Effects of climate and land use changes on present and forecasted habitat suitability for the Mojave Desert tortoise Gopherus agassizii

Models of species distribution help identify habitat for species across landscapes experiencing anthropogenic change. Under future climate and land use scenarios, the leading edges of a shifting range may play a key role in maintaining adaptation. Thus, assessing habitat suitability in both core and edge regions is essential for conservation planning. The Mojave Desert tortoise Gopherus agassizii is a long-lived species with limited dispersal abilities, persisting in a fragmented desert landscape. To expand on existing models, we conducted field surveys emphasizing range edges and understudied areas. Locality data were used to generate an updated present-day habitat suitability model and to forecast future habitat under climate and land use scenarios. Our models identified areas of currently suitable habitat and projected potential shifts. Environmental relationships indicated that tortoise habitat is associated with higher winter minimum and summer maximum temperatures, as well as soil characteristics such as high sand content and low coarse fragment content in surface horizons. Our forecasts consistently predicted declines in habitat under future scenarios, with greater losses under higher emissions and urbanization. Notably, critical habitat units were among the most vulnerable. These results suggest that combined pressures of climate change and land use will likely reduce suitable habitat for the Mojave Desert tortoise. Our findings raise concerns about the species’ capacity to adapt, the persistence of edge populations, and whether future habitat will receive adequate protection. Identifying shifting suitable areas and corridors could be vital for long-term conservation and management.