Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, 1239 Siping Road, Shanghai, 200092, China.
Institute of Hydrobiology, Chinese Academy of Sciences, 7 Donghu South Road, Wuhan City, Hubei Province, China.
Environ Sci Pollut Res Int. 2017 Oct;24(28):22688-22697. doi: 10.1007/s11356-017-9926-0. Epub 2017 Aug 16.
Vegetation severely degraded and even disappeared in the water bodies of Chaohu Lake basin, which is the fifth largest freshwater lake in the Yangtze flood plain in China, because of water pollution and eutrophication. Vegetation restoration projects have been carried out. However, the influences of water quality and hydrology on vegetation restoration from seed banks have been rarely investigated. This experiment aimed to identify the effect of water level and nitrogen loading (ammonium and nitrate) on seedling emergence and recruitment from the riparian seed bank of the river in this basin. Most of the species in the seed bank germinated under moist conditions. Under flooding conditions, however, the growth of aquatic species, especially Vallisneria natans (Lour.) Hara, was inhibited when the nitrogen concentration increased. At 0.37 mg/L NH-N in the water column, the growth of V. natans was inhibited. The results suggested that flooding was a primary limiting factor of seedling emergence. The inhibitory effect of high nitrogen loading on the growth of aquatic species was one of the main driving mechanisms of macrophyte degradation under flooding conditions; nevertheless, competitive advantage might determine the community pattern in moist habitats. Therefore, water level control and water quality improvement should be the key aspects of vegetation restoration in degraded rivers or lakes.
由于水污染和富营养化，中国长江流域五大淡水湖之一的巢湖流域水体中的植被严重退化甚至消失。已经开展了植被恢复项目。然而，水质和水文学对种子库中植被恢复的影响很少被调查。本实验旨在确定水位和氮负荷（铵和硝酸盐）对该流域河流滨岸种子库中幼苗萌发和繁殖的影响。种子库中的大多数物种在潮湿条件下发芽。然而，在洪水条件下，当氮浓度增加时，水生物种的生长，特别是菹草（Lour.）Hara，受到抑制。在水柱中 0.37mg/L NH-N 的情况下，菹草的生长受到抑制。结果表明，洪水是幼苗萌发的主要限制因素。高氮负荷对水生物种生长的抑制是洪水条件下大型水生植物退化的主要驱动机制之一；然而，竞争优势可能决定湿润生境中的群落格局。因此，水位控制和水质改善应该是退化河流或湖泊植被恢复的关键方面。
