Changes and ecological vulnerability of landscape pattern in Eastern Qilian Mountain

Based on the techniques of RS GIS and methods of the landscape ecology,the changes and ecological vulnerability of landscape patterns in the eastern Qilian Mountains were analyzed from 1994 to 2008 in this paper. The results show as follows r2008 compared with 1994,total landscape areas of forest,grassland,glacier and waterbodies were reduced by 5.0%,2.0%,2.2%and 2.0%,but those of shrubs and bare lands increased by 6.82% and 4.97%,respectively.Mean patch areas of shrub,grassland,glacier and bare landscape elements were increased by 49.0%,19.0%,1.1%and 436.6%,but those of forest and water were decreased by 9.62%and 4.12%Respectively.Meanwhile,average maximum adjacent landscape elements' distances of forest,grassland, glacier and water-bodies increased,but their contiguity reduced,and also the landscape elements contagion of internal plaque reduced.The spatial adjacent length between bush and forest landscape elements increased by 3 867 km.The spatial adjacent length of bare lands to other landscape elements increased by 5 589 km and small bare patches gradually merged into the other bigger landscape elements.In addition,landscape type ecological vulnerability index and fragmentation index were positively correlated.Our results indicate that the forest and grassland degenerated and its area decreased,water bodies dried,bare lands increased and the landscape elements of space relations were becoming simple with an increase in landscape fragmentation in the east Qilian Mountains.From the results,the areas of forest and grassland decreased due to degradation which leads to an increase in bare lands. These changes in landscape pattern and vulnerability can be attributed to human activities in the eastern Qilian Mountains.