This seminar is part of the USFS Missoula Fire Lab Seminar Series.

Wildland fires spread through combinations of living and dead vegetation and the largest fires generally occur in fuels that are dominated by living plants. While much is known about the factors that regulate fire spread through dead fuels, the controlling factors of live fuel flammability have proven elusive. Here we present an integrated exploration of the spatial and temporal variations in the live wildland fuel physical and chemical characteristics. We examine how these properties act together to influence spatial and temporal variations in many fuel characteristics that are known to heavily impact flammability. Specifically, we show how seasonal variations in foliar chemistry interact to control key fuel thermo-physio-chemical characteristics, such as foliar density, heat of combustion and moisture content and we demonstrate that live fuel chemistry is vastly different from that of comparable dead fuels. Based on these findings, we suggest that an ecological approach to exploring live fuel flammability is warranted and we show how such an approach can shed light on crown fire potential. Ultimately, our findings show that existing theories of live fuel ignition based on moisture content are heavily flawed and new approaches are needed to better characterize the likelihood of wildland fires spreading through live fuel-dominated landscapes.