Shifts from climate-driven to human-influenced fire regimes in central China over the last two millennia

Fire is a key component of Earth systems, driven by the interplay of climate, vegetation, fuel accumulation and human activities. However, the dynamics of fire occurrence and intensity in central China remains poorly understood, and distinguishing between natural and human-influenced fire regimes is a challenge. Here, we reconstructed a 40,000 year fire history from the Hanchi peatland in Lichuan City, Hubei Province. Multiple proxies were employed, including charcoal accumulation as an indicator of fire occurrence and, for the first time in China, Raman spectroscopy of charcoal was applied as a proxy for fire intensity. Furthermore, a structural equation model (SEM) was employed to disentangle the causal relationships among fire, climate variability and anthropogenic influences. Fire activity at Hanchi was characterized by infrequent but high intensity events, probably representing crown wildfires before 2 ka BP, and these were largely governed by climatic variability. Our results reveal a clear transition in fire regimes around 2 ka BP, after which fire occurrence increased while intensity declined, coinciding with human population expansion and cropland development. Fire intensity derived from Raman spectral analyses of the charcoal was critical to detecting anthropogenic fire, and provides significant potential to distinguish climate versus anthropogenic fire regimes after humans become a dominant landscape force.