Study On The Gradients Of Urban Forest Landscape In Urban Fringe Area Of Changsha City

In the process of urbanization, a series of environment problems can no longer be ignored. Some inevitable ecological environment problems can be grown up, because of the negative impact in the process of developing city, however humans can reduce the influence of ecological environment by improving the urban environment. Urban forest plays an important role in maintaining ecological balance, improving the urban environment and increasing urban biodiversity. Moreover, urban marginal area is the buffer zone, which has a very important role on connecting the city suburb and urban center.This paper applies the fundamental of landscape ecology, and utilizes the methods combined landscape pattern analysis and gradient analysis. The second type inventory data of changsha forest resource at 2003 and TM satellite image are used for the basic data, GIS technology are used for the technical support. The urban forest in changsha fringe areas was carried with landscape pattern gradient analysis, then we grasped the situation of urban forest space landscape pattern in changsha and the its basic characteristics of changsha The results show that:The results as followed:1 At the level of class, urban forest landscape, the ordinary greenbelt landscape, water area and non-forest landscape that along the transect show respective gradient characteristics.(1) From urban center to suburbs, urban forest landscape was obviously "v" distribution, the proportion of the landscape at the city fringe area was the biggest, but the non-forest landscape shows opposite phenomenon.(2) The ordinary greenbelt landscape in the city center distribution is less; the curve of the ordinary greenbelt landscape was obviously "U" distribution. The plaques density of ordinary greenbelt landscape that conjuncts urban fringe area and suburbs takes the maximal density. The degree of fragmentation was the highest, the shape was complicated.(3) The water area along the transect has little change. The degree of fragmentation was not high. It is little affected by human effects.(4) In the city center area, non-forest area is the largest and the acre of patch area is larger. The degree of fragmentation was not high and the connectivity is better. The non-forest area along the transect was changes obviously. Along with the increase of distance from the city center, the plaques area and the plaques density gradually decreased, however its shape index is increased. These all explain the fragmentation degree increase.2. The gradient analysis of landscape heterogeneity in survey region demonstrates that two landscape exponential curve on belt transect have similarity tendency. The characters of landscape shape exponential and plaque density indicate that, there are small urban forest landscape distributions in the city center, and these distributions are more concentrated, lower degree of fragmentation, and have comparison rules shape; The more close to the city suburbs, the more increase in patch density, and the shape becomes more natural. The characters of landscape homogeneity degree exponential and diversity index indicate that the conjunct region that between the outer edge of urban areas and suburban is the most plentiful types and the highest diversities.3. on the basis of comprehensive analysis the urban forest landscape pattern in the marginal zone of Changsha City, this paper put forward some countermeasures to promote the construction of urban forest in this survey region:firstly, in order to satisfy the demand of people in this area, we should construct and transform some public garden; secondly, we should reasonably decorate forest belt in the surrounding area of construction land for improving living condition; last but not least, in the process of expanding urban, we need to emphasize on the protection of forest and farmland, at the same time, we should strengthen the construction of Medium and large plaques.This paper analyzes the current situation of urban forest landscape pattern in the marginal zone of Changsha City, and put forward some countermeasures to relational departments for optimizing forest landscape pattern and rationally operating urban forest.