MIGCLIM: Predicting plant distribution and dispersal in a changing climate

Aim Many studies have forecasted the possible impact of climate change on plant distributions using models based on ecological niche theory, but most of them have ignored dispersal-limitations, assuming dispersal to be either unlimited or null. Depending on the rate of climatic change, the landscape fragmentation and the dispersal capabilities of individual species, these assumptions are likely to prove inaccurate, leading to under-or overestimation of future species distributions and yielding large uncertainty between these two extremes. As a result, the concepts of 'potentially suitable' and 'potentially colonizable' habitat are expected to differ significantly. To quantify to what extent these two concepts can differ, we developed MIGCLIM, a model simulating plant dispersal under climate change and landscape fragmentation scenarios. MIGCLIM implements various parameters, such as dispersal distance, increase in reproductive potential over time, landscape fragmentation or long-distance dispersal. Location Western Swiss Alps. Methods Using our MIGCLIM model, several simulations were run for two virtual species by varying dispersal distance and other parameters. Each simulation covered the 100-year period 2001-2100 and three different IPCC-based temperature warming scenarios were considered. Results of dispersal-limited projections were compared with unlimited and no-dispersal projections. Results Our simulations indicate that: (1) using realistic parameter values, the future potential distributions generated using MIGCLIM can differ significantly (up to more than 95% difference in colonized surface) from those that ignore dispersal; (2) this divergence increases under more extreme climate warming scenarios and over longer time periods; and (3) the uncertainty associated with the warming scenario can be as large as the one related to dispersal parameters. Main conclusions Accounting for dispersal, even roughly, can importantly reduce uncertainty in projections of species distribution under climate change scenarios.