Modeling Gopher Tortoise Population Viability Under Alternative Management Strategies.

Sustaining populations of Species at Risk (SAR) is an important goal to the US military. The Army is using Congressional authority through the Army Compatible Use Buffer (ACUB) program to purchase property development rights to sustain military training lands. These lands will remain undeveloped and habitat will be managed to support important wildlife populations. In return, these lands will serve as a buffer area between civilian populations and military activities. Limited funding must be allocated so that land use patterns can optimize the probability of long-term persistence of one or more of the target species. This paper addresses two important related questions. First, how can published literature on a long-lived species, for which little population dynamics information is currently known, inform the establishment of new reserves? Secondly, what research would significantly improve our ability to forecast the relative effectiveness of alternative reserve designs? We selected the Gopher Tortoise as our case study because of its likelihood to influence future training capabilities in the Southeast. We constructed spatially explicit individual-based simulation models using published literature and on unpublished expert advice. We conclude that, through individual-based simulation modeling, it is possible to effectively evaluate alternative land use planning proposals with respect to projections of SAR population viability. Ideally, long-term population studies and experiments covering many decades would provide the basis for projecting the response of populations to alternative management plans. However, such experiments are virtually impossible and could not inform contemporary decisions influencing species’ persistence. Model sensitivity studies suggest that ability to predict population viability under alternative management strategies could be greatly improved with specific fieldwork.