Estimating the Effects of Heterogeneous Competition in an Agent-Based Ecological Model Using GIS Raster Color

It is hypothesized that inter-species competition is one of the main factors that determine the range and distribution of Sensitive joint-vetch (SJV), a rare, tidal wetlands annual. The precise effects of this competition, however, are poorly understood by ecologists and difficult to quantify. We have constructed a detailed, agent-based simulation of SJV in its Holts Creek, Virginia, habitat. In order to shed light on these landscape-scale effects, we propose a new method of distinguishing poor from high quality plots that uses GIS to correlate the pixel color of an individual m 2 plot to its propensity for sustaining SJV. This propensity is then used to determine the vital rates of a given plot and is applied to all plants within it. Results indicate that inter-species competition plays a limiting, though by no means exclusively important, role in the spatial arrangement and rarity of SJV.