the treated seedbeds (heavy burning, light burning, 
and stripping to mineral soil) produced satisfactory 
regeneration from natural seedfall (Parker 1952). 
Decayed wood provides a satisfactory seedbed, 
especially in stands that have not been opened up by logging 
or fire. Phelps (1948) found that the majority of seedlings 
germinated on a substratvim of rotten wood. Day (1963a) 
found that spruce germination was significantly better on 
decayed wood than on mineral soil. He suggests that decayed 
wood may have special physical or chemical properties that 
stimulate germination. A rotten log is receptive to conifer 
seed, conserves moisture and resists colonization of 
herbaceous vegetation (Lees 1972). Twenty to 30 years are 
required for wood to decay to the point suitable for spruce 
13 
germination (Rowe 1955). 
Seed size has no effect on either the germination or 
the survival rate of white spruce, although larger white 
spruce seeds tend to produce bigger seedlings (Burgar 1964). 
White spruce is tolerant, but because of its small size 
during the first year, it is not able to compete with dense 
growth of herbacious vegetation, shrubs and understory trees 
(Bedell 1948, Rowe 1955). According to Plielps (1948), 
mortality among seedlings is greatest during ttie first three 
years after germination. Hall (1979) found tliat overall 
white spruce survival after planting Vv/as 75% with most of 
the mortality occuring during the first growing season. 
Waldron (1966) found that more than 60% of seedlings died 
before 4 years; survival was greater on disturbed than 
undisturbed seedbeds. Lees (1970) found that overwinter 
mortality of white spruce seedlings was greater than growing 
season mortality. Day (1964) suggests that shade reduces 
the growth rate of spruce seedlings and that 
microenvironments most suited to germination and survival 
may not be best for later developement. 
Trenching experiments had no influence on white spruce 
germination and early survival (Griffith 1931, Ackerman 1957). 
This indicates that root competition of herbaceous vegetation 
and the residual stand is not initially an important factor 
14 
in white spruce germination and initial seedling survival. 
Day (1970) suggests that root competition from the residual 
stand does reduce the survival of older seedlings. 
Leaf litter has a varying effect on the germination and 
survival of white spruce. Aspen leaves are very efficient 
in conserving soil moisture and thus may have a beneficial 
effect on the germination of white spruce (Cayford and 
Waldron 1962). Gregory (1966) found that protection of 
young white spruce seedlings from birch leaf fall increased 
first year germination and survival and continued to 
significantly enhance survival through the first 4 growing 
seasons. Leathery leaves such as those of iiard maple (Acer 
saccharum Marsh.), oak (Quercus spp.), and aspen do more 
harm than the thinner leaves of birch fBetula uauvrifera 
Marsh.) whose veination causes them to curl and dry 
(Koroleff 1954). Waldron (1963) found that the heavest 
period of white spruce seed dispersal proceeded tiie heaviest 
period of litter fall by over one month. This could have a 
significant effect on v;hite spruce regeneration, especially 
on scarified areas, as more seed would likely come in 
contact with a favorable seedbed. In stands containing a 
substantial aspen component, it is possible that leaves 
flattened by winter snow would be a limiting factor in 
15 
spruce germination (Waldron 1963). 
ii) Growth and Development: 
The current annual height increment tor white spruce 
growing free from competition has been found to increase 
slowly for the first 14 years after planting and then level 
off (Hambly 1980). These results agree v^ith those of Stiell 
(1976) who found that the current annual height increment 
for white spruce increased slowly for the first 10 years 
after planting and remained uniform from age 15 to 35 
depending on site quality. Grov/th rates start to decline at 
about 35 years (Stiell and Berry 1973). 
Young wliite spruce stands are very prone to frost 
damage. White spruce breaks dormancy around June 1, but 
heavy frosts often occur after this and damage the trees 
(Rowe 1955). White spruce flushes earlier than black spruce 
and is therefore more prone to frost damage (Fowells 1965). 
Spring frosts can cause white spruce to loose new growth, 
but other buds soon replace this loss (Argetsinger 1957). 
Cayford et al (1959) found that buds that were well advanced 
and showing green tips of foliage were often injured or 
killed by ]ate spring frosts. They suggest tliat the amount 
of bud-kiliing is entirely dependent on the degree of bud 
swelling. Clements et al (1972) found that unopened buds of 
16 
white spruce could be dainurjod by late Lsprincj Irost even 
before the buds were ready for flushiny. They also found 
that there was more damage among shorter trees than among 
taller trees. Sixty-seven per cent of the trees in a 6 year 
old white spruce plantation were affected (Clements et al 
1972). There was more frost damage among open-grown trees 
than among understory trees (Clements et al 1972). 
White spruce is classed as a tolerant species (Baker 
1949). When white spruce grows with hardwoods established 
at the same time, it may fall behind and remain an 
understory tree (Cayford 1957). The height growth of white 
sx>ruce seedlings is significantly affected by vegetative 
competition (Lees 1970). Spruce may become suppressed at an 
early age and , on stands up to 100 years of age, aspen 
suppression may reduce white spruce volume by 50% (Cayford 
1957). 
Rowe (1955) found that old white spruce trees develop 
extensive shallow root systems from which vertical sinkers 
descend into the lower soil (Rowe 1955). He suggests that 
this sometimes gives white spruce an advantage when 
competing against the deeper rooted hardwoods for moisture 
from the surface. Wagg (1967) suggests that white spruce 
will develop this typo of root system only on soils with 
excessive moisture near the surface. He found that white 
spruce developed an elongated tap root on well-drained 
uniform textured soils and a restricted tap root on soils 
with either textural changes betv^een horizons or with 
compact horizions. White spruce v^/ith this type of root 
system would likely be deeper rooted than hardwoods in the 
same stand. 
In coniferous mixtures, white spruce will reach 
dominance with balsam fir and jack pine and it will 
eventually outgrow them- Stands of this type tend to 
regenerate to balsam fir (Fowells 1965). 
Autecology of Trembling Aspen; 
i)Germination, Suckering and Establishment: 
Trembling aspen is a dioecious tree species with 
staminate and pistillate catkins usually born on separate 
trees (Maini 1968). Trembling aspen begins to produce 
flowers at about 15 years of age (Maini 1968). Flowers 
develop in April or May before foliation. Pollination is by 
wind and the fruits ripen in May or June, 4 to 6 weeks after 
flowering (Fowells 1965). Good seed crops are produced 
every second or third year (Maini 1968). Seed dispersal 
takes place a few days after ripening. The light seed can 
be carried for miles by air currents or else dispersed by 
18 
water (Fowells 1965) . 
The establishment of trembling aspen seedlings in 
nature is rare and is restricted to moist freshly exposed 
mineral soil (Maini I960). Horton and Maini (1964) found 
that when seedbeds were naturally provided with a very 
abundant quantity of trembling aspen seeds, neither severely 
nor lightly burned plots produced even a single germinant; 
the moister scalped plots produced a great many. For 
adequate aspen reproduction from seed to occur, a favorable 
seed bed, a good seed crop, and abundant soil moisture are 
required. This often happens when a fire exposes bare 
mineral soil during the spring of a good seed year 
(Zehngraff 1947). Maini (1960) found that the shortage of 
seedling origin trembling aspen stands in nature is due to; 
i) short seed viability, ii) presence of a water soluble 
germination and growth inhibitor in the seed hair, iii) 
occurrence of unfavorable moisture conditions during seed 
dispersal on upland sites that aspens usually inhabit, iv) 
susceptibility of seedlings to high temperatures that occur 
on soil surfaces blackened by fire, v) susceptibility of 
seedlings to fungal attack, vi) adverse influence of diurnal 
temperature fluctuations on initial seedling growth, and 
vii) unfavorable chemical nature of some substrates on which 
seedlings are likely to fall. 
19 
Usually the suckering of trembling aspen is so profuse 
that seedlings are excluded. Aspen root suckers grow from 1 
to 2 metres per year for the first 5 years; this enables 
them to dominate the stand early and mechanically whip 
most competitors (Day and Harvey 1980a). 
Asexual, rather than sexual, reproduction is a more 
important factor in aspen regeneration in the boreal forest. 
Trembling aspen survives the adverse conditions at the 
northern and southern limits of its range by asexual 
reproduction (Maini 1968). Aspen reproduction by formation 
of adventitious shoots on roots (or suckering) is a common 
phenomenon (Maini 1960). Maini and Horton (1966a) feel that 
warm temperature is the main envionmental factor stimulating 
aspen sucker formation. Maximum incidence and growth of 
o 
suckers occurred at a temperature of 23 C and declined 
gradually below and above this temperature (Maini and Horton 
1966a). Stenecker (1974a) suggests tiiat the apical 
dominance of parent tree crowns primarily controls 
suckering, but that once this effect is broken increased 
soil temperature promote suckering. Root depth also 
influences sucker incidence. Most suckers develop from the 
shallowest portions of the soil, within 5 cm of ground 
surface or just beneath the organic soil horizions (Jarvis 
1965). Suckers usually originate on shallow cordlike roots 
ranging from 0.5 to 5 cm in thickness (Maini 1960). This 
20 
could also be a temperature effect as the shallowest 
portions of the soil horizon also have the higliest 
temperature. Older aspen stands appear to lose the ability 
to sucker (Rowe 1955). 
The abundance of aspen suckers has also been shown to 
be related to the degree of stand disturbance (Maini and 
Horton 1966a and 1966b, Jarvis 1968). When a forest stand 
is severely disturbed, much of the surface litter is removed 
and the dark mineral soil increases in temperature. Parent 
aspen trees are often cut and tlierefore lose apical 
dominance. For abundant and vigorous suckering, strong 
light and heat must reach the forest floor (Jarvis 1965). 
Suckers originating on a single parent root system 
remain connected by parent roots even after they have 
developed their own root system. This connection remains 
alive until one of the trees dies (Maini 1960). Maini 
(1968) observed live root connections between two 65 year 
old aspen trees. 
Aspen is very intolerant of shade and grows best under 
full sunlight (Maini 1968). Maini (1960) found that height 
growth of aspen suckers was initially faster than that of 
seedlings. This is thought to be due to the well developed 
root systems on which suckers originate (Maini 1960, Barnes 
1966). 
21 
ii)Growth and Development: 
Trembling aspen is a small to mecliiun sized tree which, 
under good conditions, will reach 27 to 30 metres in height 
and 30 to 60 cm in diameter (Jarvis 19G8). As aspen trees 
get older defect and decay become more prevalent and, tor 
most aspen stands, the rotation ago is a pathological 
rotation (Jarvis 1968). In eastern Canada and tlie Prairie 
Provinces, the rotation age for trembling aspen varies from 
65 to 80 years (Jarvis 1968) . In Ontario, the optimum 
rotation age for trembling aspen is 53 years (Plonski 1974). 
Volume growth will still increase substantially after this. 
White Spruce-Trembling Aspen Succession 
a nd the Influence of Fire 
The complicated relationships between white spruce and 
trembling aspen have been the subject of much dispute since 
the early twentieth century (Fetherolf 1917, Baker 1918). 
Fetherolf (1917) regarded aspen as a permanent forest type 
that occupies a particular ecological niciie in the 
environment and can be replaced by no other species. Baker 
(1918) more correctly suggested that aspen is a temporary 
forest type occupying a transitory and subclimax stage in 
succession. Barnes (1966) feels that, although the aspen 
22 
community is best classified as temporary in a successional 
sense, the permanent features of aspen clones should not be 
overlooked. The aerial parts of trembling aspen are 
transient, but a given clone can live almost indefinately as 
long as its root system endures and its suckering ability 
does not deteriorate (Barnes 1966). 
Recent work on aspen spruce succession has shown that 
trembling aspen either re-suckers or re-seeds abundantly 
after wildfire. White spruce regenerates less successfully 
than aspen after wildfires. Because of its rapid early 
growth, trembling aspen usually dominates white spruce 
forming a stratified mixture (Day and Harvey 1980a). Highly 
productive monoculture populations are nuiintained near the 
starting point of succession (Dix and Swan 1971). The 
spruce-aspen forest is not static. It exists in a state of 
dynamic change, constantly developing, aging and renewing 
(Rowe 1961). 
Many boreal species are adapted to repetitive 
disturbances of which wildfire is the most important and 
windthrow least. The outcomes from these disturbances 
differ from those in more stable environments (Shafi and 
Yarranton 1973a). In the boreal forest, the evolutionary 
pressure is probably frequent fire re-occurrence. Most 
species are perennial, capable of rapid vegetative 
23 
reproduction and either possess underground reproductive 
organs or adaptations effective in rapid postfire 
establishment (Shafi and Yarranton 1973b). Aspen is a good 
example of a species that, due to rapid asexual reproduction 
has a tremendous capacity to colonize burns (Jarvis 1965). 
White spruce is able to retain a small proportion of 
the annual seed crop in cones which persist for the better 
part of a year (Roe 1946, Rowe 1953b). Unless a fire 
totally destroys the upper part of the tree, these seeds may 
survive and regenerate the area. Fire may also serve as the 
stimulus needed to release this seed still held in the cone 
(Rowe 1953b). This characteristic of white spruce is an 
Adaptation that could help it survive in an ecosystem 
dominated by fire. 
Invariably, the same dominant tree species that were 
present prior to a fire return immediately after the fire. 
This implies that cycling by fire rather than by succession 
is the basic mechanism for renewal in the boreal forest 
(Methven et al 1975). In northeastern Minnisota, Ohman et 
al (1973) found that the time elapsed since the last major 
disturbance, and the type of vegetation present at the time 
of that disturbance, wore importajit in determining the 
composition and the structure of present upland communities. 
When natural catastrophes are prevented, the 
spruce-aspen forest eventually becomes decadent (Rowe 1961). 
Balsam fir (Abies balsamea (L.) Mill.) is a successful 
invader of the Lake States aspen-birch-fir-spruce 
communities (Heinselman 1954, Buell and Niering 1957, 
MacLean 1960). Because of efficient fire suppression 
techniques, the poplar forests of Quetico Provincial Park in 
Ontario are developing into decadent stands and they are 
being invaded by tolerant species such as red maple (Acer 
rubrum L.) and balsam fir (Woods and Day 1977). Effective 
fire suppression in the boreal forest of Sweden over the 
past two centuries has eliminated fire as a rejuvenating 
factor in the forests of that country (Zackresson 1977). 
Rowe and Scotter (1973) suggest that, without fire, the 
forest becomes more and more homogeneous; the long-lived 
white spruce replaces pine, aspen, balsam poplar (Populus 
balsamifera L.) and birch. Results of other studies do not 
agree with this. Day and Harvey (1980a) found that the 
forest becomes less homogeneous as the time since the last 
wildfire increases. On Isle Royale, fir is a very prominent 
species and it is suggested that, in the absence of fire, it 
will maintain a dominate role and white spruce reproduction 
will become scanty (Heinselman 1973). White spruce has 
difficulty reproducing on an undisturbed forest floor 
(MacLean 1960). Observations in the uplands of the lower 
25 
Mackenzie River Valley, N.W.T., suggest that the open spruce 
forest eventually dies out if fire is excluded to be 
replaced by an almost tundra-like condition; white spruce 
seedlings are not able to germinate on the dense lichen mat 
that develops in these areas in the absence of fire (Strang 
1972). 
Conifer roinvasion after a fire depends on site 
characteristics, intensity of the burn, and chance factors 
that determine which species becomes established on the site 
(Severson and Thilenius 1976). Fire may favor white spruce 
regeneration by modifying the seedbed (Wagg 1964). Holt 
(1955) found that fire caused a decrease in litter depth, 
humus depth, root competition and shade by other vegetation; 
it caused an increase in soil moisture supply and soil 
temperature. All of these factors aid in white spruce 
regeneration, but as the texture and depth of the humus 
layer increased, the beneficial effects of burning decreases 
(Holt 1955) . Ackerman (1957) , on the other hand, found that 
the removal of organic matter by burning had an adverse 
effect upon spruce germination and survival. In the Alberta 
foothills, prescribed burning at economic and safe levels 
did not produce) a significant reduction in the organic layor 
or a large increase in the soil temperature on the site 
tested (Endean and Johnstone 1974). 
26 
On burned ground, in an open cut-over stand, the period 
of maximum white spruce germination was delayed at least 1 
1/2 months (Rowe 1952). This is likely a moisture 
deficiency effect. Reeder and Jurgensen (1979) found that 
fire induced water repellency in the forest soils of upper 
Michigan especially those soils with white pine (Pinus 
st robu s L.), red pine (Pinus resinosa Ait.) and trembling 
aspen litter. The nonwettable properties of these soils 
generally decreased rapidly over time (Reeder and Jurgensen 
1979). 
The effect of fire on the vegetative reproduction of 
aspen is complicated. In general, the abundance of aspen 
suckers increases if the area is burned (Maini and Horton 
1966b). Conversely, a very intense burn could kill the 
aspen roots and thus be used as a means of controlling aspen 
suckers. In practise, this is an inefficient method of 
controlling asy^en suckering as it is difficult to maintain 
the intense burning aiid [Persistent smouldering necessary to 
kill the shallow aspen roots that have the potential to 
sucker (Horton and Maini 1964, Horton and Hopkins 1965). 
Schier and Campbell (1978) found that a high burn intensity 
increased the depth at which suckers were initiated, 
possibly because of increased soil temperature and killing 
of the roots near the soil surface. According to Shirley 
(1931 and 1932) light burning stimulates aspen suckering by 
27 
the increased heat absorption of the blackened soil surface. 
A prescribed burn during the first dormant season following 
logging can be used to promote poplar regeneration (Perala 
1974a); two or more prescribed burns in the spring of the 
year before grov^th begins reduce the abundance of suckering 
by aspen and can be used ho eliminate aspen from an area 
(Buckman and Blankenship 1965). 
Post Logging Spruce-Aspen Succession 
Clear felling of trees results in rapid decomposition 
of litter on the forest floor; the surface and topsoil 
layers begin to mineralize and severe erosion may occur on 
steep slopes (Zhukov 1976). According to Wright (1976), 
many of the effects of a clear cut are similar to those of a 
fire except that while only a small fraction of the nutrient 
capital of the forest is lost during a forest fire, logging 
can severely deplete the available nutrient supply. This 
would likely only he true in complete biomass harvesting. 
Traditional harvesting methods leave large amounts of 
residue wood and slash behind. 
Logging often reduces the chances of effective spruce 
regeneration by opening the canopy and allowing prolific 
growth of herbs and shrubs. This increases the competition 
28 
of the forest floor. On the Peace and Slave River lowlands, 
lesser vegetation became more luxuriant with each succeeding 
year following logging; shrubs provided complete coverage 
after five years resulting in unfavorable seedbed conditions 
for spruce regeneration (Wagg 1964). Old trees which would 
have decayed to provide seedbeds are removed during logging 
operations and the ground is scarified only along haul 
trails (Rowe 1955). Surveys showed that, after normal 
logging operations in Manitoba, white spruce regeneration 
was not sufficient to provide for future well-stocked stands 
(Haig 1962). Haig 1962 modified the seed supply by 
clearcutting in strips and by shelterwood cutting; he 
modified the seedbed conditions by site preparing with the 
Athens plough and with a bulldozer blade. Excellent 
regeneration was obtained in these treated areas. 
Holt (1955) found that cutover areas "matured" after 10 
years, when the humus layer suddenly began to stirink away 
and spruce started geminating on the area. Spruce 
regeneration is still very poor on cutover areas however. 
Pogue (1946) found that in Britisli Columbia, white spruce 
restocking will not satisfy the barest minimum requirements 
even 120 years after cutting. 
29 
After a cutover, aspen s[)roiits prolilically (MacLean 
1960). Vegetative reproduction of aspen is most vigorous 
the first year following clearcut (Horton and Maini 1964). 
Some studies show that a greater number of suckers are 
produced if logging is done during the dormant season 
(Stoeckler and Macon 1956). In other experiments, more 
suckers were produced after summer logging (Maini and Horton 
1966b, Bella and DeFranceschi 1972), Regardless of cutting 
season, initial differences in numbers of suckers diminsh 
with age and practically disappear by six years of age 
(Bella and DeFranceschi 1972). Suckering is generally poor 
on areas where dense ground vegetation or slash exist at the 
time of cutting (Maini and Horton 1966a and 1966b, Bella and 
DeFranceschi 1972). Complete cleacutting appears to produce 
the most abundant sprout regeneration of aspen (Stoeckler 
and Macon 1956, Schier and Smith 1979). 
Silviculture in Post-Logged White Spruce-Aspen Forests 
i)White Spruce Plantations - Their Establishment and 
Performance: 
The survival and later growth of young white spruce 
plantations is best on areas that have received some form of 
site preparation treatment. Stiell (1958) suggested that 
30 
white spruce should be planted in furrows. He found that 
white spruce seedling survival was best when the trees were 
planted in open ploughed furrows, possibly because of the 
removal of ground competition and better soi1-moisture 
relationships (Stiell 1955). Waldron (1964) found that 
white spruce transplants suffered the highest mortality on 
undisturbed plots and tlie lowest on scalped plots. This 
reflected the intensity of vegetative competition on the 
plots. The undisturbed plots had the greatest vegetative 
competition and the scalped plots the least. Ten years 
after planting, white spruce transplant survival remained 
highest on the scalped plots (Waldron 1964). Dobbs (1976) 
found that both white spruce seedlings and transplants grew 
better on scarified plots than on unscarified plots. Mullin 
(1973) found that post-planting cultivation during the first 
and second year after planting of old field white spruce 
plantations more than doubled the survival rate over that of 
the control plantations which had been cultivated only once 
prior to planting. 
Generally, large white spruce nursery stock tend to 
survive and grow better than small white spruce nursery 
stock (Dobbs 1976). Brace (1964) found that white spruce 
nursery stock greater than 15 cm in height grew better than 
white spruce nursery stock less than 15 cm in height.In 
contrast, Waldron (1964) found that 2+3 white spruce nursery 
31 
stock had greater mortality during the first year after 
planting than 2^2 white spruce nursery stock on plots which 
had been disced and scalped. Possibly the removal of the 
protective plant cover from around these large transplants 
resulted in increased evapotranspiration stress. The 
smaller transplants were better able to withstand this 
stress (Waldron 1964). 
White spruce transplants tend to have higher survival 
and better growth rates than white spruce seedlings (Mullin 
1966)., Mullin (1975) found that, 5 years after planting, 
2+2 white spruce transplants were growing well while 2+0 white 
spruce seedlings were still growing poorly. Seedlings at the 
2+0 staeje are less efficient than transplants in overcoming 
competing herbacious vegetation (Stiell 1955). Hall (1979) 
found that white spruce seedlings which were grown for 1 or 
2 seasons in transplant beds grew better than those which 
grew only in seedbeds and these larger seedlings maintained 
their height advantage over the small ones in the plantation 
5 years after planting. 
When Dobbs (1976) compared different sizes of white 
spruce nursery stock grown on scarified and unscarified 
plots, he found that large stock on untreated plots 
outperformed small stock on treated pi ots. This could 
possibly indicate a potential "trade-off" in certain 
32 
situations between nursery stock size and site preparation. 
The method of planting tends to have a varying 
influence on the growth and development of white spruce 
plantations. Brace (1964) experimented with 3 planting 
methods. In the first two methods the seedling roots were 
placed in a horizontal plane close to the soil surface. The 
third method was the conventional wedge method that places 
the roots vertically. After 9 growing seasons, there were 
no significant differences in the survival and growth of 
white spruce due to planting method (Brace 1964). Mullin 
(1966) experimented with the wedge, slit, cone and T methods 
of planting. He found that the T method resulted in the 
lowest survival. The cone method showed no benefit in terms 
of survival or growth and he suggested that it be disgarded 
because of its greater cost. Of the two more standard 
methods, the wedge gave higher survival rates and better 
growth than the slit method (Mullin 1966b). He found that 
competition of other plant species on the site had much more 
influence than planting method on the growth of the 
plantation. 
Improper planting with any method can result in a great 
deal of mortality in young white spruce plantations. Lyons 
(1925) suggested that a tree that is improperly planted is 
started into its plantation life seriously handicapped. 
33 
Stiell (1958) found that poor planting was a major problem 
in many plantations. Seedling mortality during the first 
fev; years can often be attributed to poor planting (Stiell 
1955). Hughes (1978) found that mortality in white spruce 
plantations during the first year after planting could be 
mainly attributed to poor quality seedlings and planting 
methods. 
