Terracing stabilizes and enhances soil organic carbon sequestration benefits of revegetation on the Loess Plateau, China

Abstract

Revegetation is vital for enhancing carbon sequestration. However, the impacts of revegetation and terracing measures on soil organic carbon (SOC) content and SOC sequestration (SOCS), and the differences in the effects of revegetation measures on SOC and SOCS between sloped and terraced fields remain unclear. We conducted a field survey of cropland (CL), grassland (GL), and forestland (FL) in both sloped and terraced fields in Wuqi county, on China’s Loess Plateau. Revegetation in sloped fields significantly increased the SOC content at 0–10 cm depth (GL: p = 0.04; FL: p < 0.01). However, revegetation in terraced fields enhanced the SOC content at 0–100 cm (GL at 40–80 cm: p < 0.05; FL: p < 0.01). Terracing measures increased the SOC content, particularly in the subsoil, with the impact varying by land-use types. For FL, terracing significantly increased (p < 0.01) the SOC content in 20–40 cm, 40–60 cm, 60–80 cm and 80–100 cm by 38.2 %, 53.5 %, 41.1 % and 44.7 %, respectively. For GL, terracing significantly enhanced (p < 0.01) the SOC content at 40–60 cm and 60–80 cm by 32.0 % and 39.7 %, respectively. For CL, terracing did not significantly increase the SOC content. In sloped fields, revegetation reduced deep soil moisture and clay content, decreased subsoil SOC content, and led to an initial increase followed by a decrease in SOCS with depth. In terraced fields, revegetation enhanced SOC content and offset the negative effects on soil moisture and clay content, resulting in increased SOCS with depth. Revegetation primarily enhanced the SOCS at 0–40 cm, and terracing measures stabilized the SOCS in the 0–40 cm layers and further enhanced it in the 40–100 cm layers. In the context of soil erosion control and ecological restoration, implementing vegetation restoration with engineering measures can effectively stabilize and enhance the SOCS, fully leveraging the role of soil in mitigating climate change.