[Objective] The natural restoration of vegetation in the water level fluctuating zone (WLFZ) of the Xiaowan Reservoir on Lantsang River during a drought year were investigated to provide background information and a reference for studies related to the restoration and maintenance of vegetation in the area. [Methods] Based on a fixed sample site survey in a typical area of WLFZ in 2019

a drought year reset survey was conducted in July 2020 using a combination of unmaned aerial vehicle (UAV) remote sensing

GNSS positioning

and GIS spatial analysis to map the distribution of vegetation in WLFZ in the study area; quantitatively portray the species composition

area

cover

and distribution characteristics along a topographic gradient of vegetation in WLFZ in the drought year; and conduct a comparative analysis with the non-drought year of 2019. [Results] A total of 14 species of plants were counted

all of which were annual or perennial herbs. Cynodon dactylon

Polygonum plebeium

Epilobium hirsutum

and Ageratum conyzoides were the dominant species

accounting for 85.62%

4.22%

3.72%

and 3.12% of the total vegetation area

respectively. The proportions of C. dactylon in WLFZ were 50.21%

9.94%

and 39.85% in sections H

M

and L (high

medium

and low)

respectively; 95.53% of E. hirsutum was distributed in section H; 54.48% of A. conyzoides was distributed in section M; and 87.22% of P. plebeium was distributed in sections M and L. Most plants preferred to grow on gentle slopes below 25° in WLFZ

while E. hirsutum covered well on slopes less than 60°. Vegetation in WLFZ was influenced by topographic factors: distance to the nearest neighboring water body > elevation > slope > aspect. Drought resulted in an annual degradation of 59.75% of the vegetation

concentrated in the middle and lower parts of WLFZ

where a large amount of P. plebeium withered. [Conclusion] Vegetation recovery was more stable in the upper half of the zone than in the lower half

and the dominant species were significantly more stable than the non-dominant species

with C. dactylon and P. plebeium being more tolerant of flooding

while C. dactylon showed greater drought tolerance and recovery stability than P. plebeium. Drought stress and inundation stress had significant effects on the spatial distribution of vegetation in WLFZ. In drought years

drought stress had a slightly greater effect than inundation stress.