Rising from the Ashes: Evaluating the Potential for Peat Moss Recovery After Wildfire

Photo Credits for Video

All photographs are mine except those noted below:

Canadian Sphagnum Moss Association. Map of Peatland Distribution in Canada. 2026, https://peatmoss.com/en/peatlands/

Google Maps. Map showing wildfire-affected Morewood bog in Alvin Runnalls Forest in North Dundas, ON, and the Mer Bleue Bog in Ottawa, 2026.

Irven, Cheryl. Photo of wildfire burning with red flames at Morewood Bog in Alvin Runnalls Forest, Ontario. 21 September 2025, Farmers Forum, https://farmersforum.com/100-acre-bush-fire-burning-out-of-control-in-north-dundas/.

North Dundas Township. Three Photos of burnt Morewood bog after rain dampened severe wildfire. 23 Sept 2025, https://ottawacitizen.com/news/north-dundas-forest-fire-reduced.

Tinkess, Terry. Photo of severely burned grey-charred Alvin Runnalls Forest where Morewood Bog is located. “North Dundas Fire Crews Battle Stubborn Fire at Alvin Runnalls Forest.” The Record (Storemont, Dundas, and Russell Counties), 24 September 2025, https://www.therecordnews.ca/2025/09/24/north-dundas-fire-crews-battle-stubborn-fire-at-alvin-runnalls-forest/

Peatlands store carbon as partially decomposed plant debris, known as peat, which forms in waterlogged environments with low-oxygen, which slows the decay process. Peatlands are important as a carbon sink, have high biodiversity of plants and animals and aesthetic value, and regulate water flow.

In Fall 2025, a wildfire burned 100 acres of Alvin Runnals Forest including an area of the Morewood bog, 45km SE of Ottawa in North Dundas, ON(Fig1). This created a natural opportunity to study the potential for wildfire-affected peatland to recover. Peatland recovery requires the ability of Sphagnum to continue to absorb and retain water and to regenerate.

Understanding a peatland’s ability to recover after a wildfire is important because peatlands are a nature-based solution for climate-change mitigation. If natural recovery is expected to be poor, new Sphagnum material could be spread in post-fire restoration efforts to aid peatland recovery.

This study also examined Sphagnum from an undisturbed bog, Mer Bleue, a 3500-hectare wetland complex in the National Capital Commission’s Greenbelt(Fig1). In both bogs, the dominant groundcover vegetation is Sphagnum. Sphagnum mosses, a keystone peat-forming genus with about 350 species, cover the majority of northern peatlands, and contribute to the wet conditions necessary to prevent decomposition because they can hold many times their own weight in water.

This study tested Morewood bog cuttings across 5 burn levels (unburnt green, lightly singed, singed, partially burnt, and burnt) and compared the findings to control cuttings from Mer Bleue bog to evaluate water-holding capacity and regeneration potential(Figs2-6).

Moss samples were collected from the wild-fire-affected Morewood bog and the non-wildfire-affected Mer Bleue bog as a control and refrigerated. Two sphagnum species, S. fuscum and S. magellanicum, were identified from visual keys in moss field guides(Fig8).

Method and Material (Hydrology)

To test whether the degree of burn affected peat’s capacity to absorb water, individual moss stems from Morewood in 5 burn levels, 2 species, and different depths were cut into 1-2cm pieces, with Mer Bleue cuttings as a control (12 cuttings/type, 696 total cuttings)(Fig9). Pieces were placed in lidded labelled 4-compartment petri dishes and air-dried(Fig22). Each piece was weighed on a digital scale, the mass recorded, and re-placed in its compartment. Samples soaked for 24 hours in 30ml distilled water/dish(Fig7). Individual cuttings were then removed, air-dried 1min on filter paper, and re-weighed(Fig10). The difference between initial dried peat weight and soaked peat weight was calculated to determine each cutting’s capacity to absorb and store water.

Method and Material (Viability)

To test whether the degree of burn affected peat’s capacity to grow new buds, 1-2cm pieces for each of 5 burn levels, 2 species, and different depths from Morewood were cut and placed in numbered petri dishes (6 samples/dish) on filter paper and similar Mer Bleue cuttings as a control(Fig9). Dishes were placed in 5 grow chambers in a 6x4 layout/chamber (720 total cuttings)(Fig12). A nutritive solution was created from 3 dilutions of FloraNovaBloom to 1:70,000(Fig11). Each dish received 30ml of dilute solution and another 5ml at 5 weeks. Grow lights were on 6:00am-8:00pm daily, cool-mist humidifying 24hours/day, and distilled water added as needed. At 4, 6, 8, and 10 weeks, any viable buds were recorded, photographed, and removed, and viable cuttings per dish totalled at 10 weeks(Fig13).

