中国退耕还林还草对生态系统服务权衡与协同的影响

基于生态系统服务之间相关关系的时空动态变化，实现区域可持续发展与生态系统利益最大化，是兼顾生态保护、粮食安全、改善民生等多目标的重要途径。通过分析退耕还林还草工程县域粮食供给与地块水源涵养、土壤保持、防风固沙功能变化，评估退耕还林还草工程对生态系统关键服务之间权衡与协同关系的影响。结果表明：（1）2000-2015年，约76%工程县域的粮食供给增加，约46%和49%工程县域退耕还林还草地块的土壤保持与水源涵养功能呈提升态势，而风蚀区仅约2%工程县域的地块防风固沙功能明显提升。（2）1897个工程县域中，约24%县域粮食供给与地块水源涵养、约18%县域粮食供给与地块土壤保持之间呈显著地空间协同关系，风蚀区约38%县域粮食供给与地块防风固沙之间呈显著地空间权衡关系。（3）31%工程县域表现为多重生态系统服务供给区，其中双重服务供给县域占43%，三重服务供给县域占53%，四重服务供给县域占4%。（4）近16年，不同区域退耕还林还草工程导致粮食供给与调节服务之间呈现权衡与协同相互转换、权衡或协同程度变化等差异的空间相关关系，反映了多重生态系统服务联合权衡与协同在未来工程生态效应评估中的重要性。

The impacts of the Grain for Green Project on the trade-off and synergy relationships among multiple ecosystem services in China

It is an important way to take ecological conservation, food security and improve people''s livelihood into consideration by realizing the regional sustainable development and maximizing ecosystem benefits through the dynamic changes of the trade-off and synergy relationships among multiple ecosystem services. By analyzing the changes of grain supply in county scale, and sand fixation, soil conservation and water regulation in project plots, this paper evaluated the impacts of the Grain for Green Project (GFGP) on the trade-off and synergy relationships among multiple ecosystem services. The results showed that: (1) from 2000 to 2015, food supply increased in about 76% of the project counties. Ecosystem soil conservation and water regulation functions on the GFGP plots increased in 46% and 49% of the project counties, while ecosystem sand fixation function on the GFGP plots only increased in 2% of the project counties in the wind erosion area. (2) In 1897 counties of GFGP, the significantly spatial synergy relationship between grain supply and water regulation showed in 24% counties, and between grain supply and soil conservation in 18% counties. About 38% of the counties in the wind erosion area had significantly spatial trade-off relationships between grain supply and sand fixation. (3) In addition, 31% of the GFGP counties are presented as multiple provision areas of ecosystem services, of which 43% are dual provision counties, 53% are triple provision counties, and 4% are quadruple provision counties. (4) In the past 16 years, the divergent spatial correlations between the food supply and regulation services presented as mutual transformation of trade-offs and synergies, varied change degrees of trade-offs and synergies, which reflects the importance of the joint trade-offs and synergies of multiple ecosystem services in future assessment of ecological effects for GFGP and other ecological restoration projects.