Peatland
The formation of peatlands 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 and in basins.
[5] In their natural state, peatlands provide a range of ecosystem services, including minimising flood risk and erosion, purifying water and regulating climate.
[3][6] Peatlands are under threat by commercial peat harvesting, drainage and conversion for agriculture (notably palm oil in the tropics) and fires, which are predicted to become more frequent with climate change.
[2] A bog is a mire that, due to its raised location relative to the surrounding landscape, obtains all its water solely from precipitation (ombrotrophic).
[11] Mires are usually shallow in polar regions because of the slow rate of accumulation of dead organic matter, and often contain permafrost and palsas.
In temperate zones mires are typically more scattered due to historical drainage and peat extraction, but can cover large areas.
[12] In the early 21st century, the world's largest tropical mire was found in the Central Congo Basin, covering 145,500 km2 and storing up to 1013 kg of carbon.
[3] Peatlands interact with the atmosphere primarily through the exchange of carbon dioxide, methane and nitrous oxide,[1] and can be damaged by excess nitrogen from agriculture or rainwater.
[2] In their natural state, mires are a small atmospheric carbon dioxide sink through the photosynthesis of peat vegetation, which outweighs their release of greenhouse gases.
A study in Alaska found that methane may vary by as much as 300% seasonally with wetter and warmer soil conditions due to climate change.
[23] Peatlands are important for studying past climate because they are sensitive to changes in the environment and can reveal levels of isotopes, pollutants, macrofossils, metals from the atmosphere and pollen.
Humic materials can store substantial amounts of water, making them an essential component in the peat environment, contributing to increased carbon storage due to the resulting anaerobic condition.
[26] Upon extreme drying, the ecosystem can undergo a state shift, turning the mire into a barren land with lower biodiversity and richness.
[3] This involves cutting drainage ditches to lower the water table with the intended purpose of enhancing the productivity of forest cover or for use as pasture or cropland.
[2] In addition, the commercial extraction of peat for energy production is widely practiced in Northern European countries, such as Russia, Sweden, Finland, Ireland and the Baltic states.
[28] The use of this land by humans, including draining and harvesting of tropical peat forests, results in the emission of large amounts of carbon dioxide into the atmosphere.
The economic value of a tropical peatland was once derived from raw materials, such as wood, bark, resin and latex, the extraction of which did not contribute to large carbon emissions.
In Southeast Asia, peatlands are drained and cleared for human use for a variety of reasons, including the production of palm oil and timber for export in primarily developing nations.
[2] Drainage of tropical peatlands alters the hydrology and increases their susceptibility to fire and soil erosion, as a consequence of changes in physical and chemical compositions.
These forests occur on the margin of peatlands with a palm rich flora with trees 70 m tall and 8 m in girth accompanied by ferns and epiphytes.
The third, padang, from the Malay and Indonesian word for forest, consists of shrubs and tall thin trees and appear in the center of large peatlands.
Burning events in tropical peatlands are becoming more frequent due to large-scale drainage and land clearance and in the past ten years, more than 2 million hectares was burnt in Southeast Asia alone.
Indonesia is one of the countries suffering from peatland fires, especially during years with ENSO-related drought, an increasing problem since 1982 as a result of developing land use and agriculture.
[45] Nakaikemi Wetland in southwest Honshu, Japan is more than 50,000 years old and has a depth of 45 m.[2] The Philippi Peatland in Greece has probably one of the deepest peat layers with a depth of 190 m.[46] According to the IPCC Sixth Assessment Report, the conservation and restoration of wetlands and peatlands has large economic potential to mitigate greenhouse gas emissions, providing benefits for adaptation, mitigation and biodiversity.
[2] The drainage of peatlands for agriculture and forestry has resulted in the emission of extensive greenhouse gases into the atmosphere, most notably carbon dioxide and methane.
[clarification needed][57] To create viable soil for plantation, the mires in tropical regions of Indonesia and Malaysia are drained and cleared.
[59] Exploitation of this land raises many environmental concerns, namely increased greenhouse gas emissions, risk of fires and a decrease in biodiversity.
In addition, due to the oxygen deficient nature of the vegetation, the peat fires can smolder beneath the surface causing incomplete combustion of the organic matter and resulting in extreme emissions events.
[65] The Global Peatlands Initiative is an effort made by leading experts and institutions formed in 2016 by 13 founding members at the UNFCCC COP in Marrakech, Morocco.
[66] The mission of the Initiative is to protect and conserve peatlands as the world's largest terrestrial organic carbon stock and to prevent it from being emitted into the atmosphere.
