Linking spatially explicit species distribution and population models to plan for the persistence of species under global change. (Adaptive management framework for decision making under global change.)

Abstract: Conservation managers and policy makers require models that can rank the impacts of multiple, interacting threats on biodiversity so that actions can be prioritized. We apply an integrated modeling framework that links species distribution models, spatially explicit population models and global change scenarios, to predict the effects of threats and management to the viability of plant populations for five species in southern California’s Mediterranean-type ecosystem. The framework integrates forecasts of land use change from an urban growth model with projections of future climatically suitable habitat from species distribution models, which are linked to a stochastic population model. The population model includes species life history and demographic parameters and incorporates the effects of disturbance regimes and management actions on population viability. This framework has allowed us to: 1) rank threats by their relative and cumulative impacts on population viability, e.g., land use change, climate change, altered disturbance regimes, or invasive species, and 2) rank management responses in terms of their effectiveness, e.g., land protection, assisted dispersal, fire management and invasive species control. Too-frequent fire was often the top threat for the species we studied, and thus, fire reduction was frequently ranked among the most important management options. Projected changes in the distribution of suitable habitat as a result of climate change were generally large, but varied across species and climate scenarios; urban development often served to exacerbate loss of suitable habitat. This framework is most effective when management objectives are species-specific and when disturbance, such as fire, has a quantifiable impact on population dynamics.