Responses of Foliar δ13C Values of Woody Plants to Different Karst Rocky Desertification Degrees in Huajiang Gorge, Guizhou Characteristics of foliar δ13C values of common shrub species in various microhabitats with different karst rocky desertification degrees. Relationship among Leaf Anatomical Characters and Foliar δ13 C Values of Six Woody Species for Karst Rocky Desertification Areas