The greatest mortality of white spruce plantations 
occurs during the first 4 years after planting (Stiell 
1958). One of the most important reasons for this early 
mortality is vegetative competition. Stiell (1955 and 1958) 
found that dense grass, young aspen and birch suckers and 
sprouts from intolerant hardwoods resulted in considerable 
young white spruce mortality. Mullin (1969), in a 
greenhouse trial, found that competition from black spruce, 
grass and hard maple reduced the growth of white spruce at 
al] levels of moisture tested. Stiell (1958) found that 
while dense grass, herbacious vegetation and scattered brush 
may cause initial seedling mortality, if the seedlings 
survive later grovv^th is not reduced. White spruce growth is 
reduced when seedlings are planted under full overhead cover 
such as tall bracken fern, dense brush, suckers or a closed 
hardwood canopy (Stiell 1958). Early invasion by hardwoods 
did not decrease height growth, but did decrease diameter 
growth (Stiell 1958). Cunningham (1953) found that white 
34 
spruce plantations at Grand "Mere" Quebec planted between 
1924 and 1932 were unable to compete with volunteer red 
maple, balsam fir, white birch and aspen. He felt that 
these stands were no longer valuable as a pulpwood crop 
(Cunningham 1953), Stiell (1958) suggested that cover which 
provides side shade to white spruce but does not check 
height growth may have an early protective value on exposed 
sites. 
White spruce mortality in older plantations can result 
from mutual competition. Stiell (1955) feels that this is 
usually not important until the plantation is 30 years of 
age or older. Mortality from mutual competition is a factor 
of stocking level and height (Stiell 1976). Mortality will 
begin in a plantation established at 1.2 x 1.2 m spacing 
before the stand is 6 m. tall, but not until the height is 
12 m. if the initial spacing is 2.4 x 2.4 m, (Stiell 
1976). Subordinant white spruce trees are tolerant however, 
and they can survive long after the crown has closed in over 
them (Stiell 1955). 
Another important reason for early white spruce 
plantation mortality is poor soil and moisture conditions 
(Stiell 1958). Stiell (1958) found that white spruce plantations 
usually take twice as long to reach merchantable size on coarse 
shallow soils than on soils with adequate moisture. White 
35 
spruce plantations grow best on moist tills of loamy sand 
and sandy loam, moist lacustrine silt loams with silt and 
clay bands, fresh interbanded windblown and waterlain sandy 
loam and fine sand (Stiell 1955). Fresh and moist sites 
were generally most favourable to white spruce, but tiie 
more moist the site the greater the tendency for suppression 
and mortality from invading alders and iiardwoods before the 
spruce was well established (Stiell 1955). In a greenhouse 
study, Mullin (1969) found that the best growth of white 
spruce was achieved at the highest moisture level, in which 
the pots were cyclically raised to a drip-point twice weekly 
and permitted to dry by evapotranspiration between water 
additions. Gagnon (1961) found that, in a 31 year old 
plantation, mean annual ring width was closely related to 
the mean monthly precipitation during June, July and August 
of the proceeding year. This relationship was evident for 
the past 18 years (Gagnon 1961). 
Mortality in young white spuce plantations can also 
result from drought, frost heaving, exposure, late season 
planting with active stock or planting with poor or 
overgrown stock and browse by wild animals (Stiell 1958). 
Frost damage can cause a reduction in growtli rate especially 
in depressions and on level ground between slopes (Stiell 
1955). This damage ceases with full crown closure of the 
stand (Stiell 1955). 
36 
Initial growth of young white spruce plantations is 
very variable (Stiell 1958). Perhaps this is due to the 
varying capacity of growth of individuals in an average lot 
of stock (Stiell 1955). Generally, white spruce plantations 
grow very slowly during the first few years after planting. 
Seedlings often take several years after planting to assume 
a rapid or even a: reasonable rate of height growth (Stiell 
1976). This early period of minimal height growth, if 
prolonged, is often described as growth check. Mullin 
(1964) found that growth check reduced the leader length of 
white spruce by about 50% the first year after outplanting. 
He suggested that growth check is mainly due to competition 
from other species on the site (Mullin 1966b). 
Stiell and Berry (1973) found that the time required 
for planted white spruce trees to reacli breast height varied 
from 6 to 12 years in white spruce plantations at the 
Petawawa Forest Experiment Station. This was independant of 
site. As it is difficult to predict early growth rates, 
site index curves for planted white spruce cannot be 
reliably extended below about 15 years (Stiell 1976). 
Hambley (1980) found that current annual height increment 
for planted white spruce in northern Ontario leveled off at 
age 15 years to an average of 32 cm/year. Height growth 
starts to decline between 25 and 35 years (Stiell 1976). At 
fhe Petawawa Forest Experiment Station, white spruce 
37 
plantations, dominant height growth between 45 to 50 years 
was still about 30 cm/year on the best sites (Stiell and 
Berry 1973). 
ii) Stand Conversion: 
The effect of site quality may be important in the 
development of defects in second growth aspen stands 
(Kemperman et al 1976). When aspen is growing on poor 
sites, conversion to other species is the only sound and 
economical long term approach (Bissinger 1965). Stoeckler 
(1948) suggests that conversion planting should be 
concentrated on the coarser textured soils which do not 
reproduce as rapidly or easily to more valuable species. 
A shelterwood system is superior to a seed tree system 
in the mixedwood forest for securing white spruce 
regeneration after logging, Lees (1970) found that 
scarification under a spruce-aspen shelterwood provided a 
receptive seedbed and the residual stand provided an 
adequate natural seed supply for white spruce regeneration . 
By removing 30% of the commercial basal area in a uniform 
shlterwood felling. Day (1970) found that both the abundance 
and growth of spruce seedlings and fir were significantly 
increased. A shelterwood system provides abundant seed and 
adequate environments for white spruce germination and 
38 
growth that are not subject to excessive heating and drying. 
Waldron (1961) found that seeding white spruce in 
scalps at the base of aspen resulted in higher germination 
than seeding white spruce in either the humus layer or in 
moss and in higher survival than seeding in scalps between 
the aspen trees. He suggests that planting 2+0 nursery 
stock in scalps at the base of aspen might be a useful 
method of introducing white spruce into aspen stands. The 
cost would be less than that of planting between the aspen 
with larger stock and seedling mortality resulting from 
burial by leaf litter would be less than that if the scalps 
were seeded. 
iii)Mechanical Release of White Spruce from Aspen 
Competition: 
As aspen grows much more rapidly than white spruce, 
young suckers may quickly overtop white spruce seedlings of 
the same age. The aspen overstory has a very detrimental 
effect on the growth and productivity of the white spruce 
beneath (Lees 1970). In todays market, white spruce is a 
more valuable species than trembling aspen therefore 
silvicultural practices are usually aimed at encouraging 
white spruce reproduction and growth. 
39 
White spruce will respond to release at advanced 
stages, but most benefit will be realized early in life 
(Stenecker 1963). Lees (1966) found that the greatest 
response to release occurred in tlie 20 to 40 year age class. 
Thompson (1949) found that 20 to 30 year old white spruce 
and balsam fir showed considerably more diameter growth when 
released from competing white birch, red maple (Acer rubrum 
L.), and yellow birch (Betula alleghaniensis Britton). When 
overtopping hardwoods were removed from a 45 year old 
mixedwood stand, Daly (1950) found that diameter and volume 
growth of the conifers was stimulated. White spruce in the 
70 to 80 year age class is too old to significantly respond 
to release (Stenecker 1974b). The recuperative powers of 
young spruce are usually not affected by competition from 
aspen and, given an opportunity, spruce will respond 
favorably to release (Ontkean and Smithers 1959). Johnstone 
(1978) found that the first 5 years after logging, residual 
white spruce trees experienced a delayed release in volume 
and diameter increment and a decline in height increment. 
This indicates that the trees are unable to benefit from the 
decreased competition until their crowns have expanded 
(Johnstone 1978). 
Various methods have been used to reduce aspen 
competition in white spruce-trembling aspen stands. Plice 
and Hedden (1931) found girdling to be quite effective in 
40 
releasing spruce from an overstory of aspen and other 
hardv^oods, Clarke (1940) recorded rapid increases in 
conifer diameter growth after hardwoods in the stand were 
girdled. Girdling appears to be a good method of 
eliminating aspen competition from a site (Schier and Smith 
1979). 
Buckman and Blankenship (1965) suggest that prescribed 
burns, prior to planting or seeding white spruce, can be 
used to remove aspen competition. Kill (1970) found that 
while a spring prescribed burn did initially remove the 
aspen and other hardwoods in a spruce-aspen stand, vigorous 
sucker growth and abundant herbaceous vegetation in the 
following years created an unfavorable seedbed for the 
establishment of spruce seedlings. Perala (1974b) found 
that infrequent burning weather, low flammability of aspen, 
and prolific aspen suckering made prescribed burning a poor 
tool to convert a good aspen site to conifers. 
Problems do exist with these various mechanical release 
treatments and prescribed burning. Mechanical release 
treatments are often too expensive to apply in Canada and 
they do not last very long because the aspen will rapidly 
re-sucker. Prescribed burning requires a great deal of 
expertise and serious accidents can occur if proper 
precautions are not taken. 
41 
iv) Chemical Release of White Spruce from Aspen Competition: 
Herbicides have been used in an attempt to release 
white spruce from trembling aspen in spruce-aspen stands. 
Herbicide treatments tend to be quite effective. Tiiey are 
often much faster, have longer lasting results and are more 
efficient than mechanical release treatments (Roe 1953). 
Chemical control of undesirable forest vegetation is 
often regarded as a fairly recent post-war tool, but 
herbicides have been used since the late 1920's to control 
woody plants in tlie Lake States. Sodium arsenite, other 
arr.enicals, sodium chlorate, ammonium thiocyanate and 27% 
diesal oils are some of the older herbicides that proved to 
be reasonably effective (Rudolf and Watt 195G). These 
materials were either expensive in the quantities needed, or 
hazardous to use (Roe 1953, Rudolph and Watt 1956). 
Since World War II, many new herbicides have been 
developed. Low volatile formulations of the phenoxy acids 
were, until recently, the principal herbicides used in 
forestry (Romancier 1965, Haagsma 1968). These herbicides 
are effective in many, hut not all, forestry situations. 
Light foliar applications of 2,4-D and 2,4,5-T ester sprays 
will damage the new growth of most conifers (Arend 1965). The 
herbicide 2,4,5-T is effective against a much broader spectrum of 
species than 2,4-D (Sutton 1969). Aerial spraying of 2,4-D 
42 
has been found to be quite effective in killing overmature 
trembling aspen (Pratt 1966), but 2,4,5-T is generally more 
toxic to this species (Roe 1953). MCPA is another 
phenoxy herbicide; it is more effective than 2,4,5-T on 
some species and less effective on others (Roe 1953). Since 
1980, 2,4,5-T has not been licensed for use in forestry in 
Canada. Controversy over the environmental effects of the 
phenoxy herbicides may also result in the removal of 2,4-D 
for forestry use. 
Dinitro herbicides have been used for brush control 
(Roe 1953). These herbicides kill leaves quickly, but their 
action is less residual than that of the phenoxy herbicides 
and their use is followed by considerable resprouting (Roe 
1953). The dinitro herbicides have a high mammalian 
toxicity, leave a permanent stain on clothing and skin, and 
are inflammable under certain conditions (Roe 1953). 
Quaite (1953) used ammonium sulfamate to eliminate 
aspen. This chemical is non selective and will kill 
desirable species as well as undesirable species (Roe 1953). 
It is also costly to use due to the large amounts that are 
needed to produce the desired results (Roe 1953). Ammonium 
sulphamate is highly corrosive with hygroscopic crystals 
(Weed Science Society of America 1979) . This makes both 
storage and handling of the chemical extremely difficult. 
43 
Site preparation with paraquat and simazine resulted in 
continuing significant increases in height growth for 
planted white spruce three years after initial weed control 
treatments (Sutton 1975 a and b). Weed control 
significantly conserved soil moisture and gave highly 
significant increases in foliage nutrient concentrations 
(Sutton 1975 a and b). The fertility effect, rather than 
soil moisture conservation, was the principal cause for 
increases in white spruce height incement. 
Results of studies during the 1960*s with 
pelleted fenuron were very promising for the 
control of woody plants. Sutton (1965a) found that fenuron 
could be used to rehabilitate overmature mixedwood by 
underplanting groups of white spruce in herbicide treated 
plots. After a 10 year interval, it may be necessary to 
again release these trees from competition (Sutton 1974). 
Fenuron was safely applied at planting time to vegetation 
competing with white spruce (Sutton 1965b). Fenuron was also 
used non-selectively in a grid pattern to control both 
conifers and hardwoods; it could be applied selectively 
to release conifers from hardwood competition (Sutton 1967). 
Work with fenuron was discontinued in the late 1960*s when 
the herbicide was no longer available from the Dupont 
Chemical Company. 
44 
Mathews (1970) worked with bromacil and karbutilate 
as possible substitutes for fenuron. These herbicides were 
all quite toxic to both white and black spruce seedlings and 
were not acceptable replacements for fenuron. 
Glyphosate is a new herbicide that shows some potential 
for use in forestry. Noste and Phipps (1978) found that 
white spruce seedling survival and diameter were greater on 
plots treated with glyphosate to reduce competition. The 
results of Blackmore and Corns (1979) do not concur with 
this. They found that white spruce growth was depressed 
in glyphosate treated strips. Polhill (1978) found that 
glyphosate applied at 3.3 kg ai/ha caused minor damage to 
approximately 25% of the white spruce shoots the year following 
herbicide application. Sutton (1978) found that glyphosate 
was highly;^ effective in killing trembling aspen, white birch 
and beaked hazel; pin cherry (Prunus pensyIvanica L. f.) 
resprouted with moderate vigor. Mean second year white spruce 
height increment was greater in the glyphosate than in the 
non-herbicide treated plots (Sutton 1978). 
45 
The use of Hexazinone Herbicide in Forestry 
During the ]970’s, none of the herbicides available for 
forestry closely approxLmateci the effectiveness of fenuron. 
This factor and controversy about the environmental effects 
of the phenoxy acetic acids in forestry have stimulated 
interest in research on new herbicides. 
Hexazione is a new triazine iierbicide. Although its 
mode of action is not clearly understood, it is thought to 
be a photosynthetic inhibitor that affects the dark release 
of oxygen (Weed Science Society of America 1979). 
Hexazinone can be applied as a foliar spray, in concentrated 
solution with a *spotton-gun* or in pelleted formulation. 
Much research about hexazinone has taken place in New 
Zealand in Pinus r a d i a t a D. Don plantations (Bowers and 
Porter 197S and 1977, Coackly and Moor 1977). Hadiata pine 
is tolerant to hexazinone applied as foliage spray, up to 
rates of 7.2 kg ai/ha, but this tolerance decreases during 
the period of maximum spring flush (Bowers and Porter 1975 
and 1977). The best control of grasses, bracken, wattle and 
broom is obtained when hexazinone is applied as a foliage 
spray during the period of active weed growth (Coackly and 
Moor 1977). 
Hexazinone has been used in the loblolly pine 
plantations of the southern states (South et al 1976, 
0*Laugh]in et al 1976, Nelson et al 1977, Fitzgerald and 
46 
Fortson 1977, Turner 1979, Parker 1979, Newbold 1979, 
Hamilton 1979, Dudley and Nelson 1979). Hexazinone applied 
as a post emergent foliar spray has been found to be toxic to 
young loblolly pine at rates as low as 0.56 kg ai/ha (South 
et al 1976). Nelson et al (1977) found th^^t iiexazinone 
applied as a pre-emergent herbicide treatment at rates of 
0.56 kg ai/ha and 1.12 kg ai/ha provided adequate weed 
control without damaging young loblolly pine seedlings. 
O'Laughlin et at (1976) found that hexazinone was highly 
effective as a foliar treatment, but that dosages should not 
exceed 1.12 to 2.24 kg ai/ha. These discrepancies between 
suitable herbicide application rates are likely due to 
variation in site conditions. Herbicide applications should 
be made during the late summer otherwise considerable pine 
mortality will occur (0*Laughlin et al 1976). Activated 
charcoal root coatings of pine seedlings will absorb 
hexazinone and reduce pine phytotoxicity (Fitzgerald and 
Fortson 1979) . 
In North Carolina, aerial applications of hexazi no rie at 
rates from 1.1 to 3.4 kg ai/ha resulted in good to moderate 
weed control on 307 out of 355 hectares (Dudley and Nelson 
1979) . 
47 
Hexazinone can be selectively applied with pellet 
formulations to avoid crop species and control the competing 
species. Hexazinone as 10% active ingredient pellets applied 
in a circtilar b>and 1 uietrc away Irom tiic bole ol red 
(Que reus falcate Michx.) and post (Quercus stellate 
Wangenh.) oaks at a rate of 0.42 g.ai./2.5 cm. diameter 
resulted in 89% defoliation 18 v;eeks after treatment. When 
hexazinone pellets were placed approximately 1 laetre away 
from loblolly pine seedlings, no phylotoxicity was observed 
(Parker 1979). Hamilton (1979) found that, on sandy soils 
hexazinone "Gridballs" applied at rates of 9.G to 11,2 
kg.ai./ha provided adequate control to susceptible species; 
on heavy clays and poorly drained soils, 22.4 kg ai/ iia 
provided adequate control. Invariably, dead pines were 
affected by a "Gridball" which fell within 0.31 metres of 
the pine's root collar (Hamilton 1979). According to Turner 
(1979), 6.0 to 22.4 kg.ai/ha hexazinone "Gridball" 
formulation will provide satisfactory control of most 
hardwoods for both site preparation and pine release. Spot 
treatment of hexazinone followed by a prescribed burn can be 
used for site preparation, and hexazinone also effectively 
kills weeds in southern [’inc stands (dc-v^^bold 19 79). 
In northern England and Scotland, weed control with 
hexazinone applied as a foliage spray in April and May 
resulted in better height increment in spruce and pine tlian 
48 
hexazinone applied at other times of the year (Jones 1978). 
This suggests that competition should be removed before the 
conifers flush (Jones et al. 1980). March and May 
applications of hexazinone at rates of 1.5 to 1.8 kg ai/ha 
provide better control of both grasses and broadleaved weeds 
than August applications (Jones et al 1980). Spruce should 
not be treated with the herbicide until the new growth has 
hardened off (Jones 1978), but pines are tolerant to 
hexazinone rates of 3.6 kh ai/ha applied during the flushing 
period (Jones et al 1980). As hexazinone is little affected 
by high soil organic matter, it could be useful on sites of 
second cropping where there is a lot of surface litter 
(Jones 1978, Jones et al 1980). 
In Arkansas, hexazinone was found to control hickories 
(Carya spp.) and white oak (Quercus alba L.) very effectively 
when it was applied as an injection (Kossuth et. al. 1978). 
Mature red pine (Pinus resinosa Ait.) is quire tolerant 
to hexazinone, but the tolerance range on newly planted 
seedlings is small (Wiltrout and Holt 1978). 
Studies using hexazinone herbicide for woody brush 
control and to control competion with white spruce were 
initiated in the boreal forest in 1978 and 1979 
(Polhill 1978, Dunsford 1979). Hexazinone applied 
49 
at rates of 1,2 and 2.4 kg ai/ha, is an effective herbicide 
for controlling aspen on recent cutovers that have 
regenerated to aspen brush, and in stands where aspen is 
providing competion to white spruce regeneration (Dunsford 
1979). Hexazinone pellets, if placed in proper 
configiration to avoid white spruce roots, could be very 
effective in controlling competition in spruce plantations 
(Polhill 1978). 
50 
SECTION I 
THE POST LOGGING SUCCESSIONAL 
BEHAVIOUR OF PLANTED WHITE SPRUCE IN 
SUCKER ORIGIN TREMBLING ASPEN STANDS. 
In order to properly manage forest stands, it is 
important to understand the dynamic relationships that exist 
between the crop trees and their competitors. This section 
provides an investigation on post logging succession in two 
young white spruce plantations of different age classes. 
Methods 
i. Study Areas; 
White spruce plantations of two age classes, young 
sapling (5 years), and young pole (13 years) with heavy 
aspen competition were chosen for study. These plantations 
are located north of Thunder Bay in the B9 or Superior 
Section of the Boreal Forest Region (Rowe 1972) and in Site 
Region 3W (Hills 1961). 
Plantation 1 is located approximately 65 kilometres 
north of Thunder Bay on Highway 800 close to the junction of 
the Wolf River Rd . at 49°45* N lat. and 89^00* W long 
51 
(Appendix (App.) A, Figure Al). The area was cut over in 
1966. It was site prepared with a light prescribed burn and 
planted to white spruce in 1967. The area has since become 
infested with brush and weed trees, primarily aspen, which 
are competing with the white spruce crop. Many of the white 
spruce are suffering from severe frost damage. The site is 
gently rolling and is a very shallow sandy loam till over 
bedrock, typical of the ground moraine deposits in the 
region (Zoltai 1965). The hillocks are probably drought 
prone in dry growing seasons. Sphagnum spp. growing from 
overmoist depressions in the bedrock will trap and hold 
moisture in the hollows during wet seasons. 
Plantation 2 is located approximately 25 kilometres 
from the junction of Highway 800 along the Wolf River Rd., 
, 0 0 
close to Anders Lake at 49 00* N lat. and 89 15* W long 
(App. A, Figure A2). The area was cut over during the 
winters of 1972, 1973, and 1974. It was site prepared with 
barrels and planted to white spruce in 1975. The area has 
since become heavily infested with brush and weed trees, 
primarily aspen, which are competing with the white spruce 
crop. Some of the white spruce are suffering from frost 
damage. The site is a shallow sandy loam till over bedrock 
that is well aerated and is dry to fresh all year. 
52 
ii. Stand Description Plots: 
In both plantations, fifty square plots were randomly 
located. The size of the plot was varied depending on the 
size of the trees as described on page 55 under 'Situation 
Plots*. Larger trees exert a competitive influence over a 
larger area than smaller trees. In Plantation 1, the plot 
size chosen was 8m x 8m (area = 64m^). In Plantation 2, the 
plot size chosen was 3m x 3m (area = 9m^). This would 
compensate for the reduced number of large aspen stems per 
hectare in the older plantation. 
A modification of the Christian and Perry (1953) type 
classification (Day 1968) was used to describe the 
vegetation on each plot. The vegetation was classified 
as follows. 
1. It was divided into three layers, T, S and F where T= 
Tree Layer, S=Shrub Layer and F=Field Layer. For example, 
would mean a Tree Layer averaging 6 metres in height. 
2. The percentage area covered by the foliage of each layer 
0 5 
was estimated and recorded. For example, S ' 20 indicates 
a Shrub Layer of 0.5 metres in height that has a foliage 
surface covering of 20% of the area. 
53 
3. The standard tree symbols developed by Day (1967) 
were used to describe the 2 major species present 
in the Tree and Field Layers and the 3 major species 
present in the Shrub Layer. For example, T 15 10 indicates 
POt 
a Tree Layer composed of 15 metre aspen that has a 
foliage surface covering 10% of the area. 
This information was used to construct diagrams of the 
plantations to schematically depict conditions on plots with 
high, medium and low tree density. 
On each plot the following list of measurements were 
taken of the aspen and the white spruce. 
1. Diameter: The diameter above butt swell (5% of 
the total height up to 4 metres) was measured. 
The trees were tallied according to 1 cm diameter 
classes . 
2. Height: The heights of 3 randomly selected trees 
of each 1 cm diameter class were measured. 
3. Density and Frequency 
54 
The diameters of 5 randomly selected aspen and white 
spruce trees from both plantations were measured at 1 
metre intervals up each tree. In Plantation 1, which ranged 
from 0 to 14 cm. in diameter, a 1 cm. diameter class was 
used. In Plantation 2, which ranged from 0 to 4 cm. in 
diameter, a 0.25 cm. diameter class was used. These values 
were used to calculate the volume of each tree using 
Smalian's formula (Husch et al. 1972). This information 
was used to construct regressions that related diameter 
above butt swell to volume for the aspen and spruce in both 
plantations (App. B, Figures B1, B2, B3, and B4). The 
volume/diameter data vrere fitted using transformed and 
corrected (Baskerville 1972) regressions of the form Y=aX^. 
The total and mean volumes of aspen and white spruce on each 
plot were calculated using these regression equations. 
The cruise data were compiled and aspen density per plot 
frequency distributions were plotted. These distributions 
were used to stratify the plots into three Situation Types; 
close, medium and wide spacing according to their aspen 
density (Table 1). 
55 
Table 1. The Three Situation Types Defined At 
Plantations 1 And 2. 
SITUATION SPACING # OF ASPEN TREES / PLOT 
I Wide 0-9 
II Med i um 10-19 
III Close >20 (max. 40) 
This information was used to construct graphs relating 
the total volume of spruce per plot to the total volume of 
aspen per plot, the mean volume of spruce per plot to the 
mean volume of aspen per plot, and the mean volume of spruce 
per plot to the total volume of aspen per plot for each 
Situation Type. 
iii) Situation Plots: 
The term 'Situation* is used to describe the 
interrelationships between a planted white spruce tree and 
the aspen that surrounds it. For example, a short 
suppressed white spruce surrounded by tall dense aspen would 
be in a very different situation from a similar aged medium 
height intermediate spruce surrounded by tall sparse aspen. 
In each plantation, randomly selected 'Situations' were 
evaluated and stratified into the same three classes 
described in Table 1. 
