三峡库区消落区几种两栖植物的适生性评价

根据三峡库区消落区的环境特征,两年间通过在库区消落区山地实验基地的种植及实地淹没试验,对几种备选用于生态修复的两栖植物进行适生性评价筛选研究.结果表明:狗牙根(Cynodon dactylon)、野地瓜藤(Ficus tikoua)、尼泊尔蓼(Polygonum nepalense )、水花生( Alternanthera philoxeroides)、百喜草(Paspalum Notatum )、香根草(Vetiveria zizanioides)、苏丹草(Sorghum sudanense)在100～150d的低水位出露期内均可完成生长、发育成熟过程,可作为消落区生态恢复的备选物种.其中,苏丹草可作为速生物种,能迅速恢复水位下降后消落区的植被覆盖率;复合群落在生长期间比单一种群提前5～10d完成对地表的覆盖,群落的稳定性、耐淤积性及抗干扰性较强,次年的萌发也更好,有利于构建稳定的生态系统;狗牙根、尼泊尔蓼和野地瓜藤根系生长良好,其中狗牙根在一个生长季内根系最长可达75cm, 有利于消落区控制水土流失;在自然水淹最深为15m,淹没时间6d的情况下,复合群落组植物、尼泊尔蓼、野地瓜藤、狗牙根和苏丹草的植物均能短期耐水淹和淤泥,水花生则是在水淹较深处能够生长良好;180d水下1.0～1.5m的连续淹水实验结果表明,狗牙根和野地瓜藤的耐淹性较强,经过长达半年的淹水过程能够成活,并在次年自然萌发;同时5～25m的深部淹水实验表明,随着深度增加,狗牙根的落叶率逐步提高,在180d的淹没后能够成活,并在次年自然萌发,可作为构建消落区生态系统的两栖植物物种.

Evaluation of adaptability of plants in Water-Fluctuation-Zone of the Three Gorges Reservoir

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.