The effect of winter impoundment of the Three Gorges Dam: The degradation and convergence of pre-upland vegetation

It has been nearly five years since the Three Gorges Dam (TGD) became fully operational. After the large area of the water-level drawdown zone (WLDZ) created by the dam construction, several studies have investigated the effects of its impoundment on vegetation in this zone, but few have investigated any long-term changes in the WLDZ vegetation. In this study, we investigated changes in the vegetation in the WLDZ of 12 sites over a three year period following the dam's full start-up. We found that the number of plant species decreased significantly soon after the initial impoundment, with a similar trend in total cover of plant species. After one and three years of the dam being operational, the vegetation was found to contain many more species at higher occurrences at the 12 sites than those measured in pre-damming vegetation. Vegetation showed higher inter-site species similarities after three years than after one year, with a similar increase in similarities after one year compared to year zero.