Fire history over the past 1 500 years revealed by charcoal record from the Dongping Lake in the Lower Yellow River

Dongping Lake is the largest flood storage lake in the lower reaches of the Yellow River, and its sediment contains rich environmental information from the geological history of the basin. This study focuses on the sediment core (Core DPK, 161 cm) from Dongping Lake, in Dongping County, Shandong, China and utilizes the charcoal records from this core. Combined with grain size and loss on ignition (LOI), we reconstructed the paleo-fire evolution history in the Dongping Lake region over the past 1500 years to explore the relationship among fire events, climate change, and human activities. Results indicate that: (1) during 516—1254 AD, the Dongping Lake region experienced a transition from cold/dry to warm/humid climate. Fire incidents were frequent, but there was a decreasing trend after around 1000 AD; (2) during 1254—1922 AD, the climate was cold, with frequent alternations between droughts and floods. The combination of climate change and human activities led to a significant increase in the frequency and intensity of fire incidents; (3) during 1922—1962 AD, climate was relatively warm and humid. Due to climate change and the diversion of the Yellow River, the frequency of fire events significantly decreased and stabilized; (4) since 1962, under the background of a warm and dry climate and increased human activities, fire incidents have increased significantly. Particularly, the concentration of charcoal fragments (＞100 μm) rose sharply to the highest peak in the entire profile, accompanied by rapid coarsening of grain size, indicating intensified human interference. Further analysis suggests that climate change is a significant factor promoting fire activity in the region, while intensified human activities (such as slash-and-burn agriculture, deforestation, wars and so on) may be the primary cause of frequent fire incidents in the Dongping Lake basin. The results have important scientific significance for the prevention and management of regional forest fires under the background of global warming, and shall contribute to better serving the national strategy of ecological conservation and high-quality development of the Yellow River basin.