Aspen height growth had a marginally positive and negative relationship with mean annual and summer precipitation, respectively, whereas spruce height growth was not significantly related to either precipitation variable.
Aspen height was best predicted by a model with meristem removal, terrain ruggedness, aspect, and year.
Second, using surveys at the landscape level, we found a correlation between elk browsing intensity and aspen height, such that where elk browsing was highest, aspen were shortest.
Estimates of meristem removal in our study suggest that 75% browse of apical meristems is an important threshold for successful aspen height growth and 50% defoliation for aspen regeneration density.
Binned fecal count densities of elk, mule deer, and cattle showed strong inverse correlations with aspen height (elk: r2 = 0.83; deer: r2 = 0.92; cattle: r2 = 0.35) and aspen recruitment (elk: r2 = 0.51; deer: r2 = 0.59).
This relationship between elk browsing intensity and aspen height was stronger in burned (r = −0.53) compared to unburned (r = −0.24) areas.
Browsing pressure declined, as ungulate populations decreased during this time, but aspen height and basal diameters were constrained by dense, rapidly growing postfire conifers.
Lakeside forest was characterized by greater canopy cover, and aspen height and diameter (breast height) than upland forest, but absolute differences were quite small and there was no evidence of greater structural diversity.
However, neither recent climate change variables (TMAX, PDSI) nor atmospheric CO2 had affected aspen height growth at the scale of the entire province.
