| dc.description.abstract | There are currently no locally-derived, quantitative site-quality evaluation tools available for
major tree species in the tolerant hardwood forests of central Ontario. To estimate potential
site productivity, site-index curves from the Lake States and a preliminary set of site-form
curves for sugar maple are currently being used. Whether these tools are applicable to
central Ontario is of concern. The use of site index as a site-quality evaluation tool in
uneven-aged mixed-species stands is also questionable. It is also possible site form may not
be a valid measure of forest site quality in these types of stands either.
A random sample of 62 pure and mixed-species stands with a variety of age-class structures
in central Ontario yielded stem analyses data and stand structure information for sugar maple
(Acer saccharum Marsh.), American beech (Fagus grandifolia Ehrh.), yellow birch {Betula
alleghaniensis Britton) and red oak (Quercus rubra L.). An exploration of height-growth
patterns for each species as a function of age and diameter revealed pronounced differences
in shape (polymorphism) of height-age curves for all species with changes in site quality.
Polymorphism was also evident for suppressed vs. free-growing sugar maple trees, and for
sugar maple growing in even- vs. uneven-aged stands and pure vs. mixed-species stands.
Differences were less pronounced in height-diameter curves for all species.
Preliminary height-growth and site-index equations and curves were developed for sugar
maple, American beech, yellow birch and red oak. The central Ontario data, and curves from
this study, were then used to examine the applicability of site-index curves for these species
from the Lake States to central Ontario. The Lake States curves were shown to differ
substantially from those developed in this study, and were inaccurate in application to data
from central Ontario. A preliminary assessment of age and stand structure and species
mixture impacts on sugar maple height-growth and site index, and forest floor chemistry,
revealed no significant differences in sugar maple site index between stands of different
composition or age-class structure, and minor differences in forest floor chemistry between
stands of different species composition.
Preliminary height-growth and site-form equations and curves were also developed for these
species. The curves for sugar maple were used to validate existing preliminary curves for
sugar maple in Ontario. The curves in this study differed substantially from the preliminary
curves and the existing curves were shown to be inaccurate in application to data from this
study. An examination of site form as a site productivity measure in uneven-aged, mixed-species
stands using data from this study revealed it was unrelated to site index, basal area or
ecological variables known to affect forest site quality for these species. | |
