The Response Of Ecological Environment Quality In Guanzhong Region To The Expansion Of Urban And Rural Construction Land

Since the reform and opening up,the level of urbanisation in China has been increasing.While the rapid urbanisation process has brought about economic development,it has also caused a certain degree of damage to the resources and environment.With the development of social economy,people’s demand for construction land is increasing.The disorderly expansion of urban and rural construction land can cause problems such as imbalance in the development structure of urban and rural areas and low efficiency in the use of construction land.In the context of ecological civilization,exploring the response mechanism of ecological and environmental quality to the expansion of construction land and clarifying the relationship between the two is an important reference value for the optimal development of the spatial pattern of regional towns and cities and ecological and environmental protection.The Guanzhong Plain Urban Agglomeration is of strategic importance in China’s modernization and all-round opening-up pattern.At present,problems such as unbalanced regional development,insufficient radiation-driving capacity of the central cities,serious pollution,water shortage and poor ecological environment still exist.Therefore,in this study,the Guanzhong region of Shaanxi Province was used as the study area,and firstly analyzes the spatial and temporal evolution characteristics of urban and rural construction land in the Guanzhong region in terms of scale,expansion rate,expansion intensity and expansion pattern,and secondly constructs the remote sensing ecological index RSEI based on the GEE cloud platform to evaluate the ecological environmental quality in the Guanzhong region,and finally explores the interaction between the two through bivariate spatial autocorrelation and GWR models,with the following main findings:(1)The scale of urban and rural construction land in the Guanzhong region has steadily increased over the past 20 years,with differences in the rate and intensity of expansion among districts and counties.The scale of urban and rural construction land in the Guanzhong region increased from 1872.24km~2 in2000 to 3896.89km~2 in 2020,with the largest growth rate of construction land in 2013;there were differences in the average annual growth rate of construction land in the five prefecture-level cities,ranked in the following order:Xianyang City>Tongchuan City>Xi’an City>Baoji City>Weinan City.During the last20 years,the center of gravity for the expansion of building land in Guanzhong has been centered in Sanyuan County,Xianyang City,with a progressive movement to the northeast over the research period;In terms of spatial pattern,construction land is primarily distributed in the"southwest-northeast"direction;there are differences in the fast and slow expansion of construction land in different districts and counties over time,and the overall expansion rate of construction land has slowed since 2015;and,in terms of expansion intensity,the urban expansion intensity index of each district and county did not exceed 2%over the four time periods.The overall growth intensity is lower in the Guanzhong area.(2)The remote sensing ecological index of the Guanzhong region has shown a fluctuating upward trend over the past 20 years,and the ecological environment as a whole has developed for the better.The Guanzhong region’s RSEI index improved from 0.48 in 2000 to 0.637 in 2020,with a 1.425%average yearly growth rate.The values of the remote sensing ecological index vary by prefecture,with Baoji having the highest RSEI rating and the best ecological environment quality.The overall ecological environment grade in the Guanzhong area has a geographical distribution pattern of"poor in the centre,good surrounding;bad in the northeast,excellent in the southwest."The trend of ecological environment quality in the Guanzhong region over the past 20 years is significantly improved>slightly improved>slightly degraded>stable and unchanged>severely degraded,with the area of significantly improved areas accounting for the largest proportion,reaching 57.42%.(3)The expansion of urban and rural construction land in the Guanzhong region had a dampening effect on ecological improvement over a 20-year period,with the dampening effect diminishing in the latter part of the study..The average value of the RSEI index within the scope of urban and rural construction land from 2000to 2020 was 0.373,and the RSEI index of the construction land distribution area showed a trend of rising and then stabilizing over time.The conversion of forest land to arable land and arable land to construction land are the main types of land use transfer leading to ecological degradation in the Guanzhong region.At the district and county scales,the ratio of urban to rural construction land to RSEI shows a significant negative correlation,i.e.the greater the intensity of construction land expansion,the worse the ecological environment,but with the regulation of national macro policies,the inhibiting effect of construction land expansion on ecological environment improvement gradually diminishes.