Objective The study on the temporal and spatial evolution characteristics and driving factors of the ecosystem services of Chengdu-Chongqing urban agglomeration can help planners grasp its situation of natural resource stock and development trend on a macro scale, reasonably formulate the planning and construction strategy of Chengdu-Chongqing urban agglomeration of southwestern China, so as to promote the construction of China’s western development platform.
Method In this study, the whole region of Chengdu-Chongqing urban agglomeration was selected as the research object, and 144 districts, counties and regions were taken as the research units. The values of ecosystem services were quantified by equivalent factor method, and the bi-directional driving factor index system of “natural environment-social economy” was established. On this basis, the least square method (OLS) model was used to screen the driving factor models with significant correlation, and the geographical weighted regression (GWR) model was used to study the driving correlation between the ecosystem services, natural environment characteristics and socio-economic factors of Chengdu-Chongqing urban agglomeration.
Result (1) The total amount of ecosystem services of Chengdu-Chongqing urban agglomeration showed a significant trend of deterioration. From 1995 to 2015（totally 5 periods, i.e. 1995, 2000, 2005, 2010, 2015), the ecosystem service values of Chengdu-Chongqing urban agglomeration were 347.053, 346.408, 345.243, 343.802 and 342.392 billion CNY, respectively, showing a value decline of 0.645 billion, 1.165 billion, 1.440 billion and 1.410 billion CNY, respectively compared with the former period. (2) The spatial distribution of ecosystem services in Chengdu-Chongqing urban agglomeration was characterized by significant regional distribution in the core urban centers of Chengdu and Chongqing and the central area of Jinyun-Zhongliang Mountains. More than 90.38% of the regional ecosystem services in the whole region were in a downward trend. (3) Research results on ecological driving factors of Chengdu-Chongqing urban agglomeration showed that, five driving factors, namely rainfall, temperature, per capita GDP, forestry land ratio and population density, had significant influences on ecosystem services of Chengdu-Chongqing urban agglomeration. Among them, rainfall and land per capita GDP showed obvious negative correlation driving characteristics, the proportion of forest land showed obvious positive correlation driving characteristics, and rainfall and population density showed obvious polarization trend.
Conclusion In this study, the status of deterioration of ecosystem services in Chengdu-Chongqing urban agglomeration was clarified. The GWR (geographic weighted regression) model was constructed to quantify the different driving characteristics and driving intensities of the five main driving factors of rainfall, temperature, land average GDP, forestry land proportion and population density on the ecosystem services of Chengdu-Chongqing urban agglomeration, which provide decision-making basis for the long-term planning of Chengdu-Chongqing urban agglomeration.