phic units of interest along each transect. At each
et al. (1988) for mosses and lichens. Unknown spe-
sampling point, basic descriptions of geology,
cies were collected for later identification. A more
hydrology, near-surface soil stratigraphy, perma-
complete floristic inventory was conducted con-
frost occurrence, and vegetation were made.
currently by the Alaska Natural Heritage Program
Topographic profiles for each transect were
(Racine et al. 1997).
obtained by measuring relative elevations at
For the ground reference sites, sampling was
topographic breaks along the length of the
less intensive than the protocol used on transects.
transects. Measurements were made with an auto-
Specifically, species lists were less comprehensive
level and rod. Because the transects were located
and soil descriptions were restricted to shallow
in remote locations, they were not tied into estab-
soil pits. Active layer depth was described where
lished datum, and therefore present relative, not
possible. Field data sheets and photos are archived
actual, elevations. At each sampling station, nota-
at ABR, Inc.
tions were made describing surface form and
microrelief.
Classification
Hydrologic observations included classification
Ecosystem classification was approached at two
of the origin of water, water depth, depth to satu-
levels. First, individual ecosystem components
rated soil when water was not present in soil sam-
were classified and coded using standard classi-
pling pit, pH, electrical conductivity (EC), and
fication systems developed for Alaska or the Arc-
temperature. Water quality measurements were
tic (Table 1). Second, these ecosystem components
made with Oakton or Cole-Palmer pocket meters
were integrated to classify ecosystems at three
calibrated to standards within the range of use at
spatial scales using a variety of differentiating cri-
regular intervals in the field. When water was not
teria (Table 2).
present, pH and EC were determined in a satu-
rated paste of a mineral soil sample taken from
Ecosystem components
10- to 20-cm depth.
Vegetation types initially were classified to
Soil stratigraphy was described from soil plugs
Level IV of the Alaska Vegetation Classification
dug with a shovel to approximately 50 cm using
(Viereck et al. 1992) from data collected at sample
standard methods (SSDS 1993). Where possible,
sites based on structural and floristic criteria.
a soil core or tile probe was used to extend the
Development of a final vegetation classification
description and to determine the depth to under-
system followed an iterative process of identify-
lying gravel, if present. Descriptions for each pro-
ing and combining vegetation types that could be
file included the texture and color of each hori-
recognized on aerial photography. Vegetation
zon, the depth of organic matter, the depth of
types that were not reliably discernible were com-
thaw, the type and percentage of coarse frag-
bined with similar types. Consequently, most veg-
ments, and the presence and character of mottling.
etation types used in mapping represent a range
All profiles were photographed. To aid analyses,
of closely related types with some variability in
textural differences within a soil profile were
species composition. For example, the relatively
grouped into a single simplified texture (i.e.,
rare Closed Quaking AspenSpruce Forest, which
rocky, sandy, loamy, clayey, or organic) for a site,
was documented from field data, was combined
based on what was the dominant texture in the
with the more prevalent Closed SprucePaper
top 50 cm.
BirchQuaking Aspen Forest in the reduced code
Vegetation structure and composition were
set used for mapping. In all cases, however, an
assessed qualitatively. Percentage cover of indi-
emphasis was placed on preserving differences in
vidual species in a vegetation type was estimated
ecological significance and combining types only
visually to the nearest 5% if over 20%, and to the
where ecological function essentially was the
nearest 1% if below 20%. Dominant species were
same.
noted and a species list assembled. Total cover of
Many areas on Fort Wainwright have a highly
growth form types (e.g., tall shrubs, low shrubs,
patchy distribution of ecosystems that is related
graminoids, etc.) was evaluated independently of
to geomorphic or to other ecological processes
individual species and cross-checked for accuracy.
associated with disturbance regimes (e.g., fires).
All sites were photographed. Most species were
Areas that were mosaics of related ecosystems
identified in the field, and taxonomic nomencla-
were mapped as complexes, and the geomorphic
ture followed Viereck and Little (1972) for shrubs,
processes causing the patchiness were used as the
Hultn (1968) for other vascular plants, and Vitt
differentiating criteria. For example, thermal deg-
6
Go to contents page
Previous Page
