Vegetation Classification and Mapping Project Report - the USGS

States, fuel classes were reevaluated to relate fire behavior and overstory vegetation of eastern
deciduous forests. Fieldwork was conducted to determine which Anderson Fuel Model Classes
would be assigned to particular GRSM overstory and understory communities. Resource and
fire experts familiar with GRSM vegetation advised CRMS personnel of Anderson Fuel Model
classes that could be assigned to vegetation classes (Figures 15 and 16). This information was
used to create a rule-based model with the structure, “if this overstory and this understory of a
particular density, then that fuel model class.” The model was written in Arc Macro Language
(AML) operational in Arc/Info and provided on the attached CD.
The density and structure of understory vegetation are important in fire fuel analysis. Dense
evergreen understory vegetation tends to shade the ground and help maintain moist conditions on
the forest floor, while a light density of evergreen shrubs allows sunlight to reach the ground and
dry out the accumulated leaf litter. To address the influence of understory vegetation on fuels,
GIS overlay commands were employed to create composite data layers of preliminary fuel
classes and understory vegetation. The rule-based GIS model in Arc/Info AML format was then
run to assign Anderson Fuel Model classes to polygons in the composite overstory/understory
data set. A particular combination of overstory and understory was assigned a particular fuel
model class as integer values of 1 through 13 (Table 6). A decimal value, indicative of the
Figure 15. National Park Service resource/fire managers Mike Jenkins and Leon Konz, along
with CRMS research assistant, Robin (Dukes) Puppa, determine the Anderson Fuel Model
associated with a particular vegetation community in GRSM.
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