基于植被覆盖度的藏羚羊栖息地时空变化研究

Abstract

The distribution and dynamics of vegetation can reflect the distribution and changes of wildlife habitat to some extent. Tibetan Antelope,well-known as‘the numen of plateau',is an endemic animal on the Qinghai-Tibetan Plateau.However,the survival and distribution of Tibetan Antelope have been threatened by environmental deterioration and illegal poaching. This animal has been listed as an Class I species by the Convention on International Trade in Endangered Species( CITES) and as Category I by the Key Protected Wildlife List of China. This situation has attracted a great deal of attentions from government and conservation professionals. The population distribution of Tibetan Antelope remains unkown in Altun National Nature Reserve. The Altun National Nature Reserve,the largest inland nature reserve of China established in May of 1983,is one of the four "no man' s-lands"in China. Due to its unique natural conditions,this reserve is preserving the rich natural resources,rare wild animals and plants.In this study,we analyzed the dynamics of vegetation in Altun National Nature Reserve based on remote sensing image data and GIS tool. The Normalized Difference Vegetation Index( NDVI) data were collected in 2000,2005 and 2010. We merged the regions,which were covered by vegetation in the study years and the suitable habitats were identified through interpreting vegetation types,which can be used by Tibetan Antelopes as grazing pastures. Based on NDVI datasetscollected in different years,we calculated the vegetation coverage and analyzed the spatial and temporal variations of vegetation coverage. Moreover,the changes of habitat were analyzed on the basis of vegetation coverage variations. The results showed that the vegetation coverage of the reserve was at a low level,and grids with low vegetation coverage took up about 50% of the regions that were covered by vegetation. The grids with high vegetation coverage were mainly distributed in the southwest of Kardun inspection station. The vegetation coverage in the regions where Tibetan Antelopes mainly lived was relatively higher,and that in the regions where the animal lambed was lower. The upward trends of vegetation coverage over time reflected the increase of the reserve's carrying capacity for animals,and it may also imply that the area of suitable habitat of this animal increased. The vegetation coverage of alpine steppe dominated by feather grass experienced a significant upward trend,also suggesting that carrying capacity of the reserve for Tibetan Antelope increased. The change of spatial distribution of feather grass steppe coverage indicated that habitat of Tibetan Antelopes might spread from east to southwest. The relationship between the altitude and vegetation coverage was not significant correlated. The study of habitat variations based on vegetation coverage is meaningful and can be used for better protecting this wildlife. Furthermore,we suggested that more factors could be integrated with vegetation coverage to precisely identify suitable habitat for animals,and more field surveys and monitoring should be conducted in the future.