Forest cover and composition on the Loess Plateau during the Middle to Late-Holocene: Integrating wood charcoal analyses

The question of what the ecology communities of the Loess Plateau looked like before the extensive anthropogenic reshaping processes of the late-Holocene has stirred a long debate. A better understanding of these human-induced changes will not only help us understand the extent of paleoeconomic practices, but also inform future conservation actions on this ecologically fragile landscape. This paper presents a systematic study of wood charcoal from a series of archaeological sites, demonstrating that woody plants and woodlands were widely distributed and geographically diverse on the Loess Plateau in response to the East Asian Monsoon. In the Guanzhong Basin, oak ( Quercus spp.) woodlands were associated with a few tropical-subtropical taxa, which changed to oak and pine ( Pinus spp.) mixed forests on the eastern plateau, while on the northern plateau coniferous woodlands were dominant. On the western Loess Plateau, oak and elm ( Ulmus spp.) woodland and spruce ( Picea spp.) forests were widespread. The charcoal results suggest that human impacts on the dominant species might have begun as early as ca. 3500 cal yr BP, with oak replaced by Prunus as the dominant taxon, including many economically significant species, such as peaches ( P. persica) and apricots ( P. armeniaca). Furthermore, the charcoal data show that due to warm and wet climatic conditions in the mid-Holocene, the distribution of tropical-subtropical taxa shifted markedly northwards into the Guanzhong and Tianshui Basins, and the central part of the eastern Loess Plateau, which became characterized by high frequencies of Bamboo.