Sugar Maple, Red Maple, And Yellow Birch Growth And Mortality In Even-Aged Adirondack Northern Hardwoods

Tree diameter growth models for northern hardwoods commonly used large data sets representing a composite of stands with varying management histories, structural characteristics, and age distributions. Yet common predictor variables like diameter can show differences in growth patterns for stands with different age structures and management histories. To address that, we modeled growth and mortality for sugar maple, red maple, and yellow birch in thinned even-aged Adirondack northern hardwoods. Findings indicate that change in diameter depends on initial diameter for sugar maple, with the rate decreasing exponentially from the largest size class to the smallest. Initial diameter did not prove significant with red maple and yellow birch in these thinned stands, perhaps because of the limited sample of trees of small diameter. Stand relative density and time since treatment affected growth for all three species. Those variables also proved significant for predicting mortality of sugar maple. Analyses revealed fewer losses of sugar and red maples among the larger diameter classes, but no relationship with diameter for yellow birch. Plot relative density did not affect mortality with red maple, but time after thinning had a significant effect on survival of all species.Study Implications: Crown thinning and other methods that release upper canopy trees within even-aged stands should result in favorable postthinning growth of sugar maple, red maple, and yellow birch. Yet, the small trees of sugar maple will grow slower than larger ones after release by thinning, and small sugar and red maple have greater probability of dying. Residual stand density will temper the growth of all three species and the survival of sugar maple and yellow birch. Findings suggest that management strategies favoring removal of the large-diameter sugar maple trees of upper canopy positions from an even-aged stand (e.g., diameter-limit cutting) will result in lower rates of diameter increment within the residual stand. That should negatively affect stand dynamics and volume production and result in greater mortality among the remaining sugar and red maple. By contrast, crown thinning will enhance residual tree growth and survival, as well as stand development.