Thinleaf alder / Bluejoint
	Alnus incana ssp. tenuifolia/ Calamagrostis canadensis
	n=15
	II.B.1.b: Closed Tall Alder Shrub
	Ecosystem:Discharge Slope

 

Tall alder shrub types are well known and described for Alaska.  Thinleaf alder (Alnus incana ssp. tenuifolia) types have been described by Hanson (1953), Hogan and Tande (1983) and VanCleve et. al. (1971).  However, thinleaf alder was not identified nearby in Chugach National Forest (DeVelice, et. al., 1999) or on the Copper River (Boggs, 2000).  

 

On the Kenai lowlands, thinleaf alder / bluejoint (Calamagrostis canadensis) sites are found at toeslope positions near the coast north of Clam Gulch, and along the bluffs above the north shore of Kachemak Bay.  Thinleaf alder bluejoint is a variable type within this uniform landscape position, but all sites have tall alder (greater than 2 m), typically as a closed canopy, with abundant bluejoint cover.  Sites with a more open alder canopy, have greater bluejoint cover.  Jacob’s ladder (Polemonium acutiflorum) and water horsetail (Equisetum fluviatile) are frequently present. 

 

Around Seward, thinleaf alder is replaced by Sitka alder (Alnus viridis ssp. sinuata) in a similar community, often in floodplain wetlands and on more recent river terraces.

 

Standing water is sometimes encountered, but the water table was 210 centimeters below the surface at one site.  Organic layers are typically thin, although two plots had an organic layer greater than 1 meter thick.  pH is neutral to slightly alkaline, averaging 7.0, with one coastal site measuring 7.6.  Eleven of the 15 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.

 

             

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