Dynamic Change Of Huihe Wetland And Landscape Connectivity

The Huihe River Basin is located in the transition zone of the Da Hinggan Mountains shrub to the Hulun Buir typical grassland,which is an ecological interlaced area inlaid and distributed by forest biomes and grassland biomes.It has a high degree of spatial heterogeneity and temporal heterogeneity.By using graph theory and 3S technology,this paper conducts decision tree classification and visual interpretation of the five remote sensing images of Huihe River Basin in 1997,2002,2007,2012 and 2017.Using the method of spatial analysis,the spatial and temporal dynamic changes of landscape and the connectivity of wetland landscape were revealed by using the data of the past 20 years in Huihe River Basin.Finally,driving forces of landscape connectivity change in Huihe Wetland were discussed.The main conclusion of this paper are as follows:(1)From 1997 to 2017,the area of Huihe wetland increased by 11 km2,an increase in 0.60%.Among them,the wetland area reached the maximum in 2007,which was 1900.32 km2.In 1997-2017 these 20 years,the growth rate of urban construction land was the fastest,with a dynamic degree of 1.52% and a wetland dynamic degree of 1.496%.(2)According to the size of patches,patch types were divided.From 1997 to 2017,the number of large and large-medium patches changed a little and the area increased slightly in Huihe River Basin.The patch fragmentation in the study area had been alleviated to a certain extent.Among them,small and medium patches are more sensitive to show the environmental changes,and the number and area of patches had increased to varying degrees.From the perspective of landscape type transformation,the small patches transformed dramatically between wet meadow,water,salt meadow and typical grassland.Follow by the transformation from small patches of farmland to mountain shrubs.(3)In order to rank the importance of patches in Huihe wetland,it is found that patch area is not absolutely has positively correlationship with the importance of patches,and the function of patches also affects the importance of patches.(4)From 1997 to 2017,the landscape connectivity of wetland experienced a process of increasing first and then decreasing slightly,it showed the highest value was 0.0225 in 2007.PC values increased by 0.0020 from 1997 to 2007,and decreased by 0.0017 from 2007 to 2017.Overall,the landscape connectivity of Huihe wetland increased by 0.0003 in the past 20 years.The change of PC values of landscape connectivity under different thresholds corroborates the positive effect of distance threshold on landscape connectivity.(5)Through the driving force analysis of Huihe wetland landscape connectivity change,it can be concluded that both human and natural factors are important influencing factors of Huihe wetland landscape connectivity change.