There have been several recent theoretical and empirical studies of competition between annual plants. Despite these efforts, many empiricists and theoreticians agree that there is little understanding of the impact of spatial heterogeneity on competitive interactions between plants. This is disturbing given the patchy nature of plant distributions and the ability of patchiness and dispersal to markedly alter competitive relationships in simple discrete models. The following are lacking: 1) experiments in which the spatial distrubutions of inter- and intraspecific competitors are manipulated; 2) experiments in which the consequences of dispersal (which alters these distributions) are investigated; and, 3) a theoretical framework for investigating competitive interactions between species with nonrandom spatial patterns. This project will investigate how spatial distributions and seed dispersal influence the dynamics of competing populations of Poa annua and Senecia vulgaris. A series of single generation competition experiments in which spatial distribution is manipulated under controlled conditions will be performed. Also the effects of dispersal will be incorporated by performing field experiments in which spatial distributions and dispersal are minipulated over many generations. Parallel with these experiments a model to explore more general questions about how dispersal and spatial patterns interact to determine plant population dynamics.
