Notes on Contagious Distributions in Plant Populations

Abstract

Past experience has shown that the Poisson series is often inadequate as a model for describing plant populations. Various alternative two-parameter models have been suggested in place of the Poisson series, but they all depend on assumptions which may or may not hold. In this paper a different approach is put forward in that attention is concentrated on the mean number of plants per quadrat and an index of ‘clumping’ or ‘contagiousness’. Examples are given as to the use of these concepts to test for differences between the distribution of a plant in two localities or between two plants in the same locality.