Estimating forest crown area removed by selection cutting: a linked regression-GIS approach based on stump diameters

The purpose of this research was to develop a model that could be used to p rovide a spatial representation of uneven-aged silvicultural treatments on forest crown area. We began by developing species-specific linear regressio n equations relating tree DBH to crown area for eight bottomland tree speci es at White River National Wildlife Refuge, Arkansas, USA. The relationship s were highly significant for all species, with coefficients of determinati on (r(2)) ranging from 0.37 for Ulmus crassifolia to nearly 0.80 for Quercu s nuttalliii and Taxodium distichum. We next located and measured the diame ters of more than 4000 stumps from a single tree-group selection timber har vest. Stump locations were recorded with respect to an established gl id po int system and entered into a Geographic Information System (ARC/INFO). The area occupied by the crown of each logged individual was then estimated by using the stump dimensions (adjusted to DBHs) and the regression equations relating tree DBH to crown area. Our model projected that the selection cu ts removed roughly 300 m(2) of basal area from the logged sites resulting i n the loss of approximate to 55 000 m(2) of crown area. The model developed in this research represents a tool that can be used in conjunction with re mote sensing applications to assist in forest inventory and management, as well as to estimate the impacts of selective timber harvest on wildlife. (C ) 2000 Elsevier Science B.V. All rights reserved.