College of Life Sciences, Shanxi Normal University, Linfen 041000, China; State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA.
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Sci Total Environ. 2020 May 20;718:137355. doi: 10.1016/j.scitotenv.2020.137355. Epub 2020 Feb 15.
Large-scale vegetation restoration projects pose threats to water resource security in water-limited regions. Thus, the quantification of how vegetation cover affects soil moisture is of key importance to support effective restoration schemes in drylands. However, the current understanding of such effects remains poor. For this study, an in-situ vegetation-removal experiment was conducted at 36 herbaceous grassland sites having different community compositions and topographical conditions in two adjacent loess watersheds of the Loess Plateau, China. The effects of vegetation cover (vegetation effects) on soil moisture were analyzed across soil profiles (0-180 cm) and two growing seasons. Overall, 13 plant traits and 7 topographic and soil properties were employed to evaluate how community compositions modulated vegetation effects on soil moisture. The results showed that vegetation cover increased soil moisture in the surface layer (0-20 cm) by 6.81% during wet periods (semi-monthly rainfall >30 mm) relative to an in-situ unvegetated control, but primarily induced a decline of soil moisture in the deep soil layer (20-180 cm) by 19.44% across two growing seasons. Redundancy analysis (RDA) and structural equation modeling (SEM) suggested that these vegetation effects on soil moisture were significantly correlated with vegetative height, leaf area, shallow root allocation, and slope gradient. Our study revealed that tall, small-leaved, and shallow-rooted plants on flat topographies were beneficial to soil water retention and replenishment. This implied that current restoration strategies may be significantly improved through the development of optimal communities and diverse terracing measures. Our findings are anticipated to provide effective guidance for soil water conservation, as well as ecosystem rehabilitation in dry and degraded regions.
大规模的植被恢复项目会对水资源有限地区的水资源安全构成威胁。因此，量化植被覆盖如何影响土壤水分对于支持干旱地区的有效恢复计划至关重要。然而，目前对这种影响的认识仍然不足。在本研究中，在中国黄土高原两个相邻的黄土流域的 36 个草本草地站点上进行了原位植被去除实验，这些站点具有不同的群落组成和地形条件。分析了植被覆盖（植被效应）对土壤水分的影响，研究范围涵盖土壤剖面（0-180cm）和两个生长季节。总体而言，使用了 13 种植物性状和 7 种地形和土壤特性，以评估群落组成如何调节植被对土壤水分的影响。结果表明，与原位无植被对照相比，植被覆盖在湿润期（半旬降雨量>30mm）使表层土壤（0-20cm）的土壤水分增加了 6.81%，但在两个生长季节主要使深层土壤（20-180cm）的土壤水分减少了 19.44%。冗余分析（RDA）和结构方程模型（SEM）表明，这些植被对土壤水分的影响与植被高度、叶面积、浅层根系分配和坡度梯度显著相关。我们的研究表明，在平坦地形上，高大、小叶和浅根的植物有利于土壤水分保持和补充。这意味着通过开发最佳群落和多样化的梯田措施，当前的恢复策略可能会得到显著改善。我们的研究结果有望为干旱和退化地区的土壤水保持以及生态系统恢复提供有效的指导。
