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.
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. This plant matter has accumulated over the process of thousands of years.
“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.
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. Globally, drained and degraded peatlands release an expected two billion tonnes of carbon dioxide or more.
The restored peatland Bois-des-Bel, Quebec, 15 years after the application of the moss layer transfer technique for peatland restoration. The chambers are used to measure methane emissions. (Maria Strack / Supplied)
MLTT can, at least, stem the release of carbon from these disturbed peatlands and get them back to a point where they’re sucking up and storing it.
In short, the process involves taking material from an in-tact peatland and transferring it to a degraded peatland in a similar climate and with similar plants. These pieces of donor material are taken from the top 10 centimetres of the natural peatland, and include various types of moss, such as sphagnum moss, along with seeds and roots of plants that can regrow. “They will just kind of come along with that transfer, and we'll then be able to establish a greater diversity [in the peatland],” Strack said.
Next, companies will re-wet the impacted peatland by contouring soil that was disturbed during extraction and blocking off or potentially filling the drainage ditches that were dug to remove moisture during the extraction process. This enables the area to become wet again. After the donor material is spread on the peatland, it’s covered in mulch to keep it moist, and given a bit of fertilizer to get the plants growing.
In one 2016 paper, Strack and her colleagues went to six peatlands that have had MLTT performed on them since the 1990s. They then measured how well the restored peatlands took in carbon using the closed chamber approach. The researchers covered parts of the land in plastic boxes and used specialized sensors to see how well that parcel of land sucks up the carbon dioxide trapped in the boxes. Then, the team compared the results to nearby non-degraded peatlands, and degraded but un-restored peatlands.
In all, the paper found that the restored peatlands were better at sequestration than their degraded counterparts. In another paper, from 2019, Strack and a team found that restored peatlands became carbon sinks again after more than 14 years.
“After about 20 years, many of the sites we've measured are able to sequester or take up carbon whereas the unrestored systems would continue to release it all throughout that time period,” Strack said.
One size does not fit all
This type of restoration is widely used in the Canadian peat extraction industry. The Canadian Sphagnum Peat Moss Association(CSPMA) has pledged to restore 100 per cent of previously harvested, but not restored, peatlands.
However, this represents a small proportion of the peatland disturbance in Canada: 0.03 per cent of the country’s peatlands. There are other, larger disturbances. Land changes from agriculture are the largest, having disturbed 7,101 square kilometres, according to a 2022 paper. The next largest is mining and oil and gas, which has disturbed 3,700 square kilometres in Alberta alone.
Mining, for example, regularly sees peatlands dug up, its constituent mosses and plants left sitting on the ground, according to Lorna Harris, a researcher with Wildlife Conservation Society Canada. “And then, you know, there's no real plan for how to use that peat at the end for reclamation or restoration,” she told the Weather Network.
In oil and gas extraction, parts of the peatlands are covered with well pads, often made up of things like gravel. The process may also introduce different types of soils into the ecosystem, which can change the soil chemistry of the ecosystem and impact what plants grow there.
According to Strack, understanding how the other types of disturbances impact peatlands is another challenge. Strack and other researchers are trying to understand if MLTT could be used to recover peatlands disturbed by these other sources. “We do have to sort of learn more about how some of these other types of disturbances should be restored, and then get the industry backing to really start doing that restoration on the ground,” she added.
A post-extraction peatland 15 years after the end of peat extraction with instrumentation for ecosystem carbon exchange measurements in the distance. (Maria Strack / Supplied)
‘Irrecoverable within our lifetimes’
Increasingly, wildfires are also posing a threat to peatlands. However, other research is looking for ways to restore these peatlands as well. For example, Sophie Wilkinson, a postdoctoral researcher at McMaster University, and her team is looking at an approach similar to MLTT but geared toward restoring peatlands destroyed or damaged by fire.
Currently, the research is in its fifth year. The method involves taking a 10-centimetre wide, five-centimetre thick, “cookie-sized” transplant of sphagnum moss from donor peatlands nearby and putting them in peatlands degraded by fires to “kickstart” their recovery.
After a 2015 wildfire at Earth Creek, Alberta, the previously peat-ed area was left barren with only a few burnt tree trunks. Two years after the fire, Wilkinson and her team placed these cookies in different places at the site. Now, they’re watching the site to see if the moss begins to regrow over the area.
“A lot of peatlands have burned in Alberta over the last few years. And so whilst we've been in the field documenting peatland recovery, we really started to notice the lag between a peatland burning and a peatland beginning to recover.,” Wilkinson said.
While the results are forthcoming, Wilkinson said they’re promising. She added that, next summer, she and her team hope to have a large-scale assessment of this, and similar, tests involving moss transplants.
There are yet other challenges to peatland restoration as well. Climate change could be impacting it, for instance, by causing droughts or extreme temperatures, according to Marie-Claire LeBlanc, peatland affairs and communication manager with the CSPMA.
Further, Canada is a big country, so there’s a lot of variation in terms of peatlands. Some peatlands are also not particularly well-studied, which can throw another wrench in the works, she said.
Finally, the organic, carbon-storing matter accumulates incredibly slowly over the course of hundreds or thousands of years. This means that even a carbon-negative peatland will take a great deal of time before it reaches pre-disturbance levels. This is why Canada, which only formally protects 10 per cent of its peatlands, needs to make stronger policies, and conserve peatlands, on top of restoring them, Harris said. “All of the peat that is currently extracted,” she said. “It is irrecoverable within our lifetimes.”
Thumbnail image: A peatland one year post-fire, some shrubs have reestablished but the ground is still bare of mosses. (Supplied)
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