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Wetland Classification and Mapping of the Kenai Lowland, Alaska
Map Unit Descriptions
Ecosystem: Relict Glacial Lakebed Map Unit: LB23; LB32
Extent: LB23: 106 wetland polygons; 1408.8 ha; 0.99% of wetland area; 0.64% of wetland polygons. LB32: 68 wetland polygons; 451.6 ha; 0.32% of wetland area; 0.41% of wetland polygons. |
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 A large mixed LB23 unit in a fen east of Anchor Point (polygon 467).
A small mixed LB32 unit 15 miles northeast of Homer (polygon 10848). |
Wetland Indicators Type: Peat Average depth to water table: LB2: 11.3 cm; n=32 LB3: 9.9 cm; n=13 Organic layer thickness: LB2: 146.6 cm; n=36 LB3: 119.2 cm; n=13 Average depth to redoximorphic features: n/a Common Soils: LB2: STARICHKOF, DOROSHIN LB3: STARICHKOF, DOROSHIN Common Plant communities: LB2 component: Tufted bulrush - Tall cottongrass Sweetgale – Dwarf birch / Water horsetail Tufted bulrush – Fewflower sedge
LB3 component: Sphagnum moss - Ericaceous shrub Sphagnum moss / Tall cottongrass Sphagnum moss - Manyflower sedge |
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Accuracy assessment: 17 polygons interpreted as LB23 on
aerial photographs were field checked. 7 remained LB23; 3 each were
revised to LB32 and LB2-4; 1
each was revised to: LB2, LB3,
LB34 and LB63. 6 polygons interpreted as LB32 on aerial photographs were field checked. 4 remained LB32, 1 each was revised to LB3 and LB34. |
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The common and widespread LB23 complex occurs when the shallow water table, often sedge-dominated LB2 component and the deeper water table, sphagnum moss-dominated LB3 component are present together. These components are typically present as a relatively fine-grained patchy mosaic, rater than segregated into units too small to delineate at a scale of 1:25,000. When sedges and a shallower water table predominate, the unit is named LB23, and when sphagnum communities dominate they are named LB32.
LB23 and LB32 occupy extensive relict glacial lake bottoms, usually near the coastal margin of the lowlands. They indicate weak patterned fen development: Micro-highs, occupied by the LB3 sphagnum component, often form low ridges above ill-defined, elongate micro-lows (flarks) occupied by LB2 sedge communities.
