Spatial Variation Of Soil Seedbank Germination In Floodplain Of West Dongting Lake

The Dongting Lake is the second largest freshwater lake in China.The hydrological situation,the relationship between rivers and lakes and the sedimentation rate of Dongting Lake are affected by the impoundment of the Three Gorges Reservoir.The spatial pattern,growth rhythm and renewal potential of the vegetation community in the Dongting Lake wetland are given.The profound impact has further changed the spatial distribution of the soil seed bank in the wetland of the West Dongting Lake.In this study,the soil seed bank of the West Dongting lake floodplain was taken as the research object,and the soil samples were collected in the field for indoor greenhouse germination experiment and flooding stress experiment.The spatial differences between the germination characteristics of the five plots along the flood and the flooding direction of the swill and the swill floods and the species composition of the surface vegetation and the soil seed bank are analyzed.According to the seasonal hydrological changes of the West Dongting Lake,four water level treatments of high,medium,low and humid were set up to investigate the response of soil seed bank resistance and germination characteristics to different heights of flooding stress in the West Dongting Lake wetland;Three kinds of flooding durations,short-term and no flooding,explored the resistance of seed bank to different flooding stresses,and screened species that were more suitable for local hydrological conditions for vegetation restoration.The results show that:(1)Perennial herbaceous plants were the main components of the surface vegetation and soil seed bank germination species in the West Dongting lake floodplain,indicating that surface vegetation is an important source of soil seed bank.The similarity coefficient of soil seed bank and surface vegetation species composition in the West Dongting lake floodplainis low,between 23%and 41%.(2)The difference of spatial germination characteristics of soil seed stock in floodplain of The West Dongting lake;the number of germination species and seed density in soil seed bank showed that TYC was significantly higher than GCT in the direction of flooding flood pulse,and DLZ was significant on the flood pulse side of muddy water.Higher than DBT.Vertical distribution results indicate that the number of deep soil species and seed density is higher than that of middle and deep soils.The seed density and species richness of soil seed bank decrease with soil depth.(3)The germination characteristics of the soil seed bank of the West Dongting lake floodplain were significantly different under high,medium,low and ideal water levels;Flooding significantly inhibited the germination of soil seed bank.The number of species and seed density showed an ideal water level higher than the middle water level,and the middle water level was higher than the low water level.The lowest law of high water level.(4)The soil seed bank of the West Dongting Huzhoutan wetland had significant differences in resistance to different flooding periods,but there was no difference in flooding stress at different heights;the number of species with no water flooding was 30,and the number of long-term flooding was 19,short-term flooding.At least 17 species.It was found that 8 plants,including Rorippa globosa,Cardamine lyrata,Mazus japonicus,Phalaris arundinacea,Cardamine hirsuta,Cyperus michelianus,Cyperaceae,Carex,can germinate under the above three conditions.The above results indicate that the restoration of vegetation in the wetland of the West Dongting Lake can be used to recover the soil seed bank,and artificially introduce a few species that are mainly cloned and propagated.The germination characteristics of soil seed bank in the floodplain of the West Dongting are affected by hydrological conditions and sediment burial.The soil seed bank of the West Dongting lake floodplain is more resistant to water level fluctuations,but measures should be taken to control the flooding duration and flooding height during the germination period of the soil seed bank.This study found eight wetland plants with wide niche and strong adaptability to local hydrological conditions.Therefore,these plants can be considered for vegetation restoration on the surface of the West Dongting Lake or other large lakes.The study aims to provide a scientific basis for seasonal water level regulation in the Dongting Lake region;The study provide theoretical support for species selection of vegetation restoration in the degraded shoal wetland of the West Dongting Lake;and The study have potential application value for surface vegetation restoration of other large lakes and wetlands.