Hydrology Experiment

Overall Morewood S. magellanicum has higher water absorption than S. fuscum.

For Morewood samples, the highest water absorption occurred in unburnt green S. fuscum and S. magellanicum cuttings from 1-2cm (the second highest was the top 0-1cm). For unburnt samples of both species, absorption decreased as the distance from the top increased to a depth of 6-8cm. By contrast, for singed and lightly singed in both species, the absorption increased as the depth from the surface increased. Both species’ singed and lightly singed samples always had lower water absorption than the unburnt samples. For all depths except 6-8cm, singed S. fuscum and S. magellanicum had slightly greater water absorption than lightly singed samples (Figs 14-15).

Burnt Morewood samples had the lowest water absorption of any samples at any depth (on average, 38.5% absorption across all depths). By contrast, partially burnt cuttings had high water absorption, similar to unburnt S. fuscum. For both species, peak water absorption was at 1-2 cm for partially burnt and at 2-4cm for burnt samples. Within a species, Morewood lightly singed and singed values were similar (Figs 16-17).

Over the 12 wetting trials, the Mer Bleue control cuttings had a relative range of absorption of 44.1, 23.1, 22.3, 25.1 and 38.8% respectively for the 5 cutting depths. The largest percentage absorption was for cuttings from 1-2cm (average 429.7%) and the least from 6-8cm (average 235.5%).

Viability Experiment

For unburnt green, lightly singed, and singed Morewood cuttings, S. magellanicum viability was greater than S. fuscum viability. The percentage of viable buds decreased as the level of burn increased (Fig 21).

For Morewood S. fuscum samples, the majority of unburnt green cuttings were viable for all depths, with an average of 83.3% for all depths. However, viability decreased with increasing depth. The viability percentage of wildfire-affected cuttings was lower than for unburnt cuttings. In lightly singed cuttings, 92% of 0-1cm cuttings, half of 1-2cm, and only 25% cuttings at deeper depths were viable. For singed cuttings, only 8.4% were viable at the top two depths and 0% at deeper depths (Fig 18).

By contrast for Morewood S. magellanicum cuttings, viability was very similar for unburnt green, lightly singed and singed. Between 67-100% cuttings were viable at all depths, with small decreases in viability with increasing depth (Fig 19).

Fully burnt Morewood cuttings were non-viable at all depths. Partially burnt cuttings were non-viable at the surface (0-1cm) but increased in viability at the next two depths (33% at 1-2cm; 83% at 2-4cm) before decreasing to 42% at 4-6cm (Fig 20).

For both species and at both locations, there were viable buds that grew from cuttings at deeper depths. For both sites, S. fuscum cuttings had a lower percentage of viable buds across all burn levels than S. magellanicum cuttings.

All the Mer Bleue controls showed high percentages of viable buds at 83.3–100%. The viability percentages had good consistency across the 5 grow chambers.

Water absorption is critical for moss growth as photosynthesis requires water, but must be evaluated alongside viability to fully assess moss regrowth capacity after fire. In this experiment, all species at every level of burn had capacity for at least some water uptake, but absorption rate generally decreased with increasing burn level. Lightly singed, singed, and burnt cuttings’ water absorption increased with depth, perhaps because moss cells further below the surface were less damaged. Moss viability decreased with burn severity and depth from the surface. Fully burnt moss was non-viable at any depth. S. fuscum was less resilient to wildfire than S. magellanicum with lower water absorption and lower percentages of bud regeneration for the different levels of burn.

Although the most severely burned moss from Morewood was not viable, this study revealed that moss with mild to moderate burn damage from a wildfire can hold water and regrow(Fig24).

This research has major implications for peatland recovery and carbon sequestration. The experiment results suggest peat is resilient and can remain viable after wildfire exposure unless it is severely burnt. As the Morewood fire illustrated, a peatland can experience a wide range of burn damage(Figs23, 25-28). Hence, viable moss can remain in less damaged areas, which should be able to produce spores and spread into more severely burned areