喀斯特石漠化区不同小生境常见灌木种叶片δ13C值特征

测定了喀斯特石漠化区不同小生境内5种常见灌木（鼠李、火棘、粉枝莓、竹叶椒和烟管荚蒾）的叶片δ¹³C值，探讨喀斯特石漠化对植物水分利用空间异质性的影响.结果表明： 不同小生境植物的δ¹³C均值大小顺序为：石面>石沟>石缝>土面.土面生境中多数灌木种植株叶片δ¹³C值较其他生境偏轻；灌木叶片δ¹³C值大小顺序为：烟管荚蒾＞粉枝莓＞竹叶椒＞火棘＞鼠李.各小生境内灌木叶片δ¹³C均值和主要灌木种叶片δ¹³C值均随着石漠化加深而增大，且不同小生境间差异显著.随着石漠化的加剧，喀斯特生境结构和功能受损，小生境逐渐分异，环境逐渐向着干旱化发展.

Characteristics of foliar δ13C values of common shrub species in various microhabitats with different karst rocky desertification degrees.

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.