A web-based expert system for gypsy moth risk assessment

Ecosystem management, which is aimed at maintaining resources such as wildlife diversity, water quality, fire protection or aesthetic values, requires a regional or landscape perspective. Using a spatially explicit simulation model to test `what-ifʹ scenarios can facilitate the development of appropriate management practices at the landscape level. The state-andtransition model may provide a methodology that strikes an appropriate balance between simplicity and realism. We present a brief review of the state-and-transition methodology and then describe a computer-based implementation of a spatially explicit state-and-transition model. The implementation method is to link a rule-based qualitative simulation model with a geographic information system.