SCALES OF SEGREGATION AND AGGREGATION OF PLANTS OF DIFFERENT KINDS

This paper introduces a method for examining the scales of segregation or aggregation of two kinds of plants. It uses the mapped positions o f plants but is based on methods originally designed for contiguous qu adrat data and may be referred to as two-dimensional local quadrat cov ariance. A complementary randomization procedure makes it possible to test whether observed aggregation is merely the result of overall patc hiness. These methods are applied to analyze the spatial pattern of So lidago canadensis L. plants in an old hayfield, with and without insec t galls. In many of the 12 plots sampled, the galled and nongalled pla nts were found to be aggregated at scales around 0.7m. The randomizati on test showed, however, that this apparent aggregation was often due to the overall patchiness of the plants' dispersion, and that in some cases, within the patchiness the two kinds of plants were actually seg regated at a similar scare.