Abstract
Early stages in the evolution of three artificial grass–legume communities were monitored by tracing the development of pattern and association, and percentage cover, among the constituent legumes. The results show that patterns and associations among the legumes changed rapidly and were influenced by the presence of grasses. Even though the percentage cover of each legume was only slightly affected by the presence of grasses, the legumes tended to be more evenly distributed when grasses were present than when they were absent. This had a small limiting effect on the rates of formation of species associations. When grasses were absent, the legumes formed more intense clumps. This suggests that the presence of grasses slows down the rate of clump formation in legumes and hinders the rate of development of associations. Another effect of the grasses was to induce positive associations between the legumes; when grasses were absent, the legumes were negatively associated.