The Impact Of Land Use Change On Ecological Environment In Rural-urban Fringe

The rural-urban fringe is the frontier of urban land expansion, which has active socio-economic activities, serious man-land relationship, sharp contradiction , sensitive and fragile ecological environment, and is known as "natural laboratory" for the research of environmental effects. So the study on land use change and its environmental impact in rural-urban fringe has a higher theoretical value. However, the synthetic evaluation and analysis about the impact of land use change on ecological environment is still rare. Due to the unique political, economic and social status of Beijing, it plays an important role in the effect of buffer zone and green barrier of the rural-urban fringe, and the study on land use change and its environmental impact in rural-urban fringe has an important practical significance to harmonious development of society, economic and ecological environment.In this paper, three typical regions of Chaoyang District (interior fringe area), Shunyi District (central fringe area) and Miyun County (exterior fringe area) in Beijing are selected as the study area. Meanwhile, the RS and the GIS techniques are employed to explore the effects of land use change on ecological environment in terms of ecosystem service, ecological environment quality and ecological security. According to the results, several reasonable suggestions for sustainable development of ecological environment are proposed. The main conclusions are as follows:(1) In rural-urban fringe of Beijing, the land use structure changes obviously and the change of land use dynamic degree has obvious spatial differentiation. Meanwhile, the land use types keep rapid conversion and the landscape patterns also change very fast. Furthermore, the fragmentation and decentralization trend of cultivated land is clearly and the construction land expands in high speed and large scale.(2) The temporal and spatial dynamic trend of ecosystem service value (ESV) in rural-urban fringe of Beijing from 1996 to 2005 is analyzed by using GIS technique. The results show that different ESV has different characteristics of spatial pattern change. Meanwhile, the ESV structure changes differently in Chaoyang District, Shunyi District and Miyun County. In Chaoyang District, most of the ecosystem services functions are weakened except water purification and biodiversity. In Shunyi District, some function of the ecosystem services are weakened, for example, water conservation, water purification, soil conservation and environment purification. In Miyun County, some function of the ecosystem services are weakened, for example, water conservation, biodiversity and environment purification.(3)In order to reflect the temporal and spatial dynamic trend of ESV in the study area from 1996 to 2005 and the internal differences in each administrative unit, ecosystem service value index (ESVI) is constructed by using the grid spatial analysis technique of GIS. The results show thatâ‘ ESV continues to decline from 1996 to 2005, and the regional differentiation is obvious;â‘¡t he area of low ESV has been expanding gradually with the expanding of construction land, which results in the downward trend of ESV in the study area;â‘¢The ESV-GDP ratio in the study area is far below the national average and shows substantial decrease trend, which reflecting land use structure changes in non-positive trend. To some extent, the regional economic is developed at the price of ecosystem services;â‘£The results suggest that the change trend of ESV is consistent with that of cultivated land and water. ESV of cultivated land and water declines with the decrease of their area.(4)Four factors including natural environment, landscape structure, agricultural pollution and human disturbance are introduced to establish the ecological environment effects evaluation index system and model, which realize the dynamic evaluation of ecological environment effect. The results show thatâ‘ The ecological environment quality has a relatively large disparity in the rural-urban fringe. The area of good quality, bad quality and common quality of ecological environment in the study area occupy 60%, 35% and 5% respectively.â‘¡The classification area of ecological environment change asynchronously.â‘¢The ecological environment quality of the whole area, which is in the general level, has shown an decreasing trend.â‘£From 1996 to 2005, the ecological environment status in Chaoyang District has improved while Shunyi District and Miyun County show a downward trend .(5)The temporal and spatial dynamic trend of ecological security in rural-urban fringe of Beijing from 1996 to 2005 is analyzed in terms of landscape ecological security index (ESI), on the ground of landscape ecology theory and the stability of landscapes. Semivariogram analysis and Kriging interpolation are conducted to get the distribution map of ecological security. The results show thatâ‘ The ecological environment is strongly influenced by human activities, and the landscape indexes of patch number, landscape fragmentation and the fractional dimension have all shown an increasing trend in the study area;â‘¡Human activity has much influence on the ecological security index, giving rising to quite uneven spatial distribution of ecological security in the whole area;â‘¢The ecological security index (ESI) can be used to quantitatively evaluate the ecological environment and its evolution direction. The ESI takes on an ascending tendency from Chaoyang District through Shunyi to Miyun counties, and the area of low ESI has been expanding gradually with the acceleration of urbanization of Beijing;â‘£Different landscape types have different level of ecological security. The ecological security level of forest landscape is the highest, and the construction landscape is the lowest.(6)Targeting at the existing problems of ecological environment in rural-urban fringe of Beijing, the author puts forward several reasonable suggestions for sustainable development of ecological environment: strengthening land use planning, developing and utilizing land resources reasonably; emphasizing the construction and protection of greenbelt; speeding up the comprehensive improvement of urban environment; developing circular economy and reducing the pollution load; controlling the rural non-point source pollution and constructing ecological demonstration.