Spatio-temporal distribution pattern of vegetation coverage in Junggar Basin, Xinjiang

Vegetation coverage is an indicator used for exploring the growth of vegetation, which has attracted attention from ecologists owing to its significant role in ecological conservation and restoration. As an important component of the terrestrial ecosystem, changes in vegetation coverage reflect changes in the environment, especially with respect to arid areas. A change of vegetation coverage will trigger desertification, degradation of the eco-environment, and regional climate change. Hence, we studied the spatio-temporal distribution pattern of vegetation coverage and ephemerals in the Junggar Basin during the last few decades based on normalized difference vegetation index. The following conclusions were drawn. The vegetation coverage of the basin shows an overall upward trend, mainly because of the expansion of farmland. In particular, the southern rim has already formed an apparent continuous oasis belt, and the central part of the basin has low vegetation coverage due to a rugged environment but is relatively stable, whereas the northern part has a relatively small oasis distribution pattern. With respect to annual variation, the vegetation coverage of the basin reached the peak in July of every year, whereas the peak in the desert was in May or June; ephemeral plants clearly flourished during this phase. Ephemeral plants were distributed in the whole basin; the most prosperous region was the southern of the basin edge, and the plants decreased gradually from the edge to the center of the basin. The desert area of the central basin was the least prosperous area, but the southern and mid-eastern parts of the desert were prosperous. The expansion of the oasis has mainly had an impact on the 50-km range of the oasis edge, and the greatest impact is at the 5- to 20-km range of the oasis edge.