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

Chatziefstratiou, Efthalia K.; Bohrer, Gil; Bova, Anthony; Subramanian, Ravishankar; Frasson, Renato Prata de Moraes; Scherzer, Amy J.; Butler, Bret W.; Dickinson, Matthew B.

doi:10.1371/journal.pone.0070110

Cited by 25 publications

(7 citation statements)

References 31 publications

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“…Our bark measurements allow gross comparisons across species useful for characterizing investment strategies, but more realistic simulations of bark's insulating effects are possible. For example, recent simulation tools allow for detailed quantification of stem heating and tree mortality that incorporates information on bark thickness and structure (outer and inner bark), and starting bark moisture [57] .…”

Section: Discussionmentioning

confidence: 99%

Oak Bark Allometry and Fire Survival Strategies in the Chihuahuan Desert Sky Islands, Texas, USA

2013

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Trees may survive fire through persistence of above or below ground structures. Investment in bark aids in above-ground survival while investment in carbohydrate storage aids in recovery through resprouting and is especially important following above-ground tissue loss. We investigated bark allocation and carbohydrate investment in eight common oak (Quercus) species of Sky Island mountain ranges in west Texas. We hypothesized that relative investment in bark and carbohydrates changes with tree age and with fire regime: We predicted delayed investment in bark (positive allometry) and early investment in carbohydrates (negative allometry) under lower frequency, high severity fire regimes found in wetter microclimates. Common oaks of the Texas Trans-Pecos region (Quercus emoryi, Q. gambelii, Q. gravesii, Q. grisea, Q. hypoleucoides, Q. muehlenbergii, and Q. pungens) were sampled in three mountain ranges with historically mixed fire regimes: the Chisos Mountains, the Davis Mountains and the Guadalupe Mountains. Bark thickness was measured on individuals representing the full span of sizes found. Carbohydrate concentration in taproots was measured after initial leaf flush. Bark thickness was compared to bole diameter and allometries were analyzed using major axis regression on log-transformed measurements. We found that bark allocation strategies varied among species that can co-occur but have different habitat preferences. Investment patterns in bark were related to soil moisture preference and drought tolerance and, by proxy, to expected fire regime. Dry site species had shallower allometries with allometric coefficients ranging from less than one (negative allometry) to near one (isometric investment). Wet site species, on the other hand, had larger allometric coefficients, indicating delayed investment to defense. Contrary to our expectation, root carbohydrate concentrations were similar across all species and sizes, suggesting that any differences in below ground storage are likely to be in total volume of storage tissue rather than in carbohydrate concentration.

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Section: Discussionmentioning

confidence: 99%

Oak Bark Allometry and Fire Survival Strategies in the Chihuahuan Desert Sky Islands, Texas, USA

2013

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“…Without sufficient bark insulation, phloem and vascular cambium can exceed critical temperatures for necrosis. If the insulation capability is too low, lethal temperatures can be attained not only in phloem and vascular cambium tissues, but also in the underlying xylem (Chatziefstratiou et al ., ). We are unaware of any empirical data for sapwood temperatures during forest fires, but simulations based on measured cambium data suggest that xylem often can achieve critical necrosis temperatures (Michaletz et al ., ).…”

Section: First‐ and Second‐order Fire Effectsmentioning

confidence: 97%

Fire effects on tree physiology

2019

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Heat injuries sustained in a fire can initiate a cascade of complex mechanisms that affect the physiology of trees after fires. Uncovering the exact physiological mechanisms and relating specific injuries to whole-plant and ecosystem functioning is the focus of intense current research. Recent studies have made critical steps forward in our understanding of tree physiological processes after fires, and have suggested mechanisms by which fire injuries may interact with disturbances such as drought, insects and pathogens. We outline a conceptual framework that unifies the involved processes, their interconnections, and possible feedbacks, and contextualizes these responses with existing hypotheses for disturbance effects on plants and ecosystems. By focusing on carbon and water as currencies of plant functioning, we demonstrate fire-induced cambium/phloem necrosis and xylem damage to be main disturbance effects. The resulting carbon starvation and hydraulic dysfunction are linked with drought and insect impacts. Evaluating the precise process relationships will be crucial for fully understanding how fires can affect tree functionality, and will help improve fire risk assessment and mortality model predictions. Especially considering future climate-driven increases in fire frequency and intensity, knowledge of the physiological tree responses is important to better estimate postfire ecosystem dynamics and interactions with climate disturbances.

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“…In situ physical measurements of energy transport in flames and energy deposition in the wildland fire environment are critical for advancing fire science [ 18 ] yet are relatively sparse in the literature [ 42 , 58 , 60 ]. With the advent of modern numerical computation, the physical complexity and computational requirements of wildland fire behavior and effects models has increased, including models designed to simulate fire behavior [ 46 , 47 , 61 , 62 , 63 ], plume transport [ 64 , 65 ], and fire effects [ 66 , 67 , 68 ]. More physically realistic models and better basic understanding of fire dynamics require continued measurement development particularly of the basic heat and chemical processes occurring in fires exemplified by our study and others in the field [ 17 , 69 , 70 , 71 , 72 , 73 , 74 ] and laboratory [ 75 , 76 , 77 , 78 , 79 , 80 ].…”

Section: Discussionmentioning

confidence: 99%

The Wildland Fire Heat Budget—Using Bi-Directional Probes to Measure Sensible Heat Flux and Energy in Surface Fires

Dickinson

Wold

Butler

et al. 2021

Sensors

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Sensible energy is the primary mode of heat dissipation from combustion in wildland surface fires. However, despite its importance to fire dynamics, smoke transport, and in determining ecological effects, it is not routinely measured. McCaffrey and Heskestad (A robust bidirectional low-velocity probe for flame and fire application. Combustion and Flame 26:125–127, 1976.) describe measurements of flame velocity from a bi-directional probe which, when combined with gas temperature measurements, can be used to estimate sensible heat fluxes. In this first field application of bi-directional probes, we describe vertical and horizontal sensible heat fluxes during the RxCADRE experimental surface fires in longleaf pine savanna and open ranges at Eglin Air Force Base, Florida. Flame-front sensible energy is the time-integral of heat flux over a residence time, here defined by the rise in gas temperatures above ambient. Horizontal flow velocities and energies were larger than vertical velocities and energies. Sensible heat flux and energy measurements were coordinated with overhead radiometer measurements from which we estimated fire energy (total energy generated by combustion) under the assumption that 17% of fire energy is radiated. In approximation, horizontal, vertical, and resultant sensible energies averaged 75%, 54%, and 64%, respectively, of fire energy. While promising, measurement challenges remain, including obtaining accurate gas and velocity measurements and capturing three-dimensional flow in the field.

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

Cited by 25 publications

References 31 publications

Oak Bark Allometry and Fire Survival Strategies in the Chihuahuan Desert Sky Islands, Texas, USA

Oak Bark Allometry and Fire Survival Strategies in the Chihuahuan Desert Sky Islands, Texas, USA

Fire effects on tree physiology

The Wildland Fire Heat Budget—Using Bi-Directional Probes to Measure Sensible Heat Flux and Energy in Surface Fires

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