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Wetland Classification and Mapping of the Kenai Lowland, Alaska
Map Unit Descriptions Ecosystem: Relict Glacial Drainageway Map Unit: DW35A; DW5A3; DW3-5A
Extent: DW35A: 159 wetland polygons; 1533.2 ha; 1.08% of wetland area; 0.96% of wetland polygons. DW5A3: 125 wetland polygons; 866.3 ha; 0.61% of wetland area; 0.76% of wetland polygons. DW3-5A: 36 wetland polygons; 400.8 ha; 0.28% of wetland area; 0.22% of wetland polygons. |
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A segregated DW35A unit in the Soldotna Creek watershed (polygon 555).
A mixed DW5A3 unit in the Soldotna Creek watershed (polygon 562).
A segregated DW3-5A wetland along a terrace tread south of Clam Gulch (polygon 11611). |
Wetland Indicators Type: Peat Average depth to water table: DW3: 32.1 cm; n=36 DW4: 53.3 cm; n=4 DW5: 37.4 cm; n=14 DW5A: 38.8 cm; n=24 Organic layer thickness: DW3: 102.2 cm; n=40 DW4: 68.6 cm; n=4 DW5: 78.2 cm; n=14 DW5A: 46.3 cm; n=24 Average depth to redoximorphic features: DW3: 67.8 cm; n=6 DW4: 70.0 cm at the single site measured DW5: 135.0 cm at the single site measured DW5A: 60.7 cm; n=3 Common Soils: DW3: STARICHKOF, NIKOLAI, DOROSHIN, SLIKOK, COAL CREEK DW4: STARICHKOF, NIKOLAI DW5: NIKOLAI, STARICHKOF, TRUULI DW5A: TRUULI, NIKOLAI, STARICHKOF, Common Plant communities: DW3 component: Sweetgale – Dwarf birch / Water horsetail Barclay's willow / Bluejoint / Marsh fivefinger Sweetgale – Shrubby cinquefoil DW4 component: DW5 component: Sphagnum moss - Ericaceous shrub Lutz spruce / Barclay's willow / Field horsetail / Crowberry DW5A component: Lutz spruce / Barclay's willow / Field horsetail / Crowberry |
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Accuracy assessment: 21 polygons interpreted as DW35A
on aerial photographs were field checked. 10 remained DW35A, 3 were
revised to DW3-5A; 1 each was revised to DW3,
DW5A, DW5A3, DW5A4,
K4, RB, Rea
and SML. 13 polygons interpreted as DW5A3 on aerial photographs were field checked. 4 remained DW5A3, 2 were revised to SM, 1 each was revised to: D2-4, DW34, DW3-5A, DW5A, K43, RB and upland. 4 polygons interpreted as DW3-5A on aerial photographs were field checked. 3 remained DW3-5A, 1 was revised to LB63. |
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DW3-5A complexes are common along the margins, and outside the floodplains of 'underfit' streams. DW5A represents a forested component, and DW3 is a wet, hummocky, shrubby component. The two components typically mix: In DW35A, a shrubby, hummocky DW3 component either dominates a woodland setting, or, in DW5A3, forms the understory of a spruce forest (either black (Picea mariana) or Lutz spruce (P. X lutzii)). Uncommonly, when a more or less pure bluejoint (Calamagrostis canadensis) component (DW4) is also present, the wetland is named DW3-5A.
This complex often occupies the edge of the valley bottom, along one edge lies a rapid, short transition to either an upland or, more commonly, a discharge slope occupied by either Lutz or black spruce. The other edge of these linear units, away from the valley wall, is typically occupied by a riparian unit, often a linear Rosgen 'E' stream.
The components can segregate, with a drier forested band close to the valley wall, and a wet shrubby, hummocky component closer to the stream. When bluejoint grass (Calamagrostis canadensis) dominates uniform patches (DW4), the unit is named DW3-5A.