56 
Each Situation Plot was circular with a white spruce 
located at the centre. The average ratio of the height of 
the white spruce to the plot diameter was 1:3. Therefore, 
2 
the situation plot diameter was 9m (area =63.62 m ) on 
Pl, antati.on 1, and 3ra (area = 7.07m2  ) on Plantation 2. The 
area of the circular Situation Plots was similar to that of 
the square plots used for the Stand Description. Five of 
each of the 3 Situation Types were measured on both 
plantations. 
In each Situation Plot, the following measurements were 
taken. 
1. Height: The total heights of all aspen and white 
spruce trees were measured. 
2. Diameter: The diameters above butt swell (5% of 
the height up to 4 metres) of all aspen and white 
spruce trees were measured. 
3. Frost Damaged Tips: The number of frost damaged 
tips on the central white spruce was estimated. 
4. Crown Height: The crown height of the central 
white spruce tree was measured. 
57 
5. Crown Width: The crown width of the central white 
spruce tree was measured. 
An aspen tree close to the mean diameter of each plot 
and the white spruce located at each plot centre were cut 
down for destructive sampling. The bole of each tree was 
sectioned into 0.25 m lengths and 2 cm thick disc samples 
were taken and frozen for later stem analysis. 
The crown areas of the central white spruce trees were 
estimated using Equation 1. This equation calculates the 
area of a curved surface of a cone. The number of white 
spruce frost damaged tips per m^ crown area on the central 
white spruce trees were calculated and plotted against the 
number of aspen trees on each Situation Plot. This 
information was used to construct regressions relating the 
2 
number of white spruce frost damaged tips per m crown area 
to the aspen density per Situation Plot. 
Equation 1 A=2/3'rrrh 
A=crown area 
r=crown radius 
h=crown height 
58 
iv) Stem Analysis 
The geometric mean radius of each disc was established. 
The geometric rather than the arithmetic mean radius was 
used as the geometric mean radius is the true mean radius of 
a ellipse (Equation 2) 
Equation 2 R=(d| xd2 ) / 2 
R=geometric mean radius 
d-j=largest diameter 
d2=perpendicular bisector of the largest 
diameter 
The ring widths along 2 mean radii for each disc were 
measured with a calibrated hand lens. The geometric mean 
ring width was calculated for each year along these two 
radii. These values were used for analysis. 
Mean periodic sheath volume increments were calculated 
for the aspen and the spruce using Smalfan's formula. This 
information was used to construct growth curves for each 
tree. 
59 
Results 
The results from the two plantations are presented 
individually. 
Plantation 1: 
The results of the Christian and Perry (1953) type 
classification for plots with high, medium and low tree 
densities are shown in Figure 2. Per cent cover does not 
add up to 100% on plots where there was a lot of bare ground 
or rdtting wood. 
The total white spruce volume per plot/total aspen 
volume per plot is obviously not well related (Figure 3). 
Regression equations were not computed. The mean white 
spruce volume per plot/mean aspen volume per plot (Figure 
4), and the mean white spruce volume per plot/total aspen 
volume per plot (Figure 5) are also not well related. Thus, 
the volume of aspen per plot does not seem to affect the 
volume of white spruce. 
There is also no relationship between the Situation 
Types (shown by dot shape in Figures 3, 4 and 5) and the 
volume of white spruce. The white spruce crop trees were 
found to have the same range of volumes in all Situations 
60 
High Tree Density 
(J>=P tremulo idee7=Ledum groenlandicum , 
A-Picea ^ lauca gp^ sp. , 
^=Sphagnum sp., 
Grass 
Figure 2. Schematic description of plots with high, 
medium and low tree density at Plantation 1 . 
Height (m) Height' (m) Height (m) 
61 
Figure 3, Total volume of spruce per plot vrs. total 
volume of aspen per plot at Plantation 1. 
•^Situation I 
«s=Situation II 
■“Situation III 
Figure 4. Mean volume of spruce per plot vrs. mean 
volume of aspen per plot at Plantation i • 
62 
Fi^re 5. Mean volume of spruce per plot vrs. total 
volume of aspen per plot at Plantation 1. 
Mean Volume Spruce (dm ) 
63 
regardless of the spacing or volume of the competing aspen. 
As the number of aspen trees per plot increases, the 
2 
number of white spruce frost damaged tips per m crown area 
on the centrally located white spruce from each circular 
Situation Plot decreases (Figure 6). Situation Types II and 
III (shown by dot shape in Figure 6) with close and medium 
aspen spacing had lower numbers of white spruce frost 
2 
damaged tips per m crown area the than Situation Type I 
with wide aspen spacing. The regression of number of white 
2 
spruce frost damaged tips per m crown area (Y) plotted 
against the number of aspen trees per plot (X) was not 
significant (App. D, Table Dl). The best fitting 
regression is given in Equation 3 and Figure 6. 
Equation 3. Y=10.13+21.09/X 
R^=0.25 
Figures 7, 8, 9, 10, 11, and 12 show the volume growth 
curves calculated from stem analysis for the aspen and white 
spruce from the circular Situation Plots. 
There is a slight trend for white spruce in Situation 
Type I plots (0-9 aspen trees per plot) to put on more 
volume growth per year than the white spruce on Situation 
• L' i tiia t ion ’ 
X i tua t i or:i 
■ =L)ltual!on 1 
Pia;ure 6. White spruce frost dama^’;ed tips per unit 
crown area vrs. number of aspen trees per 
plot at Plantation 1 
Snruce Frost Damaged Tips/m Crov/n Area 
65 
Year 
Figure 7 Figure 8 Plantation 1 - The growth curves for white Plantation 1 - The growth curves for aspen 
spruce on Situation Type I plots. on Situation Type I plots. 
Year 
Figure 9 Plantation i The gwwth curves for white Figure 10. Plantation 1 - The growth curves for aspen 
spruce on Situation Type II plots. on Situation Type II plots. 
Year Year 
Figure 11. Plantation 1 - The growth curves for white Figure 18. Plantation 1 - The growth curves for aspen 
Spruce on Situation Type III plots. on Situation Type III plots. 
66 
Type III Plots (> 20 aspen trees per plot), but there is 
much overlap between the growth curves from these two 
Situation Types (Figures 7 and 11). There is also a trend 
for some of the widely spaced aspen on Situation Type I 
Plots to grow better than the closely spaced aspen on 
Situation Type III Plots, but again there is overlap between 
the growth curves from these two Situation Types (Figures 8 
and 12). Both the aspen and the white spruce on Situation 
Type II Plots (10 - 19 aspen trees per plot) grew much the 
same as the aspen and the white spruce on the Situation Type 
III Plots (Figures 9 and 10). 
When the volume growth of the white spruce is compared 
to the volume growth of the aspen for the paired aspen and 
spruce on each Situation Type, a few trends appear. 
The white spruce sampled on Situation Type I, 
Replication 4 was the fastest growing white spruce. It was 
not paired with an aspen as there were no aspen trees on 
that plot. The second fastest growing white spruce was in 
Replication 2. It was paired with a very slow growing mean 
aspen tree (Figures 7 and 8). Similarly, Replications 5 and 
1 had the two slowest growing white spruce trees. These 
were paired with the two fastest growing aspen trees 
(Figures 7 and 8). 
67 
The trends between volume growth of aspen and volume 
growth of white spruce were not as clear for Situation Type 
II ( 10 - 19 aspen trees per plot). Again though, the two 
fastest growing aspen coincided with two of the slower 
growing white spruce (Figures 9 and 10). The two slowest 
growing aspen were paired with the two fastest growing 
spruce (Figures 9 and 10). The aspen and white spruce on 
Replication 3 grew intermediately when compared to the other 
trees (Figures 9 and 10). 
The results are even more erratic for Situation Type 
III (> 20 aspen trees per plot) but they still follow the 
same general pattern. The fastest growing aspen on 
Replication 5 coincides with one of the slower growing white 
spruce. (Figures 11 and 12). One of the slower growing 
aspen on Replication 3 coincides with the fastest growing 
white spruce (Figures 11 and 12). 
Plantation 2: 
The results of the Christian and Perry (1953) type 
classification for plots with high, medium and low tree 
densities are shown in Figure 13- 
The total white spruce volume per plot/total aspen 
volume per plot is obviously not well related (Figure 14). 
Regression equations were not computed. The mean white 
68 
9 =P tremuloidesV =Corylus comuta, 
? =Salix sp. . sp. ,  ^ f «^Picea giauca 
Aster macrophylluB. 
Grass 
Figure 13 , Schematic description of plots with high, 
medium and low tree density at Plantation 2. 
Height (m) Height (m) Height (in) 
69 
spruce volume per plot/mean aspen volume per plot (Figure 
15) and the mean white spruce volume per plot/total aspen 
volume per plot (Figure 16) are also not well related. As 
at Plantation 1, the volume of aspen per plot does not seem 
to affect the volume of white spruce. 
There is also no relationship between the Situation 
Types (shown by dot shape in Figures 14, 15 and 16) and the 
volume of white spruce. As at Plantation 1, the white 
spruce crop was found to have the same range of volumes in 
all situations regardless of the spacing or volume of the 
competing aspen. 
As the number of aspen trees per plot increases the 
2 
number of white spruce frost damaged tips per m crown area 
on the centrally located white spruce from each circular 
Situation Plot decreases (Figure 17). Situation Types II 
and III (shown by dot shape in Figure 17) with close and 
medium aspen spacing had lower numbers of white spruce frost 
2 
damaged tips per m crown area than Sitution Type I with 
wide spacing. This relationship was more pronounced than 
that of Plantation 1. The regression of number of white 
2 
spruce frost damaged tips per m crown area (Y) plotted 
against the number of aspen trees per plot (X) was highly 
significant (P=0.01) (App. D, Table D2). The best fitting 
regression is given in Equation 4 and Figure 17. 
70 
500 - 
450 - 
”7 400 - 
^U  350 - 
2 300 - 
to •=Situation I 
I 250 - »-Situation II 
•=Situation III 
'3 200 . 
> 
150 - 
-p 
S 100 - 
50 - 
ai •• • 
—!*■ ■ I ■<—r* »-| 1 1 *T  
5.0 10.0 15*0 20.0 3 
Total Volume Aspen (dm*^) 
Figure 14. Total volume of spruce per plot vrs. total 
volume of aspen per plot at Plantation 2. 
100 
• • • •• ■ g KMm ^ 
90 
80 
70 
<u
3u 
 
 -Situation I 
U 60 &.  ^=Situation II w ■-Situation III 
50 
o 40 
> 
3 30 (0 
CD 
S 20 
«g «|» w • 
10 -I 
*7 1 *1 —f r* 1 1 1— 
0.4 0.8 1.2 1.6 
Mean Volume Aspen (dm-^) 
Figure 15 . Mean volume of spruce per plot vrs. mean 
volume of aspen per plot at Plantation 2. 
71 
90 
80 
70 
60 
50 
40 
30 
20 
10 
. 6 . Mean volume or spruce per plot vrs. total 
volume of aspen per plot at Plantation 2. 
,/ of Aspen/Plot 
• =Sitiiation I 
X tuation i 
n ! tua t I on ’ 
Pi{;^ure 17. White spruce frost dama^T^ed tips per unit ci'own are 
vrs. number of aspen trees per plot at I'lantatiori 
VThite Spruce' Frost Damaged Tips/n Crovm Area 
73 
Equation 4. Y=594.55-182. 251nX 
R =0.90 
Figures 18, 19, 20, 21, 22, and 23 show the volume 
growth curves calculated from stem analysis for the aspen 
and white spruce from the circular Situation Plots. 
The white spruce on all three Situation Types put on 
roughly the same volume growth per year (Figures 18, 20 and 
22). The aspen volume growth was erratic for all three 
Situation Types (Figures 19, 21 and 23). 
Unlike the results at Plantation 1, when the volume 
growth of the white spruce is compared to the volume growth 
of the aspen for paired trees from each situation plot, 
there do not appear to be any trends. Often a fast growing 
aspen is paired with a fast growing spruce as in Situation 
Type II, Replication 3 (Figures 20 and 21) and Situation 
Type III, Replication 1 (Figures 22 and 23). A fast growing 
aspen may be paired with a slow growing spruce as in 
Situation Type I, Replication 5 (Figures 18 and 19). In 
Situation Type II, Replication 2 (Figures 20 and 21), a slow 
growing aspen is paired with a slow growing spruce. In 
Situation Type I, Replication 3 (Figures 18 and 19) a slow 
growing aspen is paired with a fast growing spruce. There 
74 
Figure 18. Plantation 2 - The growth curves for white Figure 19. Plantation 2 - The growth curves for aspen 
spruce on Situation Type I plots. on Situation Type I plots. 
Year 
Figure 80 . Plantation 2 - The growth curves for white Figure 21. Plantation 2 - The growth curves for aspen 
spruce on Situation Type II plots. on Situation Type II plots. 
1 
3 
4 
5 
2 
Year 
Figure 22. Plantation 2 - The growth curves for white Figure 23. Plantation 2 - The growth curves for aspen 
apruce on Situation Type III plots. on Situation Type III plots. 
75 
appears to be no relationship between the volume growth of 
the aspen and the volume growth of the white spruce. 
76 
SECTION II 
FIELD AND GREENHOUSE TRIALS 
WITH HEXAZINONE HERBICIDE 
Six trials with hexazinone herbicide were undertaken in 
order to determine if hexazinone could be used to 
effectively control competition in conifer plantations, to 
remove unwanted brush, and to eliminate a residual stand of 
poor quality mature aspen. A greenhouse trial was also 
undertaken to determine the effect of hexazinone on various 
crop and weed species grown under controlled conditions. 
The titles, and dates of initiation and evaluation of these 
six trials are outlined in Table 2. 
77 
Table 2. Outline of the Hexazinone Herbicide Trials 
HERBICIDE TRIAL DATE INITIATED DATE(S) EVALUATED 
1. he Brush 
Control Trials 
Location 1 Early June 1978 Early August 1978 
and Mid. July 1979 
Location 2 Late June 1978 Mid. August 1978 
and Early August 
1978 
Location 3 Late July 1978 Mid. August 1979 
2. The Seedling 
Survival Trials 
White Spruce Mid June 1979 Late August 1979 and 
Black Spruce Mid June 1979 Late October 1980 
3. The Crop 
Tree Trials 
White Spruce Early July 1979 Early September 1980 
White Spruce Early July 1979 Late August 1980 
Black Spruce Early July 1979 Early September 1980 
Jack Pine Early July 1979 Early September 1980 
4. The Weed Tree 
and Brush Trials 
Trembling Aspen Mid July 1979 Late August 1980 
Willow Mid July 1979 Early September 1980 
5. TLate Ahueg uMsat ur19e7 9 Early September 1980 
Aspen Trial 
6. The Greenhouse 
Trials 
Jack Pine Mid February 1980 Early May 1980 
White Spruce Mid February 1980 Early May 1980 
Aspen Mid February 1980 Early May 1980 
Hazel Mid February 1980 Early May 1980 
78 
Methods 
1. The Brush Control Trials: 
Randomized block field trials were established at three 
locations in old cutovers in 1978 (Dunsford 1979). These 
trials are situated approximately 80 kilometres west of 
Thunder Bay close to the junction of Highways 17 and 11 near 
Shabaqua Corners in Goldie Township. This area is within 
the B9 or Superior Section of the Boreal Forest Region (Rowe 
1972) and in Site Region 4W (Hills 1961). The exact 
location of these trials is shown in App. A, Figures A3 and 
A4. 
The three locations were chosen to illustrate various 
silvicultural problems. 
Location 1 was cut over during 1974 to 1975. The area 
was not site prepared and it has subsequently regenerated to 
dense weed tree and brush species. No conifer crop is 
present (Table 3 and Figure 24). 
Location 2 was cut over in 1969. It was site prepared 
in 1971 with a V plough to cut the larger trees and to 
separate the slash (Myles 1978). Sharkfin barrels were 
dragged behind the plough. These break through the slash 
and rip into the soil surface layers and root mat (Smith 
79 
Location 1 
V-plough Undisturbed 
scalp Duff 
—4m—J 
Pin cherry =Jack = Black 8c 
Mountain .1 Pine White 
Maple, Alder Spruce 
Willow 
Figure 24. Schematic description of Locations 1,2 and 3. 
Height (n) Height (m) Height (m) 
80 
1979). This area was planted with white spruce in May 1972. 
It has since become heavily infested with weed tree and 
brush species which are competing with the white spruce crop 
(Table 3 and Figure 24) . 
Location 3 was cut over on several occasions between 
1962 to 1970. It was aerially seeded in 1972 with jack 
pine. Jack pine regeneration was very poor. In 1976 the 
area was site prepared with a TTS disc trencher. The 
trencher is a row scarifier which operates on the same 
principle as the agricultural disc harrow. It cuts into the 
soil, turning up two equidistant furrows (Myles 1978, Smith 
1979, and Murray 1980). 
In 1977 Location 3 was planted with white and black 
spruce. Conifer regeneration is still very poor at this 
location. A few scattered jack pine and white spruce trees 
are present, but these are seriously suppressed by dense 
weed trees and brush (Table 3 and Figure 24). 
81 
Table 3. Stand History and Description of Locations 1,2 and 
3. 
LOCATION DATE OF DATE AND DATE PLANTED, HEIGHT AND 
CUTOVER TYPE OF HEIGHT AND SPECIES OF WEED 
SITE SPECIES OF TREE AND BRUSH 
PREPARATION CROP IN ORDER OF 
 IMPORTANCE 
1 1974- none none Trembling Aspen 
1975 (2.5 to 4.5m)= 
Hazel (1 to 
2.5m)>Mountain 
Maple = Alde r = 
Willow=pin 
Cherry 
2 1969 1971-Vblade 1972-White Trembling Aspen 
corridors Spruce (1.5m) (3.5 to 5.5m) 
and barrels Hazel (2.0 to 
3.0)>Mountain 
Maple=Alder= 
Willow=Pin 
Cherry 
3 1962- 1976-TTS 1972 aerially Trembling Aspen 
1970 disc seeded with (2.5 to 4.5m)> 
trencher Jack Pine (1.0 Hazel (1 to 
to 1.5ra) 1977 2.5m)=Mountain 
White and Maple=Alder 
Black Spruce Willow=Pin 
(0.5m) Cherry 
The hexazinone herbicide trials were set up in the 
field as described in Table 4 
82 
Table 4. Description of the Hexazinone Herbicide Trials at 
Locations 1,2 and 3. 
LOCATION DATE HEXAZINONE PLOT DATE DATE 
APPLIED FORM SIZE ASSESSED ASSESSED 
(m) IN 1978 IN 1979 
Early DPXLE and 15x15 Early Mid . 
June Gridballs August July 
1978 1978 1979 
Late DPXLE and 20x20 Mid. Early 
June Gridballs August August 
1978 1978 1979 
Late DPXLX and 20x20   Mid. 
July Gridballs August 
1978 1979 
The experimental design was a 2 x 5 factorial 
superimposed on a randomized block design. Each field trial 
was composed of 30 plots (3 blocks x 2 forms x 5 rate and 
spacing of herbicide treatments) (Table 5) 
83 
Table 5. The Hexazinone Herbicide Treatments Applied in the 
Brush Control Trials. 
TREATMENT HEXAZINONE APPLICATION RATE SPACING 
NUMBER FORM METHOD (kg ai/ha) (mxm) 
1 Liquid -j 10 ml. of 0.0 nil 
2 (DPX-LE ) diluted 1.2 1.77 
3 solution 1.2 1.25 
4 applied by 2.4 1.25 
5 spotton—gun 2.4 0.88 
6 Solid GridbalIs (nil) 0.0 nil 
7 applied (2cc. 1.2 1.77 
8 by (Icc . 1.2 1.25 
9 hand ( 2cc . 2.4 1.25 
10 (Icc . 2.4 0.88 
Note: The trial at Location 3 was treated with DPX-LX. 
There were two treatments in the primary factor: 
hexazinone concentrated liquid (DPX 3674-LE or LX) solutions 
and hexazinone 'Gridballs* (DPX 3674-A). DPX-LE was used at 
Locations 1 and 2; DPX-LX was used at Location 3. 
There were five different rate and spacing treatments 
in the secondary factor. The two rates of application (1.2 
and 2.4 kg ai./ha) were achieved by varying the spacing 
interval between 'spot* applications of hexazinone as shown 
in Figure 25. 
84 
0.88m 
S: 1.77 1.25 0.88 
R: 1.20 1.20 2.40 2.40 
#: 3,200 6,400 6,400 12,800 
R/S: 0.3750 0.1875 0.3750 0.1875 
2 
S = spacing (m ) 
scale: L_ ■I _j 
R = rate (kg ai/ha) 
Om Im 2m # = number of spots per ha 
R/S = rate per spot (g ai) 
Figure 25. Schematic description of the rate and spacing 
treatments. 
Hexazinone is a 'spot' apolied herbicide. A spot of 
concentrated solution or a 'Gridball' pellet is applied to 
the soil surface. The herbicide is thought to move outward 
from this spot in a manner similar to that described in 
85 
Figure 26. 
Figure 26. Schematic description of the zone of effectiveness around a 
hexazinone spot. 
Locations 1 and 2 were evaluated twice, once during 
August 1978 (Dunsford 1979), and once during July and August 
1979. Location 3 was evaluated for the first time during 
August 1979. The 10 trembling aspen trees randomly chosen 
by Dunsford (1979) on each plot at Locations 1 and 2 were 
re-evaluated during July and August 1979. Ten aspen trees 
per plot at Location 3 were randomly designated for 
86 
evaluation in August 1979. 
The following measurements of the selected aspen trees 
were made on each plot. 
1. Condition Code: The effect of the various 
hexazinone treatments on the aspen was evaluated 
by assigning a subjective condition code (Table 6) 
to each of the 10 selected aspen trees on each plot. 
2. Height: The total height of each tree in metres 
was measured. 
3. Diameter: The diameter in centimetres above butt 
swell (5% of the total tree height up to 4 metres) 
was measured. 
Foliage dry weight was estimated using the branch 
diameter at point of foliation method. The diameters at 
point of foliation of all branches carrying live foliage 
were measured. The branch diameters were recorded in five 
diameter classes, 1 to 3, 4 to 6, 7 to 9, 10 to 12 or 13 to 
15 mm using the Branch Diameter Guide shown in Figure 27. 
Foliage dry weight in grams was estimated for individual 
branches using the regression equation established by 
Dunsford(1979) . These values were summed for each tree. The 
total foliage dry weight per plot was divided by 10 to 
87 
obtain the average foliage dry weight in grains per tree on 
each plot. 
F'igure27. The branch diameter guide. 
88 
The regression curve established by Dunsford (1979) 
(Equation 5) was a logarithmic transformation, therefore the 
method outlined by Baskerville (1972) was used to correct it 
(Equation 6). Logarithmic transformations tend to skew the 
variance when the derived equation is retransformed back 
into original values. This can result in underestimates of 
up to 20 per cent (Baskerville 1972) if the residual mean 
square is high. 
Equation 5 FDW =0.1816X ’ uncorrected curve 
2.0791 0.007165 
Equation 6 FDW = 0.1816X X e corrected curve 
FDW = foliage dry weight in grams 
X = branch diameter at point of foliation in mm. 
It was decided to continue to use data based on the 
uncorrected curve (Equation 5) in all analysis as the 
initial analysis of results (Dunsford 1979) was carried out 
using the uncorrected curve, and as the effect of correction 
was minimal (Figure 28). Equation 1 would provide the best 
comparison between analysis of 1978 data with 1979 data. 
89 
Curve 
079 
BRANCH DIAMETER (mm) AT POINT OF FOLIATION 
Figure 28.The plotted points show actual foliage dry weight (poW) 
and branch diameter at point of foliation (D). 
FOLIARE DRY WIEGHT (g) 
90 
Table 6. The Subjective Condition Code Used to Describe the 
Condition of the Aspen. 
CONDITION CODE 
healthy (no damage or defoliation) 0 
1-25% brown and defoliated 1 
26-5 0% *' " 2 
51-75% " " 3 
76-99% « « 4 
dead 5 
2. The Seedling Survival Trials: 
In June 1979, Replications 1 and 2 of The Brush Control 
Trial - Location 3 were hand planted with 1 1/2 + 1 1/2 
white spruce and black spruce and 2+0 jack pine nursery 
stock in three 2x5 factorial randomized block field 
trials. The purpose of this trial was to determine the 
effect of hexazinone applied in 1978 on nursery stock 
planted one year after herbicide application. 
Each 2x5 factorial field trial was composed of 2 
herbicide forms x 5 herbicide rate - spacings x 2 
replications x 20 trees/replication = 400 trees. A 
description of the treatments can be found in Table 5. 
The three species were planted on each plot in 
Replications 1 and 2 (Figure 29). Replication 3 was not 
planted because of time constraints. 
91 
Y=Jack Pine 
^=Black Spruce 
-White Spruce 
Figure 29 .Planting layout of a single plot in the Seedling 
Survival Trial. 
During the fall of 1979, three months after planting, 
the seedlings were assessed. The trees were assigned the 
same subjective condition described in the Brush Control 
Trials (Table 6) and per cent survival was measured. Height 
increment of the established seedlings was measured, but 
rabbit damage invalidated this assessment. 
