Agriculture Reference
In-Depth Information
Box 13.1 (
cont.
)
In response an industry-sponsored syndicate, the California Fair Plan serves as
insurer of last resort for those deemed too high risk for conventional fire
insurance, potentially increasing risky building decisions.
Most fires that encroach into urban environments do so as embers that land
on flammable structures. Due to mandatory evacuation orders, most homes are
vacant at the time embers land on or adjacent to homes. Homeowners that are
on site can go a long way in reducing losses due to ember-generated fires.
Staying with your home in the path of a wildfire is dangerous and as a result
most societies do not encourage homeowners to do so and often homeowners
are required to evacuate. Australia has had a long history of trying to develop
guidelines for the safe conduct of home protection. Early on it was described as
gov.au/dsp_content.cfm?cat_id=1214
)
. This is a voluntary policy and empha-
sizes the need for preparing homes in advance of fire threats so that they are
fire safe, including changing home structures as well as clearing vegetation
around the home. It has been suggested that losses in California could be
reduced with such a policy (Stephens
et al.
2009
). However, after the disastrous
2009 fires in Victoria, Australia, this policy has come under some level of
scrutiny (Cart
2009
; Haynes
et al.
2010
).
Reducing urban fuels is an avenue that has not been explored. In some
landscapes the landscaping surrounding homes is highly flammable and this
is particularly so when it is not well maintained (e.g.
Fig. 13.5b
). It appears the
biggest culprit is branches overhanging homes and dropping litter that accu-
mulates on the roof. Ignition is very likely when embers land on dry roof litter.
of control and fire impact. Fire danger rating or burning index is an integration of
weather, fuels and other fire-related factors and is commonly used to direct fire
management activities.
Indices are tailored to meet the needs of different regions. For example, the
McArthur Forest Fire Danger Index, and modifications of it, is commonly used in
Australia, or in Canada the Fire Weather Index or in the United States the
National Fire Danger Rating System. These regional assessments use broad
estimates of fuels based on published fuel models of live and dead fuels for
different vegetation types. In many regions substantial effort has gone into pro-
ducing regional fuel maps used in fire danger rating (Woodall
et al.
2005
). These
indices are sensitive to short-term changes in weather parameters and include
longer-term impacts of drought on fuel moisture (Andrews
et al.
2003
). They,
however, do a poor job evaluating short-term changes in dead fuels due to
drought-induced dieback of vegetation, which has been hypothesized to be a
critical factor in driving large fire events in California (Keeley & Zedler
2009
).
