Testing and classification of individual plants for fire behaviour: plant selection for the wildland - urban interface

Abstract

Knowledge of how species differ in their flammability characteristics is needed to develop more reliable lists of plants recommended for landscaping homes in the wildland-urban interface (WUI). As indicated by conflicting advice in such lists, such characterisation is not without difficulties and disagreements. The flammability of vegetation is often described as having four components (ignitability, combustibility, sustainability and consumability). No standards or generally recognised test procedures exist for evaluating these components in plants. Some measurements of flammability include times for ignition, rate of flame spread, flame height and heat release rate. Often, the fire behaviour characteristics of a plant are derived from its physical and chemical characteristics. Thermogravimetric analysis and other thermal analyses of ground samples have long been used to characterise the thermal degradation of vegetation. More recently, researchers have used the oxygen consumption methodology to measure the heat released due to combustion of the vegetation. Although oxygen consumption calorimetry is an improvement in characterising plant flammability, translation of laboratory results to field conditions can be problematic and tests can be expensive.

Assessing the flammability of surface fuels beneath ornamental vegetation in wildland–urban interfaces in Provence (south-eastern France)

“…However, this type of data provides basic information that is very useful for assessing the fuel hazard of Mediterranean ornamental vegetation planted in hedges even if protocols to establish flammability need to be standardised to convert results into a classification that can be used widely (Weise et al 2005;White and Zipperer 2010). Fire, 2012, 22(3) [333][334][335][336][337][338][339][340][341][342] Original publication available at www.publish.csiro.au/nid/114.htm doi:10.171/WF12006…”

Assessment of Flammability of Moroccan Forest Fuels: New Approach to Estimate the Flammability Index

“…Furthermore, this has been combined with the highly flammable nature of Mediterranean species, which favour bushfires [1][2][3]. Such fires are exacerbated by litter and shrub abundance, which are known for their propensity for recurrent fire besides the importance of fire for plant reproduction [3].…”

“…Few studies have tried to assess flammability using field-scale fire experiments [10] due to authorization, safety and cost constraints [9,11,12], while the most studies performed standardized laboratory-scale flammability measurements [2,5,7,[12][13][14][15][16][17][18][19][20][21], including some recent studies that still use the method of Valette [2,7,12,15]. Some of these methods have the disadvantage of using ground samples (do not take into account the fuel structure) and are criticized for combustion tests under conditions different from the natural conditions [1]. Other authors measured plant flammability at the shoot-level following the method of Pérez-Harguindeguy et al [22] to preserve the architecture of the plant shoots [23].…”

“…Ignitability is represented by time-to-ignition (TI) [16,30], which is widely used in plant flammability ranking (e.g., [7,16,31,32]). In terms of a fire test, combustibility is examined through flame height (FH) [1,31,33]. This FH parameter also gives insight into a fire propagation rating [14].…”

Calibration assessment of forest flammability potential in Italy

“…Although flammability components can be measured by laboratory and field experiments (e.g., Madrigal et al 2009), translation of laboratory results to field conditions is highly problematic (Fernandes & Cruz 2012). Moreover, field experiments are usually expensive (White & Zipperer 2010).…”