Changes in prehistoric wood procurement strategies in Northern China from 6500 – 2000 BP. Evidence for human preferential harvesting in the face of climatic change

In the past, humans have adapted their strategies of wood collection to shifts in the surrounding environment. Shifts in wood procurement strategies have been assumed to have been heavily influenced by changes in biomes due to shifts in climate. In these models, wood found on archaeological sites is interpreted as being representative of the surrounding environment. Around the world there is an increasing recognition that human preferences and management strategies impacted forest composition and species harvesting. We evaluated charcoal data gathered from 92 archaeological sites in northern China, with chronologies spanning the period from 6500 BP to 2000 BP. By combining the results of the analysis with published paleoenvironment records and archaeological evidence, we aimed to determine when and how there was an anthropogenic impact on wood procurement strategies. Our results indicated that a distinct spatiotemporal pattern of wood utilisation existed in northern China during the period 6500–2000 BP that could not be fully explained by changes in climate. Spatially, anthropogenically-collected woody assemblages showed remarkable differences in northern China. Northern China's climate gradually became colder and drier during the mid to late Holocene, especially during the period 4000–2000 BP. This appears to have led to a decreased use of Quercus L. in the Loess Plateau and the Guanzhong Basin. However, in the Central Plains and Shandong Peninsula, Quercus L. usage continued and increased in the late Holocene. During the same period, a striking shift in wood procurement occurred in the western part of China. In the northeastern Tibetan Plateau, wood procurement shifted from predominantly coniferous to broadleaved trees, and forest succession caused by anthropogenic collection played the significant role. Paleoclimatic information in Hexi Corridor suggests that some arbour trees in archaeological sites were not locally available, suggesting that human preference for certain wood types led them to engage in long distance transport. This finding indicates that starting after 4000 BP, climatically driven shifts in biomes were no longer a primarily influencing variable in human procurement of trees in north-western and eastern China. Key regional differences in strategy emerged. In Eastern China, wood species which humans preferred were still harvested even when climatic change reduced their availability. In North-western China, however, changes in biomes following 4000 BP meant that people needed to change the species on which they had previously relied and began to engage in long distance transport of wood.