Figure 1. Delayed tree mortality from wildland fire is a function the heat flux (time-integrated energy release) or “dose” on numerous physiological responses. Heat flux includes the heat transfer processes of radiation, convection and conduction. A) Potential physiological responses (oranges lines) over time to a fire dose relative to baseline. Dots at end of orange lines indicate tree death, while arrows indicate survival. Responses potentially affected by fire include, but are not limited to, photosynthetic rate (A), defense traits, predawn water potential causing 50% loss of stem conductivity (P₅₀), and stomatal conductance (g_s). B) Long-term, tree mortality from fire is a function of the total heat flux , plant water stress (Ψ_p) and ambient air temperature (T_a) at the time of fire, physiological responses, species traits, and exogenous factors. C) Tree binary endpoint (mortality or survival) to a fire dose. The solid line is the average tree response and dashed lines reflect the lower and upper bounds of response based on species traits and environmental stress. The grey zone denotes possible range of a species response or biological plasticity to fire; grey arrows provide examples of ranges of variation in mortality from the same heat flux or variation in heat flux that causes the same level of mortality.