干旱区生态环境知识资源中心

The investigation focuses on competitive interactions between a perennial shrub Indigofera oblongifolia and two annuals Tephrosia strigosa and Corchorus triloccularis as well as the intraspecific competition of the three mentioned species. Both intraspecific and interspecific competitions were inferred using the nearest neighbour distances between pairs of plants. Intraspecific competitive intensity was found to be greater for the annuals than that of the perennial shrub. Interspecific competition between the perennial shrub species and the two annuals was assessed by the reproductive potential of the annuals. The accumulation of phenolics in the roots of annuals was tested in response to competitive stress. The number of flowers (and fruits) in the two annuals were depressed as the distance between annual plant and the shrub (I. oblongifolia) declined. By contrast, there was greater accumulation of total soluble phenols in the annuals as the distance of the shrub became closer to the annual. The implications of competitive interactions in structuring the communities are discussed.