| The western Hulun Buir wetland is an important wetland ecological area in the cold and arid region of northern China.The wetland landscape has undergone great changes in recent years due to natural and man-made reasons.This paper takes the typical wetlands in western Hulun Buir as the research object,and with the support of remote sensing technology and GIS technology,a total of five phases of MODIS remote sensing images in 2004,2008,2012,2016 and 2020 are combined with MODIS NDVI data and SRTM SLOPE data,and a wetland landscape classification system based on MODIS images is defined The landscape information of the five phases in the study area was extracted using CART decision tree classification method to analyze the distribution of each type of landscape and the dynamic change characteristics of the landscape in typical wetlands in western Hulun Buir during 2004-2020;the landscape dynamic attitude,landscape shift matrix and center of gravity shift methods were used to analyze the changes of wetland landscape at different spatial and temporal scales,and the landscape pattern software was used to analyze the different The landscape pattern index at the level of landscape and landscape type in different time periods is analyzed by using the landscape pattern software,and the changes of climate,population and economic factors in the study area are also analyzed,so as to explore the influencing factors of the dynamic changes of the wetland landscape in the study area.The following conclusions were obtained from the paper.(1)This paper uses the CART decision tree classification method to extract the landscape information of the study area for five periods.Based on the area information of the wetland landscape,it is found that the wetland area shows an overall trend of expansion between 2004 and 2020,with the area value increasing from 10,175.90 km~2 in2004 to 11,001.59 km~2 in 2020 Among them,the area of open water landscape shrinks more,decreasing by 881.47 km~2 in 17 years;while the area of marsh wetland shows an overall expansion trend,increasing by 1707.15 km~2 in 17 years.(2)Based on the extracted landscape information,a transfer matrix Sankey diagram was produced to make the transformation between landscape types in the study area clearly visible,and the transformation between landscape types in the diagram was most dramatic in the 17 years with the transfer out and transfer in of grassland.This is related to the local agricultural policy and environmental problems such as sanding of grassland;in terms of wetland landscape,the bright water landscape shifts to swampy wetland on a large scale,and the transfer out and in of swampy wetland is more drastic,and the area of swampy wetland and grassland are mutually suppressing.(3)Using the wetland center of gravity shift model,the direction and speed of shift of the center of gravity of wetlands in five time periods were calculated.The results showed that the center of gravity of wetlands generally shifted to the southeast during the17-year period,and the distance shifted was larger and the speed shifted was faster.The center of gravity of the marsh wetlands shifted most sharply,while that of the open water landscape was relatively stable.The main impetus for the shift of the center of gravity comes from the occupation and destruction of wetland resources by human beings such as transitional grazing.(4)The results of the landscape pattern index analysis show that the landscape fragmentation of open water increased during the 17 years,and the difference between patches increased year by year;the landscape fragmentation of the marsh wetland decreased significantly,and the landscape dominance increased.From the overall landscape level,the connectivity of dominant patches in the study area becomes lower.(5)From 2013 to the present,the climate in the western part of Hulun Buir has shown a warm and dry trend.The Pearson correlation results of interannual and monthly changes of wetland dynamics with meteorological factors showed that,among the interannual changes of wetlands,the wetland area was significantly affected by the mean annual temperature,the bright water landscape area was significantly affected by the mean annual precipitation,and the rest did not show significant correlation;among the changes of wetlands in growth months,the NDVI index showed significant correlation with the mean monthly temperature,and the EVI index showed significant correlation with both the mean monthly temperature and the mean monthly precipitation However,they were not meteorological factors in the corresponding month,but in January and two months earlier,indicating that the changes in wetland vegetation in the growing months showed a lag in the changes of meteorological factors.(6)The main driving factors of population and economy in the study area were analyzed by entropy weight method.The results show that the population development of the six cities and counties where the Hulun Buir west wetland is located is stable,and the pressure on the wetland resources and natural environment is reduced.In the primary industry,animal husbandry has a great influence on wetland landscape area and structure.The discharge of industrial sewage and waste gas caused by the rapid development of the secondary industry will destroy the ecological balance of the wetland.The overall development trend is to the tertiary industry,focusing on green development,which alleviates the negative impact of overgrazing,industrial pollution and other problems on wetland landscape. |
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