EMDS users guide (version 2.0): knowledge-based decision support for ecological assessment.

Abstract

The USDA Forest Service Pacific Northwest Research Station in Corvallis, Oregon, has developed the ecosystem management decision support (EMDS) system. The system integrates the logical formalism of knowledge-based reasoning into a geographic information system (GIS) environment to provide decision support for ecological landscape assessment and evaluation. The knowledge-based reasoning schema of EMDS uses an advanced object- and fuzzy logic-based propositional network architecture for knowledge representation. The basic approach has several advantages over more traditional forms of knowledge representations, such as simulation models and rule-based expert systems. The system facilitates evaluation of complex, abstract topics, such as forest type suitability, that depend on numerous, diverse subordinate conditions because EMDS is fundamentally logic based. The object-based architecture of EMDS knowledge bases allows incremental, evolutionary development of complex knowledge representations. Modern ecological and natural resource sciences have developed numerous mathematical models to characterize highly specific relations among ecosystem states and processes; however, it is far more typical that knowledge of ecosystems is more qualitative in nature. Approximate reasoning, as implemented in fuzzy logic, significantly extends the capability to reason with the types of imprecise information typically found in natural resource science. Finally, the propositional network architecture of EMDS knowledge bases allows both the ability to evaluate the influence of missing information and the ability to reason with incomplete information.