三峡水库是当今世界最大的峡谷型水利工程,根据"蓄清排浊"的运行方案,水库的水位在145～175 m之间变化,在库区内形成了落差达30 m、面积达350 km2的消落带.三峡库区消落带面积大、水淹时间长(部分消落带水淹时间长达6个月),具有"冬水厦陆"的特点(王海锋等,2008).消落带是库区泥沙、有机物、化肥和农药进入水库的最后屏障,是陆地生态系统与水生生态系统之间的过渡地带,更是生态环境脆弱的地带(冯大兰等,2006;2008;刁承泰等,1999).消落带的治理备受关注,也成为后三峡建设的重点.%As one of the largest reservoirs in the world, the Three Gorges Reservoir ( TGR) has a huge area of water-level-fluctuation belt ( WLFB). How to manage and utilize the WLFB of the TGR has been a highly domestic and international concern. Among many management and utilization measures, the biological one seems to be very efficient and attractive, however the plants planted on the WLFB must have high flood-tolerance. In this study, the 10 hm one-year-old mulberry seedlings were planted on the WLFB (located in Xiaohe Village, Kai County, Chongqing) , with the elevation changing from 157 m through 175 m, in March, 2010, and an experiment had been conducted to investigate the flood-tolerant property of the mulberry seedlings from October, 2010 to April, 2011. During this period, the highest water level of the TGR reached 175 m and caused the complete submergence of the mulberry seedlings for 3 to 6 months. The result showed that: the area-weighted average of the bud flush ratio of the mulberry seedlings, which had suffered submergence for 90 to 118 d, was about 62. 6% . The bud flush rate was generally determined by several factors, such as depth and duration of the submergence, drainage property of the WLFB, and whether the fall branches of the seedlings were cut or not. The limitation of the flood-tolerant duration of the annual mulberry seedlings could be less than 150 d, since almost all of the annual mulberry seedlings planted on the areas below 166 m were dead when the submergence period reached 150 d. The perennial mulberry trees planted on the area under 161.8 m, however, they could flush and form new crowns normally after a 214-day submergence. This experiment indicates that the mulberry trees are highly tolerant to submergence, thus, could be one of the most adaptable species and play an important role in managing and utilizing the WLFB of the TGR.
展开▼
