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Shi Pejun; Li Xiaobing; Zhou Wuguang (Key Laboratory of Environmental Change and Natural Disaster, Ministry of Education of China, Beijing Normal University; Institute of Resources Science, Beijing Normal University, Beijing 100875)  
In recent years, many researchers attempted to monitor and research process of land cover change at a short time scale using earth observahon data by remote sensing.Temporal and spatial resolution were improved in these research, and they are very important to reduce non-certainty. On the basis of these, not only had they opened out process of regional land cover change at a short time scale, but also laid a solid foundahon for dishnguishing natural and human driving forces of these change. The relationship between terrestrial ecosystem and climate change is significant research content in global change research, and the relahonship between vegetahon and climate is one of the centres of research at all time. NOAA/AVHRR digita image is important data source in the research field ofland cover and vegetahon dynamic at a large scale. Many calculated parameters based on infrared light and near infrared light were sensihve to vegetahon growth status, produchvity, other biophysical and biochemical characterishc. NDVI(normalized difference vegetahon index) is a kind of solid vegetahon index, it has been used to describe physiological status of vegetahon, to estimate vegetahon cover degree, LAI(leaf area index), plant photosynthesis capability, exishng greenness biomass and productivity. In this research, the vegetation map based on multi-temporal NOAA/AVHRRNDVI images with 1km× 1km spatial resolution has been carried out and published[9].In mis research, the temperate meadow-steppe, the temperate typically steppe, the temperate desert steppe, the desert shrub with desert steppe and the temperate desert -the zonal vegetahon types in the arid and semi-arid regions in northem China-are chosen as objects of research. Firstly, we cany out the precision verification in the fleld for these vegetation types on the basis of global posihon system (GPS). There are 22 points, which cover three vegetation types in this research, show preferable corresponding relation betweenthe classification results and observahons. The classificahon precision is 90.1%. It is the basis of this research. Secondly, the data used in the research include multi-temporal monthly NOAA /AVHRR NDVI images with 8km × 8km spatial resolution from 1983 to 1992, themeteorologic data of 160 standard observatories in China as the same hme withremote images. Some observatories corresponding to different vegetahon types arechosen. They are Hailabethe temperate meadow-steppe, Xilinhot and Abag── thetemperate typically steppe, Erenho──the temPerate desert steppe, Yulin── trhe desert shrub with desert steppe, Jiuquan and Turpan──the temperate desert. Thirdly, the seasonal NDVI curves for different vegetation types are made by time series analysis of profile. Therefore, the annual NDVI curves are made using NDVI peak of growth season in ten years. It shows ascending trend for all vegetation types. In the mean time, the annually average temperature (T) and annually total precipitahon (P) curve are made too for 7 observatories. T shows ascending trend, P showsascending trend for 6 observatories except Erenhot annual P in Erenhot falls gently. Finally, there are corresponding relahonship among change of NDVI, T and P formost vegetahon types in the arid and semi-arid regions northern China. It means impact of T and P change on vegetahon, moreover, impact of temperature on vegetation is especially prominent, but this issue was ignored in former time. For the desert steppe, NDVI still shows ascending trend along with increasing T anddescending P correspondingly, so there should be increasing consumption of soil water in order to maintain plant growth, thereby, it exacerbates soil drought degree. It wasthe most important reason of grievous rangeland degradahon and aggravating pasture desertification at a large scale in recent years. For the Mau Us sandy land, in recent 10 years, increasing amplitude of temperature is larger than the desert steppe, but the increasing amplitude of precipitation is smaller, NDVI increasing amplitude of this region is restricted seriously, and
【Fund】: 国家自然科学基金!39899374;;“九五”国家重大基础研究项目!95-22-02
【CateGory Index】: Q948.1
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