Fuel Sampling - Wildland Fuel Fundamentals and Applications - page 139

applied to inventory data to compute loading. Most destructive sampling is done for
research rather than operational management inventory and monitoring.

8.3.3 Integrated Surface Fuel Sampling

Sampling projects are rarely designed using only one sampling approach or
technique. The diversity of surface fuel components coupled with the constraints of
limited resources always result in project-level sampling designs that compromise
statistical rigor to ensure success by integrating the above techniques and approaches.
Conventional standardized surface fuel sampling protocols nearly always
recommend using PI techniques for woody fuel loading and volume approaches
for litter, duff, shrub, and herb (Lutes et al. 2006 ). The photoload approach has
been augmented with PI, fixed-area log sampling, and volume estimates for duff
and litter (Keane et al. 2012b ). Catchpole and Wheeler ( 1992 ) mention a sampling
technique called “double sampling” where destructive techniques are used on a
subsample of FAPs to calibrate loading estimates from visual techniques. Keane
et al. ( 2012b ) used double sampling for another reason—to adjust visual estimates
using statistical regression. This melding of approaches, techniques, and intensities
may aid in successful sampling designs, but the resultant loading estimates have
different error distributions, variability, and usefulness for each fuel component.
This makes evaluating fire model performance difficult when the uncertainties of
loading estimates are different across fuel components.

8.4 Canopy Fuel Sampling

The five canopy fuel characteristics ( canopy base height ( CBH ) , canopy height
( CH ) , canopy bulk density ( CBD ) , canopy fuel load ( CFL ), and canopy cover ( CC )
in Chap. 4) can be estimated using any of four approaches. The first approach in-
volves the destructive sampling of the canopy in vertical layers within a FAP ( de-
structive canopy methods ). Here, all canopy biomass is cut, dried, and weighed
within a canopy layer for the plot area. This usually involves climbing or cutting
trees, clipping their branches within a given canopy layer, clipping and sorting
branch material into fuel components (needles, wood by diameter size class), and
then drying and weighing the fuels in a laboratory. Reinhardt et al. ( 2006b ), for
example, sampled five forested stands in the western USA using this technique to
describe CBD and CFL vertical distributions. This is obviously a time-consuming
and costly method and is only done for research studies.
The second approach involves using various instruments or sampling schemes
to indirectly measure canopy fuel variables ( indirect canopy methods ). In this
approach, various specialized equipment or protocols are used to measure stand
characteristics, such as gap fraction (percent of vertically projected canopy cover