Liangying Sun

Holocene climatic change in Hunshandake Desert

Research on the geological data of Hunshandake Desert in China monsoon region revealed that Holocene summer monsoon had experienced six prevailing periods and seven weakening periods. The climatic humidity and the vegetation had also undergone the similar periodical variation influenced by the monsoon periodicity. The period when summer monsoon prevailed or winter monsoon weakened and climatic humidity and vegetation coverage relatively increased, corresponded to the global warming events; whereas the period when summer monsoon weakened or winter monsoon prevailed and climatic humidity and vegetation coverage relatively decreased, corresponded to the arid events in middle to low latitudes and the cold events in North Atlantic. As for the changing regularity of summer monsoon intensity there were two distinct periodicities of 1456 years and 494 years, also these two periodicities had global significance.

Reconstruction of the spatial patterns of desert/loess boundary belt in North China during the Holocene

The desert/loess boundary belt is the transitional region between desert and loess, where aeolian sand and loess interlock in space and alternate in time. It, being seriously unstable in space-time, sensitive to climatic changes and with fragile ecological environment, is an ideal region for studying the global climate change. There are depositional sequences of paleosol with sub-horizontal interbedded aeolian sand and loess, and the stratigraphical evidences show that there widely exist 3–4 layers paleosol in sand lands of northeastern China, 4–5 layers in Mu Us Sandy Land and Hunshandake Sandy Land, more than 4 layers in the Qinghai Lake region and the Gonghe Basin of Qinghai Province during the Holocene. These indicate that the desert has experienced several times of extending and compacting, along with which the desert/loess boundary belt vibrated. It possesses good coherence with global climate change and eustasy. The coherence shows that the monsoon change in East Asia is the primary driving factor for the swing of desert/loess boundary belt. Besides, human influence constantly intensified the swing of the belt, especially in the south of Mu Us Sandy Land during the 2000–3000 aBP.