Evaluation from landscape pattern change can comprehensively reflect the impact of ecological policies on the ecosystem service function. However, previous assessments based on landscape patterns only considered land cover type and ignored the quality of vegetation cover, which could hardly reflect regional differences in restoration durability and sustainability. Based on the temporal phase characteristics of the vegetation index, this study proposes the concept of Persistent Green Patches (PGPs). Taking Yan'an, a key area for the implementation of ecological projects in the Loess Plateau, as a study area, the effect of ecological policies was evaluated from the pattern change of PGPs from 2000 to 2017 through Morphological Spatial Pattern Analysis (MSPA). It is found that (1) the area of PGPs was increased from 14.45% to 44.26% in Yan'an since the implementation of the ecological projects; (2) the Grain for Green projects can hardly form a short-term increase of PGPs; while the Natural Forest Protection projects can quickly increase the PGPs area, its effect would tend to be saturated or even decrease in the long term; (3) the fragmentation and connectivity of the landscape show that the ecological projects promote the connection between different green patches, and improves the overall connectivity of the PGPs. This study provides a new perspective on evaluating the effect of ecological projects, which is expected to provide a reference for the future optimization of relevant ecological policies and regional sustainable development.

景观格局变化评价可以全面反映生态政策对生态系统服务功能的影响。但是，以前基于景观格局的评估仅考虑了土地覆盖类型，而忽略了植被覆盖的质量，这几乎无法反映出恢复耐久性和可持续性方面的地区差异。基于植被指数的时相特征，本研究提出了持久性绿色斑块（PGPs）的概念。以黄土高原地区生态工程实施的重点地区延安为研究区域，通过形态空间格局分析（MSPA），对2000- 2017年PGP的格局变化进行了生态政策评价。发现（1）延安州PGP的面积从14.45％增加到44.26％自生态工程实施以来；（2）“绿色换粮”项目很难在短期内增加PGPs；虽然天然林保护项目可以迅速增加PGP的面积，但从长远来看，其效果趋于饱和甚至降低；（3）景观的破碎化和连通性表明，生态工程促进了不同绿色斑块之间的联系，并改善了PGP的整体连通性。这项研究为评价生态项目的效果提供了新的视角，有望为今后优化相关生态政策和区域可持续发展提供参考。虽然天然林保护项目可以迅速增加PGP的面积，但从长远来看，其效果趋于饱和甚至降低；（3）景观的破碎化和连通性表明，生态工程促进了不同绿色斑块之间的联系，并改善了PGP的整体连通性。这项研究为评价生态项目的效果提供了新的视角，有望为今后优化相关生态政策和区域可持续发展提供参考。虽然天然林保护项目可以迅速增加PGP的面积，但从长远来看，其效果趋于饱和甚至降低；（3）景观的破碎化和连通性表明，生态工程促进了不同绿色斑块之间的联系，并改善了PGP的整体连通性。这项研究为评价生态项目的效果提供了新的视角，有望为今后优化相关生态政策和区域可持续发展提供参考。（3）景观的破碎化和连通性表明，生态工程促进了不同绿色斑块之间的联系，并改善了PGP的整体连通性。这项研究为评价生态项目的效果提供了新的视角，有望为今后优化相关生态政策和区域可持续发展提供参考。（3）景观的破碎化和连通性表明，生态工程促进了不同绿色斑块之间的联系，并改善了PGP的整体连通性。该研究为评价生态工程的效果提供了新的视角，有望为今后优化相关生态政策和区域可持续发展提供参考。