| 沙漠与沙漠化 |
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| Changes of Vegetation and Diversity of Alpine Kobresia(Kobresia pygmaea) Steppe Meadow in Desertification Process in Northern Tibet Plateau |
WEI Xinghu1, LI Sen1, YANG Ping2, DONG Yu-xiang3, ZHANG Chun-lai4 |
| 1.College of Resources and Environment Sciences, Foshan University, Foshan 528000, Guangdong, China; 2.Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Science, Lanzhou 730000, China; 3.Department of City and Environment Plan Zhongshan University, Guangzhou 510275, China; 4.College of Resource Science and Technology , Beijing Normal University, Beijing 100875, China |
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Abstract For determining the impacts of desertification on vegetation composition, structure and species diversity of alpine Kobresia steppe meadow and understanding the causes of desertification, a margin area of severe desertification region in Anduo County, Tibet Autonomous Region, was selected as study site. According to the different levels of desertification: slight desertification (SLD)—moderate desertification(MD)—severe desertification (SD)—very severe desertification (VSD), the floristic features of total 20 samples were investigated and analyzed. The results drawn from this case study are listed as follows: ①The composition and structure of alpine Kobresia steppe meadow in SLD rangeland differed significantly from MD, SD, and VSD, the species with more drought resistance and inedible by livestock were the dominant species of SD rangelands. No any plant was found in the VSD rangelands. ②There is a significant negative correlation between different stages of desertification and species diversity from overgrazing pastures to semi\|shifting and shifting dunes. The SLD rangeland had largest mean number of species and individuals, and Richness index values, but the MD grassland had largest Shannon\|Wiener index values, Evenness index values, and smallest Simpson index values.③The vegetation cover declined significantly from 91.8%(overgrazing pastures) to34.8%(semi-shifting dunes) and to 0% (shifting dunes). ④The SLD, MD, and SD grasslands had significant higher aboveground biomass than the VSD, but no significant difference existed between the SLD, MD, and SD grasslands (P<0.05). There were significant difference in root biomass and dry matter among different desertification levels (SLD, MD, SD, and VSD).The SLD had the highest root biomass and dry matter, followed by MD, SD and VSD. ⑤Overgrazing is the primary cause of desertification of alpine Kobresia steppe meadow and it accelerates the expanding of desertification in the region.
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Received: 14 December 2006
Published: 20 September 2007
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2007, Vol. 27 
