Soil organic carbon stocks in an investigated watershed transect linked to ecological restoration practices on the Loess Plateau

Abstract

AbstractLager scale ecological restoration practices are increasing soil organic carbon (SOC) stocks. Meta‐analysis is by far the most widely applied technique for describing SOC at large spatial scales, but there is a lack of field‐based investigations on a series of individual watersheds. In this study, a watershed transect of six watersheds distributed in a hilly and gully area of the Loess Plateau was investigated in order to achieve sustainable practices. The results indicate that ecological restoration practices significantly increased SOC stocks to varying degrees (p < 0.05). Grasslands were associated with the largest SOC stocks (39.42 ± 22.21 t hm−2), which were larger than the SOC stocks of artificial immature forest (<20 years) (26.58 ± 14.32 t hm−2) in the 50 cm soil profile. However, in the long term, afforestation seems to increase SOC stocks to the level of secondary forest, 81.15 ± 4.69 t hm−2, in a suitable environment. Appropriate land use management is also an effective approach to improving soil C sequestration capacity. SOC stocks were measured as 34.11 ± 7.66 t hm−2 in abandoned terraced farmland, which was similar to the grassland SOC stocks. Soil and plant factors contributed approximately 60% to the variation in the spatial distribution of SOC stocks at 0–50 cm; their contributions increased and diminished with increasing soil depth, respectively. This study indicates naturally restored grassland and engineering practices are suitable on the Loess Plateau by investigating a watershed transect and enhances our understanding of the comprehensive contributions of environmental factors to the spatial distribution of SOC stocks on a large spatial scale.