Surface And Buried Pollen Of Loess-paleosol Deposit In South Luo River, Central China And The Paleoenvironment Change

The catchment of South Luo River in central China, locating at the environment transitional zone, is possibly an ideal region to reveal the important scientific issue about the relationship between hominid living and environmental changes, because of its sensitivity to environmental change and remarkable archaeological discoveries. While the Paleolithic artifacts survey, geomorphology, aeolian sedimental stratigraphy and geochronology were carried out prosperously, we have little explicit evidence for the paleoenvironment and its impact on hominid living. In this study, we select two artifacts-contained loess deposit profiles to reconstruct the paleoenvironment by pollen, and do the surface pollen analysis in order to illustrate the depositional record properly.40surface samples under10vegetation types in Luonan, upper catchment of South Luo River, were taken to investigate relationship between pollen assemblages and the vegetation. The results show that the surface pollen compositions reflect the vegetation quite well, with special character among different vegetation types. Under forests, the average of arboreal pollen percentages is greater than40%, and the Selaginella sinensis spore content is higher. As to woodland shrubs and shrubs, the tree pollen average is13.2%and16.6%respectively, and the shrub pollen is relatively higher than grass samples. And the grass and farmland topsoils are characterized by the low percentage of tree and shrub pollen (＜10%and＜1%), high percentage of herb pollen (＞80%). Pinus, Quercus and some other tree pollen can indicate the regional vegetation because of their dispersal ability. Quercus pollen is under-representative and so is to Pinus, quite different from general. Artemisia pollen is significantly over-represented, has poor correlation with plant coverage, and may reflect human disturbance. Gramineae can indicate plant quite well, but with low representation. High percentage of Chenopodiaceae component probably suggests human activities and predominant Selaginella sinensis may be a significant indication of forest environment. Cluster analysis (CA) and principal components analysis (PCA) can distinguish forest and non-forest vegetation well, and the pollen concentration, may assist to distinguish vegetation types, but has bad correlation with vegetation coverage.Referring to the surface pollen results, the paleovegetation and climate changes since～600ka were reconstructed qualitatively, recorded by Liuwan and Qiaojiayao loess-paleosol sequences, and then the hominid living environment was proposed tentatively. The pollen assemblages are well comparable with the stratigraphic sequences, magnetic susceptibility and organic carbon isotope, suggesting that pollen can reveal the actual paleoenvironment properly in loess sediment. The vegetation and climate experienced several periodic changes along with loess and paleosol alternation. Generally, it was probable open deciduous broad-leaved forest or forest steppe in vegetation, warm and wet in climate during paleosol development, while sparse forest grassland or grassland, relatively cooler and drier during loess deposit. According to the artifacts-buried layers, we can infer that the hominid prefer the warm and wet climate, living with open forest and forest steppe dominated by oak, elm and hackberry etc.