干旱区生态环境知识资源中心

Background: Many dryland plant communities are characterised by scattered shrubby vegetation. In such dry ecosystems, individual shrubs modify the local micro-environment and affect the surrounding plant community.

Aims: The present study was conducted in a dry Mediterranean grassland community, with scattered shrubs, to determine the impacts of biologically induced micro-environments on the surrounding plant community.

Methods: The plant community was sampled at four distances in four micro-environments, defined by cardinal compass directions (north, south, east and west) to assess vegetation composition near individual shrubs and at increasing distances from them. To quantify the impact of shrubs on surrounding species composition, we used a rarefaction approach in addition to alpha and beta diversity and cover parameters. Also, the productivity-diversity relationship was investigated.

Results: We found significant micro-environment differences in non-shrub communities in terms of vegetation, bare ground and litter cover, above-ground biomass, species richness and Shannon diversity index. The diversity-productivity relationship was best fit by unimodal and linear models. Rarefaction analysis accumulated more species in the west aspect than in the other aspects. Beta diversity values for consecutive distances were significantly higher than the farthest distances.

Conclusions: These findings suggest that shrubs create micro-environments and influence plant community characteristics according to distance and aspect, and therefore add to the complexity and biodiversity of the system; by creating diverse microhabitats they contribute to enhanced plant diversity.