9411702 Schemske Invasions of exotic plant species represent a major concern of those charged with maintaining and protecting native communities. Particular exotics have produced major ecological perturbations, and in some areas the sheer numbers of introduced plant species swamp out native floras. Once an exotic pest becomes established in an area, ecologists and resource managers would like to know where it is likely to spread and when it will get there. The factors influencing rates of invasion are important objects of study both to understand the dynamics of range expansion in general and to begin to address urgent questions of exotics management and control. The proposed research focusses on Cytisus scoparius (Scotch broom), a serious pest plant on the West Coast of North America. Observational and experimental approaches will characterize the seed dispersal distribution of this plant as contributed by the explosive opening of fruits and by secondary ant dispersal. The population consequences of relatively long-distance jumps will be evaluated in a whole field experiment manipulating the distribution of adult plants.
