Study On Soil And Water Technology And Feasibility Of Phragmites Australis Population Restoration In Degraded Wetland

Reed wetland is one of the important wetland types in Songnen Plain,which not only provides reed resource for us,but also provides habits for wildlifes with many ecological service functions.Under combined function of climate drought,water shortages and destroying reed for farming from our human beings,reed wetlands area in Songnen Plain decreased seriously with 34.8% loss 60 s ~ 70 s back and forth last century.Restoration of degraded wetlands is one of the hot points among wetlands study nowadays,but most of studies concentrate on saline-alkali soil or wetlands soil without type change,study on area where type has already occurred relatively few.Considering the construction of hydraulic connectivity,study on these areas is also necessary.This study set Phragmites Australis,a typical plant of Songnen Plain wetlands,as study object,research its emergence and growth condition in soils of diffenent age limit of degeneration and types by control experiment,then confirm the suitable water,soil and rhizome condition in order to provide scientific proof to site selection,water table depths controlling and rhizome planting on restoration of reed wetlands.The main conclusion is as following:1.In study of soil physicochemical properties,unit weights,specific gravity,density,available phosphorus(AP),power of hydrogen(pH)and conductivity(EC)is greater in saline-alkali soil and sandy soil than farmland soil and grassland soil,while porosity,total nitrogen(TN),available nitrogen(AN),total phosphorus(TP)and organic matter(OM)are opposite among soil types.Water content in farmland soil is low,and available kalium(AK)is higher in saline-alkali soil.Correlation relationship indicate that in all soils,TN,TP and OM are of positive correlation relationship(P<0.01),AN and porosity are of positive correlation relationship(P<0.01),and they have facilitation effect on population growth of P.A.;Unit weights,water content,and density are of positive correlation relationship(P<0.05),pH and EC are of positive correlation relationship(P<0.01),and they have suppression effect on population growth of P.A.,except of water content.2.In study of P.A.rhizome emergence,waterlogging do harm to rhizome of P.A.,water table depth between-10 ~ 0 cm is suitable.Farmland soil(F)and grassland soil(G)are beneficial to emergence compared to saline-alkali soil(S-A)and sandy soil(S).Suitability is F(1954)> F(1990)> G(1954,1990,2000)> F(2000)> S(1954)> S-A(2000)> S(2000)> S-A(1954).Unit weights,density,pH,EC,TN,AN and OM have great influence on emergence.The suitable burial depth of rhizome is less than 10 cm,about 5 cm,and the length of rhizome unfit for less than 15 cm.3.In study of P.A.population growth,with plant height,plant number and biomass overall consideration,water table depth have suppression effect on P.A.aboveground and underground part growth and reproduction ability with greater effect on underground part,and the suitable water depth for P.A.growth and reproduction are-25 cm ~-20 cm and-7.5 cm,respectively.Soil suitability for P.A.growth is G(2000)> G(1990)> G(1954)> F(1990)> F(1954)> F(2000)> S(1954)> S(2000)> S-A(2000)> S-A(1954).Combine with day increase of number and height,the soil suitable for P.A.growth are G(1954,2000)and F(1954),while is S(1954)in S & S-A.EC,pH,AN,TN,OM and unit weights are of significant correlation with growth of P.A.and can be used to access soil's suitability for P.A.growth.Burial depth has suppression effect on P.A.aboveground and underground part growth with greater effect on underground part.Combine with number dynamic,the suitable burial depth is about 5 cm.Combine style of rhizome has influence on growth and reproduction of P.A.,and the suitable length of rhizome is no less than 15 cm.4.Growth of P.A.have significant influence on TN and OM,which significant decreased compared with groups without P.A.growth.Water table depth has significant influence on pH,EC,TN and AN.Compared with other water table depth,pH in water table depth of-15 cm increase,and the EC increase more significant than other water table depth.TN and AN increase more significant in water table depth of-15 cm and 0 cm.