92 
The seedlings were re-assessed during October 1980. 
The trees were again assigned a subjective condition code, 
and per cent survival and height increment were re-measured. 
The 1980 results were used in all analysis. These results, 
taken a full growing season after planting, would probably 
provide the first results showing initial growth response to 
release from aspen competition. 
Many of the jack pine seedlings on both control and 
hexazinone treated plots died during the year after 
planting, and as a light covering of snow on the ground made 
it virtually impossible to find these seedlings in 1980, 
measurement of the jack pine was discontinued. 
3. The Crop Tree Trials: 
o 
Four 3 factorial randomized block field trials were 
established in June and July 1979 to determine if hexazinone 
had a detrimental effect on the crop trees shown in Table 7. 
93 
Table 7. Species and Height of Trees in the Four Crop Tree 
Hexazinone Herbicide Trials. 
TRIAL # CROP SPECIES HEIGHT (m) 
i White Spruce 1.50 
ii White Spruce 0.30 
iii Black Spruce 0.30 
iv Jack Pine 1.75 
These trials are situated close to the Brush Control 
Trials. The exact location of these trials is shown in 
App. A, Figures A3, A4, and A5. 
Each 3 factorial field trial was composed of 3 
herbicide rates x 3 herbicide spacings x 3 replications x 5 
trees per replication = 135 trees (Table 8). 
94 
Table 8.The Hexazinone Herbicide Treatments Applied in the 
Crop Tree Trials. 
TREATMENT » HEXAZINONE RATE SPACING (m) 
(g ai/spot) 
1 0 1.5 
2 0 1.0 
3 0 0.5 
4 0.1875 
5 0.1875 
6 0.1875 
7 0.3750 1.5 
8 0.3750 1.0 
9 0.3750 0.5 
The two rates of hexazinone (0.1875 g. ai/spot and 
0.3750 g. ai/spot) were chosen as this is the equivalent 
amount of herbicide that would be applied with a 1 cc or a 2 
cc hexazinone *Gridball*. Figure 26 shows how the herbicide 
applied as a 'spot* is thought to migrate through the soil. 
Hexazinone concentrated liquid (DPX 3674-LX) was used 
rather than hexazinone 'Gridballs*. The concentrated liquid 
form is faster acting than the 'Gridball* form because the 
liexazinone in the latter is included in a slowly 
disintegrating clay ball. Thus the field results with 
hexazinone concentrated liquid would be more readily 
apparent and would have more severe effects on the crop 
95 
trees. 
Two *spots* of hexazinone were applied on both side s of 
each tree as shown in Figure 30. 
During the summer of 1979, 100 branches were colle c ted 
from each species on sites adjacent to the test si tes. 
These branches were selected to represent the overall r ange 
of branch diameters for each species equally. The br anch 
diameters at point of foliation and the foliage dry we ight 
of each branch were determined. Line and curvili near 
regressions were formulated to determine the relation ship 
between branch diameter at point of foliation and fol iage 
dry weight (App. C, Figures Cl, C2, C3, and C4). 
As described in the Brush Control Trials, the condi t ion 
code, height and diameter of each tree were measured p r ior 
to herbicide treatment. 
The Crop Tree Trials were evaluated during August and 
September 1980. The trees were again assigned a subjec t i ve 
condition code, per cent survival was measured, and the 
total height and the diameter above butt swell of each tree 
was measured. Height growth of the trees was determined by 
subtracting the total height in 1979 from the total he ight 
in 1980. 
96 
Figure 30 . Schematic description of the hexri7, inonn spaclti*- 
treatments. 
97 
The regression equations relating branch diameter at 
point of foliation to foliage dry weight were not used to 
estimate the foliage dry weight of the trees. Due to the 
amount of time that had elapsed since herbicide treatment, 
any herbicide affected trees were dead while the rest 
remained healthy. This result limited the usefulness of the 
branch diameter at point of foliation method and it was 
discontinued. 
4. The Weed Tree and Brush Trials: 
Two randomized block field trials were established in 
July 1979 to determine if hexazinone had a detrimental 
effect on the weed tree and brush species shown in Table 9 - 
Table 9. Species and Height of the Trees in the Two Weed 
Tree and Brush Hexazinone Herbicide Trials. 
TRIAL # WEED TREE OR HEIGHT (m) 
BRUSH SPECIES 
i Aspen 4.0 
i i Willow 3.0 
98 
These trials are situated close to the Brush Control 
Trials. The exact location of these trials is shown in App. 
A, Figures A3 and A4. 
The methods used for each trial are presented 
individually. 
i. Aspen Weed Tree Trial 
The Aspen Weed Tree Trial was a 3 x 4 factorial 
randomized block design. There were 3 herbicide rates x 4 
herbicide spacings x 3 replications x 5 trees per 
replication = 180 trees (Table 10). 
99 
Table 10. The Hexazinone Herbicide Treatments Applied in the 
Aspen Weed Tree Trial. 
TREATMENT NUMBER HEXAZINONE RATE SPACING (m) 
(g ai/spot) 
1 0 2.0 
2 0 1.5 
3 0 1.0 
4 0 0.5 
5 0.1875 2.0 
6 0.1875 1.5 
7 0.1875 1.0 
8 0.1875 0.5 
9 0.3750 2.0 
10 0.3750 1.5 
11 0.3750 1.0 
12 0.3750 0.5 
As explained in the Crop Tree Trials, the two rates of 
hexazinone chosen were 0.1875 g ai/spot and 0.3750 g 
ai/spot. Figure 26 shows how the herbicide ’spot* is 
thought to migrate through the soil. 
The widest herbicide spacing (2.0 m) was included in 
this trial because of the wide spreading root system of 
aspen and its resulting sensitivity to hexazinone. 
As explained in the Crop Tree Trials, hexazinone 
concentrated liquid (DPX 3674-LX) was the herbicide form 
used for all treatments. 
100 
Two 'spots* of hexazinone were applied on both sides of 
each tree similar to the manner described in Figure 30 . 
As described in the Crop Tree Trials, 100 branches were 
collected from aspen on a site adjacent to the test site. 
Line and curvilinear regressions were formulated to 
determine the relationship between branch diameter at point 
of foliation and foliage dry weight (App. C, Figure C5). 
As described in the Brush Control Trials, the condition 
code, height and diameter of the aspen trees were measured 
prior to herbicide treatment. 
The Aspen Weed Tree Trial was evaluated during August 
1980. The trees were again assigned a subjective condition 
code, per cent survival was measured, and the total height 
and the diameter above butt swell of each tree was 
re-measured. Height growth of the trees was determined by 
subtracting the total height in 1979 from the total height 
in 1980. 
As discussed in the Crop Tree Trials, the regression 
equations relating branch diameter at point of foliation to 
foliage dry weight were not used to estimate the foliage dry 
weight of the trees. 
101 
ii* Willow Brush Trial 
The Willow Brush Trial was a 3 factorial random!zed 
block design. There were 3 herbicide rates x 3 spot numbers 
X 3 replications x 5 bushes per replication = 135 bushes 
(Table 11) . 
Table 11. The Hexazinone Herbicide Treatments Applied in the 
Willow Brush Trial. 
Treatment Number Hexazinone Rate Number of Spots/Bush 
 (g ai/spot)   
1 0 1 
2 0 2 
3 0 4 
4 0.1875 1 
5 0.1875 2 
6 0.1875 4 
7 0.3750 1 
8 0.3750 2 
9 0.3750 4 
As explained in the Crop Tree Trials, the two rates of 
hexazinone chosen were 0.1875 g ai/spot and 0.3750 g 
ai/spot. Figure 26 shows how the herbicide 'spot* is 
thought to migrate through the soil. 
102 
As explained in the Crop Tree Trials, hexazinone 
concentrated liquid (DPX 3674-LX) was again used for all 
treatments. 
Willow, due to its clumpy growth habit was not treated 
with different herbicide spacings. Instead, it was treated 
with either 1, 2 or 4 hexazinone spots at the base of each 
shrub as shown in Figure 31. 
As explained in the Crop Tree Trials, 100 branches were 
collected from willow on a site adjacent to the test site. 
Line and curvilinear regressions were formulated to 
determine the relationship between branch diameter at point 
of foliation and foliage dry weight (App. C,Figure C6). 
The following measurements were made on each shrub 
prior to herbicide treatment. 
1. Condition code; The same subjective condition 
code described in the Brush Control Trials 
(Table 6) was assigned to each tree. 
2. Height: The overall height of each shrub in 
metres was measured. 
3. Humber of Main Stems: The number of live main 
stems for each shrub was counted. 
103 
One Herbicid 
Spot 
Willow Shrub 
Herbicide Spot 
Tone of herbicide 
effectiveness 
Two Herbicid 
Spots 
Willow Shrub 
erbicide Spot 
ne of herbicide 
effectiveness 
Figure*31, Schematic description of the hexazinone spot placements. 
104 
The Willow Brush Trial was evaluated in September 1980* 
The trees were again assigned a subjective condition code, 
per cent survival was measured, the overall height was 
measured and the number of live stems for each shrub was 
re-counted. Total stem growth of each shrub was determined 
by subtracting the overall height in 1979 from the overall 
height in 1980 and multiplying this value by the number of 
live stems in 1980. 
As discussed in the Crop Tree Trials, the regression 
equations relating branch diameter at point of foliation to 
foliage dry weight were not used to estimate the foliage dry 
weight of the shrubs. 
5. The Mature Aspen Trial: 
A field trial was established in August 1979 to 
evaluate the effect of hexazinone on mature aspen trees. 
This trial is situated close to the Brush Control Trials. 
The exact location of this trial is shown in App. A, Figure 
A3. 
105 
An initial cruise was made of the stand. The trees 
were divided into three diameter c lasses based on diamater 
at breast height measurements. The three diameter classes 
are shown in Table 12. 
Table 12. The Three Diameter Classes in the Mature Aspen 
Trial. 
DIAMETER CLASS DBH (cm) 
S <12.0 
M 12.1-16.0 
L >16.1 
The experimental design was a 2 x 4 x 3 factorial 
randomized block design. There were two herbicide forms x 4 
herbicide rates x 3 diameter classes x 3 repl ications x 3 
trees per replication = 216 trees (Table 13). 
106 
Table 13. The Hexazinone Herbicide Treatments Applied in the 
Mature Aspen Trial. 
TREATMENT FORM RATE (# of spots DIAMETER 
NUMBER X g ai/spot) CLASS 
Liquid L 
M 
S 
2x3.750 L 
2x3.760 M 
2x3.750 S 
4x3.750 L 
4x3.750 M 
4x3.750 S 
10 6x3.750 L 
11 6x3.750 M 
12 6x3.750 S 
13 Solid L 
14 M 
15 S 
16 2x3.750 L 
17 2x3.750 M 
18 2x3.750 S 
19 4x3.750 L 
20 4x3.750 M 
21 4x3.750 S 
22 6x3.750 L 
23 6x3.750 M 
24 6x3.760 S 
107 
Hexazinone concentrated liquid (DPX-3674 LX) and 
hexazinone *Gridballs* were the two herbicide forms used. 
The hexazinone rates (0.3750 g ai/spot x 0^2,4 or 6 spots) 
were chosen as 0.3750 g equals amount of active ingredient 
that would be applied with a 2 cc *Gridball*. This would 
allow comparison between the effectiveness of the two 
herbicide forms. Figure 26 shows how the herbicide applied 
as a spot is thought to migrate through the soil. 
The hexazinone 'spots* were applied around the base of 
each tree as shown in Figure 32. 
The Mature Aspen Trial was evaluated during August 
1980. The trees were assigned a subjective condition code 
(Table 14) and per cent survival was measured. 
Table 14. The Subjective Condition Code Used to Evaluate the 
Mature Aspen Trial. 
CONDITION CODE   AMOUNT OF DAMAGE 
1 Healthy 
2 Moderate Damage 
3 Dead 
108 
Figure 32. Schematic description oi* the hexazinone spot 
treatments. 
109 
6. The Greenhouse Trials: 
Randomized block trials were established in the 
Lakehead University Greenhouse in November 1979 to evaluate 
the effect of hexazinone on four crop and weed species. The 
crop species tested were jack pine and white spruce; the 
weed tree and brush species tested were aspen and hazel. 
Both crop and weed species were grown under controlled 
conditions. The methods used for the crop and weed species 
are discussed separately. 
i. Jack Pine and White Spruce Crop Tree Greenhouse Trials: 
The root collar diameters of one hundred each of 1 1/2 
+ 1 1/2 white spruce and 2+0 jack pine nursery stock were 
measured. To minimize size variation and potential 
experimental error, seedlings within 10% of the mean root 
collar diameter were selected for study. These seedlings 
were potted and grown in the Lakehead Univesity Greenhouse 
for two months prior to hexazinone application. They were 
initially placed in a cold house maintained at an average 
temperature of 12o  C. The temperature was gradually 
increased to 20°C over a period of 4 weeks. The trees were 
then moved into the large Lakehead University Greenhouse, 
maintained at an average temperature of 22^C, and placed 
under Gro Lux and Cool White lights. At this point, the 
roots had started to regenerate and the buds were beginning 
to flush. After 4 weeks, in February 1980, when the newly 
110 
flushed shoots had completed elongation and had hardened 
off, they were treated with hexazinone herbicide. 
The experimental design was a 4 x 2 factorial 
randomized block design. These were 4 herbicide rates x 2 
spray positions x 3 replications x 5 trees per replication = 
120 trees (Table 15). 
Table 15. The Hexazinone Herbicide Treatments Applied in the 
Jack pine and White Spruce Crop Tree Greenhouse 
Trials. 
 ' T  
TREATMENT NUMBER RATE (g ai/4m ) TARGET AREA 
1 0 Foliage 
2 2.04 n 
3 4.08 M 
4 8.16 H 
5 0 Foliage + Soil 
6 2.04 
7 4.08 
8 8.16 
The four rates of hexazinone applied to the potted crop 
and weed species were designed to simulate the concentration 
of hexazinone that results from spot applications made in a 
111 
grid pattern in the field (Figure 33). In grid pattern 
applications the concentration of hexazinone in each spot 
within the grid is much higher than the average application 
rate in kilograms per hectare because only a fraction of the 
area is affected by the herbicide. The rates of hexazinone 
2 
applied in this study were 0, 2.04, 4.08 and 8.16 g ai/4m . 
These are equivalent to the within treated spot rates when 
0, 1, 2 and 4 kg ai/ha are applied in a grid pattern in the 
field (Figure 33). Figure 26 shows how the herbicide spot 
is thought to migrate through the soil. 
The rate of spray was controlled by placing the potted 
trees in a 4 metre square and spraying a preweighed quantity 
of a suspension of hexazinone in water evenly over the area 
with a 'Beauty Mist* sprayer. 
The hexazinone was applied by two methods: 1) to the 
foliage alone and 2) to the foliage and soil. In 1) the 
soil in each pot was covered with cardboard discs and the 
foliage was sprayed. In 2) the soil was uncovered and both 
the foliage and soil were sprayed. Both jack pine and white 
spruce do not often show damage from hexazinone herbicide. 
The two methods of spray application were chosen to 
determine if hexazinone applied directly to the roots and 
foliage would be more damaging than hexazinone applied to 
112 
Area a = 2 x 2 = 4m^ 
Area ^1^4. “ ^ ^ 0.25 r^ = 0.785ni^ 
IKg ai/ha grid application=lx4/0.?85=5•IKg ai/ha spot rate 
2Kg ai/ha grid application=2x4/0.785-10.2Kg ai/ha spot rate 
4Kg ai/ha grid application=4x4/0.785=20.4Kg ai/ha spot rate 
O 
5.1Kg ai/ha = 2.04 g ai/4m'^ p 
10.2Kg ai/ha = 4.08 g ai/4m 
20.4Kg ai/ha = 8.16 g ai/4m^ 
Figure 33. The relationship between spot and grid app- 
lication rates of hexazinone herbicide. 
113 
the foliage alone. 
As described in the Crop Tree Trials, hexazinone 
concentrated liquid (DPX 3674-LX) was the herbicide form 
used in all treatments. 
The following measurements of the jack pine and white 
spruce were made prior to hexazinone application. 
1. Condition Code; The same subjective condition 
code described in the Brush Control Trial 
(Table 6) was assigned to each tree. 
2. Total Height 
3. Root Collar Diameter 
The jack pine and white spruce were evaluated twice 
during February and March 1980 when the trees were again 
assigned a subjective condition code. The final evaluation 
was in May 1980. The trees were assigned a subjective 
condition code, per cent survival was measured and all green 
foliage was oven-dried and weighed. 
114 
ii. Aspen and Hazel Weed Tree and Brush Greenhouse Trials 
Aspen root cuttings and hazel root-stem cuttings were 
potted and grown in the large Lakehead University 
Greenhouse, maintained at an average temperature of 22°C, 
under Gro-Lux and Cool White lights for two months prior to 
hexazinone application. When the shoots were fully flushed, 
the aspen and hazel cuttings were treated with hexazinone 
herbicide. 
The experimental design was a randomized complete block 
design. There were 4 herbicide rates x 3 replications x 5 
trees per replication = 60 weed trees or brush (Table 16). 
Table 16. The Hexazinone Herbicide Treatments Applied in the 
Aspen and Hazel Weed Tree and Brush Greenhouse 
Trials. 
2" 
TREATMENT NUMBER RATE (g ai/4m ) 
1 0 
2 2.04 
3 4.08 
4 8.16 
115 
As described in the jack Pine and White Spruce 
Greenhouse Trials, the four rates of hexazinone applied in 
2 
these trials were 0, 2.04, 4.08 and 8.16 g ai/4m . The rate 
of spray was controlled by placing the potted trees in a 4 
metre square and spraying evenly over the area with a 
* Beauty Mist * sprayer. 
The hexazinone was applied using only the second 
method, foliage and soil, described in the Jack Pine and 
White Spruce Greenhouse Trials. As both aspen and hazel are 
quite sensitive to hexazinone herbicide and would likely be 
damaged by hexazinone applied either to the roots or to the 
foliage and roots, only one method was used. 
As described in the Crop Tree Trials, hexazinone 
concentrated liquid (DPX 3674-LX) was the herbicide form 
used for all treatments. 
The following measurements of the aspen and hazel were 
made prior to hexazinone application: 
1* Condition Code; The same subjective condition 
code described in the Brush Control Trials 
(Table 6) was assigned to each tree. 
116 
2. Total Shoot Height, 
3. Number of Shoots. 
The aspen and hazel were evaluated twice during 
February and March 1980 when the trees were again assigned a 
subjective condition code. The final evaluation was in May 
1980. The trees were assigned a subjective condition code, 
per cent survival was measured and all green foliage was 
oven-dried and weighed. 
Statistical Analyses of the 
Hexazinone Herbicide Trials 
Analyses of variance (ANOV) or covariance analyses 
(COVAR) (Steele and Torrie 1960) were generally used to show 
the significance of the differences between the treatments 
in the herbicide trials (Table 17). Preliminary analysis 
(Prelim. Anal.) (Jeffers 1959) was used to determine 
whether a detailed analysis by ANOV or COVAR was needed. 
Values for per cent survival were transformed using the 
arcsin method (Steele and Torrie 1960). These transformed 
values were used in all such analyses. 
117 
When ANOV or COVAR showed that there were significant 
differences between treatments, a Student-Newman-Keul*s test 
(S-N-K test) (Steele and Torrie 1960) was applied. When 
ANOV was used actual treatment means were compared to 
determine the significance of the differences between 
individual treatment means. When COVAR was used, adjusted 
treatment means were compared. 
118 
Table 17. The Statistical Analyses Used in the Hexazinone Herbicide Trials. 
HERBICIDE ANALYSIS PARAMETER(S) COVARIATE 
TRIAL (if applicable) 
1) The Brush COVAR estimated foliage dry Index of tree stem 
Control Trials weight volume (tree 
diameter (cm) x 
total height (cm)). 
1978 values were 
used for Locations 
1 and 2; 1979 values 
were used for 
Location 3. 
2) The Seedling ANOV i) height increment 
Survival Trials ii) transformed % 
survival 
3) The Crop Tree COVAR height growth (total Index of tree stem 
and 4) The Weed stem growth for volume (tree 
Tree and Brush wi How) diameter (cm) x 
Trials total height (cm)) 
for white and 
black spruce, jack 
pine and aspen. 
Overall height x 
# of main stems 
for willow. 1979 
values were used 
for all species. 
ANOV transformed % survival 
5) The Mature ANOV transformed % survival 
Aspen Trial 
6) The Greenhouse 
Trials 
i) Jack Pine and ANOV i) transformed % 
White Spruce survival 
ii) foliage dry weight 
ii) Hazel and Aspen ANOV transformed % survival 
COVAR foliage dry weight Total shoot length 
at time of spraying. 
119 
Results 
The results of the hexazinone herbicide trials are 
discussed in the same order as in the Methods section. 
1. The Brush Control Trials: 
The results of the three Locations are presented 
individually. 
i. Location 1: 
At Location 1, differences in the foliage dry weights 
of the aspen over the range of hexazinone treatments were 
highly significant (P=0.01, COVAR, App. E, Table El). 
Plots receiving both liquid and solid hexazinone forms 
appli ed at high rates both spacings, and those recieving low 
rates of hexazinone applied at close spacing, had 
significantly lower aspen foliage dry weights than the two 
control plots (S-N-K test, App. E, Table E2). 
When the two hexazinone forms were considered as an 
individual factor, differences in the foliage dry weights of 
the aspen were non-significant (COVAR, App. E, Table El). 
120 
When the rate and spacing treatments were considered as 
an individual factor, differences in the foliage dry weights 
of the aspen were highly significant (P=0.01, COVAR, App. 
E, Table El). The control plots had significantly higher 
aspen foliage dry weights than most of the hexazinone 
treated plots (S-N-K test. Figure 34 b). The hexazinone 
treated plots had progressively less foliage as herbicide 
rate increased and spacing decreased (Figure 34 b). 
Both forms of hexazinone applied at all rates and 
spacings reduced the foliage dry weight of the trembling 
aspen over both years that the trial was measured (Figures 
34 a and b). 
As spacing decreased and rate increased, more 
defoliation occurred and the condition of the aspen was 
reduced (Figure 35). The form of hexazinone used caused 
little difference in effectiveness (Figure 35). 
ii. Location 2: 
At Location 2, differences in the foliage dry weight of 
the aspen over the range of hexazinone treatments were 
highly significant (P=*0.01, COVAR, App. E, Table E3) . The 
hexazinone treated plots had significantly lower foliage dry 
weights than the two control plots (S-N-K test, App. E, 
121 
a) 
spacing 0 1.77 1.25 1.25 0.88 0 1.77 1.25 1.25 0.88 
Rate kg/ha> 0 1.2 1.2 2.4 2.4 0 1.2 1.2 2.4 2.4 
Treatment no= 1 2 3 4 5 6 7 8 9 10 
Significance: J 
b) 
Spacing m: 1.77 125 1.25 0.88 1.77 1.25 125 a8S 
Rate kg/ha: 12 1.2 2.4 2.4 1.2 1.2 2.4 2.4 
Treatment no: 2 3 4 5 7 8 9 10 
|1 
Significance: L_ 
Figure 34The predicted foliage dry weights adjusted by covariance analysis of the aspen at Location 1 
'*Not«! Rat* and apaeing traatmanta within aach harbiclda form that war* not aigntficantly ditfarant (P=0.0S)ar*join*d by a lln* 
1 22 
% Brown or Defoliated 
Spacing m: 0 1.77 1.2S 1.25 0.88 0 1.77 1.25 125 0.88 
Rate kg/ha: 0 1.2 1.2 24 2.4 0 1.2 1.2 24 24 
Treatment noi 1 2 3 4 5 8 7 8 0 10 
Figure 35 The condition code of the aspen at location 1 in 1979 
123 
Table E4). 
When the two hexazinone forms were considered as an 
individual factor, differences in the foliage dry weights of 
the aspen were non-significant (COVAR, App. E, Table E3). 
When the rate and spacing treatments were considered as 
an individual factor, differences in the foliage dry weights 
of the aspen were highly significant (P-0.01, COVAR, App. 
E, Table E3). The control plots had significantly higher 
aspen foliage dry weights than the hexazinone treated plots 
(S-N-K test. Figure 36 b). 
At Location 2, results were similar to those at 
Location 1 (Figures 36 a and b). Hexazinone applied at all 
rates and spacings reduced the foliage dry weight of the 
trembling aspen over both 1978 (Dunsford 1979) and 1979. 
As spacing decreased and rate increased, more 
defoliation occurred and the condition of the aspen was 
reduced (Figure 37). The form of hexazinone used caused 
little difference in effectiveness (Figure 37). 
iii. Location 3: 
At Location 3, differences in the foliage dry weight of 
the aspen over the range of hexazinone treatments were 
highly significant (P=0.01, COVAR, App. E, Table E5). 
