Agriculture Reference
In-Depth Information
Chapter 10
Fuel Concepts
Sometimes a concept is baffling not because it is profound but
because it is wrong
E.O. Wilson, American ecologist
10.1
Introduction
As detailed in this topic, wildland fuels are defined, described, and quantified based
on their use in fire behavior and effects applications, which often ignore the great
biological complexity and rich ecological context needed to fully understand them.
Woody fuels, for example, are separated into size classes based on rate of moisture
loss (Fosberg
1970
) rather than based on rates of decomposition or deposition. The
fire behavior context may also limit or compromise fuel management concepts,
applications and actions. This chapter presents a set of common fuel concepts used
in fire science and management that need further qualification if they are used cor-
rectly in an ecological context.
10.2
Important Fuel Concepts
10.2.1
Flammability
Flammability is not a useful concept without considering a myriad of combus-
tion qualities and their distribution across multiple spatial and temporal scales.
Gisborne (
1947
) noted that most fuels are similar chemically and the major dif-
ferences in burning of different kinds of wood, brush, or grass are mainly due to
variations in physical properties rather than chemical composition. Differences
in how fuels burn are typically referred to
flammability.
The concept of flam-
mability is interpreted differently all over the world. It is often defined as the
relative ease at which fuels ignite but the causal mechanisms of flammability are
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