重庆市主城区城市扩张对生态系统服务影响的时空评估

城市建设用地扩张存在无序蔓延的现象,这种现象导致了生态系统服务功能的衰退,进而影响社会、经济和生态的协调发展。以重庆市主城区为研究对象,基于DMSP/OLS数据和Landsat数据分析了2005～2015年城市扩张的时空特征,基于MODIS NDVI数据、农作物产量数据、植被覆盖类型数据、气象数据和土壤类型数据等,利用食物供给模型、CASA模型和SCS_CN模型模拟了2005、2015年单位面积粮食供给、NPP和径流深度的空间分布与变化,最后,通过相关性分析阐述了不同发展区域生态系统服务的时空变化和权衡协同关系变化,探讨了城市扩张过程中面临的问题与挑战,并对未来城市发展提出几点建议。主要结论如下:(1)将重庆市主城区按照发展水平的高低划分为发达区、发展区和远城区;时间方面,2005～2015年建设用地共增加了373.9 km~2,发达区由于建设用地分布处于较饱和状态,建设用地的扩张量最小,发展区的扩张量最大。空间方面:建设用地沿着东北西南方向延伸扩张,东北偏东方向的渝北区和江北区受"两江新区"建设的影响,建设用地增量最大;(2)2005和2015年食物供给、固碳和土壤蓄水服务功能在发达区最低,发展区次之,远城区最高,且三种生态系统服务功能均存在显著衰退现象,衰退幅度最大的区域是发展区,与城市扩张最剧烈的区域在空间上吻合;(3)生态系统服务之间的权衡与协同关系受城市发展程度的影响;(4)发展区是生态系统服务功能下降最大的区域,食物供给是衰退最显著的生态系统服务功能。通过研究发现,重庆市建设用地扩张存在"冒进"蔓延的现象,这种现象破坏了生态系统功能,降低了环境容量,影响市民居住的舒适性,为此针对城市扩张过程中出现的问题提出了几点发展建议。研究结果引为解析重庆市主城区城市化过程中的问题成因,寻求城镇化的协调发展之路,合理规划城市发展提供了科学依据。

Spatio-temporal Assessment of Urban Expansion Impacts on Ecosystem Services in Chongqing City

Abstract：The disorderly expansion of urban land leads to the decline of ecosystem service function, which affects the coordinated development of society, economy and ecology. Based on DMSP/OLS data, Landsat TM/OLS data, this paper analyzed the spatio-temporal characteristics of urban expansion. Meanwhile, based on MODIS NDVI data, crop yield data, land use data, meteorological data and soil type data, the spatial distribution and changes of food supply, NPP and runoff depth in 2005 and 2015 were simulated using food supply, model CASA model and SCS_CN model. Finally, through correlation analysis and normalization analysis, the changes of ecosystem services and trade-off or synergy are explained in different urbanization categories, discussed the problems and challenges in process of urban expansion, and gives some ideas for future urban development. The basic conclusions are as follows: ①The Chongqing city was separated into three urbanization categories (developing urban, developed urban, and rural areas). In terms of time, urban land has expanded dramatically, from 2005 to 2015 increased by 373.9 km, the urban land expansion was the smallest because of urban land distribution in developed areas was relatively saturated, development urban was the largest. In terms of space, urban land extends along the northeast and southwest directions, Yubei District and jiangbei District in the east-northeast direction were affected by the “liangjiang new area”, and the increment of urban land was the largest; ②In 2005 and 2015, the service functions of food supply, carbon sequestration and soil water storage were the lowest in developed urban areas, followed by development urban areas, and the highest in rural areas. In addition, the ecosystem service functions have showed tendency of significant decline, the largest decline area was development urban, which coincided spatially with the area with the greatest urban expansion, it showed that the change of land use type caused by urban expansion was an important reason for the decline of ecosystem service function; ③The trade-off and synergy between ecosystem services were affected by the degree of urban development; ④ Urban expansion has significant impacts on ecosystem services, the areas with biggest decline of ecosystem service was developing urban, and food supply was the most obvious service function of the recession. It was found that the rapid expansion of urban land destroys the ecosystem services, reduces the environmental capacity and affects the comfort of residence of citizens. In view of this, some ideas for the development of urban expansion are given at the end of this paper. The research results of this paper provide a scientific basis for analyzing the causes of the problems in the urbanization process, seeking the coordinated development, and Rational planning and development in Chongqing City.