Holocene fire-vegetation history and its relationship with climate and human activity revealed by lake sediments from eastern Tianshan

<p>To distinguish how climatic and human factors influence Holocene fire dynamics in arid, westerlies-dominated areas of Central Asia, we examined micro-charcoal and pollen records in well-dated sediment cores from Balikun lake, eastern Tianshan region, Central Asia. Our results show that vegetation biomass primarily controlled the suborbital-time-scale fire dynamics, with an increasing trend of fire intensity from the early to late Holocene. Evidence for substantial anthropogenic influence on fires is mainly related to the expansion of prehistoric agriculture during ~3.6-2.2 cal kyr BP in our study area. These human activities caused a departure from &#8220;natural&#8221; background fire levels that vary with climate change.</p> <p>In contrast, the human-linked fire peak in the nearby Hexi Corridor, which lies in Asian summer monsoon dominated regions of eastern China, occurred before ~3.6 cal kyr BP. This may reflect differences in the timing and sequence of cultural development under regions dominated by different circulation patterns. The weakening of the Asian summer monsoon after ~3.6 cal kyr BP likely promoted the Hexi Corridor population to migrate to eastern Tianshan, as evidenced by the similar pottery from eastern Tianshan to those of the Siba culture (4.0-3.5 cal kyr BP) that originated from the Hexi Corridor. This migration facilitated the formation of the westward cultural exchange route known as the &#8220;Painted Pottery Road&#8221;, enhancing regional human activity and causing an increase of fires in eastern Tianshan.</p>