Holocene vegetation cycles, land-use, and human adaptations to desertification in the Gobi Desert of Mongolia

Abstract

Since the end of the Pleistocene some 11,700 years ago, the landscape and vegetation of the Mongolian Gobi Desert has been profoundly changing, punctuated by the appearance of lakes, wetlands, and finally aridification. Vegetation communities have responded to these changes according to temperature shifts and northward to southward movements of the edges of East Asian monsoonal systems. Human groups have lived, foraged, and traveled through the landscape of the Gobi for millennia, adapting their technologies and systems of plant and animal use with the dramatic changes of flora and fauna, and likely contributed to the character of the vegetation communities in the region today. Pastoral nomads living in semi-arid regions are sometimes implicated as contributors to desertification. However, our research at the Ikh Nart Nature Reserve, Dornogovi Province, Mongolia has yielded geoarchaeological and phytolith data which show the opposite effect. Changing landscape and vegetation patterns from the Middle to Late Holocene suggest that early pastoralists might have contributed to a shift away from halophytic desert vegetation, and an increase in semi-arid desert-steppe grasses. We suggest that the halophytic succulents growing around saline ponds during the Mid-Holocene wet phase, were replaced by Stipa and other steppic grasses after pastoralists entered the region, increasing hillslope erosion which covered the saline sediments of the valley floor, and encouraged the growth of grass seeds carried in the dung of herd animals.