124 
a) 
Spacing nm 0 1.77 1.25 1.25 0.88 0 1.77 1.25 1.25 0.88 
Rate kg/hai 0 1.2 1.2 2.4 2.4 0 1.2 1.2 2.4 2.4 
Treatment no: 1 2 3 4 5 6 7 8 9 10 
Significance: I    
Spacing m: 1.77 125 125 0.88 1.77 125 125 a88 
Rate kg/ha: 12 1.2 2.4 2.4 1.2 1.2 2.4 2.4 
Treatment no: 2 3 4 5 7 8 O 10 
Significance: -J L- .1 
Figure 36The predicted foliage dry weights adjusted by covariance analysis of the aspen at Location 2 
Rat* and tpaeing Iraatmanta wlthM aaeh harbiclda form that wara not aignificantly diffarant (P=0.05)arajoinadbyalino 
125 
% Brown or Defoliated 
Spacing m: 0 1.77 1.25 1.25 0.88 1.77 1.25 125 0.88 
Rate kg/ha: 0 12 1.2 2.4 2.4 1.2 1.2 2J4 2.4 
Treatment no< 1 2 3 4 5 7 8 9 10 
Figure 3 7 The condition code of the aspen at location 2 in 1979 
126 
Plots receiving both liquid and solid hexazinone forms 
applied at high rate, both spacings had significantly lower 
aspen foliage dry weights than most of the other plots 
(S-N-K test, App. E, Table E6). Plots receiving hexazinone 
applied at low rate, both spacings had significantly lower 
aspen foliage dry weights than one of the control plots 
(S-N-K test, App. E, Table E6). 
When the two hexazinone forms were considered as an 
individual factor, differences in the foliage dry weights of 
the aspen were non-significant (COVAR, App. E, Table E5). 
When the rate and spacing treatments were considered as 
an individual factor, differences in the foliage dry weights 
of the aspen were highly significant (P=0.01, COVAR, App. 
E, Table E5). The control plots had significantly higher 
foliage dry weights than the hexazinone treated plots (S-N-K 
test. Figure 38). Plots receiving the high hexazinone rate 
had significantly lower aspen foliage dry weights than plots 
recieving the low hexazinone rate (S-N-K test. Figure 38). 
At Location 3, results were similar to those at 
Locations 1 and 2 (Figure 38). Hexazinone applied at all 
rates and spacings reduced the foliage dry weight of the 
aspen. 
220 127 
2004 
Q> 180 1979 4> 
160 LIQUID SOLID 
o> 
sz 140 
O) 
I 120 
w>«  100 
D 
80 
<L> 
o> 
(0 60 
40- 
20- 
O 
Spacing m: 1.77 1.2S 1.25 o.se 1.77 1.25 1.25 0.88 
Rate kg/ha: 1.2 1.2 2.4 2.4 1.2 1.2 2.4 2.4 
Treatment no: 2 3 4 5 7 8 9 10 
Significance: L- I L. -J L_ L- 
FiqureSSThe predicted foliage dry weights adjusted by covariance analysis of the aspen at Location 3 
^Not«: Rat* and apaclng traatmenta within aach harbiclda form that wara not aignlflcantly diffarant (P=0.05)araioln*d by a lino 
% Brown or Defoliated 
Spacing m: o 177 1.25 1.25 0.88 O 1.77 1.25 1.25 0.88 
Rate kg/ha: 0 1.2 1.2 2.4 2.4 O 1.2 1.2 2A 2A 
Treatment no> 1 2 3 4 5 8 7 8 0 10 
FiqureSd The condition code of the aspen at location 3 in 1979 
128 
As the hexazinone spacing decreased and the rate 
increased, more defoliation occurred and the condition of 
the aspen was reduced (Figure 39). The form of hexazinone 
used caused little difference in effectiveness (Figure 39). 
2. The Seedling Survival Trials: 
The results of the seedling survival trials are 
presented by species. 
i.White Spruce: 
In the white spruce study, there were significant 
differences between hexazinone treatments in height 
increment (P»0.05r ANOV, App.E Table E7). Treatment 6 (the 
solid control) resulted in significantly less height 
increment than Treatment 9 (solid form applied at 2.4 kg/ha 
and 1.25 metre spacing) (S-N-K test, App. E, Table E8). 
When the two forms of hexazinone were considered as an 
individual factor, differences in height increment were non- 
significant (ANOV, App. E, Table E7). 
When the rate and spacing treatments were considered as 
an individual factor, differences in height increment were 
highly significant (P-0.01, ANOV, App. E, Table E7). The 
control and the low rate of hexazinone applied at 1.25 m. 
129 
Rate Ks/ha: 0 1.2 1.2 2.4 2.4 0 1.2 1.2 2,4 2,4 
Treatment no.: 12 34 5 67 89 10 
SisnIficanceV ababbababb 
Fi3urc 40. The hcisht Increment of the White Spruce Seedling 
Survival Trial. 
^ Note: Rate and spacing treatments within each herbicide 
form that were rwt significantly different (P=0.05) are 
assigned the same letter. 
% Brown 
or 
Defoliated 
5- -100 
4l 
-75 
c 
LIQUID SOLID -50 
2l 
-25 
*-0 
Rate Kg/ha: 0 1.2 1.2 2.4 2.4 0 1.2 1.2 2.4 2.4 
Treatment no.: 1 2 3 4 5 6 7 8 9 10 
Figure 41. The condition code of the White Spruce Seedling 
Survival Trial. 
130 
spacing resulted in significantly lower height increments 
than the three other rate and spacing treatments (S-N-K 
test. Figure 40). 
Differences in the transformed per cent survival values 
over the range of hexazinone treatments were non-significant 
(Prelim. Anal.). 
The white spruce trees were all quite healthy and did 
not appear to be damaged by the hexazinone applied in 1978 
(Figure 41). 
ii.Black Spruce: 
In the black spruce study, there were no significant 
differences in the height increment over the range of 
hexazinone treatments (ANOV, App. E, Table E9). There were 
also no significant differences in the transformed per cent 
survival values over the range of hexazinone treatments 
(ANOV, App. E, Table E10). 
There do not appear to be any trends in the effect of 
the hexazinone applied in 1978 on the condition of the black 
spruce trees planted in 1979 (Figure 42). 
131 
% Brown 
Treatment no.: 12 34 5 67 89 10 
Fisure 42 The condition code of the Black Spruce Seedling 
Survival Trial. 
132 
3. The Crop Tree Trials: 
The results of each crop tree trial are presented 
individually. 
i. White Spruce (1.5 Metre) Crop Tree Trial 
Differences in the white spruce height growth over the 
range of hexazinone rate and spacing treatments were non 
significant (Prelim. Anal.). There were also no 
significant differences between the transformed per cent 
survival values over the range of hexazinone rate and 
spacing treatments (ANOV^ App. E, Table Ell). 
The white spruce trees were all quite healthy and were 
not damaged by the hexazinone treatments (Figure 43). 
ii. White Spruce (0.5 Metre) Crop Tree Trial 
Differences in the white spruce height growth over the 
range of hexazinone rate and spacing treatments were 
non-significant (Prelim. Anal.). There were also no 
significant differences between the transformed per cent 
survival values over the range of hexazinone rate and 
spacing treatments (ANOV, App. E, Table E12). 
The white spruce trees were all quite healthy and they 
were not damaged by the hexazinone treatments (Figure 44). 
133 
% Brown or Defoliated 
FIsure 43 The condition code of the White Spruce (1.5 Metre) Crop Tree Trial. 
134 
Figure 44. The condition code of the White Spruce (0.5 Metre) Crop Tree Trial 
135 
iii. Black Spruce Crop Tree Trial 
Differences in the black spruce height growth over the 
range of hexazinone rate and spacing treatments were non 
significant (Prelim. Anal.). 
Differences in the transformed per cent survival values 
over the range of hexazinone rate and spacing treatments 
were highly significant (P=0.01, ANOV, App. E, Table E13). 
Treatment 9, the high hexazinone rate applied at the close 
spacing, caused significantly greater mortality than any of 
the other treatments (S-N-K test. Figure 45). 
When the hexazinone rates were considered as an 
individual factor, differences between the transformed per 
cent survival values were highly significant (P=0-01, ANOV, 
App. E, Table E13). The high hexazinone rate caused 
significantly greater mortality than the control or low 
hexazinone rate (S-N-K test. Figure 45). 
When the hexazinone spacings were considered as an 
individual factor, differences between the transformed per 
cent survival values were highly significant (P=0.01, ANOV, 
App. E, Table E13). The close hexazinone spacing caused 
significantly greater mortality than the medium or wide 
hexazinone spacings (S-N-K test. Figure 45). 
136 
Fisure45. The survival (%) of the Black Spruce Crop Tree Trial. 
iNote: Treatments that were not significantly different (P=0.05) are joined by a line. 
% Brown or Defoliated 
Figure46. The condition code of the Black Spruce Crop Tree Trial. 
137 
As the spacing decreased and the hexazinone rate 
increased, the condition of the black spruce trees declined 
(Figure 46)• 
iv. Jack Pine Crop Tree Trial 
An analysis of covariance showed that there were 
significant differences between hexazinone treatments in 
jack pine height growth (P=0.05, App. E, Table E14). 
However, the rather discriminating S-N-K test showed that 
these differences were not significant and therefore 
treatment differences were taken to be non-significant 
(Figure 47). 
When the hexazinone rates and the hexazinone spacings 
were considered as individual factors, there were no 
significant differences in height growth (COVAR, App. E, 
Table E14, Figure 47). 
Differences in the transformed per cent survival values 
over the range of hexazinone rate and spacing treatments 
were significant (P=0.05, ANOV, App. E, Table E15). 
Treatment 9 the high hexazinone rate applied at the close 
spacing, caused significantly greater mortality than most of 
the other treatments (S-N-K test. Figure 48). 
138 
Treatment No. Significance^ 
(ranked) 
3 
7 
8 
2 
5 
4 
9 
1 
6 
Figure 47, The height growth of the Jack Pine Crop Tree Trial adjusted by covariance analysis. 
Treatment No. Significance’ 
(ranked) 
2 
3 
4 
5 
7 
8 
1 
6 
9 
Figure48. The survival (%) of the Jack Pine Crop Tree Trial. 
’Note: Treatments that were not significantly different (P=0.0 5) are Joined by a line. 
139 
% Brown or Defoliated 
Fisure 49. The condition code of the Jack Pine Crop Tree Trial. 
140 
When the hexazinone rates were considered as an 
individual factor, there were no significant differences in 
transformed per cent survival values (ANOV, App. E, Table 
E15 and Figure 48)- 
When the hexazinone spacings were considered as an 
individual factor, differences between the transformed per 
cent survival values were significant (P=0.05, ANOV, App. 
E, Table E15). The close hexazinone spacing caused 
significantly greater mortality than the medium or wide 
hexazinone spacings (S-N-K test. Figure 48). 
As the hexazinone rate increased and the spacing 
decreased, the condition of the jack pine trees declined 
(Figure 49). 
4. The Weed Tree and Brush Trials: 
The results of both weed tree and brush trials are 
presented individually. 
, I 
i. Aspen Weed Tree Trial 
In the Aspen Weed Tree Trial, differences in the height 
growth over the range of hexazinone rate and spacing 
treatments were highly significant (P=0.01, COVAR, App. E, 
141 
Table E16). Treatments 8 and 12 (hexazinone applied at the 
closest spacing at both the low and high rates) resulted in 
significantly less height growth than some of the controls 
(S-N-K test. Figure 50). 
When the hexazinone rates were considered as an 
individual factor, differences in height growth were highly 
significant (P=0.01, COVAR, App. E, Table E16 ). Both the 
low and high hexazinone rates resulted in significantly less 
height growth than the control (S~N~K test. Figure 50). 
When the hexazinone spacings were considered as an 
individual factor, differences in height growth were 
significant (P=0.05, COVAR, App. E, Table E16). The 
closest spacing resulted in significantly less height growth 
than the other three spacing treatments (S-N-K test. Figure 
50) . 
Differences in the transformed per cent survival values 
over the range of hexazinone rate and spacing treatments 
were highly significant (P=0.01, ANOV, App. E, Table E17). 
Treatments 8 and 12 (hexazinone applied at the closest 
spacing at both the low and high rates) caused significantly 
greater mortality than some of the control treatments (S-N-K 
test, Figure 51). 
Sisnificance^ 
Figure 50. The height growth of the Aspen Weed Tree Trial adjusted by covariance analysis. 
Figure 51. The survival (%) of the Aspen Weed Tree Trial. 
^Note: Treatments that were not significantly different (P=0.05) are Joined by a line. 
143 
% Brown or Defoliated 
Figure 52. The condition code of the Aspen Weed Tree Trial 
144 
When the hexazinone rates were considered as an 
individual factor, differences between the transformed per 
cent survival values were highly significant (P=0.01, ANOV, 
App. E, Table E17). Both the low and the high hexazinone 
rates caused significantly greater mortality than the 
control (S-N-K test. Figure 51). 
When the hexazinone spacings were considered as an 
individual factor, differences between the transformed per 
cent survival values were highly significant (P=0.01, ANOV, 
App. E, Table E17). The two closest spacings were 
significantly different from each other, the closest spacing 
causing the greatest mortality. The two closest spacings 
both caused significantly greater mortality than the two 
widest spacings (S-N-K test. Figure 51). 
As the hexazinone rate increased and the spacing 
decreased, the condition of the aspen trees declined (Figure 
52) . 
ii. Willow Brush Trial. 
In the Willow Brush Trial, differences in the total 
stem growth over the range of hexazinone rate and spacing 
treatments were highly significant (P-0.01, COVAR, App. E, 
Table E18). One of the control treatments resulted in 
significantly more total stem growth than any of the other 
145 
treatments (S-N-K test. Figure 53). 
When the hexazinone rates were considered as an 
individual factor, differences in the total stem growth were 
highly significant (P=0.01, COVAR, App. E, Table E18). 
Both the low and high hexazinone rates resulted in 
significantly less total stem growth than the control (S-N-K 
test. Figure 53). 
When the number of hexazinone spots applied was 
considered as an individual factor, there were no 
significant differences in total stem growth (COVAR, App. 
E, Table E18 and Figure 53). 
Differences in the transformed per cent survival values 
over the range of hexazinone rate and spacing treatments 
were highly significant (P=0.01. ANOV, App. E, Table E19). 
Treatment 9 (high rate - 4 herbicide spots) caused 
significantly greater mortality than any of the other 
treatments (S-N-K test. Figure 54). Treatments 6, 7 and 8 
(low rate - 4 hexazinone spots, high rate - 1 hexazinone 
spot and high rate - 2 hexazinone spots) caused 
significantly greater mortality than the three controls and 
treatments 4 and 5 (low rate - 1 hexazinone spot and low 
rate - 2 hexazinone spots) (S-N-K test. Figure 54). 
146 
Significance^ 
Figure 53. The total stem growth of the Willow Brush Trial adjusted by covariance analysis. 
Treatment No. Significance^ 
(ranked) 
1 
2 
3 
4 
5 
6 
7 
8 ) 
9 
Figure 54. The survival (%) of the Willow Brush Trial 
^Note: Treatments that were not significantly different (P=0.05) are Joined by a line. 
147 
% Brown or Defoliated 
Fisurc55. The condition code of the Willow Brush Trial 
148 
When the hexazinone rates were considered as an 
individual factor^ differences between transformed per cent 
survival values were highly significant (P=0.01, ANOV, App. 
E, Table E19). The high hexazinone rate caused 
significantly greater mortality than the low hexazinone rate 
or the control (S-N-K test. Figure 54). 
When the number of hexazinone spots applied was 
considered as an individual factor, differences between 
transformed per cent survival values were highly significant 
(P*0.01, ANOV, App. E, Table E19). Shrubs receiving 4 
herbicide spots suffered significantly greater mortality 
than those receiving 1 or 2 herbicide spots (S-N-K test. 
Figure 54). 
Differences in the transformed per cent survival values 
between the replications were significant (P=0.05, ANOV, 
App. E, Table E19)- Replication 3 had significantly lower 
transformed per cent survival values than Replication 1 
(S-N-K test). 
As the hexazinone rate increased and the number of 
herbicide spots increased, the condition of the willow 
shrubs declined (Figure 55). 
149 
5. The Mature Aspen Trial 
Differences in the mature aspen transformed per cent 
survival values over the range of hexazinone treatments were 
highly significant (P-0.01, ANOV, App. E, Table E20). The 
small and medium diameter classes receiving 4 and 6 
hexazinone spots suffered significantly greater mortality 
than the control treatments or the large diameter classes 
receiving 2 hexazinone spots (S-N-K test, App. E, Table 
E21). As the tree diameter decreased and the number of 
hexazinone spots increased, the per cent survival of aspen 
tended to decrease. 
When the two hexazinone forms were considered as an 
individual factor, there were no significant differences 
between transformed per cent survival values (ANOV, App. E, 
Table E20). 
When the hexazinone rates were considered as an 
individual factor, differences between transformed per cent 
survival values were highly significant (P=0.01, ANOV, App. 
E, Table E20). All of the hexazinone rate treatments were 
significantly different from each other, the highest r a tes 
causing the greatest mortality (S-N-K test. Figure 56). 
When the diameter classes were considered as an 
individual factor, differences between transformed per cent 
survival values were highly significant (P=0.01, ANOV, App. 
E, Table E20). The small and medium diameter cl asses 
150 
Fisure56. The survival (%) of the Mature Aspen Trial. The solid and 
liquid treatments applied at the same rate to trees of the same 
diameter class are combined. 
^ Note: Treatments that were not sisnificantly different (P=0.05) are joined 
by a line. 
FiSure 57. The condition code of the Mature Aspen Trial. The solid and liquid 
treatments applied at the same rate to trees of the same diame- 
ter class are combined. 
151 
suffered significantly greater mortality than the large 
diameter classes (S-N-K test. Figure 56). 
As the hexazinone rate increased and the diameter class 
decreased, the condition of the mature aspen trees declined 
(Figure 57). 
6. The Greenhouse Trials: 
The results of each greenhouse trial are presented 
individually. 
i. Jack Pine: 
Differences in the jack pine transformed per cent 
survival values over the range of hexazinone rate and 
position treatments were highly significant (P=0.01, ANOV, 
App. E, Table E23)- Treatments 4, 6 and 7 (hexazinone 
2 
applied to foliage at 8.16 g ai/4m and hexazinone applied 
2 
to foliage and soil at rates of 2.04 and 4.08 g ai/4m ) 
caused significantly greater mortality than treatments 1, 2, 
3 and 5 (hexazinone applied to foliage at rates of 0, 2.04 
2 
and 4.08 g ai/4m and hexazinone applied to foliage and soil 
2 
at 0 g ai/4m ) (S-N-K test. Figure 58). Treatment 8 
152 
Sisnificance’ 
] 
] 
Fisure 58. The survival (%) of the Jack Pine Greenhouse Trial. 
Treatment No. Sisnificance^ 
(ranked) 
3 
1 
2 
5 
6 
4 
7 
8 
Fisure 59t The actual foliage dry weight of the Jack Pine Greenhouse Trial. 
’ Note: Treatments that were not significantly different (P=0.05) are joined 
by a line. 
153 
2 
(hexazinone applied to foliage and soil at 8.16 g ai/4m ) 
caused significantly greater mortality than any of the other 
treatments (S-N-K test. Figure 58). 
When the hexazinone rates were considered as an 
individual factor, differences between the transformed per 
cent survival values were highly significant (P=0-01, ANOV, 
App. E, Table E23). The highest hexazinone rate (8.16 g 
2 
ai/4m ) caused significantly greater mortality than the 
other three hexazinone rates (S-N-K test. Figure 58). The 
2 
4.08 g ai/4m rate caused significantly greater mortality 
than the controls (S-N-K test. Figure 58). 
When hexazinone was applied at the foliage and soil 
position, jack pine survival was significantly less than 
when hexazinone was only applied at the soil position 
(P=^0.01, ANOV, S-N-K test, App. E, Table E23. Figure 58). 
Differences in foliage dry weights over the range of 
hexazinone rate and position treatments were significant 
(P=0.05, ANOV, App. E, Table E22). Treatment 8 (hexazinone 
applied to foliage and soil at 8.16 g ai/4m ) resulted in 
significantly lower foliage dry weight than treatment 3 
2 
(hexazinone applied to foliage at 4.08 g ai/4m ) (S-N-K 
test. Figure 59). 
154 
Figure 60 The condition code of the Jack Pine Greenhouse Trial. 
155 
When the hexazinone rates were considered as an 
individual factor, there were no significant differences in 
foliage dry weights (ANOV, App. E, Table E22 and Figure 
59) . 
When hexazinone was applied at the foliage and soil 
position, jack pine foliage dry weight was significantly 
less than when hexazinone was only applied at the soil 
position (P=0.05, ANOV, S-N-K test, App.E, Table E22, Figure 
59) • 
As the hexazinone rate increased and the position 
changed from foliage to foliage and soil, the condition of 
the jack pine trees declined (Figure 60)- 
ii. White Spruce 
Differences in the white spruce transformed per cent 
survival values over the range of hexazinone rate and 
position treatments were highly significant (P=0.01, ANOV, 
App. E, Table E25). Treatments 7 and 8 (hexazinone applied 
2 
to foliage and soil at rates of 4.08 and 8.16 g ai/4m ) 
caused significantly greater mortality than any of the other 
treatments (S-N-K test. Figure 61). The two controls had 
significantly higher transformed per cent survival values 
than most of the other treatments (S-N-K test. Figure 61). 
156 
Treatment No. 
(ranked) Significance^ 
1 
Figure 61. The survival (%) of the White Spruce Greenhouse Trial. 
Figure62. The actual foliage dry weight of the White Spruce Greenhouse Trial. 
’ Note: Treatments that were not significantly different (P=O.Os) are joined by a 
line. 
157 
When the hexazinone rates were considered as an 
individual factor, differences between the transformed per 
cent survival values were highly significant (P=0.01, ANOV, 
App. E, Table E25). The two highest rates (4.08 and 8.16 g 
2 
ai/4m ) caused significantly greater mortality than the 
other two rates (S-N-K test, Figure 61). The 2.04 g ai/4ir? 
rate caused significantly greater mortality than the 
controls (S-N-K test. Figure 61). 
When hexazinone was applied at the foliage and soil 
position, white spruce survival was significantly less than 
when hexazinone was only applied at the soil position 
(P=0.01, ANOV, S-N-K test, App. E, Table E 25, Figure 61). 
Differences in the white spruce foliage dry weights 
over the range of hexazinone rate and position treatments 
were highly significant (P=0.01, ANOV, App. E, Table E24). 
The two control treatments resulted in significantly higher 
foliage dry weights than most of the other treatments (S-N-K 
test. Figure 62). Treatment 2 (hexazinone applied to 
2 
foliage at 2.04 g ai/4m ) resulted in significantly higher 
foliage dry weights than treatments 7 and 8 (hexazinone 
applied to foliage and soil at rates of 4.08 and 8.16 g 
ai/4m2) (S-N-K test. Figure 62). 
158 
Figure 63. The condition code of the White Spruce Greenhouse Trial. 
159 
When the hexazinone rates were considered as an 
individual factor, differences in foliage dry weights were 
highly significant (P=0.01, ANOV, App. E, Table E24) . The 
2 
two highest rates (4.08 and 8.16 g ai/4m ) resulted in 
significantly lower foliage dry weights than the controls or 
the 2.04 g ai/4ra^ rate (S-N-K test. Figure 62). The 2.04 g 
ai/4m2rate resulted in significantly lower foliage dry 
weights than the controls (S-N-K test. Figure 62). 
When hexazinone was applied at the foliage and soil 
position, white spruce foliage dry weight was significantly 
less than when hexazinone was only applied at the soil 
position (P=0.05, ANOV, S-N-K test, App. E, Table E24, 
Figure 62). 
As the hexazinone rate increased and the spray position 
changed from foliage to foliage and soil, the condition of 
the white spruce trees declined (Figure 63). 
iii. Aspen 
Differences in the aspen transformed per cent survival 
values over the range of hexazinone rate treatments were 
highly significant (P=0.01, ANOV, App. E, Table E26) . The 
control resulted in significantly higher transformed per 
cent survival values than any of the other treatments (S-N-K 
test. Figure 64). 
160 
Figure 64, The survival (%) of the Aspen Greenhouse Trial. 
Figure 65. The foliage dry weight of the Aspen Greenhouse 
Trial adjusted by covariance analysis. 
’ Note: Treatments that were not significantly different 
(P=0.05) are Joined by a line. 
161 
% Brown or 
Defoliated 
-100 
-75 
-50 
-25 
-0 
Figure 66. The condition code of the Aspen Greenhouse Trial. 
Condition Code 
162 
Differences in the foliage dry weights over the range 
of hexazinone rate treatments were highly significant 
(P=0.01, COVAR, App. E, Table E27). The control resulted 
in significantly higher foliage dry weights than any of the 
other treatments (S-N~K test, Figure 65). 
