The detrimental effects of habitat fragmentation on animal populations, especially on threatened and endangered species, are widely documented. In contrast, the development of practical tools to predict fragmentation and design appropriate mitigation efforts has progressed slowly. An improved understanding of the dynamics of ecosystem fragmentation is required for better integration of Department of Defense land management and training objectives, while still ensuring the benefits of land rehabilitation and habitat restoration projects.

This project developed models to predict the fragmentation of animal habitats caused by training and testing operations as well as the responses of mobile animal species to habitat fragmentation and restoration efforts.

Aerial view of the San Pedro River corridor in Southeastern Arizona. Studies of birds and butterflies at this and other sites will test the generality of the modeling approach for mobile animals.

Technical Approach

Three areas of investigation were undertaken: (1) acquisition of ecological field data on the responses of animals to their habitat fragmentation, (2) the mapping of animal habitats at scales relevant to habitat management, and (3) the linking of empirical ecological data and spatially-explicit habitat information in a modeling package called the Effective Area Model (EAM). Field research targeted species of special interest to managers, including indicator taxa and sensitive, threatened, and endangered species. Habitat mapping relied on information derived from remote sensing technology and field measurements. The modeling approach projected speciesspecific edge responses, measured in the field and characterized mathematically, onto the spatially-explicit habitat maps, weighting each habitat patch according to its area and the influence of the surrounding habitat on species abundance and demographic variables.


This project has resulted in a series of peer-reviewed publications on landscape modeling and the diverse biota of desert riparian and ponderosa pine ecosystems. Applications of the EAM are ongoing in novel situations in these ecosystems and at Fort Hood, Texas and Fort Benning, Georgia. Real-world applications address the restoration of fire-prone forests, the mitigation of habitat fragmentation in riparian areas, the integration of differing habitat needs among co-occurring threatened and endangered species, and the balance of military training and environmental conservation goals. These exercises demonstrate how the EAM can help set management goals and balance training needs, endangered species management, habitat conservation and associated activities by providing a landscape-level perspective on environmental challenges. Follow-on research is ongoing under SERDP project RC-1597.


Developed as an ArcView Geographical Information System (GIS) extension, the EAM is the only tool currently available that can extrapolate edge responses to larger landscapes. It provides land managers with a spatial approach for considering how different landscape structures, resulting from alternate scenarios, can impact animal populations and ecological functions in managed landscapes. (Project Completed - 2003)