The Alaska Vegetation Classification - Alaska Geobotany Center ...

Dlstrlbutlon and Slte characterlstlcs-Small stands 01 these communities arelocally common in tundra areas (arctic and alpine) throughout the State in verywet, poorly drained sites with standing water, such as oxbow lakes, lake and pondmargins, kettles and other depressions, and very wet polygon pans. The standingwater is usually shallow (15 centimeters [6 in] or less) but probably is sometimesdeeper. Soils are poorly drained and fine textured, mineral or organic-rich, butwithout a well-presewed organic mat. Soil pH ranges from basic to acid but probablyare not extremely acid. Permafrost is present at most sites 50 to 100 centimeters(20 to 40 in) below the surface but is absent from southeastern and south-centralAlaska alpine sites.Closely related types-This is a variant of wet sedge meadow tundra, differing inhaving a codominant broad-leaved herb component. It is similar to the subarcticlowland sedge meadow (lll.A.3.f.) within the tree line, though with more herbs. Withincreasing sphagnum, it also is similar to the subarctic lowland sedge-moss bogmeadow (lll.A.3.k.). Mesic sedge-herb meadow tundra (lll.A.2.f.) is dominated bydifferent species and occupies well-drained soils, usually on slopes. The wet herbunits under the wet forb herbaceous branch of this classification (level 3, 111.8.3.) lacka significant sedge component and are generally restricted to the forested parts ofthe State.Prlmary references-Bliss and Cantlon 1957, Webber and others 1978.Communities-Carex aquatilis-Menyanfhes trifoliata (Racine 1976, Webber andothers 1978). Carex aquafilis-C. membranacea-Pefasites frigidus (Scott 1974a).Carex aquatilis-Potentilla palusfris (Bliss and Cantlon 1957, Webber and others1978). Carex nigricans-Eriophorum angustifolium-Fauria crista-gal/;-Trichophorumcaespifosum (Fox 1983, Jaques 1973). Trichophorum caespitosum-Triglochinpalustris (Webber and others 1978).lll.A.3.d. Fresh Sedge MarshDescription-These communities are dominated by tall emergent sedges, primarilyScirpus validus or Eleocharis palusfris (fig. 65). Trees, shrubs, and lichens areabsent; aquatic mosses may be present, but are not abundant. Plant cover mayappear fairly dense when viewed from the side but generally is less than 50 percentbecause the dominant plants have no leaves.Dlstrlbutlon and site characteristics-Fresh sedge marshes occur locally in deep(15 to 100 centimeters 16 to 14 in]) water of ponds, sloughs, and oxbow lakes insouth-central and southeastern Alaska. Our reports have been from coastal settingswhere fresh sedge marshes occur in fresh water, although most of these sites areinfrequently flooded by sea water during storm surges. These communities also areexpected to occur in inland lakes, ponds, and sluggish streams. Soils are mineral ororganic-rich mucks.SUCCeSSlOnal status-These communities are early colonizers of ponds and otherwater bodies and may be replaced eventually by wet sedge meadow as plant detritusand other sediments accumulate. Under certain circumstances, these communitiescould be encroached upon by horizontal growth of peat mats of adjacent bog or fencommunities180