PROGRESS IN GEOGRAPHY ›› 2009, Vol. 28 ›› Issue (3): 391-397.doi: 10.11820/dlkxjz.2009.03.010

• Original Articles • Previous Articles     Next Articles

Regional Differentiation of Vegetation Change in the Qinghai-Tibet Plateau

YU Bohua1|LU Changhe1|LU Tingting2,3|YANG Aqiang1,4|LIU Chuang1   

  1. 1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China;
    2. Collage of Resources Science and Technology, Beijing Normal University, Beijing 100875, China;
    3. State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China;
    4. Graduate University of Chinese Academy of Sciences, Beijing 100049, China
  • Online:2009-05-25 Published:2010-08-08

Abstract:

The spatial distribution and change of vegetation have an obvious characteristic of regional differentiation, which is always affected by global climate change and local human activities. This study explores regional differentiation characteristics of vegetation changes including the spatial distribution and annual variation of vegetation in the Qinghai-Tibet Plateau using 1981-2006 time-series GIMMS/NDVI as the main data source. The results showed that the vegetation coverage was the highest in the Metok and Tsona counties on the southern slope of the Himalayas, and next in the junction area of three provinces of Qinghai, Sichuan and Tibet, while it was much lower in the northern Qinghai-Tibet Plateau, the Qaidam Basin and Ali Plateau. From 1981 to 2006, the mean annual NDVI in the whole plateau showed an increasing trend, reflecting an improvement of vegetation coverage. The standard deviation(SD) of NDVI change was generally decreased, indicating a small difference among different areas and different vegetation types. The following areas, located on the fringe of all kinds of ecotone, have a lager value of SD, i.e., the Yalung Zangbo Valley, the northwestern part of Metok and Tsona counties, southern margin of the Qaidam Basin, head of the Source Areas of the Three Rivers and northern slope of the Nanshan Mountain in Qinghai; these places should be given more attention from scientists, governments of various levels and other stakeholders. SLOPE was one of the widely used indicators reflecting long time trends of vegetation coverage change. The annual values of SLOPE had a spatial distribution trend from decline to increase and then stable (no change) from south-east  to north-west. Regionally,  the  vegetation coverage had a significant decline on the southern slope of the Himalayas and the southern part of Qinghai, a moderate decline in middle and southern part of the SATR and a slight decline in its northern part and Ali Plateau. No significant vegetation changes happened in the Northern Tibetan Plateau and the Qaidam Basin, which accounted for 40% of the total area. Vegetation was significantly improved in the Yalung Zangbo Valley, and the intermontane basins of the Tanggula Ranges and Nyantsentanglha Mountains. Based on the spatial difference of SLOPE values, the plateau was divided into four regions: Ⅰ) the Pamirs Region, with an increasing vegetation index; Ⅱ) the Northern Tibetan Plateau-Qaidam Basin Region, with a stable vegetation index; Ⅲ) the Central Tibetan an Plateau-the Upper and Middle Reaches of the Yalung Zangbo River Region, with an increasing  vegetation  index,  and Ⅳ)  the  Source  Areas of  the Three Rivers-the Hengduan Mountains Region, with an decreasing vegetation index. The paper did not give a detailed description of the reasons for vegetation change in the Qinghai-Tibet Plateau due limited space. However, under the background of NDVI increase regarding the plateau as a whole, vegetation change in Region Ⅳ should be given special attention because of the controllable human activities.

Key words: NDVI;vegetation change;regional differentiation;Qinghai-Tibet Plateau