Abstract for F016

Temperate to Polar Bog & Fen
Tourbières et fens des zones tempérée, boréale et arctique

Temperate to Polar Bog & Fen includes temperate and boreal bogs and fens dominated by Sphagnum or brown mosses with ericaceous shrubs, graminoids and low scrub tree growth forms (<2 m). The driest bogs, especially in permafrost terrain, may be covered in dwarf-shrubs and lichens. The bog surface, which is raised or level with the surrounding terrain, is virtually unaffected by runoff waters or groundwaters from the surrounding mineral soils. Precipitation, fog and snowmelt are the primary water sources and, thus, all bogs are ombrogenous.

A temperate and boreal fen is a peatland with a fluctuating water table. The waters in fens are rich in dissolved minerals and, therefore, are minerotrophic. Groundwater and surface water movement is a common characteristic of fens. Surface flow may be directed through channels, pools, and other open waterbodies that can form characteristic surface patterns. The dominant materials are moderately decomposed sedge and brown moss peats of variable thickness. The vegetation on fens is closely related to the depth of the water table and the chemistry of the water present. The composition of vegetation may also reflect regional geographic variations. In general, graminoid vegetation and some bryophytes dominate wetter fens where the water table is above the surface. Shrubs are prominent in drier fens where the water table is lower. Trees appear on the driest fen sites where microtopographic features such as moss hummocks provide habitats as much as 20 cm above the water table.

Source: Faber-Langendoen, D., T. Keeler-Wolf, D. Meidinger, C. Josse, A. Weakley, D. Tart, G. Navarro, B. Hoagland, S. Ponomarenko, J.-P. Saucier, G. Fults, E. Helmer. 2014. Classification and description of world formation types. Part I (Introduction) and Part II (Description of world formations). Hierarchy Revisions Working Group, Federal Geographic Data Committee, FGDC Secretariat, U.S. Geological Survey. Reston, VA, and NatureServe, Arlington, VA.

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