Effects Of Different Treatments On The Structure And Function Of Phragmites Australis Community In The Yellow River Delta

Wetlands in Yellow River Delta are rich in biodiversity.Phragmites australis and Suaeda salsa are co-dominant plant.The growth and interspecific relationships of the two species changed with the influence of environmental and disturbances.As a result of increasingly frequent and different types of artificial disturbances,the soil are seriously salinized and degraded.Therefore,it is of great significance to study the effect that artificial disturbance has on the plant community structure and function in Yellow River Delta.(1)In this study,growth difference,dynamic and strategy was surveyed on single and mixed community of Phragmites australis and Suaeda salsa cultivated.The results showed that the growth trend of mixed P.australis was similar to that of single community on its biomass and population density.But the biomass of P.australis was higher in mixed community before September,with the density lower.The growth trend of mixed P.australis was different from single community on stem diameter and total leaf area.The trend of stem diameter was elevated type,with total leaf area fluctuating type.The growth trend of mixed S.salsa was the same as the single community on height,relative growth rate,total leaf area and biomass.The total leaf area was lower than single community,but the biomass is higher after June.The density and productivity of single S.salsa were unimodal and higher than mixed S.salsa.The growth difference between P.australis and S.salsa illustrated that they showed different growth strategy in single and mixed community and their relationship will change with improved habitat.(2)In this study,we designed four types of disturbance treatments on Form.Phragmites australis + Suaeda salsa to investigate the individual growth,interspecific relationships and community level of these two species in early and late growing reason,respectively.The results showed that in contrast to control group,the plant height,relative growth rate,stem diameter,total leaf area and density of treatment groups were obviously influenced in early growing reason while the influence decreased in late growing reason.The effects on allometric trajectories of morphology were different based on different treatments,and it was more obvious for P.australis.The interspecific relationship between P.australis and S.salsa after treatments was a competitive relationship.What`s more,the intensity of competition became increasingly fierce along with the increase of disturbance.Subsequently,competition intensity was relieved with the recovery period after the disturbance.The functional types of community changed relatively greatly after disturbance and the greater the asymmetry of disturbance was,the more obvious functional differentiation was.(3)In this study,we designed three stubble height on Form.Phragmites australis+Suaeda salsa to investigate the individual growth,interspecific relationships and community level of these two species in early and late growing reason,respectively.The results showed that in contrast to control group,the plant height,relative growth rate,stem diameter,total leaf area and density of treatment groups were obviously influenced in early growing reason while the influence decreased in late growing reason.The interspecific relationship between P.australis and S.salsa after treatments was a competitive relationship.What`s more,the intensity of competition became increasingly fierce along with the increase of clipping disturbance.Subsequently,competition intensity was relieved with the recovery period after the clipping disturbance.The functional types of community changed relatively slightly after clipping disturbance and returned to the control group level.