干旱区生态环境知识资源中心

Conservation of Mojave Desert Tortoises is founded on a set of tortoise conservation areas (TCAs) established across the range of the species. Limitations of the existing reserve design and increasing development pressures on the intervening habitat matrix underscore the need to conserve linkages between existing TCAs. We modeled linkages between TCAs using least-cost corridors based on an underlying model of suitable tortoise habitat. Results indicate that TCAs contain 55% of total historic habitat (45,340 km(2)). A minimum linkage network would contain 16,282 km(2) of habitat (20% historic). This combined area of 61,622 km(2) represents an initial framework to develop a conservation network for the species, taking into account large areas of existing high-intensity human uses such as military operations and off-highway-vehicle recreation. Models that assume more permeable habitat to tortoise connectivity reveal much broader linkages, but approximately 700 km2 of habitat within the minimum linkages are already at risk of permanent habitat loss through solar energy development. Additional conservation of occupied habitat adjacent to the minimum linkages and existing TCAs would provide security against edge effects and population declines within conservation areas, especially given limitations in existing reserve architecture. Application of these linkage models will require refinement at the local level, and questions remain about the ultimate ability of a conservation network based on these models to support viable tortoise populations and accommodate climate change. Nevertheless, conservation decisions cannot be delayed while awaiting final answers to all relevant questions. In areas proposed for permanent habitat conversion, critical linkages may be severed before they are protected.