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Wetland Classification and Mapping of the Kenai Lowland, Alaska
Map Unit Descriptions Ecosystem: Relict Glacial Lakebed
Map Unit: LB62; LB26; LB2-6
Extent: LB62: 36 wetland polygons; 481.3 ha; 0.34% of wetland area; 0.22% of wetland polygons. LB26: 27 wetland polygons; 323.8 ha; 0.23% of wetland area; 0.16% of wetland polygons. LB2-6: 8 wetland polygons; 147.3 ha; 0.10% of wetland area; 0.05% of wetland polygons. |
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 An LB26 unit in the large fen complex east of Anchor Point (polygon 70).
An LB62 unit in a large fen complex south of Ninilchik (polygon 2153).
A mixed LB2-6 unit on an upper terrace in the large fen complex east of Anchor Point (polygon 254). |
Wetland Indicators Type: Peat Average depth to water table: LB2: 11.3 cm; n=32 LB3: 9.9 cm; n=13 LB4: 19.5 cm; n=50 LB5: 57.0 cm; n=2 LB6: 31.4 cm; n=46 Organic layer thickness: LB2: 146.6 cm; n=36 LB3: 119.2 cm; n=13 LB4: 116.0 cm; n=52 LB5: 78.5 cm; n=2 LB6: 70.2 cm; n=62 Average depth to redoximorphic features: LB2: n/a LB3: n/a LB4: 79.0 cm; n=3 LB5: n/a LB6: 51.0; n=14 Common Soils: LB2: STARICHKOF, DOROSHIN LB3: STARICHKOF, DOROSHIN LB4: STARICHKOF, DOROSHIN, SALAMATOF, NIKOLAI LB6: STARICHKOF, KALIFONSKY, DOROSHIN, NIKOLAI 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 Tufted bulrush – Fewflower sedge Fewflower sedge – Tall cottongrass LB4 component: Sweetgale - Shrubby cinquefoil Sphagnum moss - Ericaceous shrub Bog blueberry – Dwarf birch – Tufted hairgrass
LB5 component:
LB6 component: Black spruce / Woodland horsetail - Labrador tea Black Spruce / Crowberry - Lingonberry Lutz spruce / Barclay's willow / Field horsetail / Crowberry |
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Accuracy assessment: The single polygon interpreted as
LB62 on
aerial photographs that was field checked remained LB62. 3 polygons interpreted as LB26 on aerial photographs were field checked. 2 remained LB26 1 was revised to LB42. None of the polygons interpreted as LB2-6 on aerial photographs were field checked. |
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The LB26 and LB62 complexes occur when a shallow water table, often sedge or sweetgale (Myrica gale)- dwarf birch (Betula nana) dominated LB2 component occurs with the woodland-to-forested LB6 component. If the shallow water table sedges or sweetgale dominate in a woodland setting, the unit is named LB26; if the forest is more or less continuous then it is named LB62.
These units are typically mixed as a woodland to moderately open forest with a dense wet sedge - sweetgale understory, at the slope break edges of subtle terraces present on larger relict lakebeds.
The LB2-6 unit is rare, but consists of all the Relict Glacial Lakebed ecosystem map components from the shallow water table, sedge and sweetgale dominated (LB2) through the sphagnum (LB3), shrub (LB4), bluejoint grass (Calamagrostis canadensis LB5), and woodland to forested (LB6) components mixed in a mosaic too fine-grained to map at a scale of 1:125,000. In one polygon named LB2-6, near Happy Valley, the components are concentrically arranged, with the wetter components towards the center, at in a small area nearly isolated from a large nearby lakebed complex. Another LB2-6 wetland, at the edge of a large complex near Kasilof, consists of a rapid transition from the wet sedge- sweetgale lakebed component to a forest on a mineral soil.
