The Growth And Development Process Of Different Functional Groups Wetland Plants In Poyang Lake And Its Effect On Long-term Flooding Response

As the the Poyang Lake ecological economic zone of Jiangxi Province up to the national development strategy, the Poyang Lake water control project was proposed, and the water level fluctuation become a research hotspot. It's arousing ecological, environmental, political, and other sectors of the community from the country even all over the world. How the plants of Nanjishan Wetland will form the distribution pattern and structure function under the long-term seasonal level fluctuation. In order to adapt to the rhythm, be fast-growing plants in the low-water period, but the nutrient required whether from the storage or soil? Which plants are able to complete their life cycle after a long time flooded and how their phenological character? All the questions are worth deep to think, also they are very important to learn more about to reveal the relationship of the Poyang Lake hydrology and plants. It was a seven months high-water period from2010to2011, Withdrawal of water we select three typical seasonal water level lakes laid with belt transect in Jiangxi Nanjishan Wetland National Nature Reserve, set four different water level gradient to show different flooded intensity. Through intensive monitoring environmental factors, observing plant community growth situation, determinating plant biomass, plants total phosphorus, total nitrogen, and organic carbon content monthly, the same as the soil nutrient. The main results as following:(1) In different month:The dynamic changes of the soil nutrients in the waveform curve are the first decreased and then increased, but the change range is not too much. The dynamic changes of Perennial plants nutrients are the first increased and then decreased waveform curve, coupling with the soil nutrient, especially significant representation in the two fast growth period; Annual plant nutrients changing trends the same as the soil nutrients change more or less. In different water level:Soil nutrients are significant different, and don't show a consistent regular, so as the plants nutrients. Correlation analysis between the plants nutrients and soil nutrients, only plants nutrients that with soil total phosphorus significantly related, but with the soil total nitrogen, organic carbon and water content are no significant correlation. In the same water level, only found the plants nutrients are significantly correlated with temperature, and haven't showed a good rule with soil nutrients and other factors. Finally, we concluded that the nitrogen and carbon that plants rapid growth needed after long-term water flooded basicly provided by themselves, and phosphorus are supplied by plants and soil together.(2) Different flooded intensity caused the different vegetation distribution patterns. Afer long term flooded, there aren't large area of Triarrhena lutarioripar and Phragmites australis community, and Carex absolutely dominant in the whole wetland community. Annuals only glow better in the lower water level gradient, Helophyte and Hydrophyte have been greatly affected by the flooded, so the community coverage and species diversity is very small, only the Zizania latifolia rise the dominance.Through correlation analysis the plant community parameters with other factors, then we found that the the number of species significant correlation with the water lever gradient. The sample of the water level gradient1where water and land junction together have the largest number of species, the sample of the water level gradient0has not been flooded also have lots of different species and families. Plant biomass correlation with not only month and water level gradient, but also with their growth potential and owner nutrient content. From the plants budding to growth, then to plant biomass and nutrient content, finally to the community species and vegetation distribution pattern, different water level gradient have a great difference.(3) We found that there are two growing period in the phnology spectrum of the Nanjishan wetland plants, especially perennials, after the withdrawal of water the plants sprouted new leaves the first time, and bud again after winter. Most plants are able to bear fruit to complete their life cycle before the flooded, except Triarrhena lutarioripar and Phragmites australis, because their flowering period close to the end of high-water period, they will be seriously affected once encounter a long flooded period. The plants growth affected by water level fluctuation, but compare with the plants in the general habitat, we found that most wetland plants are no significant impact under the flooded, just only a few species.