|n = 5|
|III.A.(3)h. Halophytic Grass Wet Meadow|
Alkaligrass (Puccinellia spp.) associations are well documented for coastal Alaska. The most common plants found along Kenai Lowland shores are Hultén’s (P. hulténii), creeping (P. phyganodes) and nutka (P. nukaënsis) alkaligrass, although dwarf alkaligrass (P. tenella ssp. alaskana) was found at one site. Individual plant preferences along a gradient from saltpannes to upland are readily observable in the tidally influenced zone, and delineation of communities is somewhat arbitrary (cf. Vince and Snow, 1984). Alkaligrass occurs most commonly between a seaside arrowgrass (Triglochin maritimum) zone, seaward and a Ramensk’s sedge (Carex ramenski) zone, inland. In Kachemak Bay, Crow and Koppen (1977) describe a nutka alkaligrass – seaside arrowgrass community; and several workers, including Boggs (2000) on the Copper River Delta, describe a monotypic nutka alkaligrass type. Others describe a creeping alkaligrass – seaside arrowgrass type, and a monotypic creeping alkaligrass type (Viereck, et. al., 1992). Hultén’s alkaligrass types are not reported.
Alkaligrass communities occur on protected tidal mudflats, below the zone where goosetongue (Plantago maritimaand seaside arrowgrass occur, but above the lowest saltpannes, occupied by slender glasswort (Salicornia maritima) and stickystem pearlwort (Sagina maxima). On the Susitna Flats, alkaligrass communities occupy Vince and Snow's (1984) 'Outer mudflats, Zones 1 (P. phryganodes) and 2 (P. nutkaënsis)' which flood a minimum of 26-46 (average = 34) and 10-20 (average = 15) times per summer, respectively.
The sites we visited are all located on the northern peninsula, though this type also occurs on the Fox River flats and along the Homer spit.
Plant cover is frequently sparse, but Hultén’s and creeping alkaligrass are found in thick stands. The most common vascular associates are goosetongue and seaside arrowgrass, although pacific silverweed (Argentina egedii), Alaskan orache (Atriplex alaskensis) and marsh arrowgrass (Triglochin palustre) were all encountered more than once.
One alkaligrass plot at the mouth of the Kenai river is underlain by 51 cm of material that contains sufficient peat to qualify as an organic horizon. Buried organic material could result from a couple of processes. Unlike on the Copper River Delta (Boggs, 2000) and Yakutat Forelands (Shephard, 1995), many Kenai Peninsula tidelands subsided, rather than uplifted during the 1964 earthquake. The subsidence resulted in tidal inundation of pre-quake uplands. A peatland was buried in a lagoon north of Nikiski. At the mouth of the Kenai and Fox Rivers, higher vegetation zones were buried. Normal depositional processes could also account for the burial of the organic material in this dynamic ecosystem. Both Cook Inlet and the Kenai River provide a substantial sediment source.
The water table is generally deep, although these types flood usually at
least twice per month, during spring tides.
The pH at the one site measured was moderately alkaline at 8.0.
All five sites are jurisdictional wetlands.
Table 1. Summary of plant frequency and average cover for plants occurring in more than 50% of plots.
|Wetland Indicator Status|
|Contact: Mike Gracz Kenai Watershed Forum PO Box 15301 Fritz Creek, AK 99603 907-235-2218||
Alaska Natural Heritage Program
and Natural Resource Institute
707 A Street, Suite 101
Anchorage, Alaska 99501
04 May 2007 09:54