Abstract: By measuring the foliar δ¹³C values of 5 common shrub species (Rhamnus davurica, Pyracantha fortuneana, Rubus biflorus,Zanthoxylum planispinum, and Viburnum utile) growing in various microhabitats in Wangjiazhai catchment, a typical karst desertification area in Guizhou Province, this paper studied the spatial heterogeneity of plant water use at niche scale and the response of the heterogeneity to different karst rocky desertification degrees. The foliar δ¹³C values of the shrub species in the microhabitats followed the order of stony surface > stony gully > stony crevice > soil surface, and those of the majority of the species were more negative in the microhabitat soil surface than in the others. The foliar δ¹³C values decreased in the sequence of V. utile> R. biflorus> Z. planispinum> P. fortuneana> R. davurica, and the mean foliar δ¹³C value of the shrubs and that of typical species in various microhabitats all increased with increasing karst rocky desertification degree, differed significantly among different microhabitats. It was suggested that with the increasing degree of karst rocky desertification, the structure and functions of karst habitats were impaired, microhabitats differentiated gradually, and drought degree increased.

Key words: karst rocky desertification, microhabitat, shrub, δ¹³C values