What is a fen?
Fens are peatlands with deep organic deposits and are influenced by slow, lateral water movement. Often referred to as “muskeg,” fens are the most extensive wetlands in the western boreal forest.
Ecological benefits
- Known as the “green rivers: of the boreal, fens transport large volumes of water and nutrients across the landscape and help to regulate water flow
- Fens help prevent downstream flooding by absorbing precipitation and run-off
- Due to deep organic deposits, fens store large amounts of carbon and help moderate climate change
- Provide important habitat for the threatened caribou
Types of fens
- Treed fens: sparsely vegetated and stunted (<10 m) tamarack, sometimes mixed black spruce, shrubs, sedges and moss. Trees make up 25-60% of the surface area
- Shrubby fens: sparse to medium density; short (<2m) shrubs (e.g. bog birch and willow) mixed with sedges and mosses. Shrubs dominate with >25% surface area
- Graminoid (open) fens: dominated with sedges, mosses and hers (e.g. buckbean) often interspersed with open water.
Vegetation
- Plant species reflect nutrient and moisture gradients
- The plant communities of nutrient-poor fens more closely resemble those of bogs, while rich fens have more diverse and robust vegetation
Hydrology
- Complex hydrology with surface, sub-surface and groundwater interactions
- High water table (at slightly below the surface) with lateral water flow often connecting wetland systems vast distances
Soil
- Deep peat deposits
- Similar to bogs but with greater composition of sedge peat
- Decomposition is slow due to the wet, cool, anoxic (oxygen-deprived) environment, resulting in the accumulation of deep organic deposits
- Depending on water sources and nutrient availability, fens can be either nutrient rich or poor
Two distinct peat layers
- Acrotem – living top layer (30-50cm)
- Catotelm – lower, non-living layer
Types of wetlands
Canada’s wetlands can be broadly categorized into two types: organic and mineral.
Organic wetlands
Organic wetlands are Otherwise known as peatlands, these wetlands have an abundance of peat accumulation on which organic soils (excluding Folisols) are developed. These types of wetlands can include swamps, marshes, or shallow open-water wetlands.
Swamps
Most commonly recognized as shoreline areas of streams, lakes and floodplains, swamps are either treed or shrubby.
What is a marsh?
Marshes are wetlands periodically inundated by standing or slowly moving water and creating nutrient-rich soil.
Shallow open-water wetlands
Shallow open-water wetlands have water depths of less than two metres, yet are too deep for emergent marsh vegetation to establish.
Mineral wetlands
Mineral wetlands are found in locations where there is an excess of water on the surface and where there is little or no organic matter or peat due to geomorphic, hydrologic, biotic, edaphic (soil-related), or climatic causes. These wetlands are distinguished by gleysolic soils or peaty phases of these soils.
Bogs
Bogs are peatlands that have deep deposits of poorly decomposed organic material (referred to as peat). They are elevated above the surrounding terrain and receive water and most nutrients from precipitation.
Swamps
Most commonly recognized as shoreline areas of streams, lakes and floodplains, swamps are either treed or shrubby.
Marshes
Marshes are wetlands periodically inundated by standing or slowly moving water and creating nutrient-rich soil.