Conversion effects of farmland to Zanthoxylum bungeanum plantations on soil organic carbon fractions in the arid valley of the upper reaches of the yangtze river, china

Farmland afforestation is an effective measure to sequester carbon (C) into soil, but the effects of different farmland conversion approaches on soil organic C (SOC) fractions in arid valley are still not clear. In this work, concentrations each SOC fraction 0–100 cm depth, litter stock (LS) and fine root biomass (FRB) (FL), abandoned land (AL) Zanthoxylum bungeanum plantations ages (with planting 8, 15, 20 28 years, abbreviated as ZB8, ZB15, ZB20 ZB28, respectively) were measured. The results showed that 1) same layer increased after conversion, these indices ranked AL > ZB28 ZB15 ZB8 FL, all them decreased with depth; 2) stock, sequestration rate by 120.1–158.9 Mg ha−1, 4.9–43.8 ha−1 0.6–1.6 yr−1, respectively, FL was converted Z. order land-use types; 3) pool management index (CPMI), LS FRB types significantly (p < 0.05) correlated CPMI, while CPMI fraction. This implies valleys mediated helpful improve size activity pools, can be used a useful estimate pools region. sense, roots should emphasized process increase sequestration.