Restoring Peatlands to Mitigate Climate Change

Peatland Restoration is a term used to describe management measures that aim to restore the original form and function of peatland habitats to favourable conservation status. The principal activity involved in restoration is management of site hydrology which in turn helps to control emissions of greenhouse gases such as carbon dioxide. Depending on the starting point, peatland sites may need drain blocking to rewet them using a variety of techniques including peat dams, plastic piling and bunding, plantation removal, pollution control, Sphagnum transfer and/or control of grazing, burning, water quantity and quality. Peatlands are among the most carbon-rich ecosystems on Earth. In a natural condition, peatlands have a net cooling effect on climate, reduce flood risk, and support biodiversity. Dianna Kopansky, UNEP’s Global Peatlands Coordinator, emphasized that “Peatlands are crucial ecosystems for people, nature and for our climate future.”

Peatlands are wetlands where dead Sphagnum moss – as well as other mosses, sedges and woody plants forming peat – accumulates over time. More than one-third of the world’s peatlands are in Canada, and they cover over 14% of Canada’s land area and store an estimated 150-160 Gt of carbon in their soils. Peatlands are wetlands that are different from marshes, shallow open-water wetlands and most swamps because of the buildup of layers of peat. This peat creates the unique conditions found in these wetlands. The first 30 to 50 centimetres of the surface of a peatland is mostly formed by living mosses and plants. Peat is found under this living layer. Peat is made up of the dead and decomposing Sphagnum mosses and the many other wetland plants that were once living at the surface, over which new, living plants have grown.

Altogether, Canada has more than one million square kilometres of peatlands, which store an estimated 150 billion tonnes of carbon, roughly equal to 25 years of the country’s current greenhouse gas emissions. This carbon is stored in the form of dead plant matter that, after falling to the ground, begins to decay and release the CO2, but at a much slower rate than normal, thanks to the moist ecosystem. Around 70 per cent of Canada’s wetlands (some of which are peatlands) have been either destroyed or degraded. Even beyond the loss of greenhouse gas storage, this can mean an increase in emissions. For example, human activities on peatlands, such as mining or peat extraction, involves draining them of moisture, meaning the dead organic material decays faster. Globally, drained and degraded peatlands release an expected two billion tonnes of carbon dioxide or more.

Conditions in peatlands are unique. Decaying peat produces humic acid, making peatland water acidic (its pH is low), nearly as much as vinegar. Also, the water in the peat is anoxic (with low oxygen content) and has low levels of nutrients, such as nitrogen. These conditions, added to the low soil temperatures of northern latitudes, make decomposition a very slow and difficult process below the surface. Many decomposing microorganisms lack much of what they need to survive in the peat layers, so instead of quickly decomposing when it dies, the moss accumulates as new moss grows at the top. This accumulation, instead of decomposition, leaves large amounts of dead plants remains as peat, which is made of 40 per cent carbon. So instead of being released in the atmosphere as carbon dioxide (CO2 is one of the products of decomposition and a greenhouse gas), carbon is stored in the peatland.1

This is why the world’s peatlands are one of the most important terrestrial carbon stores; they contain about 30 per cent of the global soil carbon and are important regulators of climate change. Globally, peatlands hold more than twice as much carbon as the world’s forests do, according to the United Nations Environment Programme. But in many places, humans have turned vast expanses of these environments from long-term carbon sinks into carbon sources. The most dominant and widespread peat-forming species in peatland ecosystems are Sphagnum mosses. They are keystone species, meaning that they modify their environment to create many peatland ecosystems. There are roughly 120 species of Sphagnum mosses worldwide. Long dubbed “wastelands,” peatlands are the most valuable terrestrial ecosystem on the planet in terms of carbon sequestration. They currently cover only about 3% of the planet’s land mass, but store more carbon (around 600 billion metric tons) than all the world’s terrestrial vegetation combined.

