Special Session - The Southwest Regional Gap Analysis Project Chair(s): Kepner, William ¹, Ramsey, Douglas², Prior-McGee, Julie³, ¹ Landscape Ecology Branch, Las Vegas, NV² Utah State University, Logan, UT³ New Mexico State University, Las Cruces, NM
Wednesday, March 31, 2004 10:00 AM - 5:00 PM Apollo Room 7

The Gap Analysis Program (GAP) is a national interagency program that maps the distribution of plant communities and selected animal species and compares these distributions with land stewardship to identify biotic elements at potential risk of endangerment. GAP uses Geographic Information System (GIS) technology to assemble and view large amounts of biological and land management data to identify areas (gaps) where conservation efforts may not be sufficient to maintain diversity of living natural resources. Historically, GAP has been conducted by individual states; however this has resulted in inconsistencies in mapped distributions of vegetation types and animal habitat across state lines because of differences in mapping and modeling protocols. This was further compounded from the lack of a national vegetation classification nomenclature. In response to these limitations, GAP embarked on a second-generation effort to conduct the program at a regional scale, using a vegetation classification scheme applicable across the US, and ecoregional units as the basis for segmenting the landscape into manageable units. The program’s first formalized multi-state regional effort includes the five states (Arizona, Colorado, Nevada, New Mexico, and Utah) comprising the Southwest Regional GAP Analysis Project (SW ReGAP).

A Comparison of Approaches for Verifying Southwestern Regional Gap Vertebrate Habitat Distribution Models. Wynne, J. Judson^*,1, Drost, Charles¹, Thomas, Kathryn¹, ¹ USGS-Southwest Biological Science Center, Flagstaff, AZ, USA

ABSTRACT- Vertebrate habitat distribution models for the Gap Analysis Program are typically developed using literature-derived information. Accuracy of these regional models is difficult to assess due to their broad geographic extent and the paucity of landscape level verification data for most of the modeled species. For Gap analysis, the recommended approach for accessing model accuracy has been to compare species lists for geographically defined areas (e.g., National Parks) with predictive habitat models to derive a measure of agreement. Due to the generalization of species lists over large areas, and a variety of associated errors and assumptions, this approach has serious limitations and is potentially misleading. We will evaluate species lists, as well as other available datasets for assessing the accuracy of vertebrate habitat distribution models. These datasets include recent National Park Service inventory studies, area-based species lists, and point-based records of species occurrence (e.g., museum specimen data and species presence/ absence data from research projects). Focusing on vertebrate habitat distribution models for Arizona and New Mexico, we will compare and contrast, as well as identify strengths and weaknesses, of these datasets for accuracy assessment.

KEY WORDS: wildlife-habitat relationships, accuracy assessment, habitat modeling, landcape scale modeling