基于过程—效应—功能—服务级联机制的森林减沙服务传输研究

Assessing Soil Loss Control and Sediment Reduction Services of Forest Following Process-Effect-Function-Service Cascade Framework

土壤侵蚀是具有当地和异地两方面效应的地表过程。土壤保持服务供给区与需求区在空间上并不是完全重叠,而是存在一定程度的空间失耦。传统的土壤保持服务评估中多以生态系统当地侵蚀产沙减少量作为减沙服务供给量,以单一的分配系数计算对外部区域提供的减沙服务量。前者忽视了土壤保持服务供给能力与土壤保持服务实际提供量的差别,从而高估了土壤保持服务。后者则忽视了泥沙输移比的空间变异,导致很高的评估结果不确定性。准确评估土壤保持服务供给及其空间传输需要充分认识其过程—效应—功能—服务的级联机制。空间分布式的泥沙传输模型为此提供了可能。以洞庭湖区湖南省境内的4个地市为研究区,按照过程—效应—功能—服务的级联框架,在区域尺度上将森林生态系统减沙服务的供给和需求耦合起来,利用融合泥沙连通度的泥沙传输模型,评估了森林生态系统减少土壤流失和泥沙输出的效应,量化了森林以承载人类直接福祉的土地为媒介向人类社会传递的减沙服务。该研究提出的方法框架为生态系统服务供给与需求的耦合提供了一个视角。

Beyond the on-site negative consequence,soil erosion has off-site negative impacts as a result of sediment delivery.The spatial decoupling between soil conservation services provision and beneficiaries is common.In previous assessments involving soil conservation services,the on-site soil erosion prevention usually is used as proxy to the soil conservation services,or a constant sediment delivery ratio is employed in estimating sediment delivery to external areas.The former approach ignores the difference between provision of soil conservation service and soil conservation services delivered to beneficiaries,and lead to an overestimation.The latter approach overlooks the spatial variation of sediment delivery ratio,and leads to great uncertainty in soil conservation services quantification.It is fundamental to understand the process-effect-function-service cascade in estimating soil conservation services provision and delivery.Fortunately,spatially distributed sediment deliver model that integrated the sedimentological connectivity concept provides an opportunity.In this study,a spatially explicit approach based on the cascade mode of soil conservation formation was employed to assess the soil loss prevention and sediment reduction services in neighboring areas of Dongting Lake in Hunan Province.The supply capacity of soil loss prevention service and sediment reduction service are integrated.Following the framework of this study,that ecosystem services supplying areas are coupled with the beneficiary areas through the ecosystem services flow.This study shows an effective avenue to coupling the ecosystem service supply and demands.