A Way Forward for Fire-Caused Tree Mortality Prediction: Modeling A Physiological Consequence of Fire

Kavanagh, Kathleen L.; Dickinson, Matthew B.; Bova, Anthony

doi:10.4996/fireecology.0601080

Cited by 77 publications

(99 citation statements)

References 52 publications

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“…High temperatures, such as those resulting from fires, can create structural deformations in leaf cell walls [19]. Similarly, model simulations suggest that the high air temperatures present during a fire could lead to extreme drops in water vapor pressure, causing cavitation in the foliage [50]. In our study, FRED doses caused clear damage to the seedling crowns and individual needles that were sampled for spectral and physiological measurements (Figure 1b-d).…”

Section: Discussionmentioning

confidence: 90%

Spectral Indices Accurately Quantify Changes in Seedling Physiology Following Fire: Towards Mechanistic Assessments of Post-Fire Carbon Cycling

et al. 2016

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Fire activity, in terms of intensity, frequency, and total area burned, is expected to increase with a changing climate. A challenge for landscape-level assessment of fire effects, often termed burn severity, is that current remote sensing assessments provide very little information regarding tree/vegetation physiological performance and recovery, limiting our understanding of fire effects on ecosystem services such as carbon storage/cycling. In this paper, we evaluated whether spectral indices common in vegetation stress and burn severity assessments could accurately quantify post-fire physiological performance (indicated by net photosynthesis and crown scorch) of two seedling species, Larix occidentalis and Pinus contorta. Seedlings were subjected to increasing fire radiative energy density (FRED) doses through a series of controlled laboratory surface fires. Mortality, physiology, and spectral reflectance were assessed for a month following the fires, and then again at one year post-fire. The differenced Normalized Difference Vegetation Index (dNDVI) spectral index outperformed other spectral indices used for vegetation stress and burn severity characterization in regard to leaf net photosynthesis quantification, indicating that landscape-level quantification of tree physiology may be possible. Additionally, the survival of the majority of seedlings in the low and moderate FRED doses indicates that fire-induced mortality is more complex than the currently accepted binary scenario, where trees survive with no impacts below a certain temperature and duration threshold, and mortality occurs above the threshold.

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Section: Discussionmentioning

confidence: 90%

Spectral Indices Accurately Quantify Changes in Seedling Physiology Following Fire: Towards Mechanistic Assessments of Post-Fire Carbon Cycling

et al. 2016

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“…However, as plants become more water stressed, they are more susceptible to xylem embolism and cavitation [26], which breaks the flow of water from the roots to the leaves and could thus make plants behave like detached branches during heating. As fire passes under and through a plant canopy, very high vapor pressure deficits can be present on the surface of the foliage, and recent research suggests that this can increase xylem cavitation [27]. This effect may be particularly strong during periods of drought when plants Figure 1.…”

Section: Whole-plant Level Linkages Between Physiology and Flammabilitymentioning

confidence: 99%

Pyro-Ecophysiology: Shifting the Paradigm of Live Wildland Fuel Research

Jolly

Johnson

2018

Fire

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Abstract:The most destructive wildland fires occur in mixtures of living and dead vegetation, yet very little attention has been given to the fundamental differences between factors that control their flammability. Historically, moisture content has been used to evaluate the relative flammability of live and dead fuels without considering major, unreported differences in the factors that control their variations across seasons and years. Physiological changes at both the leaf and whole plant level have the potential to explain ignition and fire behavior phenomena in live fuels that have been poorly explained for decades. Here, we explore how these physiological changes violate long-held assumptions about live fuel dynamics and we present a conceptual model that describes how plant carbon and water cycles independently and interactively influence plant flammability characteristics at both the leaf and whole plant scale. This new ecophysiology-based approach can help us expand our understanding of potential plant responses to environmental change and how those physiological changes may impact plant flammability. Furthermore, it may ultimately help us better manage wildland fires in an uncertain future.

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“…Significant cooling by water transport is likely to be restricted to actively transpiring trees. Furthermore, we speculate that the conditions under which such cooling is effective will be limited by the deformation and vessel collapse in the stem, because of heat-driven cavitation in foliage and thin branch vessels as a result of extreme vapor pressure deficits in the heat plume during surface fires of even moderate intensity [43]. We predict that cooling by water flux will be most important during low-intensity surface fires that are followed by long-term smoldering and heating at the base of tree stems (e.g., [44]).…”

Section: Discussionmentioning

confidence: 99%

FireStem2D – A Two-Dimensional Heat Transfer Model for Simulating Tree Stem Injury in Fires

et al. 2013

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FireStem2D, a software tool for predicting tree stem heating and injury in forest fires, is a physically-based, two-dimensional model of stem thermodynamics that results from heating at the bark surface. It builds on an earlier one-dimensional model (FireStem) and provides improved capabilities for predicting fire-induced mortality and injury before a fire occurs by resolving stem moisture loss, temperatures through the stem, degree of bark charring, and necrotic depth around the stem. We present the results of numerical parameterization and model evaluation experiments for FireStem2D that simulate laboratory stem-heating experiments of 52 tree sections from 25 trees. We also conducted a set of virtual sensitivity analysis experiments to test the effects of unevenness of heating around the stem and with aboveground height using data from two studies: a low-intensity surface fire and a more intense crown fire. The model allows for improved understanding and prediction of the effects of wildland fire on injury and mortality of trees of different species and sizes.

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A Way Forward for Fire-Caused Tree Mortality Prediction: Modeling A Physiological Consequence of Fire

Cited by 77 publications

References 52 publications

Spectral Indices Accurately Quantify Changes in Seedling Physiology Following Fire: Towards Mechanistic Assessments of Post-Fire Carbon Cycling

Spectral Indices Accurately Quantify Changes in Seedling Physiology Following Fire: Towards Mechanistic Assessments of Post-Fire Carbon Cycling

Pyro-Ecophysiology: Shifting the Paradigm of Live Wildland Fuel Research

FireStem2D – A Two-Dimensional Heat Transfer Model for Simulating Tree Stem Injury in Fires

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