Natural thinning and environmental change: an ecological process model

摘要

The proposed model of natural thinning is based on ecological processes, which integrate all relevant physiological processes. Within the traditional all-encompassing framework of carbon balance, this study develops a more instrumental framework of the reciprocal relationship between the area occupied by the average tree and the number of trees per unit area. The model includes two other terms reflecting aging of trees and effects of environmental change. Parameters of this model were estimated using data from permanent sample plots established in northern Ontario. The resulting model accurately describes natural thinning of even-aged stands and makes it possible to quantify each of the constituent processes, including the effects of environmental change on forest ecosystems. During the period 1952-1987, this effect has produced 16% increase in number of trees of a given size per unit area.