Fuel Sampling - Wildland Fuel Fundamentals and Applications - page 131

conditions (Fig. 7.1). Photos were taken of representative fuel types in a particu-
lar geographical region, and then fuel component loadings were measured for the
photo footprint and the summary of those loadings is reported next to the photo in
the photo series publication. These photo series publications are taken to the field
and the observed conditions in the field are visually matched to the best photo and
the loading measured for the photographed stand are used for the loadings of the
matched stand. A different photo can be used to estimate each of the various fuel
components. Often, photo series fuel types are stratified by vegetation conditions
(cover type, structural stage).
The photo series was introduced by Maxwell ( 1976 ), improved upon by Koski
and Fischer ( 1979 ) and Fischer ( 1981 ), and then extrapolated across the USA
( http://www.fs.fed.us/pnw/fera/research/fuels/photo_series/) . Many have taken
the photo series concept and applied it to areas that have been treated (Koski and
Fischer 1979 ), experienced severe disturbances (Vihnanek et al. 2009 ), contain
special vegetation types (Ottmar and Vihnanek 2000 ), and found in other countries
(Morfin-Ríos et al. 2007 ). Others have adapted the photo series concept to use
three-dimensional stereoscopic photos (Vihnanek et al. 2009 ). Photo series data
comprise the majority of the national fuelbeds in the FCCS database that have
been mapped across the USA by McKenzie et al. ( 2007 ) and Reeves et al. ( 2009 ).
A list of completed photo series for the US Rocky Mountains is presented in Baker
( 2009 ).
And most importantly, photo series have been developed for many local settings
to be applied at fine scales within a small geographical region. One highly valuable
aspect of the photo series is that the fire behavior fuel model (FBFM, Chap. 7) is
often documented along with fuel loadings so that FBFMs can be more easily as-
sessed in the field.
Despite its huge popularity, the photo series sampling technique has yet to be
comprehensively evaluated across many vegetation types or environmental condi-
tions. Sikkink and Keane ( 2008 ) found loading estimated using photo series ap-
proaches were often inaccurate and difficult to repeat across observers, albeit there
were some limitations in the training of the crews. Many photo series photos em-
phasize stand-level differences with oblique photos, and, as a result, some fine fuel
components, such as FWD, litter, and duff, may be hidden by the vegetation in the
photo or are undetectable because of their small size. Additionally, the photo series
cannot be used to assess the loading of duff or litter because the photos do not show
their profile depth. While photo series may give loading estimates to the resolution
needed for management decisions, other uses of loading estimates, such as predict-
ing smoke emissions and carbon inventories, may demand a more accurate and
repeatable method of loading estimate.
A new method of visually assessing fuel loading has been developed to improve
on photo series techniques and to compete with other direct sampling methods
(Sect. 8.3.3). The photoload method uses calibrated, downward-looking photo-
graphs of known fuel loads for woody, shrub, and herbaceous fuels to compare with
conditions in the field (Keane and Dickinson 2007a , b). These ocular estimates can
then be adjusted for diameter, rot level, and fuelbed height. There are different pho-
toload methods for logs, FWD, shrubs, and herbaceous material, but there are no