黄土高原典型退耕区生态系统服务权衡与协同关系研究——以延安市为例

Ecosystem service tradeoffs and synergies in typical farmland conversion area of the Loess Plateau:Taking Yan′an City as an example

在退耕还林的背景下,从多尺度分析黄土高原生态系统服务的时空变化及权衡协同关系对促进该区经济发展和生态效益多赢具有重要意义。以黄土高原退耕还林典型区延安市为例,运用InVEST模型评估1988—2018年农作物生产、碳储量、生境质量、土壤保持、产水量5种关键生态系统服务物质量,采用偏相关分析法探讨生态系统服务间的权衡与协同关系及其时空变化特征。研究结果表明:(1)受土地利用变化影响,延安市农作物生产水平、土壤保持年际变化趋势波动较大,农作物生产水平呈波动增加的趋势,土壤保持退耕还林前呈减少,退耕还林后呈波动增加的趋势,碳储量和生境质量呈逐渐增加的趋势,产水量呈逐渐减弱的趋势。(2)生态系统服务与土地利用格局联系紧密。碳储量、生境质量的高值区域以及产水量的低值区域随林地分布格局变化而变化。(3)协同关系是延安市生态系统服务间相关关系的主体,主要发生在碳储量、生境质量、土壤保持、农作物生产之间,权衡关系主要存在于产水量和其他生态系统服务之间。(4)市、县域生态系统服务间关系的差异主要发生在生境质量和土壤保持之间。

The Conversion of Cropland to Forest Project(CCFP) can improve the ecological benefits, but also threaten food security. It is important to create a win-win situation in economic development and environmental protection. In the context of returning farmland into forest, in order to further promote ecological protection and sustainable development, it is essential to identify the trade-offs and synergies of multiple ecosystem services at different spatial scales. Under the influence of human activities and the natural environment, the relationship of ecosystem services changes over time and spatial scales. Studying the spatio-temporal dynamics of these relationships is of great significance for understanding the trends in ecosystem services, evaluating the effects of returning farmland into forest, and determining appropriate land use patterns and ecological restoration measures. However, it is still a challenge to fully understand the temporal and spatial dynamics of ecosystem service relationships in the Loess hilly and gully region before and after the CCFP, due to the research on different types of ecosystem services, as well as the information about the adaptable units of ecosystem service management is often insufficient. Therefore, the purpose of this study is to identify the relationship among ecosystem services at the municipal and county levels before and after the CCFP. Using physical methods, five key ecosystem services in Yan′an City, including crop production, carbon storage and sequestration, habitat quality, soil conservation, and water yield were quantitatively evaluated from 1988 to 2018 by InVEST model. The tradeoffs and synergies among five key ecosystem services, and their temporal and spatial variation characteristics, were analyzed through partial correlation analysis. The results showed that:(1) Affected by land use changes, the interannual trends of crop production and soil conservation in Yan′an fluctuated greatly;the crop production level showed a fluctuating upward trend;the soil conservation decreased before the CCFP, fluctuated and increased after the CCFP;the carbon storage and sequestration and habitat quality showed a gradually increasing trend;the water yield decreased gradually.(2) Ecosystem services were closely related to land use patterns. Areas with high carbon storage and sequestration, habitat quality, and areas with low water yield, varied with changes in woodland distribution patterns.(3) Within the research period in Yan′an city, the ecosystem services were dominated by synergistic relationships, which mainly occurred between carbon storage and sequestration, habitat quality, soil conservation, and crop production. While water yield with other ecosystem services showed a trade-off relationship.(4) The differences in ecosystem services between city and county mainly occurred in habitat quality and soil conservation.