摘要:评估退耕还林(草)工程后生境质量的时空演化特征，对指导下一轮生态修复工程的实施以及协调区域生态系统和社会经济可持续发展具有重要意义。该研究以退耕还林(草)先行试点的陕西省延安市为研究对象，以土地利用/覆被数据为基础，运用InVEST模型评估延安市2000年、2008年和2015年生境质量；结合空间探索性分析方法，探讨生境质量的时空演变格局及其驱动因素。结果如下：1)2000—2015年延安市土地利用变化在退耕还林(草)工程驱动下以耕地向林地和草地的转移为主要特征，林地和草地面积在研究期内增加显著。2)延安市2015年生境质量整体较好，空间上呈现南高北低的格局，且研究期内呈上升趋势，区域平均生境指数由2000年的0.69增加到2015年的0.71。3)区域生境质量表现出显著的正向全局空间自相关，且空间聚类分异特征明显；南部的黄陵县和黄龙县等森林资源丰富地区主要呈现出高高集聚特征，而低低集聚区和高低集聚区交叉分布集中在北部宝塔区、子长县、安塞县、吴起县等城镇及其周边农业生产区。4)退耕还林(草)工程对区域生境质量提升有显著推动作用，因此可以通过优化土地利用格局和结构，尤其是林地草地，构建生态保护和经济发展协调平衡的政策体系，针对区域生态问题系统地提高区域生境质量和生态系统稳定性。
关键词:退耕还林(草)/
生境质量/
土地利用变化/
InVEST模型/
延安市
Abstract:In an attempt to alleviate increasing pressure caused by human activities on the environment, numerous ecological restoration projects have been implemented around the world. The 'Grain for Green' project in China is currently the largest and most extensive ecological restoration project globally. Research indicates the substantial investment given to this project has achieved significant ecological benefits. Habitat quality is an important indicator of the ability of an ecosystem to provide sustainable conditions for persistence of individuals and populations. Accordingly, this study aimed to investigate the temporal and spatial patterns of habitat quality in Yan'an City, the piloted research area of the 'Grain for Green' project, to identify the impact of the restoration project on the city. Research into the impacts of this project are of great significance for successful implementation of ecological restoration projects moving forward, as well as expanding knowledge on regional ecosystems, and on socio-economic sustainable development. Land use/land cover data of Yan'an City in 2000, 2008, and 2015 were evaluated for the study. The habitat quality index of Yan'an City in 2000, 2008, and 2015 was estimated based on the ArcGIS platform and the InVEST model. The temporal and spatial evolution pattern of habitat quality and its driving factor and spatial clustering characteristics were discussed by using the exploratory spatial data analysis. Our results showed that the main feature of land use change in Yan'an City from 2000 to 2015, driven by the 'Grain for Green' project was the conversion of cultivated land to woodland and grassland; the area of woodland and grassland increased significantly in the city during the study period. The habitat quality of Yan'an City in 2015 was relatively good, demonstrating a pattern of high habitat quality in the south, low habitat quality in the north. The habitat quality index showed an upward trend during the study period; the regional average habitat quality index increased from 0.69 in 2000 to 0.71 in 2015. Additionally, habitat quality of the study area as a whole showed significant positive global spatial autocorrelation, and habitat quality, as well as its spatial variation, indicated obvious spatial clustering differentiation characteristics. Forest-rich areas, such as Huangling County and Huanglong County in the south, exhibited predominately high-high agglomeration characteristics highlighting the need for these areas to remain the focus of ecological protection measures. Conversely, low-low and high-low agglomeration areas were found interspersed, and concentrated in the north (i.e., Baota County, Zichang County, Ansai County, Wuqi County, and in other counties as well as agricultural areas of this region); accordingly, ecological restoration in northern areas should be strengthened and consolidated. Our results indicate that the 'Grain for Green' project will likely affect the processes and functions of the Yan'an City ecosystem by changing land use patterns and structure. In particular, the increase of forestland and grassland in this area will significantly promote the improvement of regional habitat quality. Therefore, by optimizing land use pattern and structure (in particular forest and grassland habitats) will assist in the development of a more coordinated and balanced policy for ecological protection and economic development in response to regional ecological problems, while systematically improving regional habitat quality and ecosystem stability.
Key words:The 'Grain for Green' project/
Habitat quality/
Land use change/
InVEST model/
Yan'an City
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