“It’s a long-term carbon store that’s been building up for long periods of time … You need to give the system time,” Maria Strack, professor at the University of Waterloo’s department of geography and environmental management, told The Weather Network.  Over the years, Canadian scientists and companies have learned how to get the ball rolling to restore peatlands. A well-studied method called the moss layer transfer technique (MLTT) can put these vital ecosystems on the right track again, sequestering carbon dioxide rather than emitting it. However, MLTT is primarily a tried, tested, and true fix for one kind of peatland degradation: peat extraction for farm and garden products. And, while the process can handily turn an impacted peatland from carbon source to carbon sink, peatlands, and their restoration, still face many challenges in Canada.2

 So far, Brandon University peatland researcher Peter Whittington said the fastest way to regrow peat is through the “moss layer transfer method.” To restore a drained or extracted peatland, a restorer can level the remaining peat in an area and redirect water systems to ensure the land is saturated with water. Basically, in MLTT, a thin layer of moss can be moved onto the decaying moss from an existing peatland. The moss is covered with straw mulch to create a humid environment and stop it from drying out. Whittington said if the method is used within four years of peat extraction, a peatland can become a carbon-accumulating ecosystem in up to 20 years. Canada has more than 281 million acres of peatlands (25% of the world’s supply). Harvested peat moss improves plant and soil health wherever applied. Peat Moss grows more than 60 times faster than it is harvested. Peat Moss is abundant and environmentally sustainable.3

Peat extraction was responsible for about 2.1 megatonnes of carbon dioxide equivalent emissions in 2021 — about as much as the yearly emissions from five gas-fired power plants, according to Environment Canada. That does not account for the emissions the extracted peat may have been able to capture. While some experts say peat is the most sustainable way to support agriculture, others insist it’s time to stop releasing carbon and disturbing peatland ecosystems. Peatland soils contain more than 44 per cent of all the planet’s soil carbon, according to the International Union for the Conservation of Nature, despite only making up three per cent of the planet’s land surface. And while extracted peatlands can be regenerated, the process is laborious and takes years.3

Every year, about 1.3 million metric tonnes of Canada’s peatlands are dug up for sale to farmers and gardeners. With every hectare lost, planet-warming carbon dioxide is released into the air. That said, around 70 per cent of Canada’s wetlands (some of which are peatlands) have been either destroyed or degraded. Even beyond the loss of greenhouse gas storage, this can mean an increase in emissions. For example, human activities on peatlands, such as mining or peat extraction, involves draining them of moisture, meaning the dead organic material decays faster. However, this can be reversed. Once the trees have been cleared, we shift our focus to re-wetting the peatland. We do that by installing peat dams in the drains, and often flipping stumps, and smoothing the ploughed ridges and furrows. One of the great things about restoring bogs is that you can see a significant impact quite quickly.

In recent years, positive examples of restoration of drained peatlands have taken place across Canada. For example, Bois-des-Bel (in Quebec) is an area of peatland that had been extensively drained, then abandoned for 25 years with no sign of regrowth. Rewetting, creating pools and spreading sphagnum moss fragments enabled a recovery of the barren landscape to a functional ecosystem rich in flora and fauna in just five years. A study carried out 14 years after the rewetting determined that the restored peatland was once again acting as a net carbon sink. Restoration projects like this will benefit from the new natural climate solutions fund under the Emissions Reduction Plan.4 Therefore, restoring disturbed and degraded peatlands is an emerging priority in efforts to mitigate climate change. As the recovery of degraded peatlands is fundamental to achieving net-zero goals and biodiversity targets, sound science and monitoring efforts are needed to further inform restoration investments and priorities.

1 https://www.hww.ca/en/wild-spaces/peatlands.html

 2 https://www.theweathernetwork.com/en/news/weather/forecasts/inside-canadas-fight-to-save-its-peatlands

3 https://www.nationalobserver.com/2023/07/07/news/canadas-carbon-storing-peat-digs-climate-dilemma

4 https://www.decadeonrestoration.org/stories/canadas-emissions-reduction-plan-confirms-commitment-peatlands

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