This habitat is transitional between wetland and upland and between freshwater and estuarine environments. Occasionally it is inundated with water of salinity greater than 0.5 ppt. Substrata are usually organic, either peat for areas transitional between wetland and upland, or muck for areas transitional between freshwater and estuarine. Other substrata in these areas are sand (along stream channels) and clay.
Five communities can occur in this habitat: (1) Juncus balticus-Potentilla pacifica-forb, (2) Calamagrostis nutkaensis, (3) Picea sitchensis, (4) Scirpus acutus and (5) Typha latifolia. The first three communities are generally transitional between wetland and upland and are species rich. The last two communities are transitional between freshwater and estuarine, substrata are usually anoxic muck and stands are often monospecific.
The first community is similar to the high marsh communities but adds several forb species typically found in uplands, notably Achillea millefolium, Angelica lucida and Heracleum lanatum. The second community contains some of the high marsh species, but is dominated by a whole new set of species, most notably Calamagrostis nutkaensis, Pyrus fusca and Sidalcea hendersonii. The third community is very similar in species composition to the second, except Picea sitchensis is a dominant species.
Other common vascular plant associates in the first three communities are: Carex lyngbyei, Oenanthe sarmentosa, Trifolium wormskjoldii, Vicia gigantea and Festuca rubra. The fourth and fifth communities usually occur as monospecific stands.
Hamma Hamma River Delta, Skagit River Delta, Port Susan Bay, Quilceda Creek, Kennedy Creek, Johns River, Elk River, Andrews Creek, North Bay, North River, Bone River, Niawiakum River, Palix River, Bear River, Naselle River, Baker Bay.
Kunze, 1984; Ewing, 1983 and 1982; Kunze and Cornelius, 1982; Frenkel, Boss and Schuller 1978.