Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China; USDA-ARS National Soil Erosion Research Laboratory, 275 S Russell St., West Lafayette, IN 47906, USA.
Blackland Research and Extension Center, Texas A&M Agrilife Research, Texas A&M University, TX 76502, USA.
Sci Total Environ. 2021 Jan 1;750:141717. doi: 10.1016/j.scitotenv.2020.141717. Epub 2020 Aug 15.
Erosion-induced soil carbon loss has been identified as a critical process in the global carbon (C) cycle. Surface coverage substantially alters the soil erosion process and the effects of net loss or deposition on soil organic C (SOC). However, information on SOC loss induced by soil erosion at the process level is limited. The aim of this study was to investigate how runoff and erosion regimes affect dissolved and sediment-bound organic C (DOC and SBOC) loss. Thus, six simulated rainfall events were conducted on two laboratory plots (9.75 m × 1.83 m) with different surface coverages (17-83%) and coverage distributions (upslope vs. downslope) using polypropylene geotextiles. The results showed that the variability in the process of runoff and sediment yield existed as a result of altered surface coverage over the erosion zone (SS) and covered zone (SS) on the slope. Thus, the erosion regimes can be identified as deposition- and transport-dominated processes, which were the main soil erosion subprocesses. The surface coverage located downslope (SC slope) can more efficiently reduce runoff (21.9-85.7%) and sediment (67.6-98.3%) than the SC slope (runoff: 20.1-83.0%; sediment: 35.0-93.3%), which has the surface coverage located upslope. DOC (8.0-11.3 mg L) and SBOC (0.3-0.5 mg g) in the deposition-dominated process on the SC slope were higher than in the transport-dominated process on the SC slope (DOC: 6.8-10.2 mg L; SBOC: 0.2-0.3 mg g). The loading of DOC and SBOC was largely dependent on runoff and sediment yield, and DOC load contributed 83.9-89.7% of the SOC loss. Overall, laboratory results highlighted the soil C loss at different hydrological and erosion regimes (deposition- vs. transport-dominated process). This study provides important information that can be used to facilitate further implementations such as watershed modeling of soil C dynamics and the corresponding decision-making processes.
侵蚀导致的土壤碳损失已被确定为全球碳（C）循环中的一个关键过程。地表覆盖物会极大地改变土壤侵蚀过程，以及净损失或沉积对土壤有机碳（SOC）的影响。然而，关于侵蚀过程中 SOC 损失的信息有限。本研究旨在探讨径流量和侵蚀制度如何影响溶解态和沉积物结合态有机碳（DOC 和 SBOC）的损失。因此，使用聚丙烯土工织物在两个具有不同地表覆盖（17-83%）和覆盖分布（上坡和下坡）的实验室样地（9.75 m×1.83 m）上进行了六场模拟降雨事件。结果表明，由于侵蚀区（SS）和覆盖区（SS）的地表覆盖物发生改变，径流量和泥沙产率的过程变化存在差异。因此，可以将侵蚀制度识别为以沉积和输运为主的过程，这些是主要的土壤侵蚀亚过程。位于下坡的地表覆盖物（SC 下坡）比位于上坡的地表覆盖物（SC 上坡）更有效地减少径流量（21.9-85.7%）和泥沙（67.6-98.3%）。在 SC 下坡的沉积主导过程中，DOC（8.0-11.3 mg L）和 SBOC（0.3-0.5 mg g）高于 SC 上坡的输运主导过程（DOC：6.8-10.2 mg L；SBOC：0.2-0.3 mg g）。DOC 和 SBOC 的负载量主要取决于径流量和泥沙产率，DOC 负载量占 SOC 损失的 83.9-89.7%。总体而言，实验室结果突出了不同水文和侵蚀制度下的土壤 C 损失（沉积主导过程与输运主导过程）。本研究提供了重要信息，可以用于促进流域土壤 C 动态模型等的进一步实施以及相应的决策过程。
