Wildland Fire Behaviour

Wildland fires have an irreplaceable role in sustaining many of our forests, shrublands and grasslands. They can be used as controlled burns or occur as free-burning wildfires, and can sometimes be dangerous and destructive to fauna, human communities and natural resources. Through scientific understanding of their behaviour, we can develop the tools to reliably use and manage fires across landscapes in ways that are compatible with the constraints of modern society while benefiting the ecosystems. The science of wildland fire is incomplete, however. Even the simplest fire behaviours – how fast they spread, how long they burn and how large they get – arise from a dynamical system of physical processes interacting in unexplored ways with heterogeneous biological, ecological and meteorological factors across many scales of time and space. The physics of heat transfer, combustion and ignition, for example, operate in all fires at millimetre and millisecond scales but wildfires can become conflagrations that burn for months and exceed millions of hectares. Wildland Fire Behaviour: Dynamics, Principles and Processes examines what is known and unknown about wildfire behaviours. The authors introduce fire as a dynamical system along with traditional steady-state concepts. They then break down the system into its primary physical components, describe how they depend upon environmental factors, and explore system dynamics by constructing and exercising a nonlinear model. The limits of modelling and knowledge are discussed throughout but emphasised by review of large fire behaviours. Advancing knowledge of fire behaviours will require a multidisciplinary approach and rely on quality measurements from experimental research, as covered in the final chapters.

EFFECTIVENESS OF WATER-RETAINING POLYMER AS FIRE RETARDANT IN INDIRECT USE

ABSTRACT The use of fire retardants increases efficiency in fighting forest fires, however, it still presents uncertainties regarding environmental contamination, recommendations for preparation, and it lack of regulation in Brazil. In this scenario, alternative products such as water-retaining polymers, that can reduce the rapid evaporation of water, can also have positive effects in terms of reducing fire behavior. Efficiency and ways of using the water-retaining polymer as a short-duration fire retardant (indirect combat) in controlled burns in eucalyptus plantations were evaluated. Five concentrations (dilution in water), three volumes of spray solution, and two post-application times on the combustible material available in the area were evaluated. Controlled burns were conducted downwind, between 10 am and 2 pm, during dry season in the region, with micrometeorological and fire behavior assessments (fire propagation speed and length of flames). Increased spray volume and concentration of water-retaining polymer led to reductions in the spread of fire. In eucalyptus combustible material, the water-retaining polymer can be used as a fire retardant of short duration (effective up to two hours after application), considering a spray volume of 2.0 L m-2 and concentration of 0.0060% (diluted in water).

Fire effects on acorn production are consistent with the stored resource hypothesis for masting behavior

Highly variable patterns of seed production (“masting”) have been hypothesized to be driven by internal dynamics of resource storage and depletion. This hypothesis predicts that if seed production is artificially reduced, then the availability of unused stored resources should result in subsequent enhancement of the seed crop. We tested this prediction in two oak species with contrasting patterns of annual seed production (highly variable and relatively constant) by means of controlled burns at various frequencies over a 17-year period. We found that controlled burns reduced acorn production by both species in the year of the burn. In the species with relatively constant productivity, acorn production returned to baseline levels in the year following a burn; however, in the species with highly variable productivity, acorn production significantly increased the year following a burn. These results support a key prediction of the stored resource hypothesis by means of a long-term experimental test in wild tree populations.

Increased lyrebird presence in a post-fire landscape

Prescribed fires for fuel reduction affect wildlife in several ways. We observed a marked increase in superb lyrebird (Menura novaehollandiae) numbers after a controlled burn in Guy Fawkes River National Park, New South Wales, in April and May 2014. The fire occurred during the winter breeding season; however, congregations of males were often seen together in the burnt landscape, indicating an opportunistic prioritisation of foraging. The low-intensity fire cleared brush and low-level vegetation, thus decreasing foraging effort and potentially attracting the species despite the need to seek mating partners. Controlled burns therefore have the potential to attract superb lyrebirds immediately after fire due to ease of movement and foraging effort.

In-Situ Burn Guidance for Safety Officers and Industrial Hygienists

In-situ burning (ISB) of spilled petroleum has been conducted since the late 1950s. Most burns were performed from ground level on upland areas, inland waters, or test basins and the frequency of use has been relatively low. Response to the Deepwater Horizon incident reminded the spill response community of this strategy by illustrating the utility of ISB for spills offshore. Over 400 individual burns were conducted during the summer of 2010 in the Gulf of Mexico. The Deepwater Horizon response resulted in an unprecedented and extensive use of offshore ISB, and media coverage repeatedly demonstrated successful ISB operations. Ensuring responder and community safety and health is a critical aspect for conducting controlled burns of petroleum during an oil spill response. ISB presents unique issues associated with conducting controlled burns whether on land, near shore or offshore requiring relevant guidance for Safety Officers and industrial hygienists (IH). Response personnel conducting ISB must be trained specifically for burn operations. Health concerns related to conducting and monitoring the burns must be evaluated. With the large number of controlled burns conducted in the Gulf of Mexico throughout the Deepwater Horizon response, extensive experience has been obtained which can be used to update guidance and standards documents for conducting safe burn operations. This poster, targeted for the global response community, regulators and industry, covers the health and safety concerns that need to be addressed before, during and after ISB operations by Safety Officers and industrial hygienists. Specifically, the poster will be in two parts, highlighting the research to date. Part one will be a summary of the literature research and an evaluation of safety baseline information for ISB. The second part will demonstrate how to use the information from the first part and develop an ISB site safety plan by conducting a job hazard analysis and risk assessment. The end result will be a better understanding of potential ISB hazards, their associated risks, and the range of control methods available to the response community to mitigate those risks. The goal is ultimately to develop for Safety Officers and industrial hygienists a comprehensive consensus guidance document that aids in their ability to make sound risk based decisions during an emergency.