Estimation of tree growth losses caused by pest activity

Abstract

An improved method of quantitative evaluation of pest-caused reduction of tree growth is described. Radial and height growth rates were measured from discs along the bole of the tree, and growth losses were evaluated by a computer program (IMPACT). The method is independent of site characteristics or competition effects. Use of the method was demonstrated for growth losses in Pseudotsugamenziesii attributable to defoliation by Choristoneuraoccidentalis, and with slight modification it may be applied to a range of tree-pest systems. A three-dimensional graphical procedure was used to display the growth pattern.