Spatial heterogeneity in a grassland community: Use of power law

Citation
M. Shiyomi et al., Spatial heterogeneity in a grassland community: Use of power law, ECOL RES, 16(3), 2001, pp. 487-495
Citations number
29
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
ECOLOGICAL RESEARCH
ISSN journal
0912-3814 → ACNP
Volume
16
Issue
3
Year of publication
2001
Pages
487 - 495
Database
ISI
SICI code
0912-3814(200109)16:3<487:SHIAGC>2.0.ZU;2-8
Abstract
A new regression analysis was proposed to evaluate the degree of spatial he terogeneity for individual species comprising a plant grassland community. The weighted average of the heterogeneity value of all the species comprisi ng the community provides a measure of community-level heterogeneity. A fie ld survey was carried out, as an example, in order to analyze the spatial h eterogeneity of a pasture with grazing cows, using 100 quadrats 50 cm x 50 cm, each of which was divided into four smaller quadrats 25 cm x 25 cm, on a 50 m long line-transect. The frequency of occurrence for all the species in each small quadrat was recorded. The regression associated with the rati o of the theoretical and observed variances of occurrence counts was used t o analyse the frequency distribution of species in a pasture community. A g ood fit to the regression for the whole community was obtained. These resul ts indicate that (i) each species in the example was distributed more heter ogeneously than a random pattern; and (ii) the regression could well descri be the spatial heterogeneity of the grassland plant community. In most of t he observed species, spatial heterogeneity is often characterized by specie s-specific propagation traits and the architecture of plant bodies. Thus, t he spatial patterns of a grassland community can be evaluated in detail by this power-law approach. This measure is suitable for field surveys and com parative studies of grassland communities, and for other plant communities that are generally short in height.