土壤保持服务:概念、评估与展望

土壤保持服务作为一项重要的生态系统调节服务,是防止区域土地退化、降低洪涝灾害风险的重要保障。针对在全球范围内影响最大的土壤水蚀,基于土壤侵蚀、运移和输出过程,对土壤保持服务的概念、评估方法进行了梳理总结。土壤保持服务是指生态系统防止土壤流失的侵蚀调控能力及对泥沙的储积保持能力。土壤保持服务的评估往往是基于通用土壤流失方程RUSLE(Revised Universal Soil Loss Equation),以潜在土壤侵蚀量(裸地时土壤侵蚀量)与实际土壤侵蚀量之差,作为指标衡量。由于生态过程具有尺度依赖性,对土壤保持服务的有效评估,需要采用多尺度方法。土壤保持服务与人类需求紧密相关,在未来土壤保持服务研究中应强调连接土壤保持服务与人类福祉,对土壤保持服务产生、流动、使用的全过程及土壤保持服务时空动态与人类福祉变化的关系进行探究。

Soil conservation service: concept, assessment, and outlook

Soil conservation service is an important regulating service that can prevent regional land degradation and reduce the risk of flooding. Focusing on the most influential soil erosion type, water erosion, this paper first clarifies the scientific concept of soil conservation service based on soil erosion, transport, and export processes. Soil conservation service is defined as the capacity of the ecosystem to prevent soil erosion and retain sediment. Then, an analysis of the assessment methods used to evaluate soil conservation service was undertaken. Based on the revised universal soil loss equation, soil retention (calculated as potential soil erosion (erosion without vegetation cover) minus actual soil erosion) was applied as an indicator of soil conservation. The effectiveness of soil erosion at the individual-plant scale depends on plant morphology. As the scale increases, land use gradually plays an increasing role in curbing soil erosion, and large basins are more closely related to fluvial erosion and storage processes. Considering the scale-dependency of the erosion processes, a multi-scale method is needed to assess soil conservation service. The models used to quantify soil conservation service mainly address soil detachment processes only, and do not simulate soil redistribution, by ignoring processes such as sediment deposition and transport. Additional studies of sediment deposition and transport are needed. Soil conservation service can be considered a link between biophysical reality (the ecological system) and human well-being (the socio-economic system). To fully understand the effects of soil conservation on human well-being, the supply and the demand of soil conservation services both need to be measured.