基于生态供受体理论的全国水土保持重要区识别

科学评估土壤保持功能是生态保护红线划定的基础.依据生态供受体理论，针对土壤保持服务对应的水土流失这一生态问题，从水土流失的供体（水土流失量）、受体（人口密度）、辐射传输（距离水体距离）三个方面构建模型，分析土壤保持功能的重要性.结果表明全国潜在侵蚀量577.34×10¹⁰t/a，潜在土壤侵蚀随着坡度和降水量的增加而增加.土壤保持功能极重要区面积98.98×10⁴km²，主要分布在西南地区的无量山和哀牢山，黄土高原东部，东南地区的浙闽丘陵，东部地区的鲁中山区、鲁东半岛，以及辽东半岛.西南地区山高、谷深、坡陡、流急、地形稳定性差等因素造成水土流失严重，维持该地区的水土保持功能极为重要；西北地区的黄土高原土质疏松且多暴雨导致水土流失比较严重，维持该地区土壤保持功能非常重要.对比常用的生态保护功能模型，供受体理论模型除考虑自然影响因素之外，突出了人类活动的因素，对评估生态保护功能与水土保持生态风险更客观.依据供受体理论构建的土壤保持模型适用于土壤保持功能和土壤潜在侵蚀风险的评估，可作为评估生态系统安全和划定生态保护红线的重要依据.

Identifying important areas for soil and water conservation in China based on ecological donor-receptor theory

Scientific assessment of soil conservation function is the basis for determining the red line of ecological protection. Inspired by ecological donor-receptor theory, this paper analyzed the importance of soil conservation function from three aspects:the donor (soil erosion amount), the receptor (population density) and the radiation transmission (distance from body of water). The potential erosion amount in China is 577.34×10¹⁰t/a. Soil erosion increases with increasing slope and precipitation. The most important area of soil conservation function covers an area of 98.98×10⁴km², which is mainly distributed across Mt. Wuliang and Mt. Ailao in the southwest, the Loess Plateau in the northwest, the Zhejiang-Fujian hills in the southeast, the mountainous areas in the middle east of Shandong Province and the Liaodong Peninsula. Soil and water loss is very serious in the high mountains, deep valleys and steep slopes, which are susceptible to rapid runoff and poor topographic stability. It is also very important to maintain soil conservation function in the Loess Plateau of Northwest China, which is characterized by loose soil and severe soil erosion due to heavy rainfall. Compared with previously common ecological protection functional models, the supply-receptor model highlights the impact of human activities, while still considering natural factors. Thus the model is much more objective in its assessment of the ecological protection function and the ecological risk of soil conservation. This soil conservation model based on the donor-receptor theory is highly suitable for the assessment of soil conservation function and potential soil erosion risk. It can be used as an important basis for the assessment of ecosystem security and for delineating important ecological protection boundaries.