Exploring the influence of shrubs on herbaceous communities in a Mediterranean climatic context of two spatial scales

Communities of plants determine nonrandom spatial patterns defined by the intervention of abiotic and biotic factors acting at different spatial scales. We consider the influence of shrubs as one of the most important factors (biotic) affecting these spatial patterns at microscale. The macroclimate could be considered one of the most important factors (abiotic) at regional scale. To study the role and the floristic implications of each factor on the global patterns of herbaceous communities, we have developed a stratified sampling design that integrates both micro and macroscale on a 100 Km-long transect (east–west) in western central Spain. The results suggest that macroclimate could be one of the most important factors in determining herbaceous spatial patterns. Moreover, shrubs create a microspatial environmental heterogeneity that could alter such global climate patterns, modifying the spatial affinities established among species. This implies that environmental heterogeneity related to microhabitat could play a key role in spatial patterns at broad spatial scales, and consequently in the dynamics of the distribution and establishment of herbaceous species.