As the hexazinone rate increased the condition of the 
aspen declined (Figure 66). 
iv. Hazel 
Differences in the hazel transformed per cent survival 
values over the range of hexazinone rate treatments were 
highly significant (P=0.01, ANOV, App. E, Table E28) . The 
control resulted in significantly higher transformed per 
cent survival values than any of the other treatments (S-N-K 
test, Figure 67)• 
Differences in the hazel foliage dry weights over the 
range of hexazinone treatments were highly significant 
(P=0.01, COVAR, App. E, Table E29). The control resulted 
in significantly higher foliage dry weights than any of the 
other treatments (S-N-K test. Figure 68). 
As the hexazinone rate increased the condition of the 
hazel declined (Figure 69). 
163 
Figures?. The survival (%) of the Hazel Greenhouse Trial. 
Figure 68. The foliage dry weight of the Hazel Greenhouse 
Trial adjusted by covariance analysis. 
’ Note: Treatments that were not significantly different 
(P=0.05) are joined by a line. 
164 
% Brown or 
Defoliated 
-100 
-75 
-50 
-25 
-0 
Fisure 69. The condition code of the Hazel Greenhouse Trial. 
165 
DISCUSSION 
The discussion is presented in two sections in the same 
sequence used previously. The first section deals with the 
post-logging successional behaviour of planted white spruce 
in sucker origin aspen stands from 0 to 13 years after 
logging. It is necessary to be aware of the relationships 
that exist between white spruce and aspen in young white 
spruce plantations before any silvicultural release 
treatments or weeding prescriptions can be made. The second 
section discusses the results of the field and greenhouse 
trials with hexazinone herbicide. 
SECTION I 
THE POST-LOGGING SUCCESSIONAL 
BEHAVIOUR OF PLANTED WHITE SPRUCE IN 
SUCKER ORIGIN TREMBLING ASPEN STANDS 
The volume of aspen per plot appears not to affect the 
volume of white spruce at either Plantation 1 or Plantation 
2 (Figures 3, 4, 5, 14, 15 and 16). Plots which had few or 
many aspen trees contained white spruce with a similar range 
of volumes. This could be due to a number of factors. It 
is likely that variations in site and microclimate on each 
plot masked the relationship between white spruce and aspen 
166 
volumes. Possibly multi-variate analysis using ground frost 
incidence, soil depth and water relations as additional 
factors would have eliminated this variation. 
In Plantation 2 (5 years old), frost damage to white 
spruce is related to the density of trembling aspen (Figure 
17). White spruce trees that were surrounded by many aspen 
trees had less frost damage than those that were surrounded 
by few aspen trees. This relationship is not strong for 
Plantation 1 (13 years old). These results concur with 
those of Clements et al. (1972) who found that more frost 
damage occured among shorter trees than among taller trees 
and more damage occured among open grown trees than among 
protected trees. Steill (1955) found that frost damage 
ceased with full crown closure of the stand. 
The current annual volume increment curves for the 
centrally located white spruce and the aspen tree of mean 
diameter on each circular situation plot are erratic in some 
cases, but certain trends do exist (Figures 7, 8, 9, 10# 11# 
12# 18# 19# 20# 21# 22 and 23). The volume growth of white 
spruce is not affected by the density of aspen in either 
plantations (Figures 7# 9# 11# 18# 20 and 22). The white 
spruce on plots with a few widely spaced aspen trees are 
growing just as well as white spruce on plots with dense 
aspen competition. 
167 
The growth in volume of the aspen trees of mean 
diameter is also not affected by the density of aspen per 
plot (Figures 8, 10, 12, 19, 21 and 23). The current annual 
volume increment curves for the aspen at Plantation 2 are 
very erratic (Figures 19, 21 and 23). These erratic growth 
curves could have been aggravated by inaccurate counting and 
measuring of growth rings. Trembling aspen is a diffuse 
porous wood with annual rings that are extremely difficult 
to see. Kirby (1953) found that 87% of aspen ring counts he 
made in the field were inaccurate. 
When the current annual volume increment curves for the 
paired centrally located white spruce and the mean aspen 
trees on each plot are compared, certain trends become 
apparent at Plantation 1 (Figures 7, 8, 9, 10, 11 and 12). 
Fast growing spruce trees are usually found with slow 
growing aspen trees; slow growing spruce trees are usually 
found with fast growing aspen trees; intermediate growing 
spruce trees are usually found with intermediate growing 
aspen trees. It appears that a fast growing aspen tree will 
suppress its white spruce neighbor. These relationships do 
not exist at Plantation 2. According to Hambley (1980), the 
current annual height increment of planted white spruce 
increases very slowly to a maximum when the trees are about 
14 years of age. The total height of planted white spruce 
increases very little for the first 10 years; after this 
168 
the trees begin to grow rapidly (Stiell 1976, Hambley 1980). 
If volume growth can be expected to follow the same trends, 
then it is possible that the white spruce and aspen in 
Plantation 2 have not yet reached the stage of competition 
that exists at Plantation 1. Fast growing aspen trees may 
begin to limit white spruce growth at Plantation 2 as it 
matures. 
Although no actual measurements of mechanical damage 
were taken, whipping of the white spruce crowns by competing 
aspen trees was observed in both Plantations. Repeated 
years of mechanical abrasion between the aspen and white 
spruce crowns will damage the form and will probably 
decrease the value of the white spruce crop. Dead or broken 
branches provide access to various pathogens that could kill 
the white spruce prematurely. White spruce crowns that are 
limited in size by the competing aspen are no longer able to 
photosynthesize as efficiently and the growth rate of the 
tree is reduced. 
There are 1,458 aspen trees per hectare on Plantation 1 
and 13,333 aspen trees per hectare on Plantation 2. As a 
young sucker origin aspen stand increases in age, 
intraspecific competition results in the death of many 
suckers and a decrease in the number of suckers per hectare. 
A regression equation was established from Plonski's (1974) 
16^ 
relationship between number of aspen trees per hectare and 
age for Site Class 2 aspen. It was extapolated into the 
younger age classes. It was found that the number of aspen 
trees per hectare decreased from 59,524 at 8 years to 6,553 
at 15 years. If the growth rate of white spruce is not 
reduced during the 10 year period after planting, release 
treatments should be postponed. Fewer aspen stems would 
have to be treated after this point in time. It is more 
efficient to control a small number of larger competitors 
than a large number of small competitors. 
The results of this study agree with those of Hambley 
(1980). She found that response to release was best in 
older (15 year old) stands. She was of the opinion that 
these stands had already been left too long and the growth 
rate was reduced by the time release treatment ocurred. 
Younger stands did not suffer suppression and their response 
to release was not as great. Stands should be released 
prior to a reduction in growth rate (Hambley 1980) . 
Johnstone (1978) suggests that white spruce trees are unable 
to benefit from decreased competition until their crowns 
have expanded. This emphasises the need to release a white 
spruce stand from competition before the growth rate is 
suppressed. 
170 
The results of this study suggest that Plantation 2 (5 
years old) should be released before it reaches the age of 
Plantation 1 (13 years old). Plantation 1 is begining to 
show the effects of reduced white spruce volume growth due 
to competition by rapidly growing aspen trees. The white 
spruce trees in this plantation appear to be above the line 
of frost damage and would likely not suffer too much if the 
overtopping aspen canopy was partially removed. The white 
spruce trees on Plantation 2 are not suffering reduced 
volume growth because of aspen competition and trees which 
are growing under an aspen canopy are benefitting because of 
the protection from frost damage. Postponing release 
treatments in Plantation 2 for a few years until the number 
of aspen trees per hectare has decreased would be a sound 
procedure both ecologically and economically. 
SECTION II 
FIELD AND GREENHOUSE TRIALS 
WITH HEXAZINONE HERBICIDE 
1. The Brush Control Trials: 
Hexazinone, placed in a grid pattern, can be used very 
effectively to control brush. Figures 34a and 34b and 36a 
and 36b show that both forms of hexazinone applied at all 
rates and spacings reduced the foliage dry weight of the 
171 
aspen during 1978 (Dunsford 1979) and 1979 at Locations 1 
and 2. There was a reduction in foliage dry weight on the 
hexazinone treated plots from 1978 to 1979 (Figures 34a and 
b and 36a and b). Trees that were partially killed in 1978 
were completely dead by 1979. There was also a reduction in 
the foliage dry weight on the control plots at Location 1 
from 1978 to 1979. Hexazinone was observed to kill trees 
along sucker lines in the treated plots. Sometimes these 
sucker lines extended into the control plots and these trees 
died during 1979. 
The branch diameter at point of foliation method is 
both an efficient and effective way to estimate foliage dry 
weight. Figures 34a and b and 36a and b show that the 
results over both 1978 (Dunsford 1979) and 1979 do not 
differ to any great extent. The branch diameter at point of 
foliation method provides an objective system for evaluating 
the condition and health of young trees. It could be an 
extremely valuable technique for evaluating the 
effectiveness of herbicide control of perennial woody weeds. 
Figure 38 shows that hexazinone effectively reduced the 
foliage dry weight of the aspen at Location 3. Location 1 
and 2 were treated with hexazione herbicide during early 
June and late June 1978; Location 3 was not treated until 
late July 1978. This late season application of hexazinone 
172 
herbicide was not as effective in reducing the aspen 
competition. The effects of hexazinone at Location 3 did 
not appear until after foliation (mid June) 1979. The 
herbicide was applied after the active growing season at 
Location 3. Much of it had likely leached out of the 
rooting zone by the following spring. 
Although there were no significant differences between 
the aspen foliage dry weights for plots treated with liquid 
or solid hexazinone formulations, liquid hexazinone appears 
to control the aspen better. In the 'Gridball' formulation, 
the hexazinone is contained within a slowly disintegrating 
clay ball. Abundant precipitation is needed to release the 
active herbicide ingredient. In plots treated with 
•Gridballs*, it is likely that the herbicide was not 
released until after the active growing season. Much of it 
would have leached out of the aspen rooting zone by the 
following spring and therefore it was not as effective. 
2. The Seedling Survival Trials: 
The results of the seedling survival trials suggest 
that conifer crops are not affected by hexazinone if they 
are planted the year after the herbicide is applied. White 
spruce seedlings grew better on plots receiving the higher 
rates of hexazinone (Figure 40). This suggests that the 
173 
white spruce are responding favorably to release from 
competition. The black spruce grew well and had high 
survival rates regardless of the rate of hexazinone applied 
the year before. Many of the jack pine seedlings died on 
both the control and the hexazinone treated plots. This 
suggests that the jack pine were suffering from some cause 
other than hexazinone phytotoxicity. Evaluation of the 
white and black spruce seedlings should be carried out for a 
few more years in order to establish relationships between 
the degree of release from competition and volume growth of 
the conifers. 
3. The Crop Tree Trials: 
Hexazinone can be used effectively in spot applications 
to selectively release conifers from overtopping hardwood 
competition. White spruce is extremely tolerant to 
hexazinone herbicide. Even the highest rate applied at the 
closest spacing to both the 1.5 m and the 0.5 m white spruce 
did not cause a reduction in height growth. Black spruce 
and jack pine are more sensitive than white spruce to 
hexazinone herbicide. Hexazinone applied at the highest 
rate and the closest spacing reduced the per cent survival 
of these two species (Figures 45 and 48). The other 
herbicide rates did not cause any damage. These results do 
not agree with those of Jones (1978) and Jones et al. 
174 
(1980) who found that spruce was less tolerant to hexazinone 
than pine. They were working with Sitka spruce (Picea 
sitchensis (Bong.) Carr.), Norway spruce (Picea ables. (L.) 
Karst.), lodgepole pine (Pinus, contorta Dougl.), Scots pine 
(Pinus sylvestris L.), and Corsican pine nig IT a., var. 
maritima Arnold). Possibly these species react differently 
to hexazinone than white and black spruce and jack pine. 
Studies in New Zealand have shown that radiata pine is 
extremely tolerant to hexazinone (Bowers and Porter 1975 and 
1977, Coackly and Moor 1977). 
Hexazinone spot applications of up to 0.3750 g ai/spot 
can safely be applied to with 0.5 m of a white spruce tree. 
Hexazinone spot applications of 0.3750 g ai/spot should not 
be applied any closer than 1.0 m to black spruce and jack 
pine, but spot applications of 0.1875 g ai/spot can safely 
be applied to with 0.5 m of these two species. 
If hexazinone had damaged the conifers to a greater 
extent, the regressions established by the branch diameter 
at point of foliation method (App. C, Figures Cl, C2, C3, 
and C4) could have been used to estimate the amount of 
herbicide damage to the trees. There were few partially 
defoliated trees in this trial however, and this limited the 
usefulness of the branch diameter at point of foliation 
method. 
175 
4. Weed Tree and Brush Trials: 
Hexazinone will effectively control aspen and willow. 
Hexazinone applied at most rates and spacings reduced 
the height growth of immature aspen (Figure 50). This was 
mainly a result of increased mortality (Figure 51). Most 
aspen trees were either completely killed by the herbicide, 
or else they survived with little apparent damage. 
The herbicide spacing was a more important factor in 
aspen control than the hexazinone rate. Aspen is extremely 
sensitive to hexazinone and both the low and high rates 
significantly reduced the per cent survival over that of the 
controls (Figure 51). There were no significant differences 
between the two hexazinone rates applied. Hexazinone 
applied at the low rate will both effectively control aspen 
and economize on herbicide expenditure . 
The two closer spacings were much more effective in 
reducing aspen per cent survival than the two wider spacings 
(Figure 51). Even though aspen has a wide spreading root 
system, the herbicide spot application should not be placed 
farther than 1 metre from the tree to ensure complete kill. 
Willow is less sensitive to hexazinone than aspen. The 
high hexazinone rate resulted in significantly less total 
stem growth than the low rate or the controls (Figure 53). 
176 
The high hexazinone rate applied with 4 spot applications 
resulted in greater mortality than the other treatments 
(Figure 54). Unlike the aspen, willow was often only 
partially damaged by the herbicide and its condition was 
reduced (Figure 55). This means that some of the willow 
roots still remain alive and they will probably resucker in 
later years. Herbicide applications may have to be repeated 
in a few years to control willow. Only one application is 
needed to control aspen. 
App. E, Table E19 shows that there were significant 
differences between replications in the willow transformed 
per cent survival values at P=0.05. This could possibly be 
explained by site variation in the field. It is difficult 
to maintain uniform conditions in a large field trial. 
As most herbicide affected aspen trees died and the 
rest remained healthy, there was no need to use the 
regression established by the branch diameter at point of 
foliation method (App. C, Figure C5) to estimate herbicide 
damage. The branch diameter at point of foliation method 
(App. C, Figure C6) could have been used to estimate the 
amount of herbicde damage to the partially killed willow. 
177 
5. The Mature Aspen Trial 
Hexazinone can be used to eliminate an overstory of 
residual mature aspen trees. Figures 56 and 57 show that 
both solid and liquid forms of hexazinone will reduce an 
overstory of residual mature aspen trees. The higher rates 
are more effective. Large diameter trees are more difficult 
to kill than trees of small or medium diameters. The 
herbicide was applied in this trial during late August 1979. 
As discussed in the Brush Control Trials, a June or an early 
July hexazinone appication would likely have been more 
effective. Logging practises in northern Ontario often 
leave mature poor quality aspen trees. The roots of these 
trees are stimulated to sucker by the increased soil 
temperatures and stand disturbances that accompany logging 
operations. By eliminating the residual parent mature aspen 
trees, possibly these suckers will be killed by hexazinone 
which is translocated along the parent root system. Less 
hexazinone is needed to kill a few residual mature aspen 
trees than would be needed to kill each individual sucker. 
6. The Greenhouse Trials: 
Hexazinone will damage young conifer seedlings if it is 
sprayed directly on the foliage. Jack pine is slightly more 
tolerant to foliage treatment of hexazinone than white 
spruce. High rates of hexazinone do reduce the per cent 
survival, foliage dry weight and condition of both species 
178 
(Figures 58, 59, 60 and 61, 62, 63). Both species are 
damaged more by hexazinone applied to the foliage and soil 
than by hexazinone applied to the foliage alone. Hexazinone 
is absorbed more effectively through the root system. By 
applying hexazinone to the foliage and soil, the tree is, in 
effect, coming in contact with more herbicide than it would 
if hexazinone was applied to the foliage alone. 
As discussed in the Methods section, the hexazinone 
rates applied in this trial simulate the concentrations of 
hexazinone that result form spot application made in a grid 
pattern in the field. As a hexazinone spot (either 
"Gridball" or concentrated solution formulation) would not 
likely be applied directly on top of a conifer seedling, 
rates of this magnitude would not normally be sprayed 
directly on a seedling. Results from loblolly pine 
plantations in the Southern United States suggest that 
hexazinone applied as a broadcast foliage spray at rates of 
0.56 kg ai/ha and 1.12 kg ai/ha will not damage conifer 
2 
seedlings (Nelson et al. 1976). The 2.04 g. ai/4m rate 
did not significantly reduce the per cent survival or the 
foliage dry weight of the jack pine over the control. This 
rate is equivalent to a 1 kg ai/ha broadcast application 
rate (Figure 33). White spruce was slightly damaged by this 
rate, but the damage was significantly less than that which 
resulted from herbicide applications at the two higher 
179 
rates. 
Aspen was effectively controlled by all three of the 
applied herbicide rates (Figure 64, 65, and 66). Almost 
100% aspen kill resulted from all of the rates. Aspen is 
extremely sensitive to hexazinone. During this trial, vapor 
drift from some of the treated aspen killed some nearby 
untreated aspen. 
Hazel was also very effectively controlled by all three 
of the applied herbicide rates (Figures 67, 68, and 69). 
Almost 100% hazel kill resulted from all three rates. Some 
live leaf buds were found upon close examination of hazel 
that were severlely damaged. These buds may sprout and, 
given time, the hazel may recover. 
Aspen and hazel are both very sensitive to hexazinone, 
but hazel does have the ability to recover whereas aspen is 
completely killed. In stands where there is dense hazel, 
competition, conifer crop trees may have to be released more 
than once. 
180 
CONCLUSION 
Young white spruce plantations should be released 
from aspen competition prior to a reduction in volume 
growth. This usually occurs sometime between 8 and 15 
years after planting. However, it is neither necessary 
nor desirable to completely remove the aspen canopy as 
white spruce will initially benefit from the frost protection 
offered by a light aspen canopy. 
Aerial spraying with 2,4-D is the most common method 
used today to release white spruce from aspen competition. 
Such treatments are often ineffective resulting in deformed 
aspen and seriously reducing the future merchantable value 
of the aspen component of the stand. If the aerial spray 
treatment is effective, it may completely open up the 
stand by removing the protective aspen canopy and the white 
spruce could suffer from frost damage. 
Prior to the development of hexazinone herbicide, 
hand release was the only feasible method available to 
selectively release white spruce from aspen competition. 
The herbicides 2,4-D and 2,4,5-T were sometimes applied 
in frills by the hack and squirt method. Although this 
was considered to be an improvement over hand release, 
it was still not entirely satisfactory as in both cases 
181 
re-suckering tended to occur. Both hand release and hack 
and squirt were very time consuming and inefficient. It 
is difficult to use hand release treatments in 8 to 15 
year old plantations as the aspen component is quite large 
in diameter and it is hard to break or cut. To release 
a white spruce plantation prior to this is an ecologically 
unsound procedure as very young white spruce are severely 
damaged by frost and benefit from the protection of a 
light overtopping canopy. In addition, the number of aspen 
stems per hectare is very large in a young stand making 
hand release very labor intensive and time consuming. 
The number of aspen suckers rapidly decreases as the stand 
matures. 
Hexazinone herbicide provides a promising method 
of selectively releasing white spruce from aspen competition. 
It is easy to apply, it will destroy large diameter competitors 
and it will kill entire sucker lines of very young aspen. 
Conifers are very tolerant to hexazinone and it can be 
effectively used to release white spruce, black spruce 
and jack pine from many of the weed tree and brush species 
common in the boreal forest. 
182 
THE USE OF HEXAZINONE FOR WEED CONTROL 
IN SITE PREPARATION, PLANTATION ESTABLISHMENT 
AND PLANTATION TENDING IN THE BOREAL FOREST 
Hexazinone herbicide is a very powerful silvicultural tool that 
can be used to kill deciduous weed species and to release conifer crops 
in the boreal forest. It is not yet licensed for forestry in Canada, 
but this herbicide has been used considerably in radiata pine plantations 
in New Zealand and in longleaf pine plantations in the southern United States. 
This user guide discusses the use of *Gridball' and concentrated solution 
formulations of hexazinone (DPX-LE and DPX-LX). Foliage broadcast sprays 
are not discussed as these have been found to be damaging to conifers 
in the southern pine plantations (South et al 1976) and cause minimal 
damage to conifers in the boreal forest (Polhill 1978). 
183 
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184 
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186 
Additional Comments: 
1) Although the results of Dunsford (1979) and Day and Harvey (1980) 
show that there are no significant differences between the effectiveness 
of liquid and solid hexazinone formulations, upon observation the liquid 
formulation appears to be slightly more effective than the solid. The 
solid formulation is still quite effective however and, due to its ease 
of application, may be the preferred formulation, especially when untrained 
personnel are involved in herbicide applications. 
2) Hexazinone applications are best made just before the period of 
active growth. They may also be made during the period of active weed 
growth provided there is sufficient precipitation to break down the 
'Gridballs' and leach in the hexazinone. Applications made in mid-July 
and later in the season may not be effective in the year of application. 
They may be effective the next year, but herbicidal activity is reduced. 
3) Hexazinone will completely kill the root system of trembling aspen. 
When willow, alder or hazel competition is present, hexazinone applications 
may have to be repeated as the root systems of these species may not be 
completely killed by hexazinone. 
4) The rates of hexazinone given in this user guide may vary depending on 
the soil texture, amount of precipitation and age and stage of development 
of the competition. 
187 
LITERATURE CITED 
Ackerman, R.F. 1957. The effect of various seedbed treat- 
ments on the germination of white spruce and lodge 
pole pine seedlings. Can. Dep. Northern Affairs and 
Nat. Res. For. Br. Tech. Note No. 63. 
Arend, J.L. 1955. Tolerance of conifers to foliage sprays of 
2,4-D and 2,4,5-T in lower Michigan. U.S. Dep. 
Agric. For. Serv. Lake States For. Stn. Tech. Note. 
No. 437. 
Aregetsinger , L.M. 1957. Frost and other influences on the 
developement of white spruce and red pine plan- 
tations. Kimberly-Clark of Michigan Inc. 
Baker. F.S. 1918. Aspen as a temporary forest type. J. For. 
16:294-303. 
Baker, F.S. 1949. A revised tolerance table. J. For 47:179- 
181. 
Barnes, B.V. 1966. The clonal growth habit of American 
aspens. Ecology 47:439-447. 
Baskerville, G.L. 1972. Use of logarithmic regressions in 
estimation of plant biomass. Can. J. For. Res. 2:49- 
53. 
Bedell, G.H.D. 1948. White spruce reproduction in Manitoba. 
Can. Dep. Mines and Res. Mines Forests and Services 
Br. Silv. Res. Note No, 87. 
Bella, I.E. and J.P. De Franceshi. 1972. The effect of log- 
ging practises on the developement of new aspen 
stands, Hudson Bay, Saskatchewan. Can. Dep. Environ. 
For. Serv. North. For. Res. Centre. Inf. Rep. NOR-x 
-33. 
Bissinger, J. 1965. Stand conversion to other species. 
Trembling aspen in Manitoba: papers presented at the 
1965 annual meeting. Manitoba section, Canadian Ins- 
titute of Forestry; Reprinted by the Department of 
Forestry and Rural Developement, 1967. 
Blackmore, D.G., and W.G. Corns. 1979. Lodgepole pine and 
white spruce establishment after glyphosate and fer- 
tilizer treatments of grassy cutover forest land. 
For. Chron. 55:102-105. 
188 
Bowers, A. and J.F. Porter, 1975. Preliminary investiga- 
tions with DPX3674 for weed control in forestry. 
Proc. N.Z. Weed and Pest Control Conf. 28:160-164. 
Bov;ers, A. and J.F. Porter, 1977. control of forest weeds 
with DPX3674. Proc. N.Z. Weed and Pest Control Conf. 
30: 227-232. 
Brace, L.C. 1964. Early development of white spruce as 
related to planting method and planting stock height 
. Can. Dep. For. Dep. For. Publ. No. 1049. 
Buckman, R.E. and L.H. Blankenship, 1965. Repeated spring 
prescribed burning reduces abundance and vigor of 
aspen root suckering. J. For. 63:23-25. 
Buell, M.F. and W.A. Niering. 1957. Fir-spruce-birch forest 
in northern Minnesota. Ecology 38: 602-610. 
Burgar, R.J. 1964. The effect of seed size on germination, 
survial and initial growth in white spruce. For. 
Chron. 40:93-97. 
Cayford, J.H. 1957 Influence of the aspen overstory on 
white spruce growth in Saskatchewan. Can. Dep. of 
North. Affairs and Nat. Res. For. Br. Tech. Note 
No.58. 
