Abstract:In order to explore the nutrient cycling characteristics of C, N and P in Tiankeng forest communities in Dashiwei, Leye, Guangxi, the contents and stoichiometric ratios of C, N and P in plant leaf, litter and soil of forest communities inside and outside Tiankeng were compared, and their internal relationship and interaction were studied by using correlation analysis and redundancy analysis. The results showed that the leaf and litter of the forest inside Tiankeng showed a pattern of low C, low N and high P, and the soil was low C, low N and high P compared with the forests outside the Tiankeng. The C:N and C:P in leaf were significantly positively correlated with the C and N:P in litter, and C in leaf showed significantly negative correlation with P in soil. The N and N:P in leaf outside Tiankeng were significantly negative correlated with N:P in soil, and C:N in leaf was significantly positive correlated with C and C:N in soil, indicating that the C and P in litter inside Tiankeng forest might came from leaves, while C and N in leaf outside Tiankeng forests were mainly from soil. The explanation rates of soil C:N:P for the change of C:N:P of leaves and litter were 90.7% and 50.6%, respectively. The P had the highest explanation for the change of C:N:P of leaves and litter. Plants inside Tiankeng were more sensitive to the change of P content, while plants outside Tiankeng were more sensitive to the change of N content, which indicating that the forest inside Tiankeng might be the P-limited site, while the forest outside Tiankeng might be the N-limited site. The differences and associations of C:N:P in leaf-litter-soil of the forests inside and outside karst Tiankeng reflected the characteristics of nutrient cycling and the adaptation of plant community.