Abstract: Based on the measurements of the foliar δ¹³C values of seven dominant plant species on the continuous rock outcrops and nearby soils on karst hill slopes of northwest Guangxi, China, this paper analyzed the differences in the foliar carbon isotope ratio of the plants in different habitats and different seasons. The foliar δ¹³C values of test plants were significantly higher in dry season than in wet season (P<0.05). Radermachera sinica, Vitex negundo, and Clematis kweichowensis had no significant differences in their foliar δ¹³C values in wet season and dry season (P>0.05), but Rhus chinensis, Alchornea trewioides, Nephrolepis auriculata, and Pteridium aquilinum had significantly higher foliar δ¹³C values in dry season than in wet season (P<0.05), which suggested that the seasonal differences in rainfall had less effects on the foliar δ¹³C values of R. sinica, V. negundo, and deep-rooted shrub, but had great effects on those of shallow-rooted grass and shrub. No significant differences were observed in the foliar δ¹³C values of R. sinica, A. trewioides, and V. negundo on the continuous rock outcrops and nearby soils both in dry and in wet seasons (P>0.05), but the foliar δ¹³C values of the shrubs differed greatly in the two habitats both in dry and in wet seasons, suggesting that habitat condition had great effects on the foliar δ¹³C values of shrub than of deep-rooted tree.

Key words: MtQinling, Quercus aliena var acuteserrata, Niche breadth, Niche overlap