For almost three decades, China has been undergoing significant transition from a planned economy to a market economy. Fast-paced economic growth and urbanization, interacting with market-oriented reforms in land re- ...For almost three decades, China has been undergoing significant transition from a planned economy to a market economy. Fast-paced economic growth and urbanization, interacting with market-oriented reforms in land re- sources allocation, have caused profound spatial restructuring of Chinese cities. This paper examines urban expansion and land use reconfiguration in Shanghai’s central city from 1979 to 2002, with a special focus on the effect of the adoption of the land-leasing system in 1988. The empirical research, which employs GIS-based spatial analysis tech- niques to explore land use data for multiple years, indicates fundamental changes in the spatial characteristics of urban development in Shanghai after this important land policy reform.展开更多
It is important to understand how land use change impacts groundwater recharge, especially for regions that are undergoing rapid urbanization and there is limited surface water. In this study, the hydrological process...It is important to understand how land use change impacts groundwater recharge, especially for regions that are undergoing rapid urbanization and there is limited surface water. In this study, the hydrological processes and re- charge ability of various land use types in Guishui River Basin, China （in Beijing Municipality） were analyzed. The impact of land use change was investigated based on water balance modeling, WetSpass and GIS. The results indicate that groundwater recharge accounts for only 21.16% of the precipitation, while 72.54% is lost in the form of evapotranspiration. The annual-lumped groundwater recharge rate decreases in the order of cropland, grassland, urban land, and forest. Land use change has resulted in a decrease of 4 x 106 m3 of yearly groundwater recharge in the study area, with a spatially averaged rate of 100.48 mm/yr and 98.41 mm/yr in 1980 and 2005, respectively. This variation has primarily come from an increase of urban area and rural settlements, as well as a decrease of cropland.展开更多
The urban population and urbanized land in China have both increased markedly since the 1980 s. Urban and suburban developments have grown at unprecedented rates with unknown consequences for ecosystem functions. In p...The urban population and urbanized land in China have both increased markedly since the 1980 s. Urban and suburban developments have grown at unprecedented rates with unknown consequences for ecosystem functions. In particular, the effect of rapid urbanization on the storage of soil carbon has not been studied extensively. In this study, we compared the soil carbon stocks of different land use types in Beijing Municipality. We collected 490 top-soil samples(top 20 cm) from urban and suburban sites within the Sixth Ring Road of Beijing, which cover approximately 2400 km2, and the densities of soil organic carbon(SOC), soil inorganic carbon(SIC), and total carbon(TC) were analyzed to determine the spatial distribution of urban and suburban soil carbon characteristics across seven land use types. The results revealed significant differences in soil carbon densities among land use types. Additionally, urban soil had significantly higher SOC and SIC densities than suburban soil did, and suburban shelterbelts and productive plantations had lower SIC densities than the other land use types. The comparison of coefficients of variance(CVs) showed that carbon content of urban topsoil had a lower variability than that of suburban topsoil. Further findings revealed that soil carbon storage increased with built-up age. Urban soil built up for more than 20 years had higher densities of SOC, SIC and TC than both urban soil with less than 10 years and suburban soil. Correlation analyses indicated the existence of a significantly negative correlation between the SOC, SIC, and TC densities of urban soil and the distance to the urban core, and the distance variable alone explained 23.3% of the variation of SIC density and 13.8% of the variation of TC density. These results indicate that SOC and SIC accumulate in the urban topsoil under green space as a result of the conversion of agricultural land to urban land due to the urbanization in Beijing.展开更多
基金Under the auspices of the National Natural Science Foundation of China (No. 40371038)
文摘For almost three decades, China has been undergoing significant transition from a planned economy to a market economy. Fast-paced economic growth and urbanization, interacting with market-oriented reforms in land re- sources allocation, have caused profound spatial restructuring of Chinese cities. This paper examines urban expansion and land use reconfiguration in Shanghai’s central city from 1979 to 2002, with a special focus on the effect of the adoption of the land-leasing system in 1988. The empirical research, which employs GIS-based spatial analysis tech- niques to explore land use data for multiple years, indicates fundamental changes in the spatial characteristics of urban development in Shanghai after this important land policy reform.
基金Under the auspices of National Natural Science Foundation of China (No. 41101033)Program of International S & T Cooperation (No. 2010DFA92400)+1 种基金Beijing Municipal Natural Science Foundation (No. 8082010)Non-profit Industry Financial Program of the Ministry of Water Resources (No. 200901091)
文摘It is important to understand how land use change impacts groundwater recharge, especially for regions that are undergoing rapid urbanization and there is limited surface water. In this study, the hydrological processes and re- charge ability of various land use types in Guishui River Basin, China （in Beijing Municipality） were analyzed. The impact of land use change was investigated based on water balance modeling, WetSpass and GIS. The results indicate that groundwater recharge accounts for only 21.16% of the precipitation, while 72.54% is lost in the form of evapotranspiration. The annual-lumped groundwater recharge rate decreases in the order of cropland, grassland, urban land, and forest. Land use change has resulted in a decrease of 4 x 106 m3 of yearly groundwater recharge in the study area, with a spatially averaged rate of 100.48 mm/yr and 98.41 mm/yr in 1980 and 2005, respectively. This variation has primarily come from an increase of urban area and rural settlements, as well as a decrease of cropland.
基金Under the auspices of National Key Technology Research and Development Program(No.2007BAC28B01)Innovation Project of State Key Laboratory of Urban and Regional Ecology of China
文摘The urban population and urbanized land in China have both increased markedly since the 1980 s. Urban and suburban developments have grown at unprecedented rates with unknown consequences for ecosystem functions. In particular, the effect of rapid urbanization on the storage of soil carbon has not been studied extensively. In this study, we compared the soil carbon stocks of different land use types in Beijing Municipality. We collected 490 top-soil samples(top 20 cm) from urban and suburban sites within the Sixth Ring Road of Beijing, which cover approximately 2400 km2, and the densities of soil organic carbon(SOC), soil inorganic carbon(SIC), and total carbon(TC) were analyzed to determine the spatial distribution of urban and suburban soil carbon characteristics across seven land use types. The results revealed significant differences in soil carbon densities among land use types. Additionally, urban soil had significantly higher SOC and SIC densities than suburban soil did, and suburban shelterbelts and productive plantations had lower SIC densities than the other land use types. The comparison of coefficients of variance(CVs) showed that carbon content of urban topsoil had a lower variability than that of suburban topsoil. Further findings revealed that soil carbon storage increased with built-up age. Urban soil built up for more than 20 years had higher densities of SOC, SIC and TC than both urban soil with less than 10 years and suburban soil. Correlation analyses indicated the existence of a significantly negative correlation between the SOC, SIC, and TC densities of urban soil and the distance to the urban core, and the distance variable alone explained 23.3% of the variation of SIC density and 13.8% of the variation of TC density. These results indicate that SOC and SIC accumulate in the urban topsoil under green space as a result of the conversion of agricultural land to urban land due to the urbanization in Beijing.
