基于Google Earth Engine的川南城市群景观生态安全度时空分异规律

Spatio-temporal differentiation of landscape ecological security degree in southern Sichuan city agglomeration based on Google Earth Engine

川南城市群作为成渝经济圈和长江上游经济带可持续发展建设的重点区域,诊断其景观生态安全度时空分异规律对促进川南城市群的建设和生态安全监测具有重要意义.利用谷歌地球引擎(Google Earth Engine)服务平台,运用编程语言处理Landsat系列遥感图像,得到精度验证后的2000、2010和2020年的土地利用分类数据.通过景观破碎度、分离度、分维度构建景观干扰度,以地类敏感性构建景观脆弱度,采用景观生态安全度模型和空间统计学方法对20 a间川南城市群景观生态安全度的空间分布进行了评价和分析,同时采用半变异函数对景观空间分异规律开展了研究.研究表明:(1)2000—2020年川南城市群景观生态安全度总体上呈递减趋势,在空间分布上呈现出东西两侧生态安全度高,沿岷江、长江沿线生态安全度低的空间分异现象.(2)2000、2010、2020年全局自相关Moran’s I值分别为0.826、0.806、0.803,散点主要集中在第一象限和第三象限,表明高安全度和低安全度区内部差异较小,在空间上呈正相关关系.(3)2000—2020年间局部自相关的热点区域主要分布在峨眉山景区、内江市、自贡市、泸州北部等地区,冷点区域分布在沿长江、岷江和宜宾、乐山、泸州城市发展沿线,空间集聚水平呈现不稳定特征,显著水平发生变化,相邻样点之间逐渐从集聚分布向随机分布格局转变.(4)川南城市群在20 a间景观生态安全度呈现显著的空间分异特征,主要是受结构因素和非结构因素的综合影响.其中地形地貌、气候、土壤、植被等结构因素起着决定作用,城市化建设、交通道路建设及茶园—林果园经济作物的种植等非结构因素对景观演变有重要影响.研究成果为区域生态环境保护和自然资源开发提供一定的指导意义.

As the key construction area of Chengdu-Chongqing economic circle and the upper Yangtze River economic belt sustainable development,it is of great significance to diagnose the spatial and temporal variation of landscape ecological security degree in southern Sichuan urban for promoting the construction and ecological security monitoring of southern Sichuan urban.In this paper,the Google Earth Engine service platform and the programming language were used to obtain the land use classification data of validated accuracy in 2000,2010 and 2020 from Landsat remote sensing images.Landscape disturbance degree was constructed by use of landscape fragmentation degree,separation degree on the basis of different dimensions,and landscape vulnerability degree was constructed according to land class sensitivity.The spatial distribution of landscape ecological security degree in southern Sichuan urban agglomeration was evaluated and analyzed by using landscape ecological security degree model and spatial statistics method,and the spatial differentiation law of landscape was studied using semi-variance function.The results showed that:(1)From 2000 to 2020,the landscape ecological security degree of southern Sichuan urban underwent a decreasing trend on the whole,with the spatial distribution showing a spatial differentiation of high ecological security degree in the east and west sides,and low ecological security degree along the Minjiang river and Yangtze river.(2)The Moran’s I values of global autocorrelation in 2000,2010 and 2020 were 0.826,0.806 and 0.803,respectively,and the scatter points were mainly concentrated in the first and third quadrants,indicating that the internal differences between high safety and low safety zones were small,and the spatial correlation was positive.(3)From 2000 to 2020,the hot spots of local autocorrelation were mainly distributed in Mount Emei scenic spot,Neijiang,Zigong and northern Luzhou,while the cold spots were distributed along the Yangtze River,the Minjiang River and along Yibin-Leshan-Luzhou urban development line.The spatial agglomeration level was unstable and the significance level was changing.The adjacent samples took on a gradual change from agglomeration distribution to random distribution.(4)The landscape ecological security degree of the southern Sichuan urban agglomeration exhibited significant spatial differentiation in 20a,which was largely affected by the joint impacts of structural factors and non-structural factors,of which structural factors such as topography,climate,soil and vegetation play a decisive role,while non-structural factors such as urbanization construction,traffic road construction and planting of cash crops such as tea plantation,forest and orchard exerted an important impact on landscape evolution.The research findings are of guiding significance for regional ecological construction and resource development.