| dc.description.abstract | Black spruce (Picea mariana Mill. B.S.P.) is one of the most important tree
species in Canada, both ecologically and commercially. The forest industry has steadily
increased efforts to artificially regenerate areas that have been harvested resulting in
expanding areas of black spruce plantations. The increase in amount o f area and the
number of trees that are planted requires accurate tools for height and yield estimation in
these stands to ensure sustainable forest management and a dependable future wood
supply. Currently these tools are unavailable resulting in underestimated site productivity
in black spruce plantations by a site index and growth and yield model that was derived
from natural stands.
In this study, 62 sites were sampled across northern Ontario ranging from
Kirkland Lake in the east to Kenora in the west. Within each plot 3 undamaged dominant
or co-dominant trees with no indication o f suppression were felled for stem analysis.
These sites were planted, contained a minimum black spruce composition of 70%, and
were at least 40 years old. Within each plot a soil sample was collected from the C
horizon and relationships between soil characteristics and site quality were examined.
Accurate and precise growth intercept and site index models were developed from
the stem analysis data collected from black spruce plantations. These models were
compared to models for natural stands using Carmean’s (2006) data. Comparison of site
index curves between planted and natural stands showed a significant difference. Planted
stands displayed increased height growth patterns, especially in early breast height ages,
as well as enhanced total height prediction accuracy when compared to natural stands.
These height growth increases may be directly related to silvicultural activities that occur
on productive upland sites.
Soil characteristics from the C horizon were related to site productivity in black
spruce plantations. Soil pH in calcium chloride, elevation, sand, and silt content were
shown to be significant factors. Factor analysis concluded that many soil characteristics,
such as soil pH in calcium chloride, soil pH in water, Ca, Mg, Na and clay content
attributed for similar variances to site quality in terms of site index.
Due to its shallow rooting nature, and previous studies that have shown black
spruce to have a maximum attainable height of 20 to 21 m before becoming susceptible
to windthrow, a rotation age of 60 years on productive upland sites is recommended. In a
300 year scenario, productive upland black spruce sites harvested at a 60 year rotation
produced 223 % more merchantable volume than natural stands. If these stands are not
harvested until 80 years, stands could incur volume losses of at least 30 % due to
windthrow and tomentosus root rot. | |
