Anthropogenic origin of a change in the fire-climate relationship in northern China after ∼2000 yr BP: Evidence from a 15,500-year black carbon record from Dali Lake

Abstract

There are debates regarding whether a wet and warm climate or a dry and cold climate dominated Holocene fire activity in northern China on the millennial timescale, and when human activities overtook climate change as the dominant control on fire occurrence in the region. Here we present a high-resolution fire history for the past ~15,500 years from a sediment core in Dali Lake, located in the foothills of the Greater Hinggan Mountains, one of the areas of highest fire risk in China. The results demonstrate that fire activity was rare during the last deglaciation (~15,500-11,700 yr BP), gradually increased at the beginning of the Holocene, and reached its highest level during ~9000-5000 yr BP, after which there was a decreasing trend. However, after ~2000 yr BP this decreasing trend ended, and the most prominent feature is a peak in fire activity during the Medieval Warm Period (MWP). Overall, fire activity corresponded well to changes in the East Asian summer monsoon (EASM) precipitation on the millennial timescale during ~15,500-2000 yr BP, but this relationship changed after ~2000 yr BP. We propose that fire activity in northern China on the millennial timescale during ~15,500-2000 yr BP was dominated by the biofuels reserve under the control of the EASM precipitation. In contrast, with the intensification of human activities after ~2000 yr BP, human activity caused a ~62%-73% increase in fire activity, which altered the fire-climate relationship that had previously prevailed in northern China. Our results indicate that a wet-warm climate (increased EASM intensity), rather than a dry-cold climate, was the

Fire History in the Qinling Mountains of East‐Central China Since the Last Glacial Maximum

“…The period of 16-14.5 cal ka BP (chronologically overlapping with the North Atlantic H1 event) presented a high level of fire activity, associated with climatic drought caused by the abrupt weakening of the EASM (Figure 4d). While simultaneous fire events also occurred in the east of China, for example, Dali Lake (Zhang et al, 2022), Moon Lake (Wu & Liu, 2013), and Qinghai Lake (Xiao et al, 2017), possibly demonstrating globally consistent changes in fire activity (Marlon et al, 2016). Subsequently, fire activity showed a gradual decreasing trend from 14.5 to 12.9 cal ka BP because enhanced EASM increased precipitation.…”

Quantitative assessment of fire occurrence Dead Fuel Index threshold and spatio-temporal variation in different grassland types of China-Mongolia border area

“…The vegetation phenology is delayed with increasing altitude (Bao et al, 2021;Wu et al, 2021), and the DFI value is related to increasing altitude. Elevation is an important factor in the vertical distribution of vegetation in mountainous areas because it influences precipitation and air temperature (Jin et al, 2009;Zhang et al, 2011;Mu et al, 2013;Zhao et al, 2016), and may also be influenced by the population and livestock (Zhang et al, 2022).…”