Fuel Concepts - Wildland Fuel Fundamentals and Applications - page 176

10.2.4 Hazard and Risk

Hardy ( 2005 ) elucidated three major problems with using hazard and risk in fire
science and management. First, there are too many definitions of fire hazard and
risk that make consistent quantification difficult in fire management. An assess-
ment of hazard using the NWCG ( 2006 ) definition (condition that can cause injury,
illness or death of personnel, or damage to, or loss of equipment or property) will
be entirely different than one using the definition proposed by Bachmann and All-
gower ( 2001 ) (the potential fire behavior for a fuel type, regardless of the fuel type's
weather-influenced fuel moisture content). Next, assessments of hazard and risk
demand a temporal and spatial context, which has been missing from many past ef-
forts. Any evaluation must include the extent and pattern of the hazard and how long
it remains a hazard both within the fire season and over the long term. And last, the
context of hazard and risk must include an assessment of the historical or “natural”
fire regime and the ecosystem being evaluated. Chaparral ecosystems, for example,
may have high hazard for fire management but these shrublands may only burn
in high-intensity fires. Without an ecological context, ecosystems that historically
experienced large, infrequent, and high-intensity fires will always be considered
hazardous with high risk.
The quantification and mapping of hazard and risk should recognize that fuels
are always changing in space and time (Chap. 6). Too often, hazard and risk projec-
tions fail to integrate how long fuels on a stand or landscape remain hazardous or
when less hazardous fuel complexes become more hazardous. Fuel maps used as
input in fire hazard and risk software packages, such as FLAMMAP (Finney 2006 ),
seldom address changing fuel conditions over time. In the beetle example men-
tioned above, the elevated fire hazard because of red needles on pine trees killed by
mountain pine beetles only exists until the needles fall off the trees (1-3 years). If
these red-needle pines are in environments where fire seasons are short and infre-
quent, such as lodgepole and whitebark pine forests, there is a low chance that the
surface fuels will be dry enough to support fire while the red needles remain on the
trees. Moreover, the current fire behavior fuel models (FBFMs) used in most fire
hazard and risk assessments may be too coarse to detect subtle but major changes in
fuel loadings over time or after disturbances (Chap. 7). A fully integrated hazard and
risk assessment must simulate ecosystem change to meld dynamic fuel maps with
all possible weather and climate scenarios in both a fire behavior and fire effects
context (Keane and Finney 2003 ; Finney 2005 ).

10.3 A Fuel Ecology Approach

It will always be difficult to thoroughly understand wildland fuels if they are ex-
clusively analyzed and studied through the lens of fire behavior. When fuels are
defined, stratified, classified, and mapped for combustion science applications, the