Agriculture Reference
In-Depth Information
Fig. 4.3
Four typical canopy fuel profiles.
a
multiaged, multistrata stands,
b
two storied,
c
single
strata, and
d
fire-dominated stands. Each stand presents a special problem in calculating
CBD
and
CBH
There is also a maximum threshold, but this is rarely approached in nature.
CBD
values can range from zero for grasslands to over 0.7 kg m
−3
for the densest cano-
pies (Reeves et al.
2009
) (Table
4.1
).
The two main problems with
CBD
are how to define it and how to estimate it.
Cruz et al. (
2003
) defined
CBD
following the van Wagner (
1977
) approach where
canopy fuel load (
CFL,
kg m
−2
) is divided by canopy depth (
CH
-
CBH,
m), but this
average
CBD
across all canopy layers doesn't really capture the true nature of the
canopy profile; some canopy layers are denser thereby better facilitating the spread
of crown fires (Fig.
4.2
). However, selecting the maximum
CBD
value across all lay-
Search WWH ::
Custom Search