| Rapid urbanization has severely damaged the integrity and stability of the ecosystem,and caused a series of problems such as the deterioration of the ecological environment and the decline of ecosystem services.At present,studying the changes in ecosystem services and their relationships in the process of urbanization,and exploring their influencing factors,has become a key research content in the fields of ecology and geography.The Chengdu-Chongqing urban agglomeration is located in the ecologically fragile area of the upper reaches of the Yangtze River.It is one of the key areas for biodiversity conservation in my country and an important economic center in the west and the upper reaches of the Yangtze River.Clarifying the relationship and influencing factors between ecosystem services is conducive to promoting the coordinated development of ecosystem services in the region and reducing the negative impact of urbanization on the ecosystem.It is of great significance for strengthening the ecological barrier of the upper reaches of the Yangtze River and maintaining national ecological security.The research is based on ArcGIS,ArcGIS pro,ENVI platforms,combined with the InVEST model and CASA model to analyze the temporal and spatial changes of three typical ecosystem services in Chengdu-Chongqing urban agglomeration,including food productivity,carbon storage function and biodiversity;use correlation analysis,Ecosystem service change index and ecosystem trade-off coordination degree are used to explore the overall and partial,temporal and spatial trade-off/synergism distribution characteristics of Chengdu-Chongqing urban agglomeration ecosystem services;use geographically weighted logistic regression model to analyze the Chengdu-Chongqing urban agglomeration ecosystem The relationship between services explores the response of man-made(urbanization)and natural factors in order to provide a scientific reference for the planning and management work of relevant local departments,and achieve a win-win situation for the ecological environment protection and social and economic development of the Chengdu-Chongqing urban agglomeration.The conclusions of this study are as follows:(1)During the study period,the spatial and temporal distribution characteristics of food productivity,carbon storage function and biodiversity of the Chengdu-Chongqing urban agglomeration were different.Among them,the spatial distribution of grain productivity between 2005 and 2015 is significantly different:in 2005,the level of grain productivity in urban agglomerations was low in the middle and high in the east.In 2010,it was low in the west and high in the east.In 2015,there was no obvious distribution of high/low grain productivity.Aggregation phenomenon.From the perspective of the level of grain productivity in each city(district),the level of grain productivity in the eastern cities(districts)of the urban agglomeration is always higher.The cities with low levels of grain productivity in 2005 were Suining,Neijiang,Zigong,and Yibin in Sichuan Province,and the urban area of Chongqing.In 2010,they were Chengdu,Mianyang,Deyang,Suining and Chongqing in Sichuan Province.In 2015,it was mainly from Chengdu and Zigong City to the urban area of Chongqing.From the perspective of time,the grain productivity of the Chengdu-Chongqing urban agglomeration is continuously improving,and the grain productivity level of each city(district)generally shows a trend of rising first and then sharply.(2)The spatial distribution of the carbon storage function of the ChengduChongqing urban agglomeration during the study period is relatively similar.The carbon storage function is the weakest in the regions centered on Chengdu and Chongqing,the carbon storage function in most of the urban agglomeration is weak,the carbon storage function in the eastern parallel ridge valley region is stronger,and the carbon storage function in the Mount Emei area in the southwest corner of the urban agglomeration is stronger.The strongest storage function.For different land use types,forest land has the strongest carbon storage function,and construction land has the weakest carbon storage function.In 2005,the carbon storage function of each land use type was forest land>grassland>cultivated land>waterbody>unused land>construction land,in 2010 and 2015,it was forest land>grassland>cultivated land>unused land>water body>construction land.From the perspective of the carbon storage function of the cities(districts)in the city cluster,Ya'an City has the strongest carbon storage function,and Chongqing has the weakest carbon storage function.The carbon storage of each city(district)has shown a trend of a small decline first and then a sharp rise.(3)The spatial distribution of biodiversity in the Chengdu-Chongqing urban agglomeration changed little during the study period.This is reflected in the high level of biodiversity in the mountains around the urban agglomeration and the parallel ridgevalley area in the east,and the low level of biodiversity in the central Chengdu plain and hills in central Sichuan.From the perspective of changes in habitat quality levels,the area of areas with high habitat quality has increased,areas with higher,medium,and lower habitat quality levels have declined,and areas with low habitat quality levels have increased significantly.It can be seen that the habitat quality of the ChengduChongqing urban agglomeration has declined,and the level of biodiversity has declined.For different land use types,the order of biodiversity level from high to low is water body>woodland>grassland>cultivated land>construction land and unused land.For each city(district),the level of biodiversity in the area from Ziyang City to Nanchong City in the middle of the urban agglomeration,Tongnan District,Rongchang District of Chongqing,and the urban area of Chongqing is always low.Ya'an City,Leshan City,and Fengdu County,Chongqing City,Nanchuan District and Qianjiang District have relatively high levels of biodiversity.During the study period,there were 20 cities(districts)where the level of biodiversity of the urban agglomeration declined,14 cities(districts)where the level of biological diversity remained stable,and 4 cities(districts)where the level of biodiversity increased.(4)There are certain differences in the trade-off/synergism relationship of the three ecosystem services in the Chengdu-Chongqing urban agglomeration in 2005,2010 and 2015.There is always a weak synergistic relationship between food productivity and carbon storage functions.The relationship between food productivity and biodiversity was weaker in 2005,and weaker trade-off relationship in 2010 and 2015,but the strength of the trade-off has increased.There is always a significant synergy between carbon storage function and biodiversity.From the perspective of the temporal and spatial distribution characteristics of the gain and loss of the three ecosystem services in the Chengdu-Chongqing urban agglomeration,the grain productivity and carbon storage function have changed greatly during the study period,and the degree of the gain and loss of biodiversity has changed little during the study period.(5)The spatial distribution of the trade-off/synergism relationship among the three types of ecosystem services in the Chengdu-Chongqing urban agglomeration is different.The area of synergy between food productivity and carbon storage is larger than the area of trade-off,and the overall relationship is synergy.The trade-off relationship between carbon storage and biodiversity is weak in most areas,and the trade-off relationship between food productivity and biodiversity is also in most areas,but the trade-off is strong.(6)The geographic weighted logistic regression model was used to explore the correlation between the relationship between the ecosystem services of the ChengduChongqing urban agglomeration and the potential influencing factors,and it was found that the fit of this model was higher than that of the global regression model.In terms of the response of the relationship between ecosystem services to human(urbanization)influencing factors,the relationship between carbon storage and food productivity,and the relationship between carbon storage and biodiversity are mostly positive responses to population density and GDP density.Food productivity and carbon storage The relationship between population density and GDP density is mostly negative in the range of urban agglomerations.From the influence of natural factors on the relationship between ecosystem services in urban agglomerations,temperature has a relatively large impact on the trade-off/synergism relationship between ecosystem services,and the relationship between ecosystem services is affected by multiple factors. |
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