Surface and Ground Fuels - Wildland Fuel Fundamentals and Applications - page 37

Chapter 3
Surface and Ground Fuels

Wood already touched by fire is not hard to set alight
African proverb

3.1 Introduction

Surface fuels always get the most attention in fire management because it is the fuel
layer that is most often used to predict fire behavior. Most wildland fires spread
through surface fuels so the majority of the world's fire behavior prediction pack-
ages demand detailed physical descriptions of surface fuel components for fire
simulation. In fact, it is rare to have only a ground or crown fire without a fire also
burning in the surface fuel. Ground fuels were included in this chapter because they
are important to smoldering combustion; they often comprise the majority of fuel
loading in many forest ecosystems; and they are often included with surface fuels in
various sampling, classification, mapping, and simulation efforts (Lutes et al. 2009 ;
Riccardi et al. 2007a ).

3.2 Surface Fuels

The surface fuel layer contains the most diverse and complex fuel types in fire
management. Surface fuel particles are often dissimilar physically across most of
the common surface fuel types, especially considering that some are live and some
are dead. Herbaceous particles (e.g., grass blades), for example, have significantly
different properties (e.g., shape, particle density) than downed wood (e.g., branches
and logs). There are a core set of seven surface fuel components that are common
inputs to most fire models and they are also present in most surface fuel beds of
the world, especially forests (Table 3.1 , Fig. 1.2). Many ecosystems have the sur-
face fuel types of litter, shrubs, and herbaceous fuels in varying amounts above the
ground surface. Forest and shrub ecosystems nearly always have woody fuels in a
wide range of abundance and sizes.