Study On Relevant Source Area Of Pollen And Relative Pollen Productivity Estimates Of The Alpine Meadow In Northeastern Tibetan Plateau

Pollen is one of the representative indexes in the research of paleoenvironment and paleoclimate and has played an irreplaceable role in global environmental change.However,in the study of topsoil pollen,it is not a simple linear relationship between pollen and vegetation.Therefore,only with a correct understanding of the relationship between pollen and vegetation and an estimation of relevant pollen sources and relative pollen yields of pollen of various genera can a more accurate restoration of paleovegetation be achieved.Quantitative reconstruction of paleovegetation and paleoenvironment requires the relative pollen yields of local vegetation and the range of relevant pollen sources.There are many factors that will interfere with the estimation of local relative pollen yields and the range of relevant pollen sources,such as the different size and spatial distribution of plant patches,the radius size of the selected sedimentary basin,etc.Therefore,in future studies,the impact of these factors have to be minimized and the ERV model needs to be continuously improved so that the reconstruction of the paleovegetation and paleoenvironment will be more reliable.In this paper,field vegetation survey and surface soil pollen identification at 31 random sampling sites in Zeku county and Henan County of Qinghai province were carried out.Moss was used to extract pollen,and the sedimentation rate of 12 genera is obtained by using the pollen radius as follows: Poaceae(0.0402m/s),Primulaceae(0.0116 m/s)and Taraxacum(0.0287 m/s),Gentianaceae(0.0242 m/s),Leguminosae(0.0148 m/s),Ranunculaceae(0.0165 m/s),Cyperaceae(0.0410 m/s),Rosaceae(0.0079 m/s),Artemisia(0.0209 m/s),Polygonacea(0.0274 m/s),the highest rate of settlement of Cyperaceae,the lowest rate of settlement rose.The relevant source area of pollen(RSAP)and relative pollen productivities(RPP)range of 12 pollen types in grassland area of Qinghai province were estimated by ERV model.ERV model to estimate the relevant source area of pollen range is about 240 m,Using Poaceae as reference taxon(RPP is 1),the relative pollen productivities(RPPs)of 12 pollen types by ERV model shows that: Poaceae(1),and Brassicaceae(0.19±0.13),and Primulaceae(1.05±1.03),and Taraxacum(7.9±2.7),and Aster(0.00007±0.46),and Gentianaceae(0.59±0.36),and Leguminosae(0.04±0.13),and Ranunculaceae(6.0±4.4),and Polygonaceae(7.6±0.8),and Cyperaceae(3.5±0.7),and Rosaceae(4.9±3.7),and Artemisia(7.7±1.3).The characteristics of the pollen assemblage in the study area show that: The study area mainly dominated by Herb plants,and Cyperaceae,Ranunculaceae,Poaceae,Aster,Taraxacum,Artemisia,Polygonaceae were higher.And the characteristics of the vegetation types in the field survey are the same as that of the pollen assemblage of the topsoil.Therefore,the pollen assemblage can better reflect the characteristics of the vegetation in the study area.There are many reasons for the difference between the relative pollen productivity and the previous research results in this study area.Therefore,the RPPs from one region can not be directly applied to other regions.