Characteristics Of Soil Phosphorus Fractions In Differently Degraded Wetlands In Zoige

Due to the climate changing and human activities,more and more plateau wetlands have been degenerating and the ecosystem has a reverse succession.With the degeneration,decreasing of soil nutrients results in regressive successions in the ecosystem.Therefore,it is important to study the soil characteristics of the component content,distribution of marsh wetland,and the evolution mechanism of the phosphorus components in the degradation process.According to the degradation situation of flower lake,we chose the Zoige Plateau Marsh Wetland as the research subject in this paper.Combining with field investigations,we selected four types of soils,which are non-degraded soil,lightly_degraded soil,moderate soil and severe degraded soil.Modified Tiessen fraction method was used to study the forms and distribution in Zoige Plateau Marsh Wetland.We analyze the influencing factors of the phosphorus concentrations.Marsh degradation was caused by changing of the ecological environment.At the same time,it caused the changes of soil physical,chemical properties and vegetation community.Finally,those changes caused the change of soil phosphorus components.Correlation analysis was used to find the relationship between the factors and the phosphorus fractions.We try to understand characteristics of the changing phosphorus the correlation of phosphorus fractions,soil basic physo-chemical properties and vegetation community referring to related statistical data.The main results are as follows:(1)The soil total phosphorus concentrations decreased with the degradation degree.With the increasing degree of degradation,the concentrations of total phosphorus decrease significantly(P<0.05)lower than non-degraded.In 0-20cm,The soil phosphorus(P)concentrations there decrease significantly(P<0.05)lower than non-degraded but in 20-100cm is not.(2)The concentrations of H2O-Pi,KCl-Pi,NaHCO3-Pi decrease(P<0.05)lower than non-degraded significantly.NaOH-Pi only shows a trend of decrease,and others have no obvious trend(P>0.05).Organic phosphorus.Except insoluble organic phosphorus(HCl-Po)and mixed acid organic phosphorus(HS-Po),the concentrations of organic phosphorus are under decrease(P<0.05)lower than non-degraded obviously.(3)H2O-P,KCl-P,NaHC03-P,NaOH-P,HCl-P HS-P showed significant correlation with soil quality(P<0.01).Organic carbon,total nitrogen and pH.The concentrations of inorganic phosphorus showed significant positive correlation with TOC and TN(P<0.01).There was no significant correlation between soil P fractions and pH.(4)With the increase of degradation,plant community area with marsh degraded succession series were Carex mulieensis-Carex-kingcup,Carex mulieensis,Carex meyeriana,Carex mulieensis-scape Carex-Ranunculus-e.nutans-Triglochin maritimum L-Blysmus sinocompressus,Leymus secalinus The plant community succession showed significant correlation with the soluble phosphorus fractions concentrations.The concentrations of H2O-P,KCl-P,NaHCO3-P in the decrease communities were significantly(P<0.05)lower than non-degraded communities,respectively.And the surface change is greater than the mind layer.In addition,NaOH-Po,HS-Po showed significant correlation with biomass and coverage(P>0.05).(5)The results of multiple regression analysis showed that the main factor of inorganic phosphorus fractions was silt,and the main influencing factor of soil organic phosphorus was plant community.Countermeasures and suggestions.(1)Prevent wetland degradation,restoring ecology and plant communities.(2)Apply organic fertilizer to prevent soil erosion and protect soil physical properties.(3)Ensure the water source of the wetland area and restore soil moisture.