SEED AND SEEDLING BIOLOGY IN RELATION TO MODELING VEGETATION DYNAMICS UNDER GLOBAL CLIMATE CHANGE

The distribution of many plant species will change with global climate change, depending on their ability to disperse into, and establish in, new communities. Past migrations of species under climate change have been an order of magnitude slower than the rate of predicted climate change for the next century. The limited evidence available suggests that chance long distance dispersal events will be critically important in determining migration rates. We examine the JABOWA-derived gap replacement models and vital attributes/FATE models and ask: what do we need to know about dispersal and establishment to make improved projections of vegetation dynamics under climate change using these models? The minimal modifications of these models required to incorporate directional migration of species are described. To predict establishment success of species, we suggest that a more fundamental understanding is needed of how establishment ability under different conditions relates to seed and seedling attributes and how this may be affected by elevated CO2. Finally, we examine whether plant functional types based on vegetative attributes (used to model the response of adult plants) are correlated with functional types based on seed and seedling attributes. Available evidence suggests that the two sets of attributes are not strongly correlated; consequently, models of vegetation dynamics will need to incorporate seed biology explicitly.