城市扩张对北京市城乡结合部自然和农业景观的影响——以昌平区三镇为例

Abstract

Natural and agricultural landscape at the urban-rural interface is the important foundation to ensure the urban ecological security. Studying the spatio-temporal evolution of natural and agricultural landscape and its driving forces at the urban-rural interface in the context of the rapid urbanization can provide scientific support for some protection policies formulation and implementation. This paper investigates the spatial pattern of land use / land cover( LULC) in three typical townships at the urban-rural interface of Beijng by interpreting the 1999,2004 and 2010 SPOT images. One this basis,with Arc GIS spatial overlay function and land use transition matrix,this paper tries to further investigate the spatio-temporal evolution of LULC in the study area. At the same time,the spatial autocorrelation of build land and the landscape connectivity of natural and agricultural land are measured to analysis the impact of urban sprawl on the pattern and stabilityof natural and agricultural ecosystems. Finally,using a combination of quantitative and qualitative methods,the driving forces of the change of natural and agricultural landscape in the study area are analyzed. The results show that,from 1999 to2010,the town experienced a dramatic process of LUCC; build land,woodland and grassland substantially increased,accompanied by a sharp reduction of agricultural land and water area. There is dramatic mutual transfer between the various land use types,especially from agricultural land to build land,woodland,grassland,and from woodland to build land. Most of the new build land located in the neighbourhood of the existing build land,implying that the existing built-up areas have a greater influence on urban expansion. The rapid expansion of build land caused the sharp decline of the landscape connectivity of natural and agricultural land,and endangering the structural integrity and the functional stability of ecosystem in the study area. Socio-economic development,land use planning and public policy which jointly determined the LUCC structure,size and spatial distribution,were the main driving forces of pattern evolution of natural and agricultural landscape in the three towns.