Wood Charcoal From Archaeological Sites in the Qinghai Lake Basin, Western China: Implications For Human Resource Use and Anthropogenic Environmental Change

Abstract

The archaeological record of the Qinghai Lake Basin, northeast Tibetan Plateau, western China, contains charcoal-based evidence of significant changes in the distribution of local shrub land and woodland through the last 12,500 14C yr BP. These vegetation trends correspond with regional changes in hunter-gatherer settlement and patterns of Holocene climate change. This charcoal-based record is useful to address current issues concerning the timing of anthropogenic vs. climatic factors in the development of grazing lands in the northeast Tibetan Plateau.

A new find of macrofossils of Picea crassifolia Kom. in early–middle Holocene sediments of the Qinghai Lake basin and its paleoenvironmental significance

“…Recently, charcoal records from a Qinghai Lake transect (Kaiser et al, 2007) and from archaeological sites (Rhode, 2016) in Qinghai Lake basin also confirmed that spruce woodland expanded after ~9500 yr BP and grew widely until at least ~4000 yr BP.…”

“…According to the direct ages of spruce debris or cones, the age of the last living spruce trees in the basin was ~4243±143 cal yr BP (SDT section). An archaeological site (CDH) dated to ~2890±70 yr BP (3037±188 cal yr BP), located on the northern margin of Hudong Sandy Land, also contained a small amount of spruce charcoal (Rhode, 2016). However, the CDH site was dated using seeds of domesticated barley ( Hordeum vulgare ) (Chen et al, 2015), which were significantly younger than the radiocarbon ages of the wood charcoal (Dong et al, 2014).…”

“…Quantitative climatic reconstructions from pollen records from the Qilian Mountains indicated that the middle Holocene thermal maximum in the NE Tibetan Plateau was only warmer by ~1–2°C than today (Herzschuh et al, 2006). In addition, an independent charcoal record has not proven that either Pinus or Betula grew in the Qinghai Lake basin itself (Kaiser et al, 2007; Rhode, 2016), and spruce was the only gymnosperm identified from the charcoal from archaeological sites in Qinghai Lake basin (Rhode, 2016). Therefore, it is possible that the pollen of broadleaf trees such as Betula resulted from long-distance transport from distant source areas when the early summer monsoon winds were strong (Colman et al, 2007).…”

“…In the Bronze Age, clearance of the natural vegetation was thought have caused disastrous erosion, which led to a decline and colluvial coverage of two geoarchaeological sites (Lajia site and Fengtai site) near Xining (Kaiser et al, 2007). The establishment of pastoralism as the dominant economic system in Qinghai Lake basin may have accelerated the decline of spruce, accompanied by intensified late Holocene cooling and drying trends (Rhode, 2016).…”

“…6). The first permanent village settlements in the Qinghai Lake basin are dated to ~3380–2830 yr BP (~3605–2957 cal yr BP) (Chen et al, 2015; Rhode, 2016), which could be associated with forest disappearance. Overall, more evidence is needed to determine the effects of human activity on the decline or disappearance of forest in Qinghai Lake basin.…”