Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
Sci Rep. 2020 Oct 9;10(1):16927. doi: 10.1038/s41598-020-73910-7.
Massive gully land consolidation projects, launched in China's Loess Plateau, aim to restore 2667 [Formula: see text] agricultural lands in total by consolidating 2026 highly eroded gullies. This effort represents a social engineering project where the economic development and livelihood of the farming families are closely tied to the ability of these emergent landscapes to provide agricultural services. Whether these 'time zero' landscapes have the resilience to provide a sustainable soil condition such as soil organic carbon (SOC) content remains unknown. By studying two watersheds, one of which is a control site, we show that the consolidated gully serves as an enhanced carbon sink, where the magnitude of SOC increase rate (1.0 [Formula: see text]) is about twice that of the SOC decrease rate (- 0.5 [Formula: see text]) in the surrounding natural watershed. Over a 50-year co-evolution of landscape and SOC turnover, we find that the dominant mechanisms that determine the carbon cycling are different between the consolidated gully and natural watersheds. In natural watersheds, the flux of SOC transformation is mainly driven by the flux of SOC transport; but in the consolidated gully, the transport has little impact on the transformation. Furthermore, we find that extending the surface carbon residence time has the potential to efficiently enhance carbon sequestration from the atmosphere with a rate as high as 8 [Formula: see text] compared to the current 0.4 [Formula: see text]. The success for the completion of all gully consolidation would lead to as high as 26.67 [Formula: see text] sequestrated into soils. This work, therefore, not only provides an assessment and guidance of the long-term sustainability of the 'time zero' landscapes but also a solution for sequestration [Formula: see text] into soils.
中国黄土高原启动大规模沟壑土地整治工程，计划通过整治 2026 条严重侵蚀沟壑，恢复总计 2667 公顷农业用地。这是一项社会工程，农户的经济发展和生计与新生景观提供农业服务的能力密切相关。这些“零时间”景观是否具有提供可持续土壤条件（如土壤有机碳（SOC）含量）的恢复力尚不清楚。通过对两个流域（其中一个为对照流域）的研究，我们表明，整治后的沟壑是增强的碳汇，SOC 增加率（1.0）约为周围自然流域 SOC 减少率（-0.5）的两倍。在景观和 SOC 周转率的 50 年共同演变过程中，我们发现，决定碳循环的主要机制在整治沟壑和自然流域之间存在差异。在自然流域中，SOC 转化通量主要由 SOC 传输通量驱动；但在整治沟壑中，传输对转化影响不大。此外，我们发现，延长地表碳停留时间有潜力将大气中的碳封存率提高到 8，而目前的封存率仅为 0.4。所有沟壑整治工程的完成将导致高达 26.67 被封存到土壤中。因此，这项工作不仅为“零时间”景观的长期可持续性提供了评估和指导，也为土壤碳封存提供了一种解决方案。
