High variance in population densities suggests:
A high variance among equal-area counts relative to their mean indicates that individuals are concentrated unevenly across space. Clumped populations produce many quadrats with few or no individuals and a smaller number with very high counts, inflating variance above the Poisson random expectation. The variance-to-mean ratio therefore exceeds 1 under aggregation. Uniform dispersion gives unusually similar counts and a ratio below 1, while random dispersion gives a ratio near 1. “High variance” should ideally be interpreted relative to the mean rather than in isolation, because variance natural
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9