Response Of Soil Seed Bank To Water-Level Changes In The Poyang Lake Wetland

Soil seed bank is stored in the soil and the soil surface matrix viable seeds combined. Seed bank composition and change have great significance on vegetation dynamics. Study the seed bank and its response to environmental change for clarify the history vegetation succession and future trends provide an important basis. Poyang Lake is China’s largest freshwater lake, have strong hydrological process changes. To carry out the strategy of Poyang Lake wetland soil seed bank response to the water level changes study can be predicted under the condition of water level change of poyang lake ecosystem health to provide theoretical basis and practical evidence.This study selected typical sections of Poyang Lake, Collecting soil seed bank along the water-level gradient in spring and autumn, through seedling germination to study the composition, size and temporal dynamics of seed bank, and use indoor simulation training method to study the seed bank for different response pattern of water conditions.1) Through the soil seed bank seedling germination experiments, plants were identified25families,44genera and53kinds. Spring soil seed banks more than the number of species in winter, were38species and29kinds; their seed density was no significant difference, in the spring of7715±1404.11seedling/m2, winter7453±1188.59seedling/m2.2) Through the seed bank spatial and temporal distribution to research, found that the Poyang Lake different vegetation types of wetland seed banks in species composition and reserves were significantly difference in spring, the highest is Carex argyi community type of wetland, the lowest is Mudflat. There was no significant difference in winter. The seeds of submerged plant such as Vallisneria natans, Hydrilla verticillata, Ceratophyllum demersum and Najas minor were distributed in various types of wetlands, the highest number is in the lowest water-level of mudflat, the lowest number is in the highest water-level zones of Carex argyi community wetlands, Low water-level area was significantly higher than the high water-level zone, indicating that if the water level conditions change, the medium water-level area Carex cinerascens communities wetlands has evolved into a submerged plant community potential.3) Using the similarity coefficient to analysis the seed bank and standing vegetation, found that the similarity coefficient between standing vegetation and seed bank of Poyang Lake wetland was small at0.222-0.483, the highest similarity coefficient is in mudflat, the lowest in the Triarrhena lutarioriparia communities and Artemisia selengensis communities, There are only2kinds of dominant species shared by standing vegetation and soil seed bank were Carex spp. and Cardamine lyrata., mainly due to the dominant species of standing vegetation were clonal propagation plants.4) Through the indoor simulation experiments, found Poyang Lake wetland soil seed bank can respond to different water level changes, mainly under inundation conditions germination Vallisneria natans, Ceratophyllum demersum and other submerged plants, germination under moist conditions mainly Cardamine lyrata, Lindernia antipoda and other mud-flat species.There are obvious differences in spatial and temporal distribution of Poyang Lake wetland soil seed bank in the composition and quantity. Seed banks have different responses to water-level changes, indicate that water-level change of Poyang Lake wetland will affect the standing vegetation dynamics, in which the seed bank has a very important role.