Competition and Spacing in Plant Communities: The Northern Mohave Desert

Abstract

Intraspecific and interspecific spacing and competition were studied in a diverse plant community in the northern Mohave Desert [California, USA]. Measurements of the sizes of nearest-neighbor plants and the distances between them were taken for Opuntia acanthocarpa (acan), O. ramosissima (ramo) and Yucca schidigera (yucca). Competition is occurring between all intraspecific and interspecific neareast-neighbor pairs. No difference in the degree of competition could be detected between morphologically similar and dissimilar interspecific species-pairs (i.e., acan-ramo and acan-yucca). Individuals of different species occur significantly closer together than individuals of the same species. Despite the fact that ramo has a larger photosynthetic surface area (PSA) than acan in relation to bush diameter, for large sums of PSA ramo individuals are spaced closer together than acan individuals.