Ecosystem carbon sequestration of Zanthoxylum bungeanum plantations under the farmland conversion in the arid valley of the upper reaches of Yangtze River, China.

Aims: Vegetation restoration has been widely implemented to achieve carbon (C) sequestration and prevent land degradation, and this study aims to evaluate the ecosystem C pools and C sequestration effectiveness of different land-use types. Methods: In this study, the plant biomass C stock, litter C stock, soil organic C (SOC) stock and ecosystem C sequestration in Zanthoxylum bungeanum plantations (with stand ages of 28, 20, 15 and 8 years, abbreviated as ZB28, ZB20, ZB15 and ZB8, respectively), abandoned land (AL) and farmland (FL) were estimated. Results: (1) the plant biomass and biomass C stock of above-and below-ground increased after farmland conversion, and all of them ranked as ZB28 > ZB20 > ZB15 > AL > ZB8 > FL; (2) the litter stock and C stock, and SOC concentration and stock of different land-use types ranked as AL > Z. bungeanum plantations > FL, and these indices increased with the stand age; (3) the C stock of the ecosystem in FL was 115.4 Mg C ha⁻¹, and the C stock of the ecosystem increased by 8.9–66.6 Mg C ha⁻¹ and 52.4 Mg C ha⁻¹ after the conversion of FL to Z. bungeanum plantations and AL, respectively; (4) and soil C sequestration accounts for 55.6–83.6% of ecosystem C sequestration after farmland conversion. Conclusions: This implies that the conversion of farmland to Z. bungeanum plantations was the best approach in the arid valley area when the ecosystem C sequestration and economic benefits were considered. [ABSTRACT FROM AUTHOR]