基于景观生态学的辽宁中部城市群绿色基础设施20年时空格局演变

城市绿色基础设施（UGI）作为城市的重要生态屏障，是解决城市环境问题的重要途径。研究快速城市化背景下UGI的时空分布格局及形态演变，对优化城市绿色空间网络与布局、改善城市人居环境和提升城市可持续发展能力具有重要意义。利用谷歌地球引擎（GEE）平台计算了2000-2019年共约4800景Landsat影像的植被指数和水体指数，采用指数阈值分割方法，解译得到了辽宁中部城市群20年的UGI。在此基础上，运用景观格局指数和形态学空间格局分析方法（MSPA），分析了20年（2000-2019年）连续时间尺度上辽宁中部城市群UGI景观格局的演变趋势。结果表明，20年间，辽宁中部城市群UGI面积呈波动上升趋势，由2000年的170.28 km²增长到2019年275.68 km²，增幅达62%，但由于持续的城市扩张，其占城市建成区面积的比例不断下降，由2000年的25.73%下降到2019年的19.72%，表明城市绿地空间建设滞后于城市空间扩张。研究期内，城市群UGI景观破碎化程度加剧，优势景观斑块的主导性减弱，景观形态趋于不规整且复杂化，且在空间布局上更加分散，景观斑块之间的结合度变差。此外，UGI核心区随城市扩张被逐渐蚕食，并转化为边缘区、桥接区、分支和环岛区等其他类型的UGI或非UGI景观，其占UGI总面积的比例从2000年的46.2%下降到2019年的37.26%；城市边缘区UGI变化最为剧烈，更易受到城市扩张的影响。研究可为快速城市化区域UGI空间网络布局与优化和基于UGI的城市生态安全格局构建提供技术支撑和决策依据。

Spatiotemporal evolution characteristics of urban green infrastructure in central Liaoning urban agglomeration during the past 20 years based on landscape ecology and morphology

Urban green infrastructure (UGI), serving as the essentially ecological barrier of cities, is an important way to solve urban environmental problems. It is of great significance to study the spatiotemporal pattern and morphological evolution of UGI in rapidly urbanizing area for optimizing the network and layout of urban green space, improving the urban living environment and enhancing the city''s sustainable development capacity. Using the Google Earth Engine (GEE) platform, the vegetation index and water index of about 4,800 Landsat images from 2000 to 2019 were calculated, then the UGI of central Liaoning urban agglomeration was extracted by using the index threshold method in this study. On this basis, using the landscape metrics and the morphological spatial pattern analysis (MSPA), a continuous time series analysis was further conducted to explore the evolution trends of the UGI landscape pattern in central Liaoning urban agglomeration from 2000 to 2019. The results indicated that the UGI area of central Liaoning urban agglomeration showed an upward trend, increasing by 62%, from 170.28 km² in 2000 to 275.68 km² in 2019. Due to continuous urban expansion, its proportion of urban built-up area declined gradually from 25.73% in 2000 to 19.72% in 2019, indicating that urban green space construction lagged behind urban expansion. During the study period, fragmentation of the UGI in this urban agglomeration intensified, the dominant patches'' area decreased, the patches'' shape tended to be unconscionable and diverse, the UGI landscape became spatially dispersed and patches cohesion of UGI decreased. In addition, the UGI was gradually encroached on and transferred to other types of UGI, such as edge, bridge areas, branches and loop, or non-UGI landscape with the urban area expansion, its proportion in UGI decreasing from 46.2% in 2000 to 37.26% in 2019; the UGI in urban''s margin changed more intensively and was more affected by the urbanization process. This research can provide technical and decision-making supports for the layout and optimization of UGI network in rapidly urbanizing areas and the construction of UGI-based urban ecological security pattern.