Bark properties and fire resistance of selected tree species from the central hardwood region of North America

Abstract

Some physical, thermal, and chemical properties of bark of 16 tree species native to the central hardwood region were measured to determine their potential to protect the vascular cambium from damage by fire. The relationship between DBH and bark thickness for each of 16 species was determined. For purposes of monitoring seasonal trends, two species (Quercusmacrocarpa Michx. and Acersaccharinum L.) were sampled periodically during one growing season. Temperature response to bark surface heating of 11 species was monitored at the cambial layer during simulated fires conducted in the field. Bark samples were analyzed for moisture content, specific gravity, dry weight, volatile matter content, and time until ignition. Overall, during simulated fires, temperature gradients were decreased and maximum cambial temperatures were reduced as bark thickness increased. Thick-barked species had lower maximum cambial temperatures, longer times to reach peak temperatures, slower rates of heat loss, and shorter time until surface ignition. Populusdeltoides Marsh, was the most heat resistant among species tested, while Acersaccharinum was the least. Higher specific gravities were associated with higher rates at which cambial temperatures rose as well as with increased time required for surface ignition.

Examining Spatial Variation in the Effects of Japanese Red Pine (Pinus densiflora) on Burn Severity Using Geographically Weighted Regression

“…The estimated GWR model strongly suggested that the impacts of red pine trees on burn severity were not constant over space; rather, the effects varied among locations (i.e., non-stationary effects). The effect of red pine might not be the same across the entire study area; rather, it could vary among sites depending on complex environmental factors, meteorological conditions, and individual tree characteristics [19,31,[68][69][70]. However, the cause of this non-stationary effect of red pine trees on burn severity is unclear.…”

Mitigating old tree mortality in long-unburned, fire-dependent forests: a synthesis

“…Bark insulates the cambium from heat and is not easily combustible; therefore, thicker bark provides more protection. The rate of thickening differs by species, individual genetic differences, and environmental factors, and it influences how quickly this insulating layer forms (Hare 1965;Hengst and Dawson 1994). Species that develop thick bark early in life become fire-resistant sooner and are adapted to survive frequent, low-intensity fire.…”

Wildland fire in ecosystems: effects of fire on flora

“…The insulating quality of bark is also affected by its structure, composition, density, and moisture content (Hare 1965;Reifsnyder and others 1967), factors that vary among species. For example, among central hardwoods, bark of silver maple has a high specific gravity and thermal conductivity, and can transmit heat to cambial layers in less time than bark with a low specific gravity and conductivity, such as bur oak and eastern cottonwood (Hengst and Dawson 1994). Flame length (Brown and DeByle 1987), flaming residence time (Wade 1986), and stem char height (Regelbrugge and Conard 1993;Regelbrugge and Smith 1994) can be related to the amount of mortality of thinbarked trees.…”