Evaluation of adaptability of plants in Water-Fluctuation-Zone of the Three Gorges Reservoir
三峡库区消落区几种两栖植物的适生性评价

Experiments were conducted for the purpose of choosing adaptable plants to restore and reconstruct the ecosystem in Water-Fluctuation-Zone (WFZ) of the Three Gorges Reservoir in Wenzhou, Chongqin. Nine species including Cynodon dactylon, Ficus tikoua, Polygonum nepalense, Alternanthera philoxeroides, Vetiveria zizanioides, Trifolium repens, Lolium perrnne, Paspalum Notatum and Sorghum sudanense were selected for in situ growth and submerging tests for 2 years according to the characteristics of local ecological conditions. Results indicated that C. dactylon, F. tikoua, P. nepalense, A. philoxeroides, P. notatum, V. zizanioides and S. sudanense could complete their growth during 100-120 days under low water level conditions in the WFZ of the Three Gorges Reservoir and were considered as the candidate species for ecosystem restoration. Among the candidate species, S. sudanense could quickly restore the vegetation cover ratio after flooding due to its rapid growth. The complex plant community was better than a single specie community for reconstructing a stable ecosystem, as the complex community could develop a complete vegetation cover during growth period 5-10 days ahead and could have a greater tolerance to siltation after flooding compared to the single specie community. C. dactylon, F. tikoua and P. nepalense developed a strong root system which benefited soil erosion control. The flooding experiment showed that the complex community plants, C. dactylon, F. tikoua, P. nepalense, and S. sudanense could survive and recover after being submerged under 15 m of water for 6 days, indicating their high tolerance for flooding and siltation. C. dactylon and F. tikoua survived under 1.0-1.5m of water during the 180 day submerging experiment and matured under non-flooding conditions the following year. The ratio of shed leaves of C. dactylon increased with increase of water depth at the level from 5-25 m. Having survived for the 180 day submerged experiment and subsequent maturation under non-flooding conditions the following year, C.dactylon was considered a promising aquatic specie for re-vegetation in WFZ of the Three Gorges Reservoir.