| It was reported that the global warming of the earth 's surface has increased significantly in the past 100 years,which had led to sea level rise,desertification,extreme climate events and changes in land cover,which have a significant impact on the human living environment.Therefore,the research on the future global climate and environmental change has become a key concern of scholars and governments around the world.Simulating paleo-environment and paleo-climate change is an important method to predict future climate and environment changes.The changes in the climate and environment are mainly reflected in the vegetation cover,pollen has become an important proxy indicator for reflecting changes in vegetation due to its small size,large number,wide range,and resistance to corrosion.The relationship between pollen and vegetation is not a one-to-one linear relationship.It is also affected by multiple factors,including the productivity of pollen,the type and size of sedimentary basins,the way pollen spreads,and the surrounding / regional vegetation.Therefore,the research on the correspondence between pollen and vegetation has become the key to reconstructing paleo-environment and paleo-climate.In this study,based on the analysis of pollen assemblages and vegetation composition from 31 sample in the Zeku Basin of the Qinghai-Tibetan Plateau,we calculated the fall speed of main pollen taxon,analyzed the pollen-vegetation relationship of the main taxon.By running the ERV model,the relative pollen productivity and relevant source area of pollen were obtained.In addition,LOVE model was used to correct the relative pollen productivity and relevant source area of pollen.The corrected results show that the results of this study are reliable.The principal results are as follows:(1)The pollen assemblages are dominated by Cyperaceae(29.75%),Aster(21.86%),Ranunculaceae(16.99%),Rosaceae(7.84%)and Poaceae(5.1%),which mainly originate from the vegetation within 40 km of the sites(the proportion of total pollen loading reached was 83%).There is the minor representation of the pollen of arboreal plants,such as Betula,Pinus and Picea,which was wind-transported over long distances.The vegetation composition varied substantially between different sites within distances of 0–100 m of each site,resulting in a poor relationship with the pollen assemblages.However,the pollen assemblages and the vegetation composition were more similar over the distance of 0–3 km from each site,suggesting that the regionally-homogenized vegetation has a better relationship with the pollen assemblages.(2)We suggest that the surface pollen assemblages from lakes in the Qinghai-Tibetan Plateau may be greatly affected by extra-regional pollen or intrazonal vegetation in the shrub meadow.High percentages of Artemisia and Chenopodiaceae in pollen assemblages do not reflect the coverage of these taxa in the corresponding regional vegetation.Therefore,within shrub meadow environments of the Qinghai-Tibetan Plateau,these taxa should be excluded from lake-sediment-based pollen studies of regional vegetation succession and climate change.(3)The RSAP of Zeku Basin in the Qinghai-Tibet Plateau is about 1370-1430 m.The relative pollen productivities of the main taxa were: Cyperaceae(1),Aster(0.84-0.88),Ranunculaceae(0.71-0.75),Rosaceae(0.18-0.24),and Poaceae were very low(0.01-0.02).After corrected by the ERV model,the pollen-vegetation relationship of the main taxa in the study area was effectively improved.RPPs and RSAP will be affected by the type and size of the sedimentary basin,the sampling site and method,the size of the vegetation patches,and the method of vegetation survey. |
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