Study On The Spatio-temporal Evolution Of Xilingol League Wetland In Recent 35 Years

Wetland is one of the three major ecosystems of the earth,It plays an important role in protecting species diversity,making use of resource,conserving water,controling soil erosion,storing flood-water for use in a drought,supplying groundwater and so on.Xilingol League is an important ecological barrier in the north of our country.To study the evolution of the Xilingol League wetland is a great significance for the protection of the ecological environment in the region and the Inner Mongolia Autonomous Region and even the improvement of the environment in the Mongolian Plateau.Based on Landsat images,the five phases vector data of the land use are interpreted,using landscape pattern index,transfer matrix,gravity transfer method we analyzed the spatio-temporalevolution characteristics of the nearly 35 years wetlandsin the study area(from 1980 to 2015),Make a brief description of the driving factors,obtained the following conclusions:(1)The area of marsh wetland decreased gradually before 2010 and the area increased after 2010.The area of lakes and wetlands decreased significantly during 2000-2010 and the area in the other three periods increased.In 2000,the area of lakes wetlands reached the maximum.River wetlands disappeared after 2000,with a slight reduction of beach area and a slight increase of reservoir area.(2)In the past 35 years,the direction of wetland loss has mainly been that wetlands have flowed to non-wetlands,which accounts for 88.07% of the proportion of wetland loss area.The loss of wetlands was relatively serious before 2010,with a significant drop in the area lost in 2010-2015.The major loss direction of various types of wetlands is the flow of lakes to unused land,grasslands,and swamps;swamps flow to grasslands,unused land,and lakes;rivers flow to swamps,grasslands,and unused land;beaches flow to grasslands,unused land,and lakes.(3)In terms ofspatial distribution,the center of gravity from west to East is "beach land,lake,reservoir and swamp".In the past 35 years,the center of gravity of the beach has shifted to the southeast,southeast,and northwest;the center of gravity of the lake has shifted to the northeast,northeast,southwest,and northeast;swamp center of gravity has shifted to the northeast,southeast,southwest,and southwest;and the center of gravity of the swamp has been northeast,northwest,and northeast.(4)In general,the area of The Xilingol League wetland is decreasing and tends to be broken.However,the wetland landscape pattern index and the patch shape index decreased by 2.286 and 3.6742 respectively,indicating that the wetlands at the landscape level and the plaque shape became regular and simplistic.The diversity of wetlands increased and the leading position of dominant landscape was reduced.(5)From the point of view of the wetland type,marsh and lakes are the main types of the Xilingol League wetland.The marsh is the dominant landscape in the study area,with the largest area;the lake is widely distributed and has the highest degree of fragmentation.The shape of the marsh is the most irregular and is greatly affected by human activities.The landscape index of bottomlands,reservoirs,and rivers is less variable and the situation is relatively stable.(6)The evolution of wetlands is the result of a combination of natural and human factors.Increasing temperature leads to the decrease of wetland area due to the increase of evaporation.Increasing precipitation will increase the area of wetland water supply.The growth of population,cultivated land and livestock will make wetland landscape structure fragmented,and the wetland ecological environment will deteriorate,resulting in wetland degradation.The economic structure is mainly based on the second industry,which not only pollutes the wetland environment,but also makes the wetland damaged and destroyed.The effect of policies on wetlands has two sides.The construction of reservoirs will make the rivers run off and the lakes disappear,while the formulation of policies and regulations will constrain people's behavior and protect the wetlands.