Sitka alder / Marsh horsetail
	Alnus viridis ssp. sinuata / Equisetum palustre
	n=3
	IIB(1)b: Closed Tall Alder Shrub
	Ecosystem:  Discharge Slope,  Relict Lakebed

Variable Sitka alder (Alnus viridis ssp. sinuata) types are widespread in Alaska, but a marsh horsetail (Equisetum palustre) understory is not described in the literature.

Sitka Alder / marsh horsetail was found in a few flat areas along the eastern terraced margin of the large isostatically rebounded marine terrace between Kasilof and Kenai, adjacent to low-relief kame-like features.  It is characterized by a dense canopy of Sitka alder with a thick marsh horsetail understory over plentiful marsh fivefinger (Comarum palustre) and open water.  Scattered paper birch (Betula papyrifera) overtops the alder, and occasional arctic starflower (Trientalis europea) is found at all locales.  Numerous other plants are present in low numbers.  Two shrubs, high-bush cranberry (Viburnum edule) and prickly rose (Rosa acicularis), can be abundant. 

The water table was at 2 centimeters at all three locales, and the organic layer was 160 cm thick.  All plots measured 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. 

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

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