Physiognomy and Structure: Brown mosses and sedges characterize alkaline and rich fens (pH >5.5). Some sites may have high cover of minerotrophic non-hummock-forming Sphagnum species. Low shrub or graminoid physiognomy is typical with some dwarf-shrubs.

Floristics: Brown mosses such as Campylium, Drepanocladus, Scorpidium, Tomentypnum, and Warnstorfia and sedges (Carex) characterize rich fens (pH >5.5). Some sites may have high cover of minerotrophic non-hummock-forming Sphagnum species. Low shrub or graminoid physiognomy is typical. Groundwater inputs provide for the high mineral content, and soil saturation in general precludes tall vegetative growth. Shrubs are usually deciduous willows and birch, but evergreen dwarf-shrubs are not uncommon. Indicator species include Betula nana, Carex aquatilis, Carex cusickii, Carex limosa, Carex livida, Carex utriculata, Comarum palustre, Menyanthes trifoliata, Myrica gale, and Spiraea douglasii. Trees may be present at the edges or on raised hummocks where soils are not anoxic and include Callitropsis nootkatensis (= Chamaecyparis nootkatensis), Picea sitchensis, Pinus contorta, Thuja plicata, and/or Tsuga heterophylla. Floristic information was summarized from the following sources: Shacklette et al. (1969), Eyre (1980), Banner et al. (1986, 1988, 1993), DeMeo et al. (1992), Viereck et al. (1992), Kunze (1994), Talbot and Talbot (1994), Martin et al. (1995), Shephard (1995), DeVelice et al. (1999), Boggs et al. (2003, 2008a, 2008b), MacKenzie and Moran (2004), Talbot et al. (2006), and Fleming and Spencer (2007).

Dynamics:  Much literature documents the formation and succession of peatlands in Boreal, Temperate and Pacific Coastal settings (Banner et al. 1988, 2005, Mitsch and Gosselink 2000, and many others). These processes tend to take several hundreds to thousands of years, are well-documented and will not be repeated here. The purpose of this section is to discuss dynamics from disturbance. Natural disturbance events along north coast peatlands play an important role in slowing and reducing organic matter accumulation on specific types of sites. The main types of natural disturbance on the north Pacific coast 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 "re-starts" a 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). Logging has also been shown to increase Sphagnum growth, through increased sunlight availability (Banner et al. 2005).

Landslides, fire and changes to water table depth and water source will alter the amount, composition and competition of peatland moss and higher vascular plant species. Fire can remove surface vegetation in dry seasons and stimulate the growth of Sphagnum spp. such that hummocks develop where once a depression occurred (Banner et al. 1988), shifting the small-scale local mosaic of swale and hummock within a peatland occurrence. Lowering the water table can allow trees such as Pinus contorta, Tsuga heterophylla, and Betula papyrifera to expand into peatland areas. Disturbance may bring the influx of mineral-rich waters from surrounding uplands (particularly along drainage channels), and flora characteristic of bogs is replaced by fen plants such as Spiraea spp., Salix spp., Pyrus spp., Juncus spp. and Carex spp. (Banner et al. 1988). Succession of mined peatlands depends on the degree of humification of the remaining substrate and hydrology. On unhumified peatmoss Sphagnum spp., Drosera rotundifolia, Rubus chamaemorus, and Ledum groenlandicum can regenerate and new Sphagnum peat can accumulate in pits and pools after mining (Banner et al 1988).

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 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 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.

Monitoring peat wetlands is an important source of information as to whether observed changes are due to natural climatic or successional cycles or direct changes of water sources by human hands, or other indirect effects of human activity that may cause sedimentation, draining, flooding, or other changes to peatlands.