Spatial variation in forest growth after disturbances in a northern hardwood ecosystem and its relationship with underlying environmental factors

Abstract

Disturbances can change the structure and function of forest stands. Under the same disturbances, spatial variation in forest growth can arise from interspecific differences and spatially varying environmental factors. In this study, I analyzed the spatial variation in the growth of two forest stands in Hubbard Brook Experimental Forest. Either a calcium addition or a clear-cut disturbance was introduced to the forest stands. To focus on the influence of environmental factors, I isolated the interspecific differences by using a “Forest Change Index” to indicate the forest growth condition. Comparing the inter-plot differences in forest growth before and after the disturbances, I found the spatial variation patterns to be highly persistent. Only a high magnitude disturbance like a clear-cut can disrupt the original spatial variation pattern, which may still recover with the recovery of the forest stand. Furthermore, a linear regression analysis on the environmental variables proves their significant influence on the spatial variation in forest growth. But a generalized joint attributes model analysis shows that the influence of different environmental variables varies for different species, which implies the nearly constant resource differences determined by environmental factors in each plot may be the main cause of the spatial variation in forest growth.