title: Diversity and above-ground biomass patterns of vascular flora induced by flooding in the drawdown area of China's Three Gorges Reservoir.
abstract: Hydrological alternation can dramatically influence riparian environments and shape riparian vegetation zonation. However, it was difficult to predict the status in the drawdown area of the Three Gorges Reservoir (TGR), because the hydrological regime created by the dam involves both short periods of summer flooding and long-term winter impoundment for half a year. In order to examine the effects of hydrological alternation on plant diversity and biomass in the drawdown area of TGR, twelve sites distributed along the length of the drawdown area of TGR were chosen to explore the lateral pattern of plant diversity and above-ground biomass at the ends of growing seasons in 2009 and 2010. We recorded 175 vascular plant species in 2009 and 127 in 2010, indicating that a significant loss of vascular flora in the drawdown area of TGR resulted from the new hydrological regimes. Cynodon dactylon and Cyperus rotundus had high tolerance to short periods of summer flooding and long-term winter flooding. Almost half of the remnant species were annuals. Species richness, Shannon-Wiener Index and above-ground biomass of vegetation exhibited an increasing pattern along the elevation gradient, being greater at higher elevations subjected to lower submergence stress. Plant diversity, above-ground biomass and species distribution were significantly influenced by the duration of submergence relative to elevation in both summer and previous winter. Several million tonnes of vegetation would be accumulated on the drawdown area of TGR in every summer and some adverse environmental problems may be introduced when it was submerged in winter. We conclude that vascular flora biodiversity in the drawdown area of TGR has dramatically declined after the impoundment to full capacity. The new hydrological condition, characterized by long-term winter flooding and short periods of summer flooding, determined vegetation biodiversity and above-ground biomass patterns along the elevation gradient in the drawdown area.
authors: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing, China; State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, China.
authors: Qiang
authors: Q
authors: Wang
authors: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, China; College of Resources and Environmental Science, Chongqing University, Chongqing, China; College of Architecture and Urban Planning, Chongqing University,Chongqing, China.
authors: Xingzhong
authors: X
authors: Yuan
authors: School for Resource and Environmental Studies, Dalhousie University, Halifax, Nova Scotia, Canada.
authors: J H Martin
authors: JH
authors: Willison
authors: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, China; College of Resources and Environmental Science, Chongqing University, Chongqing, China.
authors: Yuewei
authors: Y
authors: Zhang
authors: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, China; College of Resources and Environmental Science, Chongqing University, Chongqing, China.
authors: Hong
authors: H
authors: Liu
mesh_terms: D044822:Biodiversity; D018533:Biomass; D002681:China; D031744:Cynodon / Q000502:physiology*; D029786:Cyperus / Q000502:physiology*; D055868:Floods; D045483:Rivers