Study On Vegetation Coverage And Its Dynamic Change Of Beijing Suburbs By Remote Sensing

Vegetation coverage, the ratio of vegetation occupying a unit area , is a very important parameter in the study of climate and ecological models, and a comprehensive index of the earth's surface situation covered by vegetation community. The study of the change and the estimation of vegetation coverage is important in the research of the change of ecology-environment system,hydrology,ecology and world environment change.This paper summarized the basic methods of measuring vegetation coverage. There are two basic methods of measuring vegetation: the ground-based measurement and estimation of vegetation coverage from remote sensing data. This paper also introduces the basic theories of monitoring vegetation coverage form remote sensing data, analyses the peculiarity, advantage and shortage of each method. Based on the method of dimidiate pixel model for vegetation coverage estimation, the current model is improved.The paper introduces the deducing process of two parameters of the improved model. The reason why we choose this method to do the research is that the model can be considered as a useful method to large areas estimation of vegetation coverage. The principle is easy to be understood and grasped. The model is a efficient way which observes the change of vegetation coverage, it can be used to all kinds of vegetation types and different scales of remote sensing data.On the base of the dimidiate pixel model, take the Huairou district of Beijing suburb for example, and get the 1992 and 2004 Landsat TM data, monitored the two years'vegetation coverage. Based on the results, the paper counts and analyses the change and the tendency of this change. This paper analyses the change of vegetation coverage of Huairou District from two aspects: the political villages and the geographical landscape. In the total, the vegetation coverage is increased during the passed 12 years, but the change is not very obvious. The northern area vegetation coverage has increased, because the protection in the last 12 years was better. On the contrary, the southeastern area vegetation coverage has degenerated seriously . This shows the fact that the social and economic development, urban construction has a very negative impact on the vegetation coverage, and human action can influence natural ecology greatly, It is vital for us to harmonize humanity and nature. The result of this paper can provide certain reference for the modern agriculture and sustainable development.