Sitka alder / Shieldfern
Alnus viridis ssp. sinuata / Dryopteris expansa  
n= 9
IIB(1)b: Closed Tall Alder Shrub
Ecosystem: Discharge Slope

Sitka alder (Alnus viridis ssp. sinuata) types are widespread and variable in Alaska (Viereck et al 1992), but a shieldfern (Dryopteris expansa) understory has not been previously described in the literature.

Sitka Alder / sheildfern is uncommon.  It usually is found on steep back- and footslopes near the coast. 

Tall Sitka alder (greater than 2 meters) and shieldfern cover are nearly complete (95-100%).  Bluejoint grass (Calamagrostis canadensis) is present at about 20% cover.  Field horsetail (Equisetum arvense), red elderberry (Sambucus racemosa), and arctic starflower (Trientalis europea) are common associates.  

This can be an upland type.  The water table was at 150 centimeters at the one site where it was measured.  However, redoximorphic features (soil evidence that the water table is seasonally high) were found closer than 30 cm from the surface at two sites.  At the one nearly level location (on the toeslope of a steep gully), along the coast between Clam Gulch and Ninilchik, a 150 cm thick organic layer was measured, with redox features at 12 cm.  Four of the nine plots sampled could be classified 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. 

   Soil Series n Hydric Criteria number
REDOUBT 2
COHOE 1  
NAPTOWNE 1  
QUTAL 1  
CHUNILNA 1 2B3
NIKOLAI 1 1
SPENARD 1 2B3

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

         Wetland Indicator Status

 Plant

f

 Average Cover

   Alaska National
Shrubs
Alnus viridis ssp. sinuata 1.0 98.3 FAC FAC, FACW*
Low Shrubs
Ribes laxiflorum 0.7 0.5 na
Herbs/Graminoid
Dryopteris expansa 1.0 61.7 FACU FACU, FACW
Calamagrostis canadensis 1.0 19.7 FAC FAC, OBL
Equisetum arvense 1.0 3.2 FAC* FAC*, FACW-
Sambucus racemosa 1.0 2.0 FACU* FACU*,
Trientalis europaea 1.0 1.7 FAC FAC*, FAC
Equisetum sylvaticum 0.7 7.8 FACU FACU, FACW
Gymnocarpium dryopteris 0.7 3.8 FACU UPL, FAC
Moss 1.0 2.5      

 


 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
907-235-2218
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 09:36