Agriculture Reference
In-Depth Information
Table 3.2 Loadings (kg m −2 ) of each of the eight primary fuel components for the surface and
ground fuel layers (Table 3.1 ) along with a measure of variation (coefficient of variation is in
parentheses %) for selected undisturbed shrub and pine fuel beds in the USA. These loadings were
taken from default inputs in the First Order Fire Effects Model (FOFEM), (Reinhardt et al. 1997 ),
fuel characteristics classification system (Ottmar et al. 2007 ), and Keane et al. ( 2012 ), while the
uncertainty estimates (in parentheses) were estimated from Keane et al. ( 2012 ). Coefficient of
variation is the variation expressed as percent of the mean
Fuel
comp
Low
sagebrush
Chamise
chaparral
Pinyon-
juniper
Ponderosa
pine
Jeffrey pine
Loblolly
pine
Lodgepole
pine
1 h
0.00 (0)
0.01 (60)
0.01 (110)
0.02 (80)
0.02 (80)
0.02 (75)
0.07 (86)
10 h
0.01 (200)
0.01 (200)
0.02 (300)
0.08 (193)
0.18 (193)
0.0 (0)
0.14 (131)
100 h
0.00 (0)
0.01 (140)
0.02 (440)
0.08 (185)
0.22 (185)
0.0 (0)
0.05 (253)
1000 h 0.00 (0)
0.0 (600)
0.11 (600)
0.66 (105)
2.21 (105)
0.0 (0)
0.59 (125)
Shrub
0.22 (50)
2.97 (202)
0.09 (202)
0.05 (177)
0.04 (177)
0.30 (150)
0.05 (78)
Herb
0.04 (251)
0.01 (850)
0.01 (850)
0.06 (44)
0.04 (44)
0.02 (102)
0.03 (127)
Litter
0.02 (110)
0.01 (100)
0.20 (100)
0.63 (58)
0.33 (58)
0.21 (103)
0.51 (64)
Duff
0.19 (105)
0.23 (150)
1.23 (150)
1.90 (55)
5.50 (55)
0.97 (120)
4.02 (64)
3.3.2
Special Ground Fuel Types
Plant roots are a ground fuel type that is often ignored in many fuel sampling ef-
forts. Roots are relatively unimportant to fire spread and intensity because of their
heterogeneous spatial distributions and position below the ground. However, fires
will long persist and travel in dead roots causing major problems in fire suppres-
sion efforts. Smoldering root fires may be difficult to detect and may eventually
transition into a surface fire given the right environmental conditions. There are few
operational or research sampling methods to quantify root biomass, and fewer stud-
ies have described root combustion properties. Many recognize the great amount of
carbon from roots in the soil profile.
Another important ground fuel type includes the diverse organic soils of the
world's wetlands (Fig. 3.3g ). Wetlands are fresh, saline, or brackish water bodies
where biomass accumulates over time to create large deposits of organic soils. The
organic matter at the bottom of the wetland better fit the definition of soil rather than
fuel because of their high mineral contents, but many of these wetlands experience
seasonal drying and often burn. These wetlands include the pocosin swamps of the
southeastern USA; the boreal peat soils and bogs of Canada, USA, and Russia; the
freshwater marshes of China; and the peatlands of Indonesia. In soils terminology,
these soils are often called histosols because of high mineral contents and thick
histic (organic) epipedons. Histosols are wide spread across various wetland set-
tings, but there are many other soil types that also have high organic fuels that do
not fully meet the classification requirements of a histosol. Gelisols, for example,
are associated with areas of permafrost and have significant organic accumulation,
but they do not meet the definition of a histosol. However, many gelisols burn when
dry. Soils not deep enough to meet the histosol requirements may still have a thick
 
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