Bog habitats may develop in various situations, depending on the climate and topography.
By location and water source Bogs may be classified on their topography, proximity to water, method of recharge, and nutrient accumulation.
Valley bog peat bogs,
Tierra del Fuego Province, Argentina These develop in gently sloping valleys or hollows. A layer of peat fills the deepest part of the valley, and a stream may run through the surface of the bog. Valley bogs may develop in relatively dry and warm climates, but because they rely on ground or surface water, they only occur on acidic substrates.
Raised bog ,
Estonia, which is rich in raised bogs These develop from a lake or flat
marshy area, over either non-acidic or acidic substrates. Over centuries there is a progression from open lake, to a marsh, to a
fen (or, on acidic substrates, valley bog), to a
carr, as
silt or peat accumulates within the lake. Eventually, peat builds up to a level where the land surface is too flat for ground or surface water to reach the center of the wetland. This part, therefore, becomes wholly rain-fed (ombrotrophic), and the resulting acidic conditions allow the development of bog (even if the substrate is non-acidic). The bog continues to form peat, and over time a shallow dome of bog peat develops into a raised bog. The dome is typically a few meters high in the center and is often surrounded by strips of fen or other wetland vegetation at the edges or along streamsides where groundwater can percolate into the wetland. The various types of raised bog may be divided into: •
Coastal bog •
Plateau bog •
Upland bog •
Kermi bog •
String bog •
Palsa bog •
Polygonal bog Blanket bog , US, supports populations of
English sundew (Drosera anglica). , Ireland In cool climates with consistently high rainfall (on more than c. 235 days a year), the ground surface may remain waterlogged for much of the time, providing conditions for the development of bog
vegetation. In these circumstances, bog develops as a layer "blanketing" much of the land, including hilltops and slopes. Although a blanket bog is more common on acidic substrates, under some conditions it may also develop on neutral or even
alkaline ones, if abundant acidic rainwater predominates over the groundwater. A blanket bog can occur in drier or warmer climates, because under those conditions hilltops and sloping ground dry out too often for peat to form – in intermediate climates a blanket bog may be limited to areas which are shaded from direct sunshine. In
periglacial climates a
patterned form of blanket bog may occur, known as a
string bog. In Europe, these mostly very thin peat layers without significant surface structures are distributed over the hills and valleys of Ireland, Scotland, England, and Norway. In North America, blanket bogs occur predominantly in Canada east of
Hudson Bay. These bogs are often still under the influence of
mineral soil water (groundwater). Blanket bogs do not occur north of the 65th latitude in the northern hemisphere.
Cataract bog A
cataract bog is a rare ecological community formed where a permanent stream flows over a granite outcropping. The sheeting of water keeps the edges of the rock wet without eroding the soil, but in this precarious location, no tree or large shrub can maintain a roothold. The result is a narrow, permanently wet habitat. ==Uses==