Trade‐off between vegetation type, soil erosion control and surface water in global semi‐arid regions: A meta‐analysis

Soil erosion control and water resource protection can closely interact during restoration of terrestrial ecosystems. In semi‐arid ecosystems, an urgent issue is how vegetation restoration can achieve the goal of soil erosion mitigation and water conservation, which in turn, feeds back to ecosystem functioning. We reviewed 78 articles from 22 countries in semi‐arid areas to evaluate the effects of vegetation type (i.e. forest, grassland and scrubland) on runoff and sediment yields across different environmental conditions (i.e. vegetation coverage, rainfall intensity, slope gradient and soil texture). Our meta‐analysis shows that runoff and sediment reduction both increased as the vegetation coverage increased, and tended to be stable when vegetation coverage exceeded 60%. Vegetation provided a greater benefit for sediment reduction than for runoff control under intense rainfall. Grasslands were generally more effective in reducing sediment than other vegetation types. Forests, grasslands and scrublands were most efficient in soil erosion control on 20°–30°, 0°–25° and 10°–25° slopes respectively. Grasslands and scrublands generally performed better with respect to soil erosion control on moderately coarse soils, whereas forests were most effective on medium‐textured and moderately fine soils. Synthesis and applications. Effective restoration and soil erosion control in semi‐arid ecosystems strongly depends on the selection of vegetation type. Our study further indicates that, for land managers, it is critical to consider local slope, and soil texture, and maintain appropriate vegetation coverage to achieve ecosystem sustainability. Grasslands might be particularly suitable to optimize the trade‐off between soil erosion control and surface water resource in semi‐arid regions. 抽象 半干旱区水保型植被恢复过程中如何实现水土流失控制且维系地表水资源的目标，并进一步反馈于植被生态系统功能，是目前亟待解决的问题。 本研究基于公开发表的来源于22个国家、78篇关于半干旱区植被对土壤侵蚀影响的文献报道，应用Meta‐analysis方法，系统评价了不同植被类型（林地，草地和灌木地）在不同环境条件（植被盖度、降雨强度、坡度和土壤质地）下对径流量和产沙量的影响。 研究结果表明，植被减流效应和减沙效应均随植被盖度的增加而增加，并在植被盖度达到60%时趋于稳定。强降雨下，植被减沙效应大于其减流效应。总体上，三种植被类型中，草地具有最高的减沙效应。林地、草地和灌木地分别在20°‐30°、0°–25°和10º‐25°坡度范围内表现出较高的减流效应和减沙效应。且草地和灌木地在中等粗糙质地土壤中的减流效应和减沙效应较高，林地在中等质地和中等细密质地土壤中的减流效应和减沙效应较高。 综合应用：半干旱区的水保型植被水土流失调控的有效性很大程度上取决于适宜的植被类型。本研究表明，在全球半干旱区，建设草地植被可有效实现水土流失调控与地表水资源维系的权衡。同时，在水保型植被建设过程中，应综合考虑坡度和土壤质地等实际情况并维持适宜的植被盖度，以实现植被生态系统的可持续性。 Effective restoration and soil erosion control in semi‐arid ecosystems strongly depends on the selection of vegetation type. Our study further indicates