Table 8 (cont.). Description of ecotypes found on Ft. Wainwright, central Alaska, 1998.
Class
Description
Riverine Moist
Riverine areas with moist, loamy soils and vegetation dominated by tall shrubs. The well-drained soils usually lack
Tall Scrub
organic horizons (indicating frequent flooding), are slightly acidic, lack permafrost, and have moderately deep water
tables. The closed canopy is dominated by willows (Salix arbusculoides, S. alaxensis, S. bebbiana, S. lasiandra) or Alnus
tenuifolia. Calamagrostis canadensis, and Equisetum arvense also are common.
Riverine Wet
Riverine areas with wet, loamy soils and vegetation dominated by low shrubs. The poorly drained soils occur along
Low Scrub
channels near slow moving rivers and headwater streams. The vegetation is dominated by willows (Salix planifolia),
ericaceous shrubs (Ledum groenlandicum, Vaccinium uliginosum) and sedges.
Riverine Wet
Riverine areas with wet, loamy soils and vegetation dominated by sedges. Soils are poorly drained, have ground water
Meadow
near the surface, usually lack organic horizons (indicating frequent flooding), lack permafrost, and are associated with
abandoned channels and oxbows. Vegetation is dominated by Carex aquatilis and C. rostrata. Riverine Marshes, also
included in this class, are dominated by Scirpus validus, Equisetum fluviatile and Typha latifolia.
Riverine
Unvegetated or partially vegetated (<30% cover) river bars that are flooded frequently. Colonizing species include Salix
Barrens
alaxensis, S. interior, and Equisetum arvense.
Riverine
A mosaic of ecotypes associated with fluvial processes (river, active and inactive floodplains). Common ecotypes include
Complex
Riverine Moist Needleleaf Forest, Riverine Moist Broadleaf Forest, Riverine Moist Tall Scrub, Riverine Wet Low Scrub,
Riverine Wet Meadows, and Riverine Barrens.
Lacustrine
These types are most commonly found on wet, organic soils at the borders of ponds and lakes, vegetation is dominated
Fen Meadow
by herbs. Soils have moderate to thick organic horizons of herbaceous peat, are neutral (pH), minerotrophic, and lack
permafrost. Vegetation is dominated by Potentilla palustris, Equisetum fluviatile, and Carex aquatilis. Associated species
include Menyanthes trifoliata, C. rostrata, Eriophorum russeolum and C. canescens.
Lakes and Ponds
Lacustrine water bodies with or without submerged or floating vegetation (e.g. Potamogeton spp., Nuphar polysepalum,
Lemna minor, or Hippuris vulgaris). Lakes may be oxbows along rivers, bedrock controlled, or thaw basins.
Lower/Upper
Lower perennial rivers, both braided and meandering, that are relatively far from their sources. Peak flooding generally
Perennial River
occurs during spring breakup when ice jams, or in summer after heavy rainfall or rapid glacial melting. Some water
flows throughout the year. Upper perennial rivers generally are small streams.
Human Modified
Barren or partially vegetated (<30% cover) areas resulting from human disturbance.
and an additional 6 complex units that were com-
dominated by Lowland Wet Needleleaf Forest,
binations of ecotypes occurring in highly patchy
Lowland Wet Low Scrub, Lowland Fen Meadow,
areas (Table 8). This final grouping of ecotypes
and Thermokarst Forest and Scrub Complexes
was derived from 409 integrated terrain units
that were not found in the YMA. The Tanana Flats
(geomorphicvegetation combinations) (see
also differed in that ecotypes often were highly
App. A). Much of this reduction and simplifica-
patchy, resulting in the mapping of extensive com-
tion resulted from combining geomorphic types
plex units. One common forest ecotype, Lowland
that had similar texture and combining similar
Wet Needleleaf Forest (dominated by Black
vegetation types that had small differences in
Spruce) was the dominant component of the Low-
canopy cover (open vs. closed) (see Table 3).
land ForestThermokarst Complex.
The maps reveal large differences in the distri-
Ecosections. Although separate ecosection
bution of ecotypes between the YMA and the
maps have not been included in this report to
Tanana Flats (Table 9, Fig. 23 and 24). The Yukon
reduce the volume and redundancy of material,
Maneuver Area was dominated by Upland Moist
they are essentially the same as the geomorphic
Needleleaf Forest, Upland Wet Needleleaf Forest,
maps because geomorphology is the differentiat-
Upland Moist Broadleaf Forest, Upland Moist
ing characteristic (see Geomorphology section). The
Mixed Forest, and Lowland Wet Needleleaf For-
ecosection concept differs from a straight geomor-
est. The YMA also had a few scattered patches of
phology map, however, in that conceptually the
Alpine Rocky Dry Dwarf Scrub and Alpine Rocky
ecosection map is intended to include the eco-
Moist Tall and Low Scrub that were not found on
types that generally are associated with each geo-
the Tanana Flats. In contrast, the Tanana Flats was
morphic unit (Table 7). For example, Weathered
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