Abstract:

The Mongolian Plateau is a sensitive area for coping with global changes. It is also the only place for three of the nine routes of migratory birds. Lakes play the role of “indicator” and “life posthouse” in the plateau ecological environment. Relatively few research results have been presented on the changes of lakes in the Mongolian Plateau at home and abroad. Most of them focused on the analysis of typical and large lakes. Research on their causes has focused on meteorological and human factors, while that on small lakes and the relationship between the lake area and the soil environmental factors are relatively weak. Based on the Landsat remote sensing imagery, the information of the lake area above 1 km² per year on the Mongolian Plateau from 2000 to 2020 was extracted by the MNDWI water body index. The results of the temporal and spatial change characteristic analysis of the lake area showed that: (1) The area and the number of lakes have decreasing and increasing trends before and after 2009, respectively. Overall, the area and the number of lakes depicted a decreasing trend from 2000 to 2020. (2) The changes of lakes of different grades were quite different. The changes of the super large- and medium-sized lakes were relatively stable. Furthermore, the large-sized lakes showed the largest reduction. (3) The changes of the lakes in different regions also differed. These changes in the northwest were relatively stable, while those in the central and eastern regions were more dramatic. (4) Before 2009, the number of lakes in the dense areas in the central and eastern regions decreased, resulting in the weakening of the spatial distribution agglomeration of lakes in the study area. After 2009, the newly added lakes in the sparse area in the central region were scattered, weakening their spatial distribution agglomeration. (5) The correlation between the lake area and the annual average temperature, annual precipitation, annual evaporation, vegetation index, and four layers of soil moisture was relatively significant. The degree of influence exhibited in the two time periods significantly differed. Mastering the temporal and spatial changes of the lake in the Mongolian Plateau and their causes can provide a reference for the climate regulation, biodiversity protection, and climate disaster reduction research in the Mongolian Plateau and the whole world.

Key words: lakes, temporal and spatial changes, influencing factors, Mongolian Plateau