Responses of Ecosystems to Ecological Compensation in a Key Ecological Function Area of the Loess Plateau

生态系统对生态补偿的响应研究——以黄土高原丘陵沟壑水土保持生态功能区为例（英文）

Evaluation of the ecological effects of eco-compensation policies helps analyze policy rationality and feasibility and provides scientific and practical bases for perfecting eco-compensation systems. Taking the key ecological function area of the Loess Plateau, China as a case study, we have evaluated ecosystem responses to the Grain-for-Green Project that commenced in 1999. Six indicators were selected to assess changes in ecosystem structure, quality and function. The results showed that implementation of the Grain-for-Green Project has reduced sloping cropland by 1571 km2 and increased ecological land by 1337 km2. The increase in ecological land alters ecosystem structures across the study area and the decline in sloping cropland reduces farming activity interference; both of these are conducive to the restoration of natural vegetation. From 2000 to 2010, the vegetation cover of grassland, desert and forest ecosystems increased 10.89%, 8.34% and 4.24% respectively and average NPP rose 51%, with an average annual growth rate of around 5%. This indicates that eco-compensation has promoted the improvement of ecosystem quality. Total biomass of ecosystems increased two times on average from 2000 to 2010, meaning that the carbon sequestration capacity of ecosystems also increased. The reduction in the area of water loss and soil erosion and the increase in retained runoff by forests indicate an improvement in ecosystem function and services on the Loess Plateau.

生态补偿是保护国家重点生态功能区的政策保障。评价生态补偿政策的生态效果则有利于分析生态补偿政策的合理性和可行性,从而为生态补偿政策的完善提供科学依据。论文以实施退耕还林还草的黄土高原丘陵沟壑水土保持生态功能区为例,通过研究生态系统对生态补偿的响应特征,反映生态补偿对生态系统的影响和生态效果。研究选择了反映生态系统结构、质量和功能6个指标,分析自1999年实施退耕还林工程以来,2000年到2010年研究区生态系统的变化。研究结果表明:(1)退耕还林(草)工程促使研究区坡耕地规模减少1571 km2,生态用地面积扩大了1337 km2,有效地改善了生态系统结构,减少了人类活动对土地的干扰,有利于自然植被的恢复;(2)退耕还林工程实施以来,研究区不同生态系统植被盖度和NPP均有增加。从2000到2010年,草地、荒漠和林地生态系统的植被盖度分别增加了10.89%、8.34%和4.24%。平均NPP在10年间增加了51%左右,年均增长达5%左右,表明生态补偿促进了生态系统质量的改善;(3)从2000到2010年,研究区总生物量平均增大了2倍,各县区生物量年均增长率达11%左右,说明生态系统固碳功能显著增大。水土流失面积减少和林地拦截的径流量增大则意味着水土保持功能正在增强。显然,生态补偿对生态系统服务功能的影响也是非常积极而显著的。