Crowberry Labrador tea
Empetrum nigrum Ledum palustre ssp. decumbens   
n = 19
II.C.2.e. Open Low Ericaceous Shrub Bog
Ecosystem: Relict Lakebed / Drainageway, Depression

This is a common Alaskan type.  These dominants can occupy alpine areas where peat is not well developed, but in the Alaska Vegetation Classification (Viereck, et. al., 1992) those communities are classified as ericaceous shrub rather than shrub bog.

On the lowlands, the crowberry (Empetrum nigrum) - Labrador tea (Ledum palustre ssp. decumbens) type is widespread but more common south of Clam Gulch, primarily on relict glacial lakebeds.  It is sometimes found on abandoned relict drainageways in locales where peat is deeper.   

This community is dominated by a dense low cover of crowberry with abundant Labrador tea on a hummocky mossy peat.  Shrub birch (Betula nana) and bog blueberry (Vaccinium uliginosum) are often common to abundant.  Cloudberry (Rubus chamaemorus) and the dwarf shrubs lingonberry (Vaccinium vitis-idaea) and bog cranberry (Vaccinium oxycoccos) are often present.  

Peat is usually over 1 meter thick.  The water table is typically close to the surface, but was greater than a meter deep at three locations.  pH was only measured at one site where it was strongly to very strongly acid (5.0).  Seventeen of 19 plots visited are jurisdictional wetlands, while the other two are close calls.  

These peatlands are curious, the peat depth meets the soils hydric criterion, but sometimes the water table is very deep.  Where it is deep, these sites might represent dry years, dry times during the year, or suggest that a longer-term drying trend is prevalent.  See the discussion in the depression ecosystem description.

Table 1. Summary of plant frequency and average cover for plants occurring in more than 50% of plots.

   Soil Series n

Hydric Criteria number

STARICHKOF 7 1, 2B2, 3
1Proposed series, definitely hydric


Table 2.  Summary of plant frequency and average cover for plants occurring in more than 50% of plots.

          Wetland Indicator Status


f  Average Cover   Alaska National
Empetrum nigrum 1.0 51.6 FAC FACU, FACW
Ledum palustre ssp. decumbens   1.0 43.2 FACW FACW
Betula nana 0.9 25.1 FAC FAC, OBL
Vaccinium vitis-idaea 0.9 5.3 FAC FAC
Vaccinium uliginosum 0.8 11.3 FAC FACU+, FACW
Dwarf shrubs
Vaccinium oxycoccos 0.9 0.6 OBL OBL
Salix1 fuscescens   0.7 2.4 FACW FACW
Andromeda polifolia 0.6 3.3 OBL OBL
Rubus chamaemorus 0.9 17.1 FACW FACW
Equisetum arvense 0.6 13.0 FAC* FAC*, FACW-
Moss 0.8 88.4
Lichen 0.7 0.8
1 Plant with known morphological adaptation for occurrence in wetlands (USACE, 1987)


 Introduction and Key to Plant Communities  

Introduction and Key to Ecosystems

    Kenai Hydric Soils    Map Unit Summary    Methods    Glossary

Contact: Mike Gracz
Kenai Watershed Forum 
PO Box 15301
Fritz Creek, AK  99603
The Alaska Natural Heritage Program
Environment and Natural Resource Institute
University of Alaska, Anchorage
707 A Street, Suite 101
Anchorage, Alaska  99501

04 May 2007 09:39