Vegetation changes during the past 40,000 years in Central China from a long fossil record

Abstract

This paper describes the palynological, sedimentological and geochemical results obtained from a 6 m core taken from Lake Dajiuhu in Shennongjia Mountains, central China, spanning the last 40,000 BP. The site is located in a subtropical area which is known for harboring many endemic species. The pollen record shows that past climate changes during the Glacial allowed the persistence of warm trees and even subtropical taxa. The percentages of arboreal pollen taxa vary from 40% before and during the last glacial period to ∼60% during the Holocene. The δ13C data indicate that the dominant vegetation was composed of C3 plants. However, despite the continuous presence of tree taxa around the site, the total organic carbon indicates that the biomass was very low during the glacial period (MIS 3 and 2), related to the dominance of conifers and evergreen tree taxa, which are very low biomass producers. The total organic carbon (TOC) started to increase steadily at the end of the last glacial period (end of MIS 2), which reflects the sharp increase in the amount of Sphagnum spores recorded at the end of MIS 2, marking the beginning of the peat bog formation and the increase of the in-situ biomass. The summergreen taxa, which increased during the Holocene, may have also contributed to the TOC increase.