New evidence for Holocene vegetation variations and their drivers in an East Asian sandy land: A perspective from aeolian sand-paleosol deposits

Abstract

Past vegetation responses to climate change in semi-arid and arid regions are not yet well understood, especially in northeastern China. This study provides new evidence for long-term vegetation changes and their possible driving forces in northeastern China's Songnen sandy lands by employing a multiproxy approach applied to well-dated aeolian sand-paleosol sediments. Pollen analyses and data on total organic carbon (TOC) are used to reconstruct paleovegetation dynamics whereas grain size data are used for interpreting independent paleoclimate changes. Results show that Chenopodiaceae and Ephedra plants dominated in a brief early period that was followed by an abrupt transition to Artemisia and Asteraceae plants with the encroachment of dry steppes between 9000 and 7000 cal yr BP. From 7000 to 3200 cal yr BP, Chenopodiaceae plant dominated the region. During the 3200 to 400 cal yr BP interval Ulmus, Salix, and Tribulus abundance increased while Chenopodiaceae abundance decreased. After 400 cal yr BP, Poaceae plants generally expanded and the regional landscape alternated between dry steppe and steppe. In addition, changes in the regional vegetation exhibit 1000 yr periodic oscillations especially during 9000 to 4500 cal yr BP. By comparing these features with regional climate change, we suggest that regional paleovegetation dynamics were linked to East Asia Summer Monsson (EASM) circulation. These findings reveal a pronounced long-term relationship between vegetation and climate change in semi-arid regions worldwide.