| The Mongolian plateau has a vast territory,obvious climate change and fragile and sensitive ecological environment.Lakes play the role of "indicator" and "life station" in the ecological environment of the plateau.Based on Landsat,MODIS and ERA5-Land data,this study analyzed the temporal and spatial variation characteristics of the area and number of lakes over 1 km~2 in the whole Mongolian Plateau and different basins from2000 to 2020,and further explored the influence of various environmental factors on the lake area in the whole Mongolian Plateau and different basins.The results are as follows:(1)The change of the number and area of lakes in the Mongolian Plateau can be divided into two stages: from 2000 to 2009,the number and area of lakes showed a significant decrease trend,and recovered slightly in2009-2020,and decreased as a whole.The number decreased by 92,with a change rate of-11.17%,and the area decreased by 1443.92km~2,with a change rate of-7.46%;Extra-large lakes and large lakes contributed greatly to the reduction of lake area before 2009,while extra-small lakes contributed greatly to the restoration of lake area after 2009.The larger the lake area,the more stable the change of the number,and the largest change of the number of extra-small lakes;The lakes in the Mongolian Plateau are generally distributed in multiple centers,spreading outward,with little change in the northwest lake agglomeration area and great change in the central and eastern lake agglomeration area.Shrinking lakes were the most in the two time periods around 2009,and they were widely distributed.Before 2009,more lakes died,which weakened the concentration of lake distribution.After that,although more lakes were added,their distribution was scattered,which made the concentration of lake distribution continue to weaken.(2)During the study period,the area and number of lakes in the first-class basins decreased,with the largest decrease in the inner flow area and the smallest decrease in the Arctic Ocean basin.The lake area of most sub-basins in each first-class basin has decreased,among which the lakes in the eastern basin-Wuzhumuqin basin,the Ergun River basin in the Pacific basin and the Selenger River basin in the Arctic Ocean basin have decreased greatly.Due to the disappearance of lakes,the spatial concentration of most sub-basins has weakened.(3)During the study period,the vegetation index at annual scale and monthly scale showed a significant increase trend,and the soil moisture in the fourth layer at annual scale and monthly scale showed a significant decrease trend,while other environmental factors showed no significant change trend.In space,the annual average temperature,vegetation index and soil moisture in the fourth layer at annual scale and monthly scale in most parts of the Mongolian Plateau showed a single trend,while other environmental factors showed an opposite trend in the northeast and southwest regions.(4)There are some differences in the influence of environmental factors on lakes in different basins.Before 2009,the lake area decreased,and the contribution of deep soil moisture was greater.After that,the restoration of lake area was closely related to meteorological factors,surface environmental factors and shallow soil moisture.The increase of lake area in each basin is greatly influenced by meteorological factors,surface environmental factors and shallow soil moisture,while the factors affecting the decrease of lake area in different basins are quite different.The influence of the interaction of various factors on the lake is mostly nonlinear enhancement,and the interaction of vegetation index and other factors in the internal flow area plays an important role in the spatial differentiation of lake changes;In the Pacific basin and the Arctic Ocean basin,the interaction between deep soil moisture and other factors plays an important role in the spatial differentiation of lake changes in the sub-basin where the lake area is significantly reduced;The interaction between meteorological factors and surface environmental factors has a key influence on the spatial differentiation of lake changes in the sub-basin,where the lake area has an obvious increasing trend in the later period or the whole research period.The influence of various environmental factors on lakes in different basins has a certain lag effect,and the time span is quite different. |
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