The Effect Of Different Water Level Environment On The Growth And Natural Distribution Of Carex Cinerascens In Poyang Lake

Affected by global change and human activities,the hydrological pattern of wetland ecosystem has changed greatly,which has a great impact on the growth,development and distribution of wetland plants.In this paper,taking the Nanji wetland of Poyang Lake as the research area,taking Carex cinerascens as the research object,the physiological and ecological adaptation characteristics of C.cinerascens under different water level environment were studied and analyzed through indoor control experiment and field investigation.The distribution pattern and community characteristics of C.cinerascens under different elevation and surface water conditions were clarified.By observing and analyzing the response law of physiological and ecological characteristics of C.cinerascens to different water level environment,the ecological amplitude of water level of C.cinerascens was established,which provided data support for further revealing the succession mechanism and distribution pattern of wetland vegetation community,and provided important scientific basis for wetland hydrological regulation,ecological restoration and biodiversity protection.The main conclusions are as follows;(1)Under the flooding gradient of 8 cm and 16 cm,C.cinerascens could adapt to the water level environment quickly.In the flooding range of 24-40 cm,C.cinerascens could adjust the content of various substances to adapt to the flooding environment.However,under the flooding gradient of 48 cm and 56 cm,the waterlogging gradient exceeded the plant threshold and the plants began to wither and die.Under the fluctuation intensity of 0.2 cm/d,the plant growth was better than that of the control group,and the physiological indexes were better.In the fluctuation range of 0.4-1.2 cm/d,the adaptation time of plants to fluctuating water level environment was directly proportional to the fluctuation intensity.Under the fluctuation intensity of 1.4 cm/d,the cell membrane structure of C.cinerascens was damaged,exceeding the plant regulation limit.(2)Under the condition of stable water level,the tolerance range of plants is 0-32 cm,and the growth threshold is 32 cm.Under fluctuating conditions,0-0.4 cm/d is the optimal fluctuation intensity of plant growth,and 0.6-1.0 cm/d is the fluctuation range of plant growth tolerance.When 1.0-1.4 cm/d exceeds the tolerance threshold,the plant can not normally grow to complete the complete life cycle.The results of the plasticity of plant morphology and photosynthetic pigments showed that the adaptability of the morphology and the plasticity of the photosynthetic pigments of C.cinerascens to the environment is the aboveground biomass>chlorophyll a>chlorophyll b>plant height>underground biomass,where the plant height is the adaptability of the plasticity intensity in the falling water level is higher than the rising water level and the stable water level.The adaptability of the plasticity intensity of the above-ground biomass in the stable water level change is better than that in the continuous fluctuating water level environment,and the total biomass and the underground part of the biomass are in the habitat where the water level rises and changes.The adaptability of medium plasticity strength is better than that of the habitats with falling and stable water level changes.The evolution potential of the three photosynthetic pigments in the rising water level changing habitat is greater than that of the falling and stable water level environments.(3)C.cinerascens in the range of 0-56 cm water level,in addition to soluble sugar content,the other physiological and ecological indicators of C.cinerascens from the falling water level to the rising water level showed a good Gaussian fitting effect with the change of water treatment intensity.Through the comparative analysis of the fitting results,the suitable ecological breadth of C.cinerascens soluble protein was the largest,so the suitable ecological range of C.cinerascens was [-2.54,2.42] cm.The results showed that the optimum ecological range of C.cinerascens was [-0.16,0.18] cm.The results showed that there was a positive correlation between ecological breadth and plasticity index of C.cinerascens.