Landscape level validation of a Douglas-Fir beetle stand hazard-rating system using geographical information systems

Abstract

A geographical information system (GIS) and historical infestation data were used to validate a Douglas-fir beetle hazard-rating system currently in use by the USDA Forest Service in parts of the West. This hazard-rating system is based on stand characteristics including percent Douglas-fir basal area (BA), stand BA, average Douglas-fir dbh, and stand age. To validate the hazard-rating system, stand information and aerial detection survey maps from 1996-1999 were combined in a GIS. Analyses determined that the highest amount of acreage infested and highest tree mortality occurred in moderate- and high-hazard stands, although the total area of these stands was less than that in other hazard classes. Furthermore, as beetle populations shifted from endemic to epidemic population levels, more acres were infested and tree mortality was greater in high-hazard areas. The use of spatial technologies and aerial detection survey maps provided a novel alternative for validating a forest insect hazard-rating system. © 2004 by the Society of American Foresters.