We analyze a system of diffuse competition in an ant community in a coffee agroecosystem. The community is constrained by space since the dominant competitor (Azteca sericeasur) has a limited range of influence within which it excludes other species, but outside that range, the other species may persist. We use a simple dynamic model in which variable A, the dominant competitor, competes strongly with variable S, the collection of all other species in the system, the latter acting as a strong competitor in the context of diffuse competition. Two qualitatively distinct outcomes are expected depending on the strength of competition: 1) a simple monotonic increase in species richness as distance from the Azteca nest increases, or 2) a range of distance from the nest in which there is bi-stability, bookended by critical transitions. Studying five nests in wet and dry seasons over a two-year period, we find evidence for bi-stability.