Fire is an important influencing factor in the evolution of the earth's ecosystem and is widely involved in the interaction between global climate, vegetation environment and human activities. The combustion of biomass promotes greenhouse gas emissions and accelerates the biosphere material circulation . The control and use of fire broadens human recipes and promotes the evolution of human behavior. Therefore, the systematic evolution of global fire and its relationship with vegetation ecology and climate environment have always been an important research content in global change. At present, long-scale fire activity records in East Asia are relatively scarce, mainly concentrated in the South China Sea and the Loess Plateau area. Based on the determination of black carbon concentration/deposition flux, there are certain differences in the reconstruction results of different studies. There are still many questions about the changes in the frequency of fires in the cyclone of the ice-interglacial period and the driving mechanism of natural wildfires. Recently, Li Xiaoqiang's team from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences cooperated with Tianjin Geological Survey Center of the China Geological Survey and other units to conduct a comprehensive study on the G3 drilling hole in the North China Plain region. Based on the analysis of various indicators such as carbon chip statistics, spore powder analysis, magnetic formation age and organic carbon isotopes, the history of fire activity in East Asia for two million years has been reconstructed. The relevant research results were published in the international journal Quaternary Science Reviews. The first author of the paper is Associate Researcher Shen Hui, our institute, and the corresponding author of is Researcher Li Xiaoqiang.
This study results show that there have been significant fluctuations in fire activities in the North China Plain since the Quaternary period, and are affected by a combination of factors such as solar radiation, vegetation environment, biomass, and human activities. The concentration of carbon chips during the period 2.1–0.3 Ma is relatively low, indicating that the fire activity is relatively weak during this period and the frequency of natural wildfires occur is not high. Among them, the concentration of carbon chips fluctuated significantly during the Mi Pleistocene climate transition period, indicating that natural wildfires were extremely unstable during the climate transition period. Since 300,000 years ago, the concentration of carbon chips has increased significantly, indicating that fire activity in North China is relatively active and natural wildfires occur frequently. At the same time, the concentration of carbon chips shows a corresponding relationship with deep-sea oxygen isotopes and loess-paleosoil particle size. The concentration of carbon chips during the ice age is relatively high, indicating that wildfires occur more frequently during the dry and cold climate. The peak of carbon chip concentration often occurs during the ice gap between the ice period, indicating that regional fires often occur during the climate transition period. Comparison of
G3 drilling carbon chip concentration, organic carbon isotope and deep sea oxygen isotope, loess-paleosoil particle size and earth orbit eccentricity comparison chart
and the spore powder analysis results, the frequency of fire is significantly related to vegetation type, and there are also differences in the controlled factors of fire under different ecological backgrounds. In the grassland vegetation environment, the concentration of charcoal chips is mainly positively correlated with the ratio of Artemisia genus and Artemisia/Vegara. This may be because the biomass generated by the Artemisia genus grassland is relatively higher than that of vegetation represented by Cegarae . During the forest vegetation period, the concentration of charcoal chips is positively correlated with the tree/non-tree ratio and coniferous content, indicating that the abundant biomass generated by the forest environment and the flammability of coniferous trees also affect the frequency of natural fire. In addition, the concentration of carbon chips showed an inverse correlation with the organic carbon isotope. For example, during the 2.1–1.65 Ma period, the organic carbon isotope was significantly positive, reaching the peak of the entire study period, while the concentration of carbon chips was extremely low, indicating that the fire activity was not active during the C4 plant abundance.
G3 drilling carbon chip concentration power spectrum analysis
power spectrum analysis results show that there is a significant 40 kyr cycle in the concentration of carbon chips, indicating that climate change under the control of solar radiation is one of the important influencing factors of fire activity in East Asia. It is worth noting that the large number of human controlled use of fire since the Middle Pleistocene has had a significant impact on global fire activities. The concentration of carbon chips in the G3 drilling hole was relatively low during the period 2.1–0.3 Ma, and there was no obvious connection with the number of archaeological sites in northern China, indicating that the fire during this period was a natural wildfire. Dry and cold climatic conditions may have prompted the frequent occurrence of fires for 300,000 years ago, providing more opportunities for ancient humans to learn how to control the use and manage fires.On the other hand, the widespread use of fire by humans may also promote the increase in the frequency of fire activity. For example, the rapid increase in carbon chip concentration during the 0.3 Ma and 0.05 Ma period corresponds to the rapid increase in the number of archaeological sites, indicating that humans began to play an important role in the evolution of fire.
Comparison of fire activity and archaeological sites and fire pit ruins since 2.1Ma in northern China
Through the comprehensive application of a variety of analytical indicators, this study systematically sorted out the history of fire activity in the North China Plain for two million years, the response process of natural fire during the ice-interglacial cyclone, the frequency of fire occurrence under different vegetation environments, and the mutual influence of fire and human activities since the early Pleistocene, providing an important basis for understanding the evolution process of long-scale fire in East Asia and its driving mechanism.
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