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Wetland Classification and Mapping
of the Kenai Lowland, Alaska
Map Unit Descriptions
Ecosystem: Depression Map Units: D23; D32
Extent: D23: 218 wetland polygons; 288.0 ha; 0.20% of wetland area; 1.32% of wetland polygons. D32: 138 wetland polygons; 232.2 ha; 0.16% of wetland area; 0.84% of wetland polygons. |
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 A segregated D23 depression near Nikiski (polygon 1261).
A mixed D32 depression near Nikolaevsk (polygon 6971). |
Wetland Indicators Type: Peat Average depth to water table: D2: 6.8 cm; n=5 D3: 10.0 cm n=1 Organic layer thickness: D2: 146.2; n=5 D3: 121.0; n=3 Average depth to redoximorphic features: n/a Common Soils: D2: STARICHKOF and DOROSHIN Common Plant communities: D2 component: Tall cottongrass - Livid sedge Beaked sedge – Water horsetail D3 component: |
| Accuracy
assessment:
23 polygons interpreted as D23 on aerial photographs were field checked. 9 remained D23, 1 each was revised to: D1-3, D2, D1-4 and D34. 3 each were revised to D32 and uplands. 4 were revised to D3. 12 polygons interpreted as D32 on aerial photographs were field checked. 2 remained D32, 3 each were revised to D3 and upland; 1 each was revised to LB3, D2, D21 and D23. |
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D23 and D32 map units are small but widespread and common depression ecosystem wetlands. They are depressions with sedge and shrub dominated plant communities. If sedges predominate the depression (often with the shrubs sweetgale (Myrica gale) and dwarf birch (Betula nana)) with a water table close to the surface, the unit is named D23, and if other shrubs dominate, with a deeper water table, it is named D32. In segregated units, shrubs form a ring around a more central sedge community; in mixed units the sedges occupy micro lows while the shrubs, often with deep sphagnum moss, form hummocky micro high spots. Depressions are most common on younger glacial surfaces, especially on the moraines between Nikiski and Sterling, and east of Sterling.
