Lyngbye’s sedge – Water horsetail
Carex lyngbyei – Equisetum fluviatile
n = 4
III.A.3.f. Subarctic Lowland Sedge Wet Meadow
Ecosystem: Kettle

While the Lyngbye’s sedge (Carex lyngbyei) type is well described in Alaska, and is described as mixed with other halophytes (salt-loving plants), it has not been described mixed with non-halophytic water horsetail (Equisetum fluviatile).

Both the measured sites were found near an interesting lagoon northeast of Nikiski.  1950 aerial photography reveals that the current lagoon was formerly a lake with a fringing peatland.  Probably, 1964 earthquake subsidence resulted in the breach of the narrow berm separating the former lake from Cook Inlet.  The shoreline probably rebounded some, post-quake (Combellick, 1997).

Now, saltwater plants are mixed with species associated with freshwater.  One lobe of the former lake/peatland is only rarely, if at all influenced by saltwater, and that is where the lyngbye sedge - water horsetail type is located.  Concentric plant communities radiate from the center, which is a floating mat.  

Beaked sedge (Carex utriculata) dominates at the center and grades outward to a community dominated by Lyngbye's sed water horsetail.  Moving further outward, water horsetail and western water hemlock (Cicuta douglasii) become more abundant, and beaked, then Lyngbye’s sedge drop out, eventually giving way to bluejoint grass (Calamagrostis canadensis) along the upland fringe.  

Standing water is abundant; the water table is just below the litter and clumps of sedge.  The floating organic layer is about 20 centimeters thick.  pH was slightly acid (6.3).  This type is always a jurisdictional wetland.

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
Carex lyngbyei   1.0 43.0 OBL OBL
Equisetum fluviatile 1.0 32.5 OBL OBL
Lemna minor 1.0 7.0 OBL OBL
Cicuta douglasii   1.0 7.0 OBL OBL
Carex utriculata 1.0 5.5 OBL OBL
Epilobium palustre 1.0 2.8 OBL OBL
Open water 1.0 3.8      

 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 09:38