TITLE:
Climate Variation and Disturbance Regime Affect Stand Composition and Structure of the Boreal Forests in Southwest Yukon of Canada
AUTHORS:
Shyam K. Paudel, Suzanne W. Simard, Craig R. Nitschke, John L. Innes
KEYWORDS:
Stand Structure, Composition, Density, Basal Area, Climate Variability, Ecosystem, Disturbance
JOURNAL NAME:
Open Journal of Forestry,
Vol.5 No.4,
March
25,
2015
ABSTRACT: The cold
and dry boreal forests of the Southwest Yukon are dominated by white spruce (Picea glauca), trembling aspen (Populus tremuloides) and balsam poplar (Populus balsamifera), and the variability in structure
and composition of stands depends on the favourability of disturbance, climate
and site conditions for stimulating regeneration. In this study, we
investigated relationships between stand structure and ecological, climatic
and disturbance factors in the southwest Yukon. We found that white spruce
dominates mature forests across the landscape, but it is regenerating
proportionately less than trembling aspen. Nevertheless, regeneration of all
the three species was abundant following any type or severity of disturbance.
Height and diameter of both species varied with several environmental
variables, particularly site physiography. Mixed stands of aspen and white
spruce were more productive than pure stands of aspen or spruce. However,
overall productivity in mixed stand decreased when density of aspen was more than
1000 stems/ ha. These results suggested that mixed stands of deciduous and
coniferous species where appropriate should be promoted maintaining aspen
density below 1000 stems/ha as the productivity declined beyond this threshold.
Similarly, we suggest carrying out selection harvesting of co-dominant trees
and regular thinning of intermediate trees to promote the height and diameter
growth of the remaining trees.