Dynamic Analysis And Ecological Evaluation Of Landscape Pattern In Greater Bay Area Based On GEE

The construction of the Guangdong-Hong Kong-Macao Greater Bay Area is an important initiative of the Party Central Committee in the national strategy of "One Belt,One Road",which is of great significance,and in February 2019,the Outline of the Development Plan of the Guangdong-Hong Kong-Macao Greater Bay Area emphasized the construction of the Guangdong-Hong Kong-Macao Greater Bay Area towards the goal of a world-class city cluster.Starting from the landscape pattern of the Greater Bay Area,this study analyzes and evaluates the dynamic changes of the landscape pattern and ecological environment quality of Hong Kong,Macao,and nine mainland cities in the Greater Bay Area,namely Guangzhou,Shenzhen,Zhuhai,Foshan,Huizhou,Dongguan,Zhongshan,Jiangmen,and Zhaoqing,through the GEE cloud platform,to provide data support for the protection and future construction direction of the ecological environment in the Guangdong-Hong Kong-Macao Greater Bay Area.This paper uses the GEE cloud platform to obtain Landsat remote sensing images of the Guangdong-Hong Kong-Macao Greater Bay Area for four years,1990,2000,2010 and 2020,to analyze the spatial and temporal evolution patterns of the landscape pattern of the Guangdong-Hong Kong-Macao Greater Bay Area from 1990 to 2020.Meanwhile,the remote sensing ecological index model was constructed by extracting four indicators,namely greenness,humidity,dryness and heat,to monitor and evaluate the ecological environment quality of the study area in a long time series from 1990 to 2020.The following results were finally obtained:(1)At the level of patch type:during 1990-2020,the patch area index(CA)and landscape percentage index(PLAND)of forest land and construction land both showed an increasing trend,while for the three patch types of agricultural land,water and other land,the values of these two indices showed a decreasing or stable constant trend,indicating that The area of both construction land and forest land is expanding,while the area of agricultural land,watershed,and other land is gradually shrinking.The trend of continuous increase of aggregation(AI),average patch area(AREA-MN),and cohesion(COHESION)indices of forest land and construction land indicates that the degree of fragmentation of forest land and construction land is decreasing and gradually tends to be aggregated.The fragmentation of the landscape pattern of the two patch types of agricultural land and other land deepens.The landscape pattern of the water patch type continued to fragment from 1990 to 2010,and only tended to agglomerate between 2010 and 2020.(2)At the landscape level level:the value of the number of patches index(NP)decreased from 1556847 to 1273160,then increased to 1424772 in 2010 and decreased to 1133263 in 2020,and the trends of the patch density index(PD)and edge density(ED)were consistent with them,and these indices were positively correlated with fragmentation,so indicating that The years 1990-2000 and 2010-2020 tend to be in the state of aggregation,and 2000-2010 tend to be in the state of fragmentation.While the trend of aggregation(AI)in 2000-2020 is the opposite of the above indices,the index values decreased from 93.83%to 93.56%respectively,and then increased to 94.15%,and the trend of spreading(CONTAG)index is consistent with it,and these two indices are positively correlated with aggregation,so it indicates that 2000 The trend of the spreading index(CONTAG)is consistent with it,and these two indices are positively correlated with the aggregation,so it indicates that it tends to fragmentation in 2000-2010 and aggregation in 2010-2020.The indices of maximum patch index(LPI),separation(DIVISION),aroma uniformity(SHEI)and aroma diversity(SHDI)showed a more stable state.In general,the shape complexity of the Guangdong-Hong Kong-Macao Greater Bay Area increased and the landscape fragmentation enhanced during 2000-2010,and the fragmentation of the patches was slowed down after 2010 and gradually converged to the aggregation state.After analyzing the influence of the policies of the governments of Guangdong,Hong Kong and Macao,such as the Special Plan for Building a Quality Living Area for Guangdong,Hong Kong and Macao,the Key Action Plan for the Construction of a Livable Bay Area around the Pearl River Estuary,and the Special Plan for Cooperation in Infrastructure Construction of Guangdong,Hong Kong and Macao,the landscape fragmentation of the Guangdong,Hong Kong and Macao Greater Bay Area was reduced and turned to the trend of aggregation by strengthening environmental management and ecological protection measures in 2011.(3)During the period 2000-2010,the ecological grade of the Guangdong-Hong Kong-Macao Greater Bay Area tends to be moderate in general,and the area with poor,good,and excellent ecological grades tends to decrease,while the area with poor and moderate ecological grades tends to increase,due to the accelerated expansion of the construction of urban agglomerations in the Guangdong-Hong Kong-Macao Greater Bay Area during this period,which caused the decrease of the area with good and excellent ecological grades.During the period 2010-2020,the area with good and excellent ecological grades in the Guangdong-Hong Kong-Macao Greater Bay Area has a significant increase,which is mainly related to the national emphasis on ecological environmental protection and the implementation and landing of the Plan for the Construction of Cross-border Greenways in the Bay Area.At this stage,the area with poor ecological grade has a tendency to increase,but the increase is within a manageable range compared to the area with poor ecological grade in 2000.This also reveals that we need to grasp the painful points in the next ecological protection and construction work,and mainly focus on the area with poor ecological grade to carry out comprehensive remediation and improvement.