关键词: 大屯海, 湖泊沉积物, 硅藻, 富营养化, 砷污染, 多重环境压力

Abstract: To understand the effects of different water levels and nitrogen concentrations on growth and biomass allocation of Scirpus nipponicus seedlings in Momoge National Nature Reserve, we conducted a controlled experiment with three levels of water depth (5, 35, 65 cm) and three levels of nitrogen  (4, 8, 12 mmol·L^-1). The results showed that water levels had significant effects on the growth, biomass accumulation and allocation of S. nipponicusseedlings (P<0.05). With water level increasing, individual height of plant increased, tiller number, tuber number and root biomass decreased, the biomass of rhizome, tuber, belowground, aboveground parts and total biomass all increased first and then decreased, biomass allocation to aboveground increased, but that to belowground (include root and tuber) decreased. Nitrogen concentration had significant effects on the plant height, tuber number, aboveground and belowground biomass allocation (P<0.05), but had no effect on tiller number and biomass accumulation (P>0.05). In summary, the optimum water level for the growth of S. nipponicus seedlings was 35 cm. Low water level had a positive effect on the absorption and utilization of nitrogen by plants. Both high water level and high nitrogen concentration had a negative effect on the growth of S. nipponicus.

Key words: Datun Lake, lake sediment, diatom, eutrophication, arsenic pollution, multiple environmental stressor.