Influence of water level on four typical submerged plants in wetlands of Lake Dongting

?????????????????????????????????????????????????????????????????????????.???????????????????????????????????.?????????????????????????????????????????????????4??????25?50?75?100 cm??????????Potamogeton malaianus?????Hydrilla verticillata?????Vallisneria natans??????Ceratophyllum demersum?????????????????????.??????1?????????????0.09%???0.09%???3.04%????20.87 mg/kg????10.7 mg/kg????326.67 mg/kg????6.97 mg/kg???6.59 mg/kg????1.21%????2.09%?2???????????????????100?75 cm?????????50?25 cm??????????????25 cm?????????2?75 cm???????????????100 cm??????????????3?100 cm????????????????????75 cm?????????????????????50 cm??????????????????4?100 cm?????????????75?50 cm???????????25 cm??????.???????4???????????????????????????????????????50~100 cm?????????????????????????.;Due to global changes and high-intensity human activities, serious environmental problems (e.g., the advance of dry season in Lake Dongting wetlands, continuous decline water levels season, reduction shallow depressions) have led large-scale extinction submerged plants wetlands recent years. In-depth study effect low level on growth is great significance for guiding restoration plants. We take typical Dongting, a lake connected Changjiang River China, as model system, set up 4 depth gradients (25, 50, 75 100 cm) simulate hydrological environment depressions field where are mainly distributed responses growth, biomass, enzyme activity Potamogeton malaianus, Hydrilla verticillata, Vallisneria natans Ceratophyllum demersum depth. The results showed that: (1) nutrient content early stage was 0.09% total nitrogen, phosphorus, 3.04% potassium, 20.87 mg/kg alkaline 10.7 available 326.67 6.97 nitrate, 6.59 ammonia 1.21% organic carbon, 2.09% matter. After 2 months, different bottom different. cm pools higher than that 50 25 pools. Ammonia matter carbon contents pool were highest; (2) suitable P. malaianus H. it V. C. demersum; (3) Under conditions, conducive reproduction biomass accumulation malaianus. verticillata demersum, beneficial natans; (4) at strong activity, followed by levels, weakest. indicated greatly influenced characteristics four concluded plant populations 50-100 should be considered ecological waters. It promotion population aquatic ecosystems.