Integrating plant physiology into simulation of fire behavior and effects

Abstract

Summary Wildfires are a global crisis, but current fire models fail to capture vegetation response to changing climate. With drought and elevated temperature increasing the importance of vegetation dynamics to fire behavior, and the advent of next generation models capable of capturing increasingly complex physical processes, we provide a renewed focus on representation of woody vegetation in fire models. Currently, the most advanced representations of fire behavior and biophysical fire effects are found in distinct classes of fine‐scale models and do not capture variation in live fuel (i.e. living plant) properties. We demonstrate that plant water and carbon dynamics, which influence combustion and heat transfer into the plant and often dictate plant survival, provide the mechanistic linkage between fire behavior and effects. Our conceptual framework linking remotely sensed estimates of plant water and carbon to fine‐scale models of fire behavior and effects could be a critical first step toward improving the fidelity of the coarse scale models that are now relied upon for global fire forecasting. This process‐based approach will be essential to capturing the influence of physiological responses to drought and warming on live fuel conditions, strengthening the science needed to guide fire managers in an uncertain future.

Fire, flammability and functional traits at the forefront of global change ecology

“…First, they reveal management-relevant axes of flammability trait variation for the two study species that are strongly influenced by tissue moisture (and by extension, drought tolerance traits). As climate and fire regimes change, there has been a push to incorporate these types of physiological response traits into global-scale fire risk and behaviour models (Dickman et al, 2023). Boving et al (2023) then demonstrate how their "ignitabilitycombustibility" proxy is linearly correlated to leaf water potentials.…”

Plant hydraulics at the heart of plant, crops and ecosystem functions in the face of climate change

“…Recent studies have shown the major role of physiological traits (vulnerability to cavitation, hydraulic segmentation and transpiration regulation) on both leaf and canopy fuel moisture content (Ruffault et al ., 2023), but more research is needed to scale up predictions from the leaf or canopy level to the stand or landscape levels. It is also necessary to achieve a better integration between short‐term physiological LFMC models (Balaguer‐Romano et al ., 2022; Ruffault et al ., 2023) and microclimatic variation driven by the fire‐plume so that this effect can be added to dynamical fire behaviour modelling (Dickman et al ., 2023).…”

Live fuel moisture and water potential exhibit differing relationships with leaf‐level flammability thresholds

“…Progress in pyro‐ecophysiology requires communication between plant physiologists and fire scientists who have, until recently, focused largely on questions within their fields rather than linkages between them. For example, fire behaviour models rarely incorporate plant physiology beyond generalizations of live fuels into broad functional groups, while relationships between plant water and various aspects of fire ecology, including fire behaviour and the ecological effects of fire, are largely unresolved (Dickman et al, 2023; Jolly & Johnson, 2018). Additionally, these two fields often use different metrics to assess tissue hydration and its effects on drought, fire impacts and vegetation characteristics.…”