Carbon, Nitrogen and Phosphorus Stoichiometry in Natural and Plantation Forests in China

Abstract

Ecological stoichiometry is essential for understanding the biogeochemical cycle in forest ecosystems. However, previous studies of ecological stoichiometry have rarely considered the impacts of forest origins, which could help explain why to date so much uncertainty has been reported on this subject. In this study, we tried to reduce this uncertainty by examining carbon (C), nitrogen (N) and phosphorus (P) in roots, litter and soil in both natural and plantation forests throughout China. The sampled forest sites were divided into three groups according to the identified succession stages: early (ES), middle (MS) and late (LS) stages. Our results show that soil C, N and P concentrations were significantly higher in natural (NF) than in plantation (PL) forests. As succession/growth proceeded, P concentrations significantly increased in litter, roots and soil in NF, while the opposite occurred in PL. These results indicate that NF are able to use P more efficiently than PL, especially in the LS. Furthermore, the higher root N:P ratio indicates that the growth of PL was limited by P in both MS and LS. Our results also suggest that geographical and climatic factors are not the dominant factors in the differences in P between NF and PL, and, even more clearly and importantly, that native forests with native species are more capable of conserving P than planted forests, which are frequently less diverse and dominated by fast-growing non-site native species. These results will help improve biogeochemical models and forest management throughout the world.