Concept

Mire

Résumé

A mire, peatland, or quagmire is a wetland area dominated by living peat-forming plants. Mires arise because of incomplete decomposition of organic matter, usually litter from vegetation, due to water-logging and subsequent anoxia. All types of mires share the common characteristic of being saturated with water, at least seasonally with actively forming peat, while having their own ecosystem. Like coral reefs, mires are unusual landforms that derive mostly from biological rather than physical processes, and can take on characteristic shapes and surface patterning. A quagmire is a floating (quaking) mire, bog, or any peatland being in a stage of hydrosere or hydrarch (hydroseral) succession, resulting in pond-filling yields underfoot. Ombrotrophic types of quagmire may be called quaking bog (quivering bog). Minerotrophic types can be named with the term quagfen. There are four types of mire: bog, fen, marsh and swamp. A bog is a mire that, due to its location relative to the surrounding landscape, obtains most of its water from rainfall (ombrotrophic). A fen is located on a slope, flat, or in a depression and gets most of its water from soil or groundwater (minerotrophic). Thus, while a bog is always acidic and nutrient-poor, a fen may be slightly acidic, neutral, or alkaline, and either nutrient-poor or nutrient-rich. A marsh is a type of wetland within which vegetation is rooted in mineral soil but some marshes form shallow peat deposits well known as Mires. Swamps are characterized by their forest canopy and, like fens, are typically of higher pH level and nutrient availability than bogs. Some bogs and fens can support limited shrub or tree growth on hummocks. The formation of mires today is primarily controlled by climatic conditions such as precipitation and temperature, although terrain relief is a major factor as waterlogging occurs more easily on flatter ground. However, there is a growing anthropogenic influence in the accumulation of peat and peatlands around the world, including through both conservation efforts as well as climate change-induced destruction by droughts and forest fires.

Source officielle

https://en.wikipedia.org/wiki/Mire

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