Combining and competing effects between precipitation and temperature on Holocene fire regime evolution inferred from a sedimentary black carbon record in southwestern China

Abstract

Wildfires are sensitive to climate change, but their response to changes in temperature and precipitation on long timescales is still disputed. In this study, we present a ~9.4 ka black carbon mass sedimentation rate (BCMSR) record from Lake Ximenglongtan (XMLT), southwestern China, to elucidate the Holocene fire regime and its linkages to climatic conditions. The results indicate that the regional fire activity was low during the early Holocene (before 7.6 cal ka BP), increased notably at 7.6 cal ka BP, and continued to increase gradually during the mid- to late Holocene until 2.2 ka. The episodes of higher fire occurrence reflected by higher BCMSR over the last 2.2 ka might be more likely related to the intensified human activities. The cool and humid climate during the early Holocene limited the spread of fire, while warming and drying at ~7.6 cal ka BP triggered higher fire occurrence. Instead of temperature, changes in precipitation dominated fire regime variation during the mid- to late Holocene. On millennial timescales, we suggest that Holocene fire variability has been predominantly controlled by the combined effects of Northern Hemisphere (NH) summer and winter insolation that influenced monsoonal precipitation and fire season temperature, respectively. Indian Ocean Dipole (IOD) events may also have affected fire incidence through influencing monsoon intensity.

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

“…The increase in fire activity caused by intensified human activity during the late Holocene has been confirmed by many other studies of northern China (Huang et al, 2006;Wang et al, 2013;Miao et al, 2016;Mu et al, 2016;Pang et al, 2021) and elsewhere (Ning et al, 2020;Barhoumi et al, 2021). For example, Wang et al (2013) proposed that fire activity increased significantly in the Daihai Lake region during the late Holocene, possibly linked to an increase in human activity after ~2300 yr BP.…”

“…Mu et al (2016) showed that fires linked to agriculture may have led to increased biomass burning associated with agricultural activity after ~2000 yr BP in the Horqin Sandy Land in southeastern Inner Mongolia. In addition, although the Holocene evolution of fires in southwestern China differs from that in northern China, Ning et al (2020) suggested that the higher fire occurrence in the region over the past 2200 years was likely related to intensified human activities.…”