5 Conclusion

Bridging local meteorological conditions, vegetation, and anthropogenic influences to understand fine-scale fire regimes, our identification of ecoregion flammability thresholds (EFTs) is an essential step in providing managers and researchers a way to monitor the ongoing shifts in local fire regimes, as well as anticipate changing fire seasonality. Our results also highlight precipitation, temperature, and seasonality as important climatic drivers of EFTs, providing insight into how those critical thresholds and their association with the local environment can further shift under anticipated widespread drying trends. Additionally, our analyses further highlight regional variability in the role fuel moisture plays with fire – that, for example, an assumed threshold of between 8 and 12% commonly used in prior research does not work for all temperate coniferous forests (Figures 2a, 3). We present a dataset of 772 identified EFTs representing critical thresholds with fire for much of the Earth’s terrestrial surface. Additionally, we identify the inflection point slope estimate (IPSE), an essential component in interpreting the EFT as a driver of wildfire. These global data can and should be used as a steppingstone for understanding and managing fire regimes at the ecoregion level under continued anthropogenic climate change and constantly evolving land-use practices. Identifying the critical EFT as we have done therefore provides an important stage for future wildfire research.