The Construction Of Ecological Security Pattern And Its Spatial And Temporal Evolution Analysis In The Source Region Of The Pearl River Based On MCR Model

With the rapid economic growth and the continuous expansion of urbanization,various ecological and environmental problems such as depletion of natural resources,deterioration of environmental quality,serious soil erosion and destruction of mineral resources have followed.Frequent environmental problems are bound to threaten regional ecological security and sustainable economic development.How to balance the contradiction between regional economic construction and ecological environment security has become a major issue in the construction of land space ecological security.The construction of regional ecological security pattern is an important way to alleviate the contradiction between people and land,ensure ecological security,maintain social stability and sustainable economic development,and is of great significance to the ecological restoration of land space.’Source identification-resistance surface construction-corridor extraction’is the basic paradigm of ecological security pattern construction.Ecological source is an ecological patch with strong value and function in the ecological environment,and it is also the source of species migration and diffusion.Therefore,the identification of source is the key link in the construction of ecological security pattern.In this paper,the source area of the Pearl River is taken as the research object,and the ecological source is extracted by considering the importance of ecosystem services and landscape connectivity to improve the accuracy of source identification.Based on the minimum cumulative resistance model Minimal Cumulative Resistance(MCR)model,the ecological security pattern of the source region of the Pearl River in the past 30 years was constructed,and the spatial and temporal dynamic evolution was analyzed.The main research contents and conclusions are as follows:(1)In recent 30 years,the ecological source patches in the source region of the Pearl River showed scattered distribution characteristics.The patches with continuous and concentrated spatial distribution are mainly located in the border area between Qujing City and Wenshan Prefecture,which is also the area where the river on the east side of Nanpan River flows through.The forest land in this area is widely distributed and the altitude is low,which is suitable for species migration and energy flow.The total patch area of the ecological source area was compared in 1990,2000,2010 and2020.The total patch area of the ecological source area was the largest in 2000,which was 8270.53km~2.(2)The high value areas of ecological resistance surface are concentrated,and these areas are mostly human activities.In the past 30 years,the distribution area of the high value area of the resistance surface has been increasing,and the distribution area of the high value area of the resistance surface in 2020 is the largest.Comparing the results of the resistance surface before and after the correction,it is found that the high value area of the resistance surface is more densely distributed after the correction,and the results of the resistance surface after the correction can better reflect the influence of human activities on the interior of the landscape unit.(3)The distribution pattern of ecological network is a tree network structure,which is distributed along the river flow direction of Beipanjiang River and Nanpanjiang River from the northeast of the basin.The number of ecological corridors in the four phases of data was 55,55,45 and 45,respectively.Comparing the spatial distribution patterns of ecological corridors in the four periods,the ecological corridors were the most densely distributed in 2000,especially at the junction of Qujing City and Wenshan Prefecture on the east side of the basin,which was the area with the highest ecosystem service value in that year.(4)The number of ecological nodes identified in the four data from 1990 to 2020was 24,28,23 and 22,respectively.By comparison,the number of ecological nodes in2000 was the largest and the spatial distribution was the densest.From 2000 to 2020,the number of ecological nodes is decreasing.In 2020,the number and spatial distribution density of ecological nodes will be minimized.(5)In the past 30 years,the spatial distribution of ecological network in the source area of the Pearl River has been complicated.Ecological sources,ecological nodes and ecological corridors are mainly distributed around the Beipanjiang and Nanpanjiang rivers.Affected by human activities,there are certain risks in the ecological security pattern in some areas of the Pearl River source region in the past 30 years.In view of the sensitive and fragile areas in the source analysis results,corresponding suggestions are given to increase a certain width of vegetation buffer zone around important sources,nodes and corridors to ensure regional ecological security and sustainable economic development.