Composition And Distribution Of Vegetation In The Water Level Fluctuating Zone Of The Lantsang Cascade Reservoir Based On 3S Technology

With the development of a large number of tall dams and large cascade reservoir projects in the Lantsang River Basin,a large water level fluctuating zone(WLFZ)containing cascading reservoirs has formed.This newborn ecosystem is related to the sustainable development of hydropower projects,and has become a new problem to be studied urgently.In this paper,taking WLFZs in the Huangdeng,Xiaowan and Nuozhadu Reservoirs in the Lantsang River Basin as study areas,and uses 3S technology to carry out the field data collection of the vegetation in the WLFZs,through the acquisition of UAV data and multispectral image vegetation Classification,GIS topographic distribution analysis,etc,discuss the species types,coverage,distribution characteristics,dominant species and pioneer species of the naturally restored vegetation in the WLFZ of each study area.This study provides first-hand data on the natural restoration of vegetation in WLFZs,and gives a useful reference for its ecological restoration as a consequence of hydropower cascade development in the Lantsang River Basin,and it also proves that 3S technology is an attractive choice for the survey of vegetation in the WLFZ of a reservoir.The conclusions are as follows:(1)Polygonum plebeiu,Cynodon dactylon,Xanthium,Ageratum comyzoides,Eleusine indica,Digitaria sanguinalis and Verveine are the dominant species of vegetation that could be naturally restored in the WLFZ,among which Cynodon dactylon,Digitaria sanguinalis and Verveine are pioneer species,and Xanthium and Ageratum comyzoides promote each other in the form of associations,and are hence stable and suitable for mixed planting.(2)The vegetation in the study area of the fluctuating zone is mainly annual and perennial herbaceous plants,and Cynodon dactylon is a common restoration species in the fluctuating zone;Vegetation restoration is affected by many factors,such as reservoir age,plant growth periods,topographic conditions,climate,population structure,interactions among species,and so on.(3)The plant coverage of each study area increases first and then decreases along the elevation gradient zone from bottom to top,that is,the lower part of the WLFZ<the upper part of the WLFZ<the middle of the WLFZ,and the vegetation coverage is negatively correlated with the flooding time;The vegetation coverage shows a decreasing trend with increasing slope.Gentle slopes are more suitable for the growth of vegetation,where the most suitable slope is about 0?25°,although when the slope is more than 60°,it is difficult for vegetation to recover naturally.(4)The dominant species are different in each distance section.As a whole,the vegetation coverage is the largest at the middle distance from the water body,and then gradually decreases toward the nearest and farthest distances,especially at the farthest distance.There is less vegetation at a long distance;The aspect of vegetation distribution is relatively consistent with the aspect of the experimental area itself.In the four study areas,the aspect of vegetation covering a large area covers almost all directions,and there is no obvious indication in the aspect of the slope.