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A measure for spatial heterogeneity of a grassland vegetation based on the beta‐binomial distribution
Author(s) -
Shiyomi Masae,
Takahashi Shigeo,
Yoshimura Jin
Publication year - 2000
Publication title -
journal of vegetation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 115
eISSN - 1654-1103
pISSN - 1100-9233
DOI - 10.2307/3236569
Subject(s) - quadrat , grassland , spatial heterogeneity , plant community , spatial distribution , negative binomial distribution , ecology , spatial ecology , grazing , common spatial pattern , vegetation (pathology) , biology , statistics , mathematics , species richness , shrub , poisson distribution , medicine , pathology
. A method is proposed to estimate the frequency and the spatial heterogeneity of occurrence of individual plant species composing the community of a grassland or a plant community with a short height. The measure is based on the beta‐binomial distribution. The weighted average heterogeneity of all the species composing a community provides a measure of community‐level heterogeneity determining the spatial intricateness of community composition of existing species. As an example to illustrate the method, a sown grassland with grazing cows was analysed, on 102 quadrats of 50 cm × 50 cm, each of which divided into four small quadrats of 25 cm × 25 cm. The frequency of occurrence for all the species was recorded in each small quadrat. Good fits to the beta‐binomial series for most species of the community were obtained. These results indicate that (1) each species is distributed heterogeneously with respective spatial patterns, (2) the degree of heterogeneity is different from species to species, and (3) the beta‐binomial distribution can be applied for grassland communities. In most of the observed species spatial heterogeneity is often characterized by species‐specific propagating traits: seed‐propagating plant species exhibited a low heterogeneity/random pattern while clonal species exhibited a high heterogeneity/aggregated pattern. This measure can be applied to field surveys and to the estimation of community parameters for grassland diagnosis.