MAPPING OF SPECIES RICHNESS FOR CONSERVATION OF BIOLOGICAL DIVERSITY - CONCEPTUAL AND METHODOLOGICAL ISSUES

Biodiversity mapping (e.g., the Gap Analysis Program [GAP]), in which vegetative features and categories of land use are mapped at coarse sp atial scales, has been proposed as a reliable tool for land use decisi ons (e.g., reserve identification, selection, and design). This implic itly assumes that species richness data collected at coarse spatiotemp oral scales provide a first-order approximation to community and ecosy stem representation and persistence. This assumption may be false beca use (1) species abundance distributions and species richness are poor surrogates for community/ecosystem processes, and are scale dependent; (2) species abundance and richness data are unreliable because of une qual and unknown sampling probabilities and species-habitat models of doubtful reliability; (3) mapped species richness data may be inherent ly resistant to ''scaling up'' or ''scaling down''; and (4) decision-m aking based on mapped species richness patterns may be sensitive to er rors from unreliable data and models, resulting in suboptimal conserva tion decisions. We suggest an approach in which mapped data are linked to management via demographic models, multiscale sampling, and decisi on theory. We use a numerical representation of a system in which vege tation data are assumed to be known and mapped without error, a simple model relating habitat to predicted species persistence, and statisti cal decision theory to illustrate use of mapped data in conservation d ecision-making and the impacts of uncertainty in data or models on the decision outcome.