Ecology - Wildland Fuel Fundamentals and Applications - page 93

Fig. 6.3 Possible changes
in fuelbed loadings for four
fuel components and two
wildland fire regimes: a
frequent low severity fires, b
stand-replacement fires. The
fuel components are canopy
fuel load (CFL: thick line ),
duff and litter (DUFF: dashed
line ), fine woody debris
(FWD: thin line ), and coarse
woody debris (CWD: dotted
line )
documented for hemlock/Douglas-fir forests (Agee and Huff 1987 ), southeastern US
pine savannas (Thaxton and Platt 2006 ), and whitebark pine ecosystems (Keane and
Parsons 2010 ).
Different fuel accumulation trajectories often result as a consequence of the
distribution of severity, intensity, and pattern of fires in a fire regime (Fig. 6.3 ).
For ecosystems with frequent fire regimes, repeated fires are constantly reduce
fuels on the forest floor thereby keeping all dead fuel loads low (Fig. 6.3a ).
However, shrub and herbaceous loadings may become the dominant surface fuel
components because they are adapted to survive fire and all other component
loadings are low due to consumption by fire. After stand-replacement fires in
forests, the dead snags of the fire-killed trees eventually fall and create high log
loads for many years or until the next fire (Fig. 6.3b ). Fine woody fuels peak
right after the fire, and then decline until established trees become large enough
to contribute significant FWD. Shrub and herb biomass peaks in the open condi-
tions left after the fire and declines as tree density and overhead shade increase.
Litter and duff loadings slowly increase over time; litter increases as a result of
increased growing biomass and duff increases as deposition is greater than de-
composition over time.