Phenology is a major determinant of tree species range

Global warming is expected to have a major impact on plant distributions, a n issue of key importance in biological conservation. However, very few mod els are able to predict species distribution accurately, although we know s pecies respond individually to climate change. Here we show, using a proces s-based model (PHENOFIT), that tree species distributions can be predicted precisely if the biological processes of survival and reproductive success only are incorporated as a function of phenology. These predictions showed great predictive power when tested against present distributions of two Nor th American species - quaking aspen and sugar maple - indicating that on a broad scale, the fundamental niche of trees coincides with their realized n iche. Phenology is shown here to be a major determinant of plant species ra nge and should therefore be used to assess the consequences of global warmi ng on plant distributions, and the spread of alien plant species.