Comparative study of the stoichiometric characteristics of karst and non-karst forests in Guizhou, China

Carbon (C), nitrogen (N), and phosphorous (P) levels and their stoichiometry in plant components (leaves, branch trunks, roots) of trees in a karst forest and non-karst forest are compared. The results show that the C contents, C:N and C:P ratios of dominant species in the karst forest were lower than those in the non-karst forest, but the N and P and the N:P ratio were higher; C:N:P ratios in plant organs of trees in the karst forest were in the order of trunks > roots > branches > leaves. However, C:N:P ratio in the non-karst forest trees were trunks > branches > roots > leaves. Moreover, ratio of C:N:P in trunks was highest and lowest in leaves in both forests. In non-karst forest trees, N:P was in the order of leaves > roots > branches > trunks. There were no significant differences in the ratio of N:P in different plant components of trees in the karst forest. However, in karst and non-karst forest trees, the ratio of N:P in leaves was highest; positive correlations between N and P contents, and N and N:P ratios were observed in both karst and non-karst forests (p < 0.001). Negative correlations between P and N:P ratios (p < 0.05) were observed in karst forest trees, while positive correlations were observed in non-karst forest trees.