Converting evergreen broad-leaved forests into tea and Moso bamboo plantations affects labile carbon pools and the chemical composition of soil organic carbon.

This study aimed to explore the effects of conversion from evergreen broad-leaved forests (EBFs) to tea plantations (TPs) and Moso bamboo (Phyllostachys heterocycla var. pubescens) plantations (MBPs) and the subsequent long-term intensive management on the soil carbon pool and the chemical composition of soil organic carbon (SOC). Soil samples from three layers (0-10, 10-30 and 30-60 cm, respectively) were collected from adjacent EBFs, TPs and MBPs in An'ji County, Zhejiang Province, China. The physico-chemical properties of soils, including bulk density, SOC and its different fractions were determined. The chemical composition of SOC was also measured using 13C-nuclear magnetic resonance spectroscopy (NMR). The results showed that conversion from EBFs to TPs and MBPs decreased the concentrations of water soluble organic carbon (WSOC), light and heavy fraction organic carbon (LFOC, HFOC) and humus carbon (HC) (P < 0.05), reduced the O-alkyl C and carbonl C content, but increased the alkyl C, Aromatic C, aromaticity and the ratio of alkyl C/O-alkyl C (A/O-A) (P < 0.05). These results suggested that intensive management markedly altered the chemical structure of SOC and labile carbon pools. Our results demonstrated that converting EBFs to TPs and MBPs had a negative effect on SOC content and a positive effect on SOC stability. Therefore, management practices such as rational fertilization and sod cultivation are recommended after land-use conversion.