A sedimentary record of fire evolution history and its response to climate change and human activities during the last 7000 years from Lake Qionghai, southeastern Tibetan Plateau

Abstract

The occurrence of fire is related to climate, vegetation, and human activity. The Qionghai Lake catchment, situated on the southeastern margin of the Tibetan Plateau, exhibits well-developed vegetation and a high fire frequency and is located in Xichang City—a settlement with a long-standing historical legacy. It is therefore one of the most suitable areas to study the fire-climate-vegetation-human connection. In this study, we reconstruct the fire evolution history of Lake Qionghai over the last 7000 years using AMS ¹⁴C dating, along with an analysis of charcoal accumulation rate (CHAR) and major pollen taxa. Our results reveal two distinct phases in Holocene fire dynamics: (1) During the period of 7000–620 cal yr BP, fire activity exhibited a sustained decrease, which may have been linked to the reduction in lightning due to the temperature drop during that period. (2) From 620 cal yr BP to the present‌, a marked increase in fire activity has been accompanied by a pronounced decline in woody plants, coinciding with the proliferation of anthropophilic plant—Poaceae. We propose that the increased fire activity in the catchment area has become increasingly influenced by human activities, particularly through population growth, settlement expansion, and the adoption of slash-and-burn agricultural practices that collectively intensified fire regime.