Carbon, Nitrogen and Phosphorus Stoichiometry and Its Influencing Factors in Karst Primary Forest

The stoichiometric characteristics of C, N, and P in plants result from long-term adaptation to environmental conditions. In this study, we analyzed leaf, branch, and soil C, N, and P stoichiometry in a karst primary forest plant community in China. The results showed that N and P content in leaves was higher than that in branches, while C content in the latter was higher than in leaves. Moreover, the coefficient of the variation in C, N, and P content in branches was greater than that in leaves but there was no significant difference in said coefficients in soil. The values of the C:N and C:P ratios were both branch > leaf > soil, whereas the value of the N:P ratio was leaf > branch > soil. There was also a significant positive correlation between leaf nitrogen (LN), leaf phosphorus (LP), branch nitrogen (BN), and branch phosphorus (BP) concentrations but no significant correlation between leaf carbon (LC), branch carbon (BC), and other element concentrations. We found that leaf stoichiometry was strongly influenced by species diversity, whereas branch stoichiometry was mainly influenced by leaf and species diversity; the environmental factors influencing the stoichiometric characteristics of leaves and branches were mainly altitude, soil pH, and total soil P. Finally, these results are relevant as they are helpful to understand the adaptation mechanisms and eco-geochemical processes in karst forest plants and they can also provide a scientific basis for vegetation restoration and reconstruction in these degraded ecosystems.