Distribution pattern of vegetation in water-level fluctuation zone of the Three Gorges Reservoir as affected by differential flooding regimes

The different hydrological regimes caused by artificial reservoir construction is the main factor affecting the patterns of community vegetation in the water-level fluctuation zone. The flooding stress in the high-intensity flooding area is an important factor affecting vegetation, but species competition in the low intensity flooding area is a key stress factor affecting vegetation. Plants growing under different flooding regimes in the typical water-level fluctuation zone of the Three Gorges Reservoir were studied in order to explore the effect of plant flooding tolerance and optical resource competitiveness(plant height) on vegetation distribution patterns. The results showed the following:(1) A total of 41 plants species were distinguished and analyzed in the studied area, including 4 plants with high submergence tolerance and low competitiveness, making up 70.99% of total biomass; 23 plants with low submergence tolerance and high competitiveness, making up 28.02% of total biomass; 14 plants with low submergence tolerance and low competitiveness, making up less than 1% total biomass; and no plants with high submergence tolerance and high competitiveness in the water-level fluctuation zone;(2) The plants with high tolerance and low competitiveness dominated in the water-level fluctuation zone with high flooding intensity, those with low tolerance and high competitiveness dominated in the water-level fluctuation zone with high competitive pressure, and plants with low tolerance and low competition were only sporadically distributed at the shorelines;(3)The biomass pattern of vegetation along an inundation gradient showed a tendency to increase first and then decrease. This study could help us understand the mechanisms of vegetation distribution patterns at the water-level fluctuation zone of the Three Gorges Reservoir and provide basic knowledge on vegetation restoration and reconstruction in this zone.