Nearctic Boreal Bog and Fen - Code: Ne11C

Nearctic Boreal Bogs and Fens are unique wetlands that are widely distributed throughout temperate and boreal regions of the continent. While bogs and fens can be quite rare in middle latitudes, boreal bogs, often called muskegs, are a large component of the BOREAL CONIFER FOREST. Variable in form, and formation, bogs and fens share one major feature – the presence of peat. Peat is a dense accumulation of partially decayed plant material that forms in anaerobic or acidic conditions. The formation of peat facilitates the formation of bogs by absorbing large amounts of water creating a spongy and saturated environment. In turn, many plants in bogs and fens facilitate the creation of peat by excreting acidic tannins that preserve plant material.
Bogs are a diverse set of wetlands that can take many forms. In general, bogs have deep peat deposits (>12in/30cm), are nutrient poor, strongly acidic (pH <5.5), and are derived from lakes and precipitation, not ground water. Bogs usually form on poorly drained soils in valleys or on plateaus and often evolve slowly from other wetland types as peat accumulates and acidification occurs. The vast muskegs of the boreal and arctic zone form above clay soils or permafrost. Most bogs outside of the boreal zone are quaking bogs that are floating mats of peat and sphagnum. Quaking Bogs are often associated with deep kettle lakes created by retreating glaciers, these bogs form slowly around the margins of the lake and grow inwards. The bog mat is usually quite thick (2ft/0.6m) and the entire surface moves like a waterbed when you walk on it. In kettle lake bogs, floating mats of vegetation insulate the lake and create a cool microclimate that often has isolated pockets of boreal vegetation. Bogs have a wide array of plants, with many rare species adapted to acidic and nutrient poor environments. Most bogs include a ground mat dominated by Sphagnum moss (Sphagnum spp.) and various sedges (Carex spp.), especially Few-seed Sedge (Carex oligosperma). Shrubs in the family Ericaceae are abundant in bogs – this includes Bog Laurel (Kalmia polifolia),Cranberry (Vaccinium macrocarpon), Small Cranberry (Vaccinium oxycoccos), Lingonberry (Vaccinium vitis-idaea), and Bog Bilberry (Vaccinium uliginosum). Bogs are often ringed in small, stunted trees like Black Spruce (Picea mariana), White Spruce (Picea glauca) and Tamarack (Larix laricina). Many plants have overcome the nutrient poor conditions by becoming carnivorous and insect eating plants like sundews (Drosera spp.), pitcherplants (Sarracenia spp.) and bladderworts (Utricularia spp.) are found here. Orchids have also adapted to this environment by using mycorrhizal fungi to extract nutrients from peat. The majority of temperate and boreal orchids are found in bogs and fens.
While bog formation occurs under a variety of conditions, the conditions needed to create fens are much more specific. Fens typically form in areas where the water-table is very close to the surface. Water is often supplied by mineral rich ground water which flows slowly across the surface in a sheet. The waterlogged soil creates anaerobic conditions which allows for the accumulation of thin layers of peat. The mineral rich ground water is often associated with marl or limestone bedrocks that are heavy in carbonate minerals like calcium, magnesium and potassium. These minerals in solution create the alkaline conditions associated with “rich” fens. As peat accumulates, it can create a buffer between mineral rich ground water and soils. This allows for increased growth of Sphagnum which leads to acidification. Acidified fens or “poor” fens have plant life much more similar to bogs and over time can transition into bogs. Plants typically associated with alkaline fens include Shrubby Cinquefoil (Potentilla fruticosa), Wooly-fruit Sedge (Carex lasiocarpa), and a variety of brown mosses (Calliergon, Campylium, Drepanocladus). Fens also differ from bogs in having a notable lack of Sphagnum moss and ericaceous shrubs like blueberry and cranberry. Fens are often associated with NEARCTIC SEDGE AND GRASSLAND MARSHES, EASTERN GLADES AND BARRENS, and Limestone Alvars (Sidebox X).
Pocosins are peat forming bog that are found in the se. United States, mostly within EASTERN PINE SAVANNAS. These bogs are similar to boreal bogs in many ways but are usually dominated by evergreen shrubs like Shining Fetterbush (Lyonia lucida), Inkberry (Ilex glabra) and Swamp Titi (Cyrilla racemifolia). Trees are more common in pocosins than other bog types and Pond Pine (Pinus serotina) and Longleaf Pine (Pinus palustris) are often present.