Fire-Induced Tree Mortality

This project is a continuation and expansion of several past research projects on fire-induced tree mortality. Please see individual project page for details on specific projects (Douglas-fir and Fire, Post-fire Tree Mortality, Wildfire effects in grand fir-hemlock forests). 

Tree mortality is an obvious and important consequence of fire in forested ecosystems. Yet our understanding of how fire kills trees is surprisingly rudimentary. Current models of fire-induced tree mortality use simple linear models optimized for a small set of commercially important species and most incorporate only single parameters for defense (bark thickness) and injury (crown scorch). Not surprisingly, the utility of these models have been called into question by managers and scientists. Crucially, we lack an understanding of the direct and indirect role of climate in determining post-fire tree mortality. This gap in understanding greatly limits our ability to accurately predict mortality from fire and extrapolate to novel climates, which in turn limits application of appropriate management actions to increase forest resilience to wildfire and estimate fire-caused feedbacks to the global carbon cycle. 

We are conducting the first continental-scale characterization of climatic influences of fire-induced tree mortality using an unprecedented database of over 87,000 trees of 24 species across forests in the Western and Southeastern United States. Our analysis focuses on (1) evaluating the accuracy of currently used models and (2) assessing the influence of pre-fire climate on fire-induced tree mortality using the current framework of the existing software systems FOFEM, BehavePlus, and FFE-FVS.


Heat transfer process involved in tree mortality.
Post-fire crown injury in Pinus ponderosa. Heat from fires causes diverse visual injuries to crown foliage, buds and branches. These injuries are linked to several potential mechanisms that result in stress, reductions in tree growth and branch and whole tree death
(Credit: Drawing by R. Van Pelt. From Varner et al. 2021)

Select Publications & Products

Varner, J. Morgan; Hood, Sharon M.; Aubrey, Doug. P.; Yedinak, Kara; Hiers, J. Kevin; Jolly, W. Matthew; Shearman, Timothy M.; McDaniel, Jennifer K.; O’Brien, Joseph J.; Rowell, Eric M. 2021. Tree crown injury from wildland fires: Causes, measurement and ecological and physiological consequences. New Phytologist.

USDA Forest Service Rocky Mountain Research Station. 2019. Is That Tree Dead? Quantifying Fire-Killed Trees to Inform Salvage and Forest Management.  Science You Can Use Bulletin. Issue 36. 11 p.

Hood S, Varner M, van Mantgem P, Cansler CA (2018) Fire and Tree Death: Understanding and Improving Modeling of Fire-induced Tree Mortality. Environmental Research Letters 13:113004. 

Grayson, L.M., Progar, R.A. & Hood, S.M. (2017) Predicting post-fire tree mortality for 14 conifers in the Pacific Northwest, USA: Model evaluation, development, and thresholds. Forest Ecology and Management, 399, 213-226.

Hood, S. & Lutes, D. (2017) Predicting post-fire tree mortality for 12 western US conifers using the First-Order Fire Effects Model (FOFEM). Fire Ecology, 13, 66-84.

Kane, J.M., Varner, J.M., Metz, M.R. & van Mantgem, P.J. (2017) Characterizing interactions between fire and other disturbances and their impacts on tree mortality in western U.S. Forests. Forest Ecology and Management, 405, 188-199.

Fire-induced tree mortality models are used to develop post-fire salvage guidelines. Here are Forest Service guidelines for the Northern and Pacific Southwest Regions:

USDA Forest Service Region One. 2017. Post-fire Assessment of Tree Status. Vegetation Classification, Mapping, Inventory and Analysis Report. Report 17-17 v2.0. December 21 2017.

Smith SL, Cluck DR (2011) Marking Guidelines for Fire-Injured Trees in California. Report RO-11-01. USDA Forest Service, Forest Health Protection, Region 5, CA, 15 p.

ResearchGate Active Project website