Study On Plant Community Succession And Vegetation Dynamics In The Wulagai River Basin In The Past 20 Years

The study of plant community succession and vegetation dynamics has always been one of the hot scientific issues in ecology.The interpretation of the law of plant community succession and the determination of the influence of climatic and anthropogenic factors of vegetation dynamics can provide a scientific basis of watershed degradation,ecosystem restoration and the implementation of comprehensive management policies.This study area is the wulagai river basin.Explain the succession characteristics of the plant community in the basin based on the plant community surveys at corresponding points in 1997 and 2018.The normalized vegetation index?NDVI?of the basin was used in 1997-2018 to combine plant communities.The survey and residual trend?RESTREND?method distinguishes the effects of climatic and human factors on vegetation dynamics in the Wulagai River Basin.The purpose of this paper is to examine the changes in vegetation affected by human factors and to assess the impact of pasture management methods and land use policies on vegetation dynamics in the study area.The paper obtained the following research results:?1?From 1997 to 2018,the species distribution of plant communities in the corresponding meadows in the study area was relatively uniform,the ecosystem was stable,and the degradation trend was not obvious;the dominant species in the wetland and typical grassland plant communities were replaced,the substitution phenomenon of Stipa grandis and Stipa krylovii in the typical grassland plant community indicates that the community ecosystem was relatively fragile.?2?From 1997 to 2018,the overall change of NDVI in the study area showed a gradual upward trend.Although the trends of the three vegetation types were slightly different,they all showed an upward trend.?3?The residual trend method had a good correlation between NDVI_maxax and precipitation,and the temperature dependence was not significant.During 1997-2003,the residuals showed a downward trend,indicating that vegetation gradually degraded;during 2004-2008,the residuals showed a slow upward trend,while the residuals showed a significant upward trend during 2009-2018.The implementation of new policies on grassland restoration and grassland management had helped to curb the rising trend of population and grazing rate,resulting in the improvement on vegetation in large areas of the region.