Research On Gradient Changes Of Green Space In Urban And Rural Areas

Taking the southeast quadrant transect of Zhengzhou as an example (the transect starts from the Zhengzhou Railway Station, using Jing-Guang Railway as the axis line and extending 3km to the east and west sides, continuing the transect to the border of Zhengzhou City from Xie Zhuang Station), based on the topography and land-use map of Zhengzhou with aerial photo and field survey data in 2008, the article classified the green space landscape in the study area into nine types: farmland, garden plot, woodland, grassland, nursery, vegetable land, water, urban green and unused land. In order to compare the differences between urban and rural areas, the transect was divided into six gradients artificially (6km each gradient). This article selected some parameters such as landscape diversity, landscape fragmentation, landscape fractal dimension and so on, then did data statistics and results analysis and obtained the characteristic of landscape pattern in each gradient zone. By analyzing the features of gradient change of green space in different gradients, it put forwards the current problems and optimizing countermeasures, providing scientific basis for ecological construction of Zhengzhou City. The main findings are as follows:The analysis results of the composition of green space landscape showed that the spatial distribution of green space presenting an increasing trend generally along the gradient direction. Green space of each gradient zone accounts for 16.54%, 47.40%, 82.45%, 87.55%, 76.06%, and 89.06% respectively. Meanwhile, the composition analysis on component of each gradient zone indicated that green space based mainly on urban green in urban centers, farmland and garden in the marginal zone and farmland in rural . This illustrates that extension direction of urban space and economic structure directly influenced the composition and proportion of the type of green space landscape.The result of analyzing gradient changes of green space pattern showed that landscape features of the green space in each gradient varied greatly. Landscape diversity and evenness index showed a downtrend along the gradient direction; it states that the extent of human interference weakens gradually as the distance from the city becomes farther. In the direction away from the city center, landscape types are distributed more randomly. Analysis on the patch and edge density of landscape showed that the degree of fragmentation of green space took on a downward trend along the gradient direction and the average patch area became gradually larger. Landscape fragmentation and marginal division near the city center appeared largest. It shows that the deepest these areas are interfered by urbanization, the most complex the land use patterns and the weakest the ecological stability will be. Since the average shape index was increasing along the gradient direction, this meant that farther away from the city center, the stronger the material exchange ability and the more stable the ecosystem. These characteristics of pattern change indicated that urbanization influence made the pattern of green space seriously fragmentized, ecological stability reduced and environmental quality depraved. The smaller the urbanization interference is, the more random the distribution of green space will be, resulting in more complex patch shapes, thus making a more stable ecology and the higher the value of ecosystem services.The correlation analysis of green spatial pattern and urbanization index showed that there was a strong relationship between landscape pattern of green space (including diversity index, patch density, edge density, shape index, fractal dimension and etc.) and urbanization interference. According with the relevant model, we know that the laws between urbanization degree and green spatial pattern are as follows: the greater the urbanization interference, the smaller the landscape diversity. The greater the separation and the more simple and regular the patch shape, the lower the ecological stability. It illustrated that controlling the expansion of urban space and reducing the interference of urbanization were the important way to maintain landscape diversity and ecological stability of green space.Combined with field survey, it was found that there were many problems in the green space. Currently, there is a serious waste of land resources, decline in soil quality, reduction of farmland area, pollution of waters, lack of public active space, poor quality of afforestation and as well as many other problems. For the problems above, taking the landscape ecology plan theory as the instruction, with enhancing the green space landscape multiplicity and stability as the goal, this article put forwards some optimization measures for the green space in the study area: taking effective measures to limit the speed and the way of urban expansion with scientific planning, rational development and utilization of land resources;as well as increasing efforts to combat industrial pollution and removing the solid waste with environmental protection methods; protecting farmland from encroachment and guiding the farmers scientifically in accordance with the situation of their land and strengthening the governance of water pollution and constructing wetland protection zone to improve water quality through natural means; increasing public green space and building country park and scenery recreation resort to improve the environmental quality of marginal zone; perfecting infrastructure, improving the green level and maintenance management level, carrying out special green planning for railway and airport and constructing a traffic environment with fresh air and harmony ecology; using native species to build ecological green corridor and form ecological network system of green space and providing a green barrier for ecological security of city center; establishing protected sites area and reflecting the landscape's cultural value by green space.