Resumo

SANTIBANEZ-ANDRADE, Gabriela et al. Environmental Heterogeneity in a Xerophytic Shrubland. Bol. Soc. Bot. Méx [online]. 2009, n.85, pp.71-79. ISSN 0366-2128.

Biotic and abiotic heterogeneity in spatial and temporal scales were characterized for two areas of the xerophytic shrubland of the "Pedregal de San Ángel" (REPSA) ecological reserve. Nine floristic groups were identified and they showed a differential distribution of the plant species that inhabit this community. Each one of the groups was named according to the key species, therefore they were considered as determinants in the communities physiognomy. Through the use of multivariate analysis (TWINSPAN and CANOCO) we observed that species composition in the groups is modified in spatial and temporal scales. This study suggests that variation of some abiotic factors such as soil depth and slope influences differentially the systems heterogeneity. Temporal heterogeneity was evident since there was a different floristic composition in this area during the dry and the rainy season.

Palavras-chave : heterogeneity; microenvironment; xerophytic shrubland; multivariate analysis.