Peatlands or mires are terrestrial wetland ecosystems characterised by deep, layered depositions of peat. Peat is a result of incomplete or partial decomposition of organic matter as water-logged conditions prevent organic matter from decomposing completely.
Peatlands can hence be considered an intermediate between wetland and fully terrestrial habitats as their surfaces are hydrated for long periods of time despite often having limited amounts of standing water. Most peatlands occur in the northern mid to high latitudes and the rest occur in intertropical zones like Southeast Asia. North America, Europe and Russia house the largest peatland areas.
Peat is essentially accumulated when the carbon that is stored in plant biomass via photosynthesis exceeds the loss of carbon from the biomass to the atmosphere by the process of decomposition and the loss of carbon dissolved in water through hydrological flow. In other words, the rate of organic matter accumulation is much greater than the rate of decomposition, resulting in accumulation of peat.
Peatlands are relatively poor in species richness when compared to other ecosystems around them. However, due to the unique environment of peatlands, species that are only specialised to this ecosystem are sometimes found. Peatlands are known for the presence of carnivorous plants like Drosera and Sarracenia along with the large number of Sphagnum moss species (peat moss). In cooler climates, plants like Sphagnum mosses, sedges and shrubs are found, whereas in warmer climates, graminoids and woody vegetation gives rise to most of the organic matter.
Peat takes up to 10,000 years to develop, making it impossible to recreate in a shorter period. Thus, it is essential to conserve these lands as peat cannot be considered a renewable resource that can be replaced easily.
Why are peatlands important?
Through the process of peat formation and accumulation, peatlands are carbon rich ecosystems that store and sequester more carbon than any other terrestrial ecosystems. Peatlands are storages of large amounts of carbon and their degradation releases huge quantities of greenhouse gasses into the atmosphere, causing increased risk of global warming. Restoring peatlands can significantly reduce greenhouse gas emissions. Damage to peatlands also causes immense biodiversity loss.
Peatlands contain 30 percent of the world’s soil carbon and cover only about 3 to 4 percent of land, making them critical for preventing and mitigating effects of climate change, preserving biodiversity, minimising flood risk and ensuring drinking water. As carbon from dead plants is stored in the form of peat, it provides a net-cooling effect, helping to mitigate the climate crisis.
In their natural, wet state, peatlands provide regulatory ecosystem services such as minimising risk of flooding and drought, regulating water flows, and preventing seawater influx. Wet peatlands lower the temperatures in surrounding areas, providing refuge from extreme heat and are also less prone to forest fires, helping to preserve air quality.
Peatlands are used for economic activities such as agriculture, forestry, horticulture, excavation for energy generation and other uses. In many parts of the world, peatlands supply essentials such as food, fibre and other products to sustain local livelihoods. They also house important archaeological and ecological information like pollen records.
What are threats to peatlands?
Peatlands are threatened by anthropogenic activities such as conversion of peatlands for agriculture, burning, resource extraction, and mining by draining the land is one of the main threats to the ecosystem. Nitrogen deposition brought in by atmospheric pollution affect these ecosystems. In mountainous areas, degradation is caused due to activities like over-grazing. Logging of tropical peatlands and peat extraction for agricultural uses also deplete these ecosystems.
Some traditional methods of peat extraction like hand cutting peat blocks are less damaging, however, modern methods of peat extraction destroy surface vegetation and dry out the surface layers for easy extraction of peat.
The following are the main threats to peatlands:
Drainage:
Peatlands are drained to make way for timber plantations and to cultivate other commercial or agricultural crops. During the conversion of peatlands for other purposes, the water is drained out to make the surface of the peatland drier. This process increases decomposition of the organic matter in the upper layers of the peatland, resulting in more carbon dioxide being released into the atmosphere.
Over time, this phenomenon leads to soil compaction and subsidence, making it difficult to restore them. The plant communities are also affected greatly as there is a loss of water supply for shallow rooted plants like mosses, causing a great change in the overall ecology of the ecosystem. Draining of peatlands reduces the quality of drinking water as it gets polluted with organic carbon and other pollutants that were previously contained within peat.
Invasive species:
Sensitive ecosystems like peatlands are not immune to invasive species that threaten native wildlife and vegetation. Invasives have a tendency to spread and establish in foreign environments rapidly, out competing native species. Degraded peatlands are prone to invasive species, enabling plants like Rhododendron and self-seeding conifers to colonise the land, making it both drier and unsuitable for native plants to dwell in.
Commercial Extraction:
Extraction of peat for commercial purposes (like fuel and agricultural uses) leads to loss of vegetation and affects the ecosystem, releasing large amounts of CO2 into the atmosphere. It also increases the risk of flooding and pollution due to increased erosion and sedimentation.
Excess nutrient inflow:
Peatlands often occur near agricultural land, making them subject to inflow of excess nutrients, pesticides, limes and fertilizers used in the agricultural land. These excess nutrients lead to nutrients imbalances in the peatlands. Excess nutrients could lead to growth of algae that adversely affects the water quality, nutrient balance and productivity of the ecosystem. This also affects the native vegetation and impacts the fauna which rely on it.
Overgrazing:
Overgrazing by cattle, sheep and deer can be unsustainable for peatland ecosystems. Trampling physically damages the surface vegetation of peatlands and give rise to tracks that become channels for erosion. Overgrazing also leads to loss of peat forming vegetation (resulting in lesser peat being formed), leading to the drying out of surface layers.
Other threats to peatlands include:
- Wildfires in degraded peatlands as a result of dry vegetation and parched soil. These fires can last for weeks as the vegetation after degradation is much more ignitable. These wildfires have a negative impact on local vegetation and wildlife and the scorched soil is more vulnerable to wind and water erosion.
- Illegal dumping of wastes due to their isolated nature. This leads to bog degradation and gives rise to multiple other problems like drying out, wildfires, etc.
- Ecotourism attracts many visitors who trample on the surface vegetation and bring about changes like reducing the peatland’s ability to form peat and creating tracks in the land which leads to soil erosion.
Conservation of Peatlands
Conservation and restoration of existing peatlands is essential to maintain greenhouse gas levels in the atmosphere and to protect species of flora and fauna that are native to these habitats. These ancient ecosystems are a result of thousands of years of peat accumulation and must be conserved to maintain ecological balances.
Conservation measures include stopping degrading activities like conversion of peatlands to agricultural lands, draining, over-grazing, etc. Restoration practices like reinstating waterlogged conditions for peat formation must also be encouraged.
Economic measures like emissions trading schemes, carbon markets, payment for ecosystem services, environmental bonds, government-backed carbon price guarantee, can be introduced.
The Global Peatlands Initiative is an international partnership formed to save this ecosystem as the world’s largest terrestrial organic carbon stock. This initiative includes the partnership of 46 countries along with 4 major tropical peatland countries (Indonesia, Republic of Congo, Democratic Republic of Congo and Peru) who have come together to conserve, restore and sustainably manage peatlands on a global scale.
Conclusion
Restoration, although expensive, mainly involves regulating site hydrology by activities like rewetting the peatland using techniques like peat dams, plastic piling and bunding, plantation removal, pollution control, Sphagnum transfer, etc. Peatlands can be partly restored by preventing water levels from declining further by blocking drainage canals and planting native plants could help retain water in the soil. Restoring peatlands can help to restore natural capital and its ecosystem goods and services. Studies have estimated that restoring peatlands could prevent the release of 394 million tonnes of CO2 equivalents per year.
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Written by: Y.S.K Sivani