Sphagnum moss - Round sedge
Sphagnum spp. - Carex rotundata
n = 8
III.A.3.j. Subarctic Lowland Sedge Bog
Ecosystem: Relict Lakebed / Drainageway, Kettle, Depression

The sphagnum moss - round sedge community described here is similar to Rosenbergs (1986) red cottongrass (Eriophorum russeolum) round sedge (Carex rotundata) community, found around the mouth of the Kenai River, and sometimes has a red cottongrass component.  We sampled a larger area with more plots, so are able to discriminate two types, a sphagnum moss (Sphagnum spp.) round sedge community and the sphagnum moss red cottongrass community described elsewhere in this document.

Found on well-developed peatlands over relict lakebeds, this is one of the only communities (along with the Sphagnum - leatherleaf community) on the Kenai lowlands that can indicate ombrotrophic bog development.  An ombrotrophic bog is a peatland that has built a sufficiently thick sphagnum layer to perch a precipitation-derived groundwater lens above the local groundwater table.  These perched lenses are theoretically very poor in nutrients, since the groundwater in them is entirely derived from precipitation, unlike the local groundwater table, which is flowing with some contact with the mineral soil below.  

Thick sphagnum mats with sparse vegetation cover dominated by round sedge and a few other taxa such as bog rosemary (Andromeda polifolia), bog cranberry (Vaccinium oxycoccos) and round sundew (Drosera rotundifolia) characterize this type.  

The organic horizon is at least one meter thick.  The water table can be close to the surface, but it was nearly a meter (36) below the surface at one site. The pH is strongly to very strongly acid (average = 4.8).  All sites visited are jurisdictional wetlands.

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

        Wetland Indicator Status



 Average Cover

  Alaska National
Dwarf shrubs
Andromeda polifolia 1.0 4.0 OBL OBL
Vaccinium oxycoccos 1.0 1.1 OBL OBL
Carex rotundata 1.0 11.1 OBL OBL
Drosera rotundifolia 0.9 2.1 OBL OBL
Eriophorum russeolum   0.8 2.3    FACW FACW


 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 10:03