SPATIOTEMPORAL DEMOGRAPHIC-PROCESSES IN PLANT-POPULATIONS - AN APPROACH AND A CASE-STUDY

Suggests an approach combining theory and experiments to describe and analyse the effects of seed dispersal and seed dormancy on the population dynamics of annual plants. The approach is based on the identification of 3 potential sources of recruitment to plant populations: local reproduction; the soil seed bank; and the net gain from dispersal. Mathematical expressions for the different sources in the form of specific combinations ("components') of demographic variables and parameters are derived from a dynamic model of an annual populaiton in a spatially and temporally variable environment. An experimental procedure for quantifying the model components was used to investigate the joint effects of dispersal and dormancy on the dynamics of populations of the desert annual Stipa capensis. Seed dormancy and, in particular, seed dispersal were important in determining spatial (between-habitats) and temporal (between-years) changes in the density of the studied populations. -from Authors