Tree species' responses to environmental changes during the last glacial: evaluating alternative hypoteses using a spatially-explicit migration model

Abstract

The MIGRATE model has been used to perform a series of simulations of the response of trees to rapid environmental changes; two alternative forms of initial distribution have been examined, as have the influences of habitat availability and the reproductive and dispersal characteristics of the trees. The results provide a basis for a critical test of the form of the glacial refugial distributions of trees in a region. They also provide strong support for the hypothesis that mesic trees in southern Italy were able to respond to the rapidly fluctuating environment of the last glacial because, during unfavourable periods, they occupied numerous scattered refuges in suitable microhabitats within the landscape. They then could expand rapidly across the landscape during even short intervals of relatively favourable conditions.