Limitation to plant species coexistence at a point: a study in a New Zealand lawn

Abstract. Limitation in the number of species that can coexist at a single point was examined by point‐quadrat sampling of a lawn. Three treatments were examined: Control, Herbicide‐treated to remove grasses, and Mechanically perturbed to remove all plants, with 10 replicates of each. The Control plots showed an almost constant degree of niche limitation, variance in richness between points being half that expected under the null model. The herbicided plots showed a significantly lesser degree of niche limitation for the first three months after herbiciding, even though the degree of plant overlap had already recovered by the first sampling time. Six weeks after mechanical perturbation, there was no evidence of niche limitation, but the extent of, and statistical evidence for, niche limitation increased until, 10 months after perturbation, community structure was as strong as in the Control.