Research On Spatiotemporal Evolution Of Land Use And Optimization Of Ecological Network Pattern In Guiyan

With the rapid development of regional social economy,the mode and intensity of land use are constantly changing the urban spatial pattern,and affecting the surrounding resources,ecological environment and ecological network pattern.The extreme change of global climate,the continuous degradation of ecological environment and the conflict between land use and ecological environment affect human survival and development to varying degrees.To improve the quality of natural ecosystems,concepts such as "biodiversity conservation","sustainable development","ecological priority" and "green development" have emerged.As the provincial capital of Guizhou Province,an ecologically civilized city in the typical karst mountain area and an important ecological barrier in the upper reaches of the Yangtze River and Pearl River,Guiyang needs to further coordinate the relationship between economic development,land use and ecological environmental protection and promote the construction of national ecological civilization pilot zone during the "14th Five-Year Plan" period.Therefore,in this study,dynamic attitude model,gravity center migration model,landscape pattern index and habitat quality model were used to analyze and study the spatio-temporal evolution of land use and its internal mechanism in Guiyang City,so as to explore the impact of dynamic change of land use on habitat quality and ecological network,which is helpful to improve and optimize the ecological network pattern in Guiyang City.To construct an ecological network system that is more in line with the "ecological priority" principle in the current urbanization process of karst mountain areas,so as to provide scientific basis for land use planning and urban planning of karst mountain cities,and provide practical reference for optimizing the overall urban spatial pattern,enhancing urban safety and resilience,enhancing the comprehensive value of space,and promoting urban renewal and green development.To help Guiyang ecological civilization construction and high quality development in the new era.The main conclusions of the study are as follows:(1)The spatio-temporal evolution of land use and the change of landscape pattern showed that the area of cultivated land,woodland,grassland and unused land decreased year by year from 2005 to 2020,while the area of water area and construction land increased year by year.The dynamic rate of construction land was as high as 13.48%,with a large expansion intensity.The main source areas involved cultivated land,forest land and grassland,which resulted in significant changes in the landscape pattern index of cultivated land,forest land and grassland.As an important ecological space,the patch dominance of forest land and grassland was destroyed.(2)The study on the influence of temporal and spatial changes of land use on ecological network pattern shows that in the next 15 years,the ecological space such as forest land and grassland will continue to decrease,and the construction land will continue to radiate outward along the central urban area and Qingzhen city to complete the urban expansion.In the past 30 years,the expansion of construction land led to the degradation of habitat quality.The proportion of excellent grade habitat quality decreased year by year in all districts and counties,while the proportion of poor grade habitat quality increased significantly with the rapid urban development.The ecological source area was reduced by land use conversion and construction land expansion,and the ecological matrix was damaged,which reduced the integrity of ecological network.The increase of construction land reduces the ecological connectivity of river corridor and increases the difficulty of biological migration.The underlying surface of the existing ecological node has a high degree of hardening and its area is constantly expanding,which increases the resistance of ecological circulation between source areas.The existing ecological network focuses on the ecological security of the central urban area,with single types of ecological corridors and less radiation range of ecological nodes.The expansion of construction land leads to the ecological flow fracture among sources,nodes and corridors,and the overall connectivity of the ecological network is not high,and it does not fully play a positive role in maintaining the stability of the regional ecosystem and promoting the improvement of the level of biodiversity.The study on the construction of ecological network pattern based on the temporal and spatial changes of land use showed that,according to the results of habitat quality evaluation and model research methods,10 ecological source patches,67 key ecological corridors,16 potential ecological corridors,14 ecological pinch points and 14 ecological obstacles were identified in Guiyang.The evaluation study of ecological network structure shows that the overall connectivity of the constructed ecological network is not high,the degree of closure of the network is low,and there is still a lack of interconnection between a certain node and other nodes.Therefore,it is necessary to re-plan,design and optimize the constructed ecological network to improve the integrity and stability of the ecological network.(3)According to the results of habitat quality evaluation and the method of model research,10 ecological source patches,67 key ecological corridors,16 potential ecological corridors,14 ecological spots and 14 ecological obstacles were identified in Guiyang.The evaluation study of ecological network structure shows that the overall connectivity of the constructed ecological network is not high,the degree of closure of the network is low,and there is still a lack of interconnection between a certain node and other nodes.Therefore,it is necessary to re-plan,design and optimize the constructed ecological network to improve the integrity and stability of the ecological network.(4)Based on the ecological network construction and evaluation results,and combined with the actual situation of the study area,the ecological network of Guiyang was perfected and optimized from four aspects,so as to maintain the stability of the Guiyang ecosystem and improve the biodiversity:(1)The study was divided into four ecological functional areas,namely,key ecological protection area,ecological conservation area,ecological buffer transition area and ecological occupation construction area.At the same time,planting trees and grass,culvert,overpass,urban green belt and riverbank green belt construction were adopted to weaken the resistance of hardened pavement and hydrology.(2)Add 10 key protection and optimization areas of ecological source,and make the area where Aha Lake is located as the centralized display of Guiyang green core and ecological civilization,and implement strict control.(3)The Wujiang River Basin was protected as a regional ecological landscape belt.At the same time,8 river corridors,4 mountain corridors and 149 low-resistance ecological channels were added.The corridor width was set to200 m to increase the route selection of species migration and the efficiency of ecological circulation.(4)47 ecological stepping stones were added to make up for the shortage of primary and secondary ecological nodes and special ecological nodes in the upper part of the overall ecological network.At the same time,39 ecological restoration nodes were added to strengthen the restoration of ecological weak points,and node buffer zones were set up to repair ecological spots and ecological obstacles.