7th Workshop on Forest Fire Management - EARSeL, European ...

REMOTE SENSING OF FUEL MOISTURE CONTENT: ADVANCES IN
MEASUREMENT AND MODELLING
F.M. Danson
Centre for Environmental Systems Research, School of Environment and Life Sciences,
University of Salford, Salford, UK
f.m.danson@salford.ac.uk
Abstract: Vegetation live fuel moisture content (FMC) is routinely measured
in areas prone to wildfires as it has an important influence on the probability
of ignition of the vegetation, and also affects the rate at which fires
may spread. FMC is easy to measure in the field, requiring only the fresh
and dry weight of a vegetation sample. Field sampling is often limited both
in space and time however and recent remote sensing research has attempted
to develop methods for spatial mapping of FMC. This paper reviews this
research including, the fundamental physical relationships between FMC
and other variables, empirical work on FMC estimation, assessing the role
of canopy reflectance modelling, and conclusions on research priorities.
1 - Introduction
Vegetation live FMC is controlled by the interaction of plant physiology, soil
moisture and atmospheric conditions. It is therefore spatially and temporally
highly variable and difficult to map using ground measurements which
are normally sparse in space and time (Chuvieco et al., 2002).
Dimitrakopoulos & Papaioannou (2001) showed that for many
Mediterranean species a FMC value of 100% (or less) represents the ‘moisture
of extinction’, and ignition is possible. Spatial and temporal mapping
of FMC will therefore provide critical information on when and where the
moisture of ignition is reached.
FMC may be described as a ‘composite’ variable because it is determined by
a combination of two independent physical properties of the vegetation,
the leaf equivalent water thickness (EWT) and the leaf dry matter content
(DM), both with units of g cm-2 (equation 1):
FMC (%) = EWT/DM *100 (1)
In field sampling however, FMC is more easily estimated from leaf sample
fresh and dry weights.
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