Moist
(site moisture)
(climate not included,
(Modified ADGGS)
except for alpine types)
(generally not
Based on climate
included in initial
maps or
map coding)
topographic zone
Figure 3. System for hierarchically classifying ecosystem components into integrated terrain units that explicitly
denote ecosystem components and aggregating and simplifying these ITUs into ecotypes.
files of ecosystem components along topo-
a system based on landform-soil characteristics
sequences and by hierarchically aggregating plots
originally developed by Kreig and Reger (1982)
by ecosystem components, and (3) derivation of
and modified for this study (App. A). Organic
a reduced set of ecotypes by identifying the most
units were those used in wetland classification for
common relationships and central tendencies. In
Canada (NWWG 1988). Surface-forms were clas-
development of the ecotype classes, we also tried
sified according to the system developed by
to use ecological characteristics (primarily geo-
Washburn (1973) for periglacial microtopography.
morphology and vegetation structure) that could
Soils were classified according to Keys to Soil Tax-
be interpreted from aerial photographs. We also
onomy (Soil Survey Staff 1998). During classifica-
developed a nomenclature for ecosystems that
tion of geomorphic units in the study area, we also
explicitly relates ecological characteristics in a ter-
relied on the geologic map of the Fairbanks Quad-
minology that can be easily understood.
rangle (Pw et al. 1966) and the terrain unit map
Because ecosystems are highly complex and
of the Blair Lakes area (Kreig 1986).
variable, aggregation of detailed characteristics
described in the field (e.g., soil stratigraphy and
Ecosystems
vegetation composition) was necessary. For each
Classification of ecosystems at the ecotype level
component we used a hierarchical approach to
involved (1) simplification and aggregating detailed
aggregation (Fig. 3). For geomorphology we hier-
ground information on the structure and compo-
archically aggregated clasts, textures, layers, and
sition of ecological components to reduce com-
lithofacies into geomorphic units (architectural
plexity, (2) identification of relationships among
elements) using the approaches of Miall (1985)
terrain components by developing graphic pro-
9
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