|Bluejoint / Dwarf birch|
|Calamagrostis canadensis / Betula nana|
|n = 8|
|II.C.2.f? Open Low Shrub Birch-Willow Shrub|
|Ecosystem: Riparian, Relict Drainageway, Depression, Discharge Slope|
Bluejoint / dwarf birch is not described elsewhere and does not fit into classes defined in The Vegetation of Alaska (Viereck et. al., 1992). Dwarf birch (Betula nana) peatland types without other shrub associates are not described for Alaska, but are common on the Kenai lowlands. Viereck, et. al. (1992) describe a “Shrub birch” type under the closed low scrub class (II.C.1.a.), and cite a Betula nana community (Craighead, et. al. 1988; Hopkins and Sigafoos, 1951; and Racine and Anderson, 1979). In Chugach National Forest, DeVelice, et. al. (1999) describe the same, broad Betula nana, (dwarf birch) type. All of these describe a dry, alpine tundra type with highly variable species composition.
On the Kenai, by contrast, 241 of the 904 plots used in this analysis have dwarf birch cover greater than 10%, none of them in tundra or alpine positions. The Alaska Vegetation Classification (Viereck, et. al., 1992) class ‘II.C.2.d Open Low Shrub Birch-Ericaceous Shrub Bog” fits better, but requires ericaceous shrub associates; while the II.C.2.f class, perhaps the closest fit, requires willow associates. Barclay willow (Salix barclayi), was found at 6 plots visited, but always at less than 5% cover. Thirty-four plots in three community types on the Kenai lowlands have shrub birch as a co-dominant, without significant willow or ericaceous shrub cover. A new vegetation class is needed: II.C.2.x: “Open Low Shrub Birch- Graminoid Fen”.
Fen is a widely accepted term, and many of the names in the Alaska Vegetation Classification should be revised to reflect the commonly used peatland terminology of: 1) bog for perched or depressional ombrotrophic peatlands; 2) fen for peatlands with some degree of minerotrophy; and 3) patterned ground for peatlands underlain by permafrost.
Bluejoint (Calamagrostis canadensis) / dwarf birch is primarily found along underfit stream valley bottoms particularly near the valley walls. This type can also be found in disturbed peatlands (e.g. by logging, or near culverts), and two sites are located where a stream spreads across the large peatland complex east of Anchor Point.
A closed canopy of tall bluejoint tops open dwarf birch. Scattered Barclay willow may be present, and water horsetail (Equisetum fluviatile) and marsh fivefinger (Comarum palustre) are both usually found in low spots between bluejoint tussocks, often near small pools of open water.
A thick organic mat is present, and the water table is typically close to
the surface. All eight plots
sampled qualify as jurisdictional wetlands.
Table 1. Frequency of occurrence and hydric status of soil series named at NRCS holes. Bold type indicates soils on the NRCS Alaska hydric soils list.
2. Summary of plant frequency and average cover for plants occurring
in more than 50% of plots .
|Wetland Indicator Status|
|Betula nana||1.0||14.8||FAC||FAC, OBL|
|Salix1 barclayi||0.8||2.4||FAC||FAC, FACW|
|Calamagrostis canadensis||1.0||52.3||FAC||FAC, OBL|
|1 Plant with known morphological adaptation for
occurrence in wetlands (USACE, 1987)
|Contact: Mike Gracz Kenai Watershed Forum PO Box 15301 Fritz Creek, AK 99603 907-235-2218||
Alaska Natural Heritage Program
and Natural Resource Institute
707 A Street, Suite 101
Anchorage, Alaska 99501
04 May 2007 09:37