Physiognomy and Structure: Vegetation is predominantly dwarf-shrubs or herbaceous (vascular or nonvascular) plants with a moss-dominated ground layer. Stunted trees may be present or a mosaic of patches of stunted trees amongst the mostly herbaceous area.

Floristics: Acidic fen herbaceous species include Carex anthoxanthea, Carex aquatilis var. dives (= Carex sitchensis), Carex limosa, Carex pauciflora, Carex pluriflora, Comarum palustre, Cornus canadensis, Dodecatheon pulchellum, Drosera rotundifolia, Geum calthifolium, Nephrophyllidium crista-galli, Parnassia kotzebuei, Rubus chamaemorus, and Sanguisorba menziesii. Moss species include Sphagnum fuscum, Sphagnum austinii, Sphagnum henryense, Sphagnum pacificum, Sphagnum papillosum, Sphagnum rubellum, Sphagnum mendocinum, and Philonotis fontana var. americana. Liverworts include species of Nardia, Marsupella, and Scapania. Shrub species include Andromeda polifolia, Betula nana, Empetrum nigrum, Kalmia microphylla, Ledum groenlandicum, Ledum palustre ssp. decumbens, Myrica gale, Salix pulchra, Vaccinium cespitosum, Vaccinium oxycoccos, and Vaccinium uliginosum. Stunted (<5 m) tree species, if present, include Callitropsis nootkatensis (= Cupressus nootkatensis), Picea sitchensis, Pinus contorta var. contorta, Pinus monticola, Thuja plicata, Tsuga heterophylla, or Tsuga mertensiana.

Neutral to alkaline fens may have brown mosses such as Campylium, Drepanocladus, Scorpidium, Tomentypnum, and Warnstorfia. Indicator species include Betula nana, Carex aquatilis, Carex cusickii, Carex lasiocarpa, Carex livida, Carex utriculata, Comarum palustre, Menyanthes trifoliata, Myrica gale, Spiraea douglasii. Trees may be present at the edges or on raised hummocks where soils are not anoxic and include Tsuga heterophylla, Thuja plicata, Callitropsis nootkatensis, Pinus contorta var. contorta, and/or Picea sitchensis.

Along the coast, Pinus contorta does not occur north of Juneau in southeastern Alaska; however, further inland it does occur much farther north in the Yukon Territory. Treed bogs in the Pacific Northwest have mostly Pinus contorta var. contorta or Callitropsis nootkatensis but can include some Tsuga heterophylla, Tsuga mertensiana, or Thuja plicata. Ledum groenlandicum is generally the dominant shrub understory species; other shrubs include Vaccinium uliginosum, Juniperus communis, Myrica gale, or Gaultheria shallon. Low-shrub species include Empetrum nigrum, Kalmia microphylla, and Rubus chamaemorus. Herbaceous species include sedges such as Eriophorum angustifolium, Trichophorum cespitosum, Carex livida, or herbs such as Sanguisorba officinalis, Triantha glutinosa, or Drosera rotundifolia. Dominant bryophytes include Sphagnum spp. and Racomitrium lanuginosum.

Floristic information was summarized from the following sources: Shacklette et al. (1969), Knight et al. (1970), Thorne (1976), Sawyer et al. (1978), Slack (1979), Eyre (1980), Kruckeberg (1984), Banner et al. (1986, 1988, 1993), Keeler-Wolf (1986), Sawyer (1986), DeMeo et al. (1992), Viereck et al. (1992), Kunze (1994), Talbot and Talbot (1994), Jimerson et al. (1995), Martin et al. (1995), Shephard (1995), DeVelice et al. (1999), Boggs et al. (2003, 2008a, 2008b), Kagan et al. (2004), MacKenzie and Moran (2004), Talbot et al. (2006), and Fleming and Spencer (2007).

Dynamics:  Natural disturbance events along north coastal peatlands play an important role in slowing and reducing organic matter accumulation on specific types of sites. The main types of natural disturbance are landslides, windthrow, and fluvial activity (Banner et al. 2005). Peatlands on steep slopes experience landslides and windthrow events which tend to mix soil and slow the buildup of organic layers. On more gentle terrain, disturbance is less frequent, which allows for a deep accumulation of organic matter. Disturbance here is of small and localized scale. Large-scale disturbance such as major blowdown or severe fire are infrequent (>1000 years).

Fire, when it does occur, stimulates growth of mosses that prefer bare substrates, and starts the successional sequence of different mosses and vascular plants. Fires also increase nutrient availability and may temporarily create a carbon sink. Fire scars on stumps within herbaceous bogs and fens have been observed, pointing to a need for more study (Banner et al. 2005, J. Rocchio pers. comm. 2013). It has been documented that Native Americans burned herbaceous wetlands of the Olympic Peninsula annually to keep trees from invading wetland openings (Anderson 2009).

In addition to disturbance, there are natural cycles and interplay between the advancement and retreat of peat levels (the buildup of peat that alters depth of rooting zone relative to groundwater, or decrease in peat depth from an increase decomposition due to drought) and encroachment peat into surrounding uplands (paludification) or the reverse, surrounding upland species that may shade out moss species. Generally, the greatest (annually measurable) change generally occurs on the edges of fens and bogs and at the tops of hummocks. These small-scale dynamics depend on the type of wetland and specific local site characteristics that cannot be generalized in a group description. Some examples are given here. In Alaska, species that dominate the early stages of succession in newly formed ponded basins include Equisetum variegatum, Equisetum fluviatile, and Comarum palustre, while Sphagnum species invade the surface and help in forming peat. Acidic and nutrient-poor-tolerant vascular species eventually dominate such sites, including Myrica gale, Empetrum nigrum, Vaccinium uliginosum, Andromeda polifolia, and Vaccinium oxycoccos. The late-successional stage of a peatland supports various community types, depending on the pH, waterflow, and nutrient status of a site, such as Myrica gale / Empetrum nigrum and Picea sitchensis / Sphagnum plant associations. Peat buildup, patterned ground, and changes in water table are recurrent aspects of peatland development rather than unidirectional successional events. For this reason it is unlikely that any of the late-seral peatland communities are stable in the sense of climax vegetation (K. Boggs and T. Boucher pers. comm. 2008). In Washington, some fens can be indefinitely maintained by groundwater discharge; sometimes succession from rich fen to poor fen/bog may occur in these situations but often is dependent on water chemistry and level of discharge and fire (J. Rocchio pers. comm. 2012).

Treed bogs of the Pacific Northwest represent forests with soils that have taken hundreds to thousands of years to develop, a topoedaphic climax that is relatively stable over time. Tree regeneration frequently occurs on raised organic microsites on the remains of previous trees. Tree growth is very slow. Longer-term succession is probably influenced by paludification and climatic patterns that dictate drainage, either favoring poorer drainage, increased tree mortality, and more open canopy; or improved drainage, greater tree growth, and a more closed canopy. These patterns can also favor individual tree species based on their tolerance or intolerance of wet soils. The widespread yellow-cedar decline, which covers 200,000 ha in southeastern Alaska, is an example of a climate-induced tree death that has resulted in a composition shift away from yellow-cedar due to this mortality (Hennon et al. 2008). Windthrow can cause soil mixing that reverses the paludification processes on a small scale, where productivity may be increased (Banner et al. 2005).