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EQUIVALENCE OF COMPETITORS IN PLANT COMMUNITIES: A NULL HYPOTHESIS AND A FIELD EXPERIMENTAL APPROACH
Author(s) -
Goldberg Deborah E.,
Werner Patricia A.
Publication year - 1983
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1983.tb07912.x
Subject(s) - biology , null hypothesis , ecology , equivalence (formal languages) , interspecific competition , competitor analysis , homogeneity (statistics) , intraspecific competition , plant community , statistical hypothesis testing , null model , alternative hypothesis , relative species abundance , coexistence theory , abundance (ecology) , species richness , econometrics , statistics , mathematics , management , discrete mathematics , economics
One of the underlying assumptions of both theoretical and empirical community ecology is that the processes determining community composition and abundance of species are interactions specific to particular pairs of species. However, we argue that, in sessile plants at least, competitive interactions are not usually species‐specific and that there exists a large degree of equivalence of the effect of species of similar growth form on the ability of any particular species to establish within a community. This null hypothesis of equivalence of competitive effects is based on three characteristics of plants: homogeneity of resource requirements among autotrophs; low encounter probabilities between individuals of any particular species pair; and the predominance of size asymmetries between competing individuals (e.g., seedling‐adult interactions.) We present an experimental design to quantify competitive interactions among plant species under field conditions and therefore enable statistical comparisons of competitive abilities among species. The competitive effect of one “neighbor” species on one “target” species is measured as the slope of a regression of performance of target individuals on biomass (or other measure of amount) of its immediate neighbors. Use of the design to test for equivalence of competitive effects and other advantages are described.