Cayford, J.H., V. Hildahl, L. D. Nairn and M. P. H. Wheaton. 
1959. Injury to trees from winter drying and frost 
in Manitoba and Saskatchewan in 1958. For. Chron. 
35:282-290. 
Cayford, J.H. and R.M. Waldron. 1962. Some effects of leaf 
and needle litter on greenhouse germination of white 
spruce and jack pine seed. For. Chron. 38:229-231. 
Christian. C.S. and R.A. Perry, 1953. The systematic des- 
cription of plant communities by the use of symbols. 
J. of Ecology 41:100-105 
Clarke, W.B.M. 1940. Experimental girdling in mixedwood 
stands in Mew Brunswick. Dominion For. Serv. Silv. 
Res. Note No.62. 
Clements, J.R., J.W. Fraser and C.W. Yeatman. 1972. Frost 
damage to white spruce buds. Can. J. For. Res. 2:62 
-63. 
Coackley, A. and R.H. Moor, 1977. DPX3674- A broad spectrum 
herbicide for weed control in forestry. Proc. N.Z. 
Weed and Pest Control Conf. 30:233-237. 
189 
Crossley, D.I. 1955. Mechanical scarification to induce 
white spruce regeneration in old cut-over spruce 
stands. Can. Dep. Northern Affairs and Nat. Res. 
For. Br. Tech. Note No. 24. 
Cunningham, G. C. 1953. Growth and development of coniferous 
plantations. Can. Dep. Res. and Dev. Silv. Res. Note 
No. 103. 
Daly, E.S. 1950. Improvement cutting in a mixedwood stand. 
Can. Dep. Res. and Dev. For. Br. For. Res. Div. 
Silv. Lflt. No. 46. 
Day, R.J. 1963a. Spruce seedling mortality caused by ad- 
verse summer microclimate. Dep. For. Publ. No. 
1003 . 
Day, R.J. 1963b. Additional watering to improve spruce ger- 
mination in the Crowsnest Forest. For. Res. Br. Cal- 
gary, Alta. Unpub. M.S. 
Day, R.J. 1963c. Regeneration in old cut-over spruce stands 
eleven years after scarification. For. Res. Br. 
Calgary, Alta. Unpub, M.S, 
Day, R.J. 1964. The microenvironments occupied by spruce 
and fir regeneration in the Rocky Mountains. Dep. 
For. Publ. No. 1037. 
Day, R.J. 1967. A plea for standard tree name abbreviations 
. For. Chron. 43. 121-134. 
Day, R.J. 1968. Aerial spray assessment for regeneration re- 
lease. Faculty of Forestry, University of Toronto, 
Ontario. Unpub. M.S. 
Day, R.J, 1970. Shelterwood felling in late successionial 
stands in Alberta’s Rocky Mountain subalpine forest. 
For. Chron. 46:380-386. 
Day, R.J. and E.M. Harvey. 1980a, Forest dynamics in the 
boreal mixedwood. In Proc. Boreal Mixedwood Conf. In 
press. 
Day, R.J. and E.M. Harvey. 1980b. Velpar (Hexazionone) Her- 
bicide for brush control and regeneration release in 
the boreal forest. Interm. Report for DuPont (Can- 
ada) Ltd. 
190 
Dix, R.L. and J.M. Swan. 1971. The roles of disturbance and 
succession in upland forest at Candle Lake, Saskat- 
chewan. Can. J. Bot- 49:657-676. 
Dobbs, R.C, 1976. Effect of initial mass of white spruce and 
lodgepole pine planting stock on field performance 
in the British Columbia interior. Can. For. Serv. 
Pacific For. Res. Cent. BC-X-149. 
Dudley, C.S. and L.R. Nelson, 1979. Aerial application of 
Velpar on first and second year loblolly pine 
plantations in North Carolina. [Abstract]. In Proc. 
32nd Annual Meeting Southern Weed Sci. Soc., 1979. 
January 23—25. Forestry Section. In press. 
Dunsford, L.M. 1979. Field trials with Velpar (hexazinone) 
herbicide for brush control and regeneration release 
in the boreal forest. Undergrad. Thesis, School of 
Forestry, Lakehead University, Thunder Bay, 'P', 
Ontario. 
Endean, F. 1972. Soil temperature, seedling growth, and 
white spruce regeneration. In White spruce: the 
ecology of a northern resource. Edited by R.G. 
McMinn. Can. For. Serv. Dep. Environ. North. For. 
Res. Centre. Inf. Rep. NOR-X-40. pp.15-20. 
Endean, F. and W.D. Johnstone. 1974. Prescribed fire and 
regeneration on clearcut spruce-fir sites in the 
foothills of Alberta. Environ. Can. Can. For. Serv. 
Inf. Rep. NOR-X-126. 
Fetherolf, J.M. 1917. Aspen as a permanent forest type. J. 
For. 15:757-760. 
Fitzgerald, C.H. and J.C. Fortson, 1977. Activated charcoal 
root dips and velpar phytotoxicity in pine seedlings 
. [Abstract]. Proc. Ann. Meeting Southern Weed Sci. 
Soc. 30:280. 
Fowells, H.A. 1965. Silvics of forest trees of the United 
States. U.S. Dep. Agric. For. Serv. Washington D.C. 
Agriculture Handbook No.271. 
Gagnon, D. 1961. Rainfall and width of annual rings in 
planted white spruce. For. Chron. 37: 96-101. 
Gregory, R.A. 1966, The effect of leaf litter upon es- 
tablishment of white spruce beneath paper birch. 
For. Chron. 42: 251-255. 
191 
Griffith, B.G. 1931. The natural regeneration of spruce in 
central British Columbia. For. Chron. 7:204-219. 
Haagsma, T. 1968. The chemistry of phenoxy herbicides and 
picloram. Paper for O.P.F.A. course on "Herbicides 
in Forest Management". Feb. 21, 1968. 9 pp. 
Haig, R.A. 1962. Regeneration in Manitoba. For. Chron. 38: 
74-78 . 
Hall, J.P, 1979. Early survival and growth of four age 
classes of white spruce seedlings in western New- 
foundland. Can. For. Serv. Nfld. For. Res. Centre, 
St. John's, Nfld. Inf. Rep. N-X-165. 
Hambley, E.S.L. 1980. Growth of young black and white 
spruce in northern Ontario. Prepared under contract 
for Ontario Ministry of Natural Resources. For. Man. 
Section, Toronto, Ont. Unpub. M.S. 
Hamilton, R.A. 1979. A chemical method to reduce hardwood 
competition on pine sites. In Proc. 32nd Annual 
Meeting Southern Weed Sci. Soc. 1979. January 23- 
25. Forestry Section. In press. 
Heinselman, M.L. 1954. The extent of natural conversion to 
other species in the Lake States aspen-birch type. 
J. For. 52:737-738. 
Heinselman, M.L. 1973. Fire in virgin forests of the Boun- 
dary Waters canoe area, Minnesota. Quarternary 
Research. 3:329-382. 
Hills, G. A. 1961. The ecological basis for land-use 
planning. Ont. Dept. Lands For., Res. Br. Res. Rpt. 
46. 
Holman, H.L. 1927. Natural regeneration of spruce in 
Alberta. For. Chron. 3:3pp. 
Holt. L. 1955. White spruce seedbeds as related to natural 
regeneration: a digest prepared at the request of 
the Woodlands Section Council. Canadian Pulp and 
Paper Association, Pulp and Paper Research Institute 
of Canada. 
Horton, K.W. and J.S. Maini. 1964. Aspen reproduction: its 
characteristics and control. Can. Dep. For. Res. 
Br. Monogr. No. 64-0-12. 
192 
Hughes, E.L. 1978. Assessment of recent plantations of pine 
and spruce in the Bathurst area of New Brunswick 
1975-1976. Can. For. Serv. Dep. Fisheries and 
Environ. Maritimes For. Res. Cent. Inf. Rep. M-X-85. 
Husch, B,, C.S. Miller and T.W. Beers, 1972. Forest Men- 
suration. John Wiley and Sons, Toronto, Ontario. 
Jarvis, J.M. 1965. Silvics and ecology. Trembling aspen in 
Manitoba: papers presented at the 1965 annual 
meeting. Manitoba Section, Canada Institute of 
Forestry; Reprinted by the Department on Forestry 
and Rural Development, 1967. 
Jarvis, J.M. 1968. Silviculture and management of natural 
poplar stands. In Growth and utilization of Poplars 
in Canada. Edited by J.S. Maini and J.H. Cayford. 
Dep. For. and Rural Dev., Ottawa, pp.70-87. 
Jeffers, J.N.R. 1959. Experimental design and analysis in 
forest research. Almquist and Wiksell, Stockholm. 
Johnstone, W.D. 1978. Growth of fir and spruce advance 
growth and logging residuals following logging in 
west-central Alberta. Can. For. Serv. North. For. 
Res. Centre. Edmonton, Alta. Inf. Rep. NOR-X-203. 
Jones, R.G. 1978. Weedkilling with a bonus. Forestry and 
British Timber. 7:15-16. 
Jones, R.G., G.R. Jones, E.Scott and S.J. Godding. 1980. An 
evaluation of Hexazinone as a selective forestry 
herbicide. In Proc. Weed Control in Forestry Conf., 
April 1-2, 1980. University of Nottingham, U.K. 
U.K. Ass. of Applied Biologists, pp. 217-225. 
Kemperman, J.A., N.F. Lyon, and S. Navartil. 1976. In- 
cidence and volume of defect in second growth apen 
stands in northern Ontario. Ontario Ministry of 
Natural Resources, For. Res. Br. North. For. Res. 
Unit, For. Res. Rep. No. 102. 
Kill, A.D. 1970. Effects of spring burning on vegetation in 
old partially cut spruce-aspen stands in east-cen- 
tral alberta. Can. For. Serv. Dep. Fisheries and 
Forestry. For. Res. Lab. Edmonton, Alta. Inf. Rep. 
A-X-33. 
Kirby, C.L. 1953. Accuracy of ring counts in poplar. Can. 
Dep. Res. Dev. For. Br. For. Res. Silv. Lflt. 85. 
Koroleff, K. 1954. Leaf litter as a killer. J. For. 52: 178 
-182. 
193 
Kossuth, S.V., J, Young, I Voeller, and H.A. Holt. 1978. 
Four season injection of hardwoods. Weed Research 
18: 161-167. 
Le Barron, R.K. 1945. Mineral soil is a favorable seed bed 
for spruce and fir. U.S. Dep. Agric. Lake States 
For. Exp. Stn. Tech. Note No. 237. 
Lees, J.C. 1963. Partial cutting with scarification in 
Alberta spruce-aspen stands. Can. Dep. For. For. 
Res. Br. Publ. No. 1001. 
Lees, J.C. 1966. Release of white spruce from aspen com- 
petition in Alberta’s spruce-aspen forest. Can. 
Dep. For. Publ. No. 1163. 
Lees, J.C. 1970. Natural regeneration of white spruce under 
spruce-aspen shelterwood, B-18a Forest Section, 
Alberta. Can. For. Serv. Dep. Fisheries and Forestry 
Publ. No. 1274. 
Lees, J.C. 1972. Site factors contributing to spruce re- 
generation problems in Alberta’s mixedwood. In 
White spruce: the ecology of a northern resurce. 
Edited by R.G. McMinn. Can. For. Serv. Dep. Environ 
. North For. Res. Centre. Inf. Rep. NOR-X-40. pp. 
8-14 . 
Lyons, R.W, 1925. Artificial regeneration of white spruce. 
For. Chron. 1: 9-19. 
Maclean, D.W. 1960. Some aspects of the aspen-birch-spruce- 
fir type in Ontario. Can. Dep. For. For. Res. Div. 
Tech. Note No. 94. 
Maini , J.S. 1960. Invasion of grassland by Populus 
tremuloides in the Northern Great Plains, Ph.D. 
Thesis, Univ. of Saskatchewan, Can. 
Maini, J.S. 1968. Silvics and ecology of Populus in Canada. 
In Growth and utilization of poplars in Canada. 
Edited by J.S. Maini and J.H. Cayford. Dep. For. and 
Rural Dev. pp. 20-69. 
Maini, J.S. and K.W. Horton, 1966a. Vegetative propagation 
of Populus spp. 1. influence of temperature on for- 
mation and initial growth of aspen suckers. Can. J. 
Bot. 44: 1183-1189. 
194 
Maini, J.S. and K.W. Horton. 1966b. Reproductive response 
of Populus and associated Pteridium to cutting, 
burning and scarification. Can. Dep. For. and Rural 
Dev. For. Br. Dep. Publ. No 1155. 
Mathews, A.G. 1970. The effect of rate of application and 
leaching of bromacils and "Tandex" on the growth and 
survival of black and white spruce seedlings. 
Forestry Research Report, Faculty of Forestry, Univ. 
of Toronto, Ont. Unpub. M.S. 
Methven, I.R., C.E. Van Wagner, and B.J. Stocks. 1975. The 
vegetation on four burned areas in northwestern 
Ontario. Petawawa Forest Experiment Station, Inf. 
Rep. PS-X-60. 
Mork, E. 1938. Germination of spruce and pine seed at 
various temperatures and degrees of moisture. 
Reports of the Norwegian Forest Research Institute 
No. 21. 
Mullin, R. E. 1964. Reduction in growth of white spruce 
after outplanting. For. Chron. 40: 488-493, 502. 
Mullin, R. E. 1966a. Comparisons between seedlings and tran- 
splants in fall and spring plantations. Ont. Dep. 
Lands and For, Res. Br. Res, Rep. No. 85. 
Mullin, R. E. 1966b. Influence of depth and method of 
planting on white spruce. J. For. 64: 466-468. 
Mullin, R. E. 1969. Effects of competition on post-planting 
growth of potted white spruce. Tree Planters Notes. 
20: 19-22. 
Mullin, R. E. 1973. Post planting cultivation aids old field 
white spruce plantations. Tree Planters Notes. 24: 6 
-7. 
Mullin, R. E. 1975. Old field planting of white spruce. Tree 
Planters Notes. 26: 3-4, 21. 
Murray, T.S. 1980. T.T.S. disc trench scarifier. Can. For. 
Serv. Maritimes For. Res. Centre. Tech, Note No, 9. 
Myles, D.V. 1978. A compendium of silvicultural equipment. 
Forest Management Institute. Inf. Rep. FMR-X-115. 
Nelson, L.P., J.D. Walstad, C.S. Dudley and J.H. Breland, 
1977. Preemergence herbicide treatments for lob- 
lolly pine plantations. Proc. Ann. Meeting Southern 
Weed Sci. Soc. 30: 261-268. 
195 
Newbold, R.A. 1979. Integrating weed control methods in 
southern pine management. In Proc. 32nd. Ann. 
Meeting Southern Weed Sci. Soc., 1979. January 23- 
25. Forestry Section. In Press. 
Noste, N.V. and H.M. Phipps, 1978. Herbicide and container y/ 
system effects on survival and early growth of 
conifers in northern Wisconsin. For. Chron; 54: 
209-212 
Ohman, L.F., C.T. Cushwa, and R.E, Lake. 1973. Wilderness 
ecology: the upland plant communities, woody browse 
production, and small mammals of two adjacent 33- 
year-old wildfire areas in northeastern Minnesota. 
U.S. Dep. Agric. For. Serv. Gen. Tech. Rep. No. 7. 
O'Laughlin, T.C., L.R. Nelson, J.d. Walstad, J.H. Breland 
and J.E. Voeller, 1976. Velpar and other preemer- 
gence herbicides for use in establishment of lob- 
lolly pine plantations. Proc. Ann. Meeting Southern 
Weed Sci. soc. 29: 262-268. 
Ontkean, G. and L.A. Smithers, 1959. Growth of Alberta 
white spruce after release from aspen competition. 
Can. Dep. of Northern Affairs and Nat. Res. For. Br. 
Mimeo 59-L. 
Parker, J.A. 1979. Control of single oak trees (Quercus 
spp.) with hexazinone pellets. In Proc. 32nd Ann. 
Meeting Southern Weed Sci. Soc., 1979. January 23- 
25. Forestry Section. In press. 
Parker, W.A. 1952. Spruce regeneration on deep moss after 
logging. Can. Dep. of Res. and Dev. For. Br. Silv. 
Lflt. No. 62. 
Perala, D.A. 1974a. Prescribed burning in an aspen-mixed 
hardwood forest. Can. J. For. Res. 4:222-228. 
Perala, D.A. 1974b. Repeated prescribed burning in aspen. 
U.S. Dep. Agric. For. Serv. North Cent. For. Exp. 
Stn., St. Paul, Minn. Res. Note NC-171. 
Phelps, V.H. 1948. White spruce reproduction in Manitoba 
and Saskatchewan. Can. Dep. of Mines and Res. Mines 
For. and Services Br. Silv. Res. Note No.86. 
Phelps, V.H. 1951. Survival of white spruce seedlings. 
Can. Dep. of Res. and Dev. For. Br. Silv. Lflt. No 
56. 
Plice, M.J., and G.W, Hedden. 1931. Selective girdling of 
hardwoods to release young growth of conifers. J. 
For. 29:32-40. 
Plonski, W.L. 1974. Normal yield tables (metric) for major 
forest species of Ontario. Ontario Ministry of 
Natural Res. For. Div. 
Pogue, H.M. 1946. Regeneration and growth of white spruce. 
Dep. of Lands and For., B. C. For. Serv. Victoria, 
B.C. 
Polhill, B.E. 1978. A herbicide trial for plantation 
release in the Thunder Bay District. Undergrad. 
Thesis, School of forestry, Lakehead University, 
Thunder Bay, *P', Ontario. 
Pratt, R.H.M. 1966. Aerial spraying with 2,4-D to eliminate 
trembling aspen. Woodlands Review Section 67:460- 
462. 
Quaite, J. 1953. Poisoning with "amnate" to eliminate 
aspen. Can. Dep. of Northern Affairs and Nat. Res. 
For. Br. Silv. Lflt. No. 94. 
Reeder, C.J. and M.F. Jurgensen. 1979. Fire induced water 
repellency in forest soils of upper Michigan. Can. 
J. For. Res. 9:369-373. 
Roe, E.I. 1946. Extended periods of seedfall of white spruce 
and balsam fir. U.S. Dep. Agric. For. Serv. Lake 
States For. Exp. Stn. Tech. Note No. 261. 
Roe, E.I. 1953. Foliage spraying in chemical bruch control. 
U.S. Dep. Agric. For. Serv. Lake States For. Exp. 
Stn. Misc. Rep. No. 21:17-21. 
Romancier, R.M. 1965. 2,4-D and 2,4,5-T and related 
chemicals for woody plant control in the south- 
eastern United States. U.S. Dep. Agric. For. Serv. 
Georgia Forest Research Council, Macon, Georgia. 
Rep. No. 16. 
Rowe, J.S. 1953a. Delayed germination of white spruce on 
burned ground. Can. Dep. Res. and Dev. For. Br. 
Silv. Lflt. No.84. 
Rowe, J.S. 1953b. Viable seed on white spruce trees in 
midsummer. Can. Dep. of Northern Affairs and Nat. 
Res. For. Br. Silv. Lflt. No. 99. 
197 
Rowe, J.S. 1955. Factors influencing white spruce repro- 
duction in Manitoba and Saskatchewan. Can. Dep. of 
Northern Affairs and Nat. Res. For. Br. Tech. Note 
No . 3 . 
Rowe, J.S. 1961. Critique of some vegetational concepts as 
applied to forests of northwestern Alberta. Can. J. 
Bot. 39:1007-1016. 
Rowe, J.S. 1972. Forest regions of Canada. Can. B'or. Serv. 
, Ottawa, Ont. Publ. No. 1300. 
Rowe, J.S. and G.W. Scotter. 1973. Fire in the boreal 
forest. Quat. Res. 3:444-464. 
Rudolf, P.O. and R.J. Watt, 1956. Chemical control of brush 
and trees in the Lake States. U.S. Dep. Agric. For. 
Serv. Lake States For. Exp. Stn. St. Pap. No. 41. 
Schier, G.A. 1975. Deterioration of aspen clones in the 
middle Rocky Mountains. U.S. Dep. Agric. For. Serv- 
Intermt. For. Range Exp. Stn. Res. Pap. INT-170. 
Schier, G.A. and R.B. Campbell. 1978. Aspen sucker regen- 
eration following burning and cutting on two sites 
in the Rocky Mountains. For. Sci. 24:303-308. 
Schier, G.A. and A.D. Smith. 1979. Sucker regeneration in 
a Utah aspen clone after clearcutting, partial 
cutting, scarification and girdling. U.S. Dep. 
Agric. For. Serv. Intermt. For. Range Exp. Stn. Res. 
Note INT-253. 
Severson, K.E. and J.F. Thilenius. 1976, Class!fication of 
quaking aspen stands in the Black Hills and Bear 
Lodge Mountains. U.S. Dep. Agric. For. Serv. Rocky 
Mt. For. Range Exp. Stn. Res. Pap. RM-166. 
Shafi, M.I. and G.A. Yarranton. 1973a. Diversity, 
floristic richness, and species evenness during a 
secondary (post-fire) succession. Ecology 54:879-902 
Shafi, M.I, and G.A. Yarranton. 1973b. Vegetational hetero- 
geneity during a secondary (post-fire) succession. 
Can. J. Bot. 51:73-90. 
Shirley, H.L. 1931. Does light burning stimulate aspen 
suckers? J. For. 29:524-525. 
198 
Shirley, H.L. 1932. Does light burning stimulate aspen 
suckers? II J. For. 30:419-420. 
Smith, C.R. 1979. Silvicultural equipment reference ca- 
talogue for northern Ontario. Ontario Ministry of 
Natural Resources. 
South, D., R.H. Crowley, and D.H. Gjerstad, 1976. Recent 
herbicide weed control results in pine seedbeds. 
Proc. Ann. Meeting South. Weed Sci. Soc. 29:300-308 
Steele, R.G.D. and J.H. Torrie, 1960. Principles and pro- 
cedures of statistics with special reference to the 
biological sciences. New York - Toronto - London: 
McGraw-Hill Book Conpany, Inc., 481 pp. 
Steill, W. M. 1955. The Petawawa plantations. Dep. North. 
Affairs and Nat. Res. For. Br. For. Res. Div. Tech. 
Note. No. 21. 
Steill, W.M. 1958. Pulpwood plantations in Ontario and 
Quebec. Woodl. Sect. Index. Can. Pulp. Pap. Ass. No. 
1770 (F2). 
Steill, W.M. 1976. White spruce: artificial regeneration in 
Canada. Can. Dep. Environ. For. Serv. For. Man. 
Inst. Inf. Rep. FMR-X-85. 
Steill, W.M. and A.B. Berry. 1973. Developement of un- 
thinned white spruce plantations to age 50 at 
Petawawa Forest Experiment Station. Can. Dep. 
Environ. For. Serv. Publ. No. 1317. 
Stenecker, G.A. 1963. Results of a 1936 release cutting to 
favour white spruce in a 50 year old white spruce- 
aspen stand in Manitoba. Can. Dep. For. For. Res. 
Br. Publ. No. 1005. 
Stenecker, G.A. 1974a. Factors affecting the suckering of 
trembling aspen. For. Chron. 50:32-34. 
Stenecker, G.A. 1974b. Selective cutting to release white 
spruce in 75 to 100 year old white spruce trembling 
aspen stands, Saskatchewan. Can. Dep. Environ. For. 
Serv. North. For. Res. Centre. Inf. Rep. NOR-X-121. 
Stoeckler, J.H. 1948. The growth of quaking aspen as 
affected by soil properties and fire. J. For. 46: 
727-737. 
199 
Stoeckler, J.H. and J.W. Macon. 1956. Regeneration of aspen 
cutover areas in northern Wisconsin. J. For. 52:13- 
16. 
Strang, R.M, 1972. Succession in unburned subartic wood- 
lands. Can. J. For. Res. 3:140-143. 
Sutton, R.F. 1965a. Rehabilitation of overmature mixedwood 
with white spruce after dybar (fenuron) treatment. 
Can. Dep. For. Dep. For. Publ. No. 1124. 
Sutton, R.F. 1965b. Stand improvement with white spruce 
planted with concurrent dybar (fenuron) treatment. 
For. Chron. 41:108-111 
Sutton, R.F. 1967. Dybar (fenuron) a siIviculturally under- 
rated brush killer. Woodlands Review Section. Pulp 
and Paper Magazine of Canada. March pp. 3-6. 
Sutton, R.F. 1969. Chemical control of competition in plan- 
tations. For. Chron. 45:1-5. 
Sutton, R.F, 1974. white spruce group planting in herbicide 
-treated, overmature mixed wood: 11-year results. 
For. Chron. 50:1-3. 
Sutton, R.F. 1975a. Enhancement by herbicidal site pre- 
paration. Can. J. For. Res. 5:217-223. 
Sutton, R.F. 1975b. Nutrition and growth of white spruce 
outplants: enhancement by herbicidal site pre- 
paration. Can. J. For. Res. 5:217-223. 
Sutton, R.F. 1978. Glyphosate herbicide : an assessment of 
forestry potential. For. Chron. 54:24-28. 
Thompson, CC. 1949. Releasing conifers in a young hardwood 
stand. Can. Dep. mines and Res. Mines, For, and 
Sci. Serv. Br. Silv. Lflt. No. 3 4 . 
Tucker, R.E., J.M. Jarvis and R.M. Waldron. 1968. Early 
survival and growth of white spruce plantations. 
Riding Mountain National Park, Manitoba. Can. Dep. 
For. and Rural Dev. For. Br. Dept. Publ. No. 1239. 
Turner , B.Jr., 1979. Georgia tests a new forest herbicide. 
In proceedings 32nd Annual Meeting, Southern Weed 
Sci. Soc., 1979. January 23-25. Forestry Section. 
In press. 
Wagg, J.W.B, 1964, White spruce regeneration on the Peace 
and Slave River lowlands. Can. Dep. For. For. Br. 
Dep. For Publ. No. 10069. 
200 
Wagg, J.W.B. 1967. Origin and developement of white spruce 
root-forms. Can. Dep. For. and Rural Dev. For. Br. 
Dep. Publ. No. 1192. 
Waldron, R.M. 1961. Seeding white spruce at the base of 
aspen. For. Chron. 38:224-227. 
Waldron, R.M. 1963. August-November seed and litter fall in 
a mature white spruce stand. For. Chron. 39:333. 
Waldron R.M. 1964. The effect of preplanting ground treat- 
ment on early survival and growtli of planted white 
spruce. Tree Planters Notes. 65: 6-8. 
Waldron, R.M. 1966. Factors affecting natural white spruce 
regeneration on prepared seedbeds at the Riding 
Mountain Forest Experimental Area, Manitoba. Can. 
Dep. For. and Rural Dev. For. Br. Dep. Publ. No. 
1169. 
Weed Science Society of America. 1979. Herbicide handbook 
of the Weed Science Society of America, Fourth 
Edition. Illinois. W.S.S.A. Herbicide Handbook 
Committee. 
Wiltrout, T.R. and H.A. Holt, 1975. Prospects of control- 
ling vegetation in new forest plantaions. Proc. 
North Cent. Weed Control Conf. 30:31-36. 
Woods, G.T. and R.J. Day, 1977. Ecological effects of 
forest fire in poplar communities in Quetico 
Provincial Park. Ontario Ministry of Natural 
Resources. Atikokan District, North Central Region. 
Fire Ecology Study. Rep. No. 6. 
Wright, R.F. 1976. The impact of forest fires on the nut- 
rient influxes to small lakes in northeastern Min- 
nesota. Ecology 57:649-663. 
Zackrisson, O. 1977. Influence on forest fires on the north 
Swedish boreal forest. Oikos 29:22-23. 
Zehngraff, P. 1947. Possibilities of managing aspen. U.S. 
Dep. Agric, For. Serv. Lake States For. Exp. Stn. 
Lake States Aspen Report No. 21. 
201 
Zhukov, A.P. 1976. The impact of anthropogenic factors on 
forest biogiocenoses in Siberia. In Man and the 
Boreal Forest. Edited by C.O. Tamm. Stockholm. 
Swedish National Research Council. 
202 
APPENDIX A 
Maps showing exact locations of Plantations 1 and 2 
and the Hexazinone Herbicide Trials. 
Scale (Km) i L_J 1 
12 3 
Figure Al. The location of Plantation 1 relative to Highway 
527 and the Wolf River Road. 
204 
/ 
f 
/ 
r 
\ 
r / 
Scale (Km) I t—i—i 
Figure A2 The location of Plantation 2 relative to the 
Wolf River Road and Anders Lake. 
I 
205 { 
I 
206 
I 
t 
/ Brush Control/ 7 
Trial Loc. 3/ / 
I 
\ 
\ 
\ 
\ 
\ 
Figure A5» The location of the Black Spruce Crop Tree Trial. 
208 
APPENDIX B 
Regressions relating diameter above butt swell to volume 
for the aspen and the white spruce at Plantations 1 and 2. 
2 09 
45- 
40. 
35’ 
30. 
25 
20. 
15 
10. 
5’ 
Bl. Points plotted represent diameter above 
butt swell and volume of aspen at Plantation 
1. 
210 
Figure B2. Points plotted represent diameter above butt 
swell and volume of white spruce at Plantation 
1. 
Volume (dm 
211 
Figure B3* Points plotted represent diameter above butt 
Bwell and volume of aspen at Plantation 2. 
Volume (dm 
212 
Figure B4. Points plotted represent diameter above butt 
swell and volume of white spruce at Plantation 
2. 
Volume (dra 
213 
APPENDIX C 
Regression curves relating foliage dry weight to branch 
diameter at the point of foliation. 
214 
D 
FDW = 0.587x77.651 
32 
28 
24 
20 
16 
12 
8 
4 
0 
1.0 1.2 
BRANCH DIAMETER (cm) AT POINT OF FOLIATION 
Cl Points plotted represent branch diameter and foliage dry weight 
of Picea glauca. 
2^5 
BRANCH DIAMETER (mm) AT POINT OF FOLIATION 
Fiqure C2. Points plotted represent branch diameter and foliage dry weight 
of Picea qlauca. 
FOLIAGE DRY WEIGHT (q.) 
216 
BRANCH DIAMETER (cm) AT POINT OF FOLIATION 
Figure C3. Points plotted represent branch diameter and foliage dry weight 
of Picea mariana. 
FOLIAGF DRY WEIGHT (q.) 
217 
BRANCH DIAMETER (cm) AT POINT OF FOLIATION 
Figure C4. Points plotted represent branch diameter and foliage dry weight 
of Pinus banksiana. 
FOLIAGE DRY WEIGHT (q.) 
218 
Figure C5» Points plotted represent branch diameter (X) 
and foliage dry weight (Y) of Populus 
tremuloides. 
FOLIAGE DRY ^^IGHT (G) 
219 
BRANCH DIAMETER (cm) OF POINT OF FOLIATION 
Figure C6. Points plotted represent branch diameter and foliage dry weight 
of Salix ssp. 
FOLIAGE DRY WEIGHT (q.) 
220 
APPENDIX D 
Analysis of variance of the regressions relating number 
of frost damaged tips per unit white spruce crown area 
to number of aspen trees per plot for Plantations 1 and 2. 
221 
Table D1: White Spruce Frost Damaged Tips per Unit Crown Area 
vrs. Number of Aspen Trees / Plot at Plantation 1. 
Anova of Regression 
Source of Variation df SS MS VR 
Reg. Y - X 1 467.3335 467.3335 4.2935 N.S. 
Residual 13 1 ,415.024 108.848 
Total about y 14 1 ,882.3575 
Table D2. White Spruce Frost Damaged Tips per Unit Tree Crown Area 
vrs. Number of Aspen Trees / Plot at Plantation 2. 
Anova of Regression 
Source of Variation df SS MS VR 
Reg Y - X 1 576,325.8 576,325.8 122.1406 
Residual 13 61 ,341.076 4,178.5443 
Total about y 14 637,666.88 
^ Note: ** means significant differences at P = 0.01 
222 
APPENDIX E 
Analysis of variance, analysis of covariance, and Student- 
Newman-Keul‘s test tables for the Hexazinone Herbicide Trials. 
223 
Table El: Analysis of Covariance: Location 1, Estimated Mean Foliage Dry Weight per Tree in Grams 
Note: ** means significant differences at P = 0.01 
2 24 
■o CO OO CNJ 
•I— CO CO o 
LO 13 . . • • 
crcvj o I— 00 
•I- 
-o CO I— <T> 
*1— >ed- CO LO I— 
O CVJ O ^ LO 
CO f— r— 
■o LO CO I— 
cr» "Sj- <NJ 00 LO 
oOo  OJ LO LO CM CM 
LO I— CM 
CM CM 00 
00 O LO VO 
CO CO OO 
-O LOOr— 
•I— «5i- CM OO )— 
!3S • • • . 
crcM r- o cr> 
•I— CO 
-a LO I— 
CM CM CM 
CO 3 
cr CM CO 
no CM VO 
•I— CM I— I— CO 
o O 
CO VO VO 
■o CM I— 
•r- CM oo 
CM 3 • • • • 
CTi— •— I— CM 
•r- 
CT> crt 
■O CM CO 
LO T- o o • • 
I— 00 VO 
o I— I— 
CO r— f— 
XJ CO P^ 
•I- VO o 
3 0 0 • • 
cr CO I— 
•I— CO CO 
<u 
*a 4-> 
<D 
c o 
ea 
i- 
fO 0> Q 
CD +-> *0 
—' CcD —cn^ -M<y  
.1o- '— o 
O Si to Q5. 
 
 3QC  *oo>  <D 
h- u- QC CO U- o 
a> c= 
-O OJ "O ofO  
■P O) 
CJ -l-> 
JO •r- to *0 3 c: 
s- cn 
a. <c oo 
Table E2: Predicted Foliage Dry Weights for all Hexazinone Treatments at Location 
Note: Treatments that were not significantly different (P=0.05) are joined by a line. 
225 
Table E3: Analysis of Covariance: Location 2, Estimated mean foliage dry weight per tree in grams. 
Note: ** means significant differences at P = 0.01 
226 
•o 00 oo 
•I— 00 O Lr> 
ir> rs • • • • 
crcvj o I— CO 
•»- I— CM 
■O LT> r— CM 
•I— CM crt o 
13 • • • • 
CrCM I— «sj- '5:3- 
•t- CM CM 
■o c» uo 
•r- CO 00 VO 
O CM o ^ LT> 
C/5 CM OO 
T3 LO ^ LO 
^ CM un tn 
cn 
O CM OO I— 
CO 
XJ LO VO 
CM CM LT> VO 
CO 
o VO CM 
CO o 
C'J 
E "O r-" LO LO 
O •r— CM CM 
CTi CM OO 
VO r>. 
foO  
o 
■o OO OO 
•I— CM uo o 
CT3 o CM CM 
CO 00 
to 
•4C->  "O LO CTi CM 
•r- CM CM 00 
OO =3 . • . • 
cr«— I— CO VO 
•I— cr> cT) 
-M 
■o C0 5;3- 
VO *r- O O '5;C C7^ 
03 o O VO 
OO O CT> 
S- 
O CM I— 
CO o 
</) o =3 0 0 
x-»-:>  LO 00 CM I— 
CT> CM CM 
O) 
cu 8^ 
Of) ■o +J 
ca (U 
c cn 
(O 
i- 
“O «3 dJ o ^ Li_ 
■M 
a c CD 4-> ~a ^ cn^ Qj 
•Tr~3     C33-P E<u o•I — *•—   
•P fd 3: X3 
Q. O (t3 <0.0 OJ <u 
LL. cat: OO u- C o 
CL. c 
Tc3u  T3 IC3 
o ^■S 
o 
(U o -M •r— to 
X3 T3 =3 
s- c CD 
Si'-S* 
Cl. CO 
Note: Treatments that were not significantly different (P = 0.05) are joined by a line. 
227 
Table E5: Analysis of Covariance: Location 3, Estimated mean foliage dry weight per tree in grams. 
Note: ** means significantly different at P = 0.01 
228 
■o tnor— 
•I— *:d- csj Ln 
crv I— .... 
O c\j I— ro o 
CO ro CO 
■O CO I— 
•I— ^ c\j CTi 
3 • • • 
crcvj I— cr> • 
•r- cvi ro 
 I ro 
"O 00 VO 00 
•I- ^ 00 LO ro 
CD r“ .... 
I— O CVJ O LO CT^ 
CO ro ro 
*0 oorosi- 
•I— "sj" 00 ro 
o • • • • 
LO o-cvi o CO I— 
ro •r~ CO ^ 
c 
o 
Ti ■O LT> CD I— •r- CVJ CSJ 
fO 
O ro 0“i I— "Si" 
O CD 
*o CM CTi 
•r— CM t— CM O 
CM CTi I— 
ccu  CO I— 
fl3 “O LO cr> 
<U •I— CM CO 
s- 
+-> o CO 
CO 
<D 
S “O LO CM 
•I- CM CM I— 00 
oo I-  • • • • 
M O r— I— <>J- OO 
CO 
X 
T3 'O 
•I— CD ooO in 
CO 
o ^ r— 
CO CO 
s> 
o 
ro 
CM 
3 0 0 
cr oo CO 
cr> ro CM 
t 
■o CU 
O) 
cr> ■o 4-J 
fO OJ 
_X CD 
c 
s- 
-c ^ qa>j  ou-  
c o> 4-> -o 
o (U ^    
B — c cn-P *t3 •I   
ea Ofo  c *T—a  
O- (O 30.0 Q) 
Qi CO Li_ C s 
o. c 
<L) •TD itj 
co -o <U t3 o 
LU 4-> O) 
O 4-> 
(V ••rO-  to 3 
JQ S- 
cO ET-^ C7> •r— 
a. c CO 
Note: Treatments that were not significantly different are joined by a line. 
229 
CO CO CO 
C•)cV J 
ic ■K 
CO o o 
on cvi 
CsJ oo 
CO cr> cr> I— CO CO 
c\j oo cvj ■!;t- ^ CM 
oo O cr> I— 1— 
cy> r— r— CTt r— CO 00 
CO CM o CM OO cr> o CO 
CO 
CO ■si" o CO I— 00 
^ CO r— LO 
<T> I— CTl cn 
c: C7) 
o c 
•r— 
O 
<o 
Q. 
CO CO 
fO </> 
C 4- oB 
O i/J 
•r- +J (/) t/> Qt: 
«o = i£!x 
<u u O fl3 
a uu or u- &- 
V. 
3 I— «3 o la O 0.0) 
4-> 
m C i- o 
CO CZ I— LU CM 
Table E7: Analysis of Variance of the White Spruce Seedling Survival Trial 
- Shoot Elongation 
Note: * means significant differences at P = 0.05 
Note: ** means significant differences at P = 0.01 
230 
*o cn 
I— O O CO 
o 
CO 
"O LO o 
•I- CO CO cn 
CO 3 • • • 
0"«— I— 
LO O 
•r- CO CO cr> 
CO 
o CO 
CO 
*0 LO 
•r- O 
c3r 0 0 ^•  
“O C'' ^ 
•r- CO CO 
O r— LO 
oo 
"O LO I  
•r- ^ CO CO 
^ 3 • • • 
CXCO I— LO 
■a o 
•I— CO CO 
CO 
CTi— r— LO 
-o 00 
•r-«>J-COr— 
LO 3 • • • 
CTCO O LO 
■o 00 
•r- 00 
o CO o LO 
CO 
“O lO 'CJ- 
•e— ^ CO 
r— . • . 
O CO r— 
CO 
XJ 
O) 
c <u 
(O 
S- 
to 
—• <i> 
c cn Q. 
IQJ  -SiC CT» 
fO E CL) O •!- I— 
OJ C +-> <0 4-> 
C o (O CL (o 
I— Lt. Qc: CO cc=n 8 
-8 o 
 tco  
I— o 
*o 
•r“ 
JO 
S- 
Table E8: White Spruce Seedling Survival Trial 
“ Shoot Elongation for all Hexazinone Treatments 
Note: Treatments that were not significantly different (P = 0.05) are joined by a line. 
231 
Table E9: Analysis of Variance of the Black Spruce Seedling Survival Trial 
- Shoot Elongation 
Source of Variation df SS MS VR 
Re pi i cations 15.95 15.95 1.79 N.S 
Treatments 110.53 12.28 1.38 N.S 
Forms (ma) 0.51 0.51 N.S. 
Rates + Spacing (Mi) 68.30 17.07 1 .91 N.S. 
F X R & S 41 .72 10.43 1 .17 N.S, 
Error 80.28 8.92 
To tal 19 206.77 
Table ElO: Analysis of Variance of the Black Spruce Seedling Survival Trial 
- Percent Survival (aresin transformation) 
Source of Variation df SS MS VR 
Replications 208.34 208.34 2.18 N.S. 
Treatments 1,175.86 130.65 1 .37 N.S 
Forms (Ma) 5.95 5.95 N.S. 
Rates + Spacing (M) 362.80 90.70 N.S. 
F X R & S 307.11 201.78 2.11 N.S. 
Error 860.67 95.63 
Total 19 2,244.87 
232 
Table Ell: Analysis of Variance of the White Spruce (1.5m) Crop Tree Trial 
- Percent Survival (arcsin transformation) 
Source of Variation df SS MS VR 
Re pi i cations 2 52.25 26.13 1 .00 N.S. 
Treatments 8 209.02 26.13 1 .00 N.S. 
Rate (Ma) 2 52.25 26.13 1 .00 N.S. 
Spacing (Mi) 2 52.25 26.13 1 .00 N.S. 
R X S 4 104.52 26.13 1 .00 N.S. 
Error 16 418.03 26.13 
Total 26 679.31 
Table E12: Analysis of Variance of the White Spruce (0.5m) Crop Tree Trial 
- Percent Survival (arcsin transformation) 
Source of Variation df SS MS VR 
Replications 2 52.25 26.12 N.S. 
Treatments 8 365.78 45.72 N.S. 
Rate (Ma) 2 209.02 104.51 1.88 N.S. 
Spacing (Mi) 2 52.25 26.13 N.S. 
R X S 4 104.51 26.13 N.S. 
Error 16 888.32 55.52 
Total 26 1 ,306.36 
233 
Table El3: Analysis of Variance of the Black Spruce Crop Tree Trial 
- Percent Survival (arcsin transformation) 
Source of Variation df SS MS VR 
Replications 2 39.22 19.61 N.S. *★] 
Treatments 8 2,554.30 319.29 9.49,*
Rate (Ma) 2 502.31 251 .16 7.47„ , 
Spacing (Mi) 2 1 ,047.38 523.69 15.57** 
R X S 4 1 ,004.61 251.15 7.47 ' 
Error 16 538.09 33.63 
Total 26 3,131 .61 
^Note: ** means significant differences at P = 0.01 
234 
fO 
•r- 
s- 
H- 
O 
CL 
oe  
(U 
u 
rO 
'■O 
O) 
x: x: 
e 
CD 
CO 
•r— +J 
CO JZ 
>> cn 
cl i 
(U 
8 8 
C h- 
•I- cz 
S-. as 
o 
CD I 
cu 
X3 
(O 
Note: * means significant differences at P = 0.05 
235 
Table E15: Analysis of Variance of the Jack Pine Crop Tree Trial 
- Percent Survival (arcsin transformation) 
Source of Variation df SS MS VR 
Replications 2 502.31 251.15 2.74 N.S. 
Treatments 8 2,301.48 287.69 3.14*1 
Rates (Ma) 2 149.67 74.84 N.S. 
Spacing (Mi) 2 1 ,072.85 536.42 5.86 *1 
R X S 4 1,078.96 269.74 2.95 N.S, 
Error 16 1,464.27 91 .52 
Total 26 4,268.05 
^Note: * means significant differences at P = 0.05 
236 
CM 
Table E16: Analysis of Covariance of the Aspen Weed Tree Trial 
- Mean Tree Height Growth 
Note: ** means significant differences at P = 0.01 
Note: * means significant differences at P = 0.05 
237 
Table E17: Analysis of Variance of the Aspen Weed Tree Trial 
- Percent Survival (Arcsin transformation) 
Source of Variation df SS MS VR 
Replications 2 42.97 21 .48 N S 
Treatments 11 32,543.19 2,958.47 36 .81 
Rate (Ma) 2 8,127.65 4,063.82 50.56J1  
Spacing (Mi) 3 15,839.96 5,279.99 65.70 ★*] 
R X S 6 8,575.58 1 ,429.26 17.78 
Error 22 1 ,768.20 80.37 
Total 35 34,354.35 
^Note: ** means significant differences at P = 0.01 
o 
o 
II 
Table E18: Analysis of Covariance of the Willow Brush Trial 
- Total Stem Growth per Shrub 
Note: ** means significant differences at P 
239 
Table E19: Analysis of Variance of Willow Brush Trial 
- Percent Survival (Arcsin transformation) 
Source of Variation df SS MS VR 
Re pi i cations 2 601 ,10 300.55 4.14 
Treatments 8 10,561.64 1,320.20 18.08 
Rate (Ma) 2 7,778.50 3,889.25 53.25 
*2 
★*2 
Number of Spots (Mi) 2 1,658.09 829.05 11,35 
R X N 4 T,125.03 281 .26 3.85 
*1 
Error 16 1,168.61 73.04 
Total 26 12,331.35 
Iwote: * means significant differences at P = 0.05 
Note: ** means significant differences at P = 0.01 
240 
Table E20: Analysis of Variance of the Mature Aspen Trial 
- Percent Survival (arcsin transformation) 
Source of Variation df SS MS VR 
Replications 2 249.89 124.94 
Treatments 23 65,831.25 2,862.23 6.07 1 
Form (Ma) 1 1 ,499.33 1,499.33 3.18 N.S, 
Rate (Me) 3 34,811 .04 11,603.68 24.59**1 
Diam.Class (Mi) 2 17,241.82 8,620.91 18.27**1 
F X R 3 2,947.36 982.45 2.08 N.S 
F X D 2 249.88 124.94 N.S. 
R X D 6 5,596.01 932.67 1.98 N.S. 
F X D 6 3,485.81 580.97 1.23 N.S 
Error 46 21 ,703.03 471 .81 
Total 71 87,784.17 
^Note: ** means significant differences at P = 0.01 
241 
242 
Table E22: Analysis of Variance of the Jack Pine Greenhouse Trial 
- Foliage Dry Weight (gram/tree) 
Source of Variation df SS MS VR 
Replications 2 25.01 12.50 N.S. 
Treatments 7 362.48 51 .78 2.78 ' 
Rate (Ma) 3 150.13 50.04 2.69J.S, 
Position (Ml) 1 1 32.92 132.92 7.13 1 
R X P 3 79.43 26.48 1 .42 N.S, 
Error 14 260.90 18.64 
To tal 23 648.39 
Table E23: Analysis of Variance of the Jack Pine Greenhouse Trial 
- Percent Survival (arcsin transformation) 
Source of Variation df SS MS VR 
Replications 2 244.42 122.21 N.S. :*2 
Treatments 7 15,185.77 2,169.40 9.23 ★★2 
Rates (Ma) 3 9,397.41 3,132.47 13.33 **2 
Position (Mi) 1 4,287.22 4,287.22 18.24 
R X P 3 1 ,501.14 500.38 2.13 N.S, 
Error 14 3,290.86 235.06 
Total 23 18,721.05 
Note: * means significant differences at P = 0.05 
2 
Note: ** means significant differences at P = 0.01 
243 
Table E24: Analysis of Variance of the White Spruce Greenhouse Trial 
- Foliage Dry Weight (gram/tree) 
Source of Variation df SS MS VR 
Repl ications 2 2.88 1 .44 1 .84 N.S, 
Treatments 7 78.07 11 .15 14.27**1 
Rate (Ma) 3 63.71 21.24 27.17**1 
Position (Mi) 1 4.81 4.81 6.15 2 
R X P 3 9.55 3.18 4.07 *2 
Error 14 10.94 0.78 
Total 23 91 .89 
Table E25: Analysis of Variance of the White Spruce Greenhouse Trial 
- Percent Survival (arcsin transformation) 
Source of Variation df SS MS VR 
Repl i cations 2 619.89 309.95 2.20 N.S. 
Treatments 7 16,579.69 2,368.53 
Rate (Ma) 3 10,593.06 3,531 .02 25.06 1 
Position (Mi) 1 2,932.67 2,932.67 20.81**1 
R X P 3 3,053.96 1,017.97 7.22**1 
Error 14 1 ,972.77 140.91 
Total 23 19,172.35 
^Note: ** means significant differences at P 0.01 
2 
Note: * means significant differences at P 0.05 
2 44 
Table E26: Analysis of Variance of the Aspen Greenhouse Trial 
- Percent Survival (arcsin transformation) 
Source of Variation df SS MS VR 
Replications 2 384.87 192.44 N.S.**-, 
Treatment 3 12,533.89 4,177.96 18.47 ' 
Error 6 1,357.36 226.23 
Total 11 14,276.12 
^Note: ** means significant differences at P = 0.01 
245 
Table E27: Analysis of Covariance of the Aspen Greenhouse Trial 
- Foliage Dry Weight (g/tree) 
Note: ** means significant differences at P = 0.01 
246 
Table E28: Analysis of Variance of the Hazel Greenhouse Trail 
- Percent Survival (arcsin transformation) 
Source of Variation df SS MS VR 
Replications 2 0 0 0 ★★I 
Treatments 3 13,914.49 4,638.16 29.59 
Error 6 940.58 156.76 
Total 11 14,855.07 
^Note: ** means significant differences at P = 0.01 
247 
Table E29: Analysis of Covariance of the Hazel Greenhouse Trial 
- Foliage Dry Weight (g/tree) 
Note: ** means significant differences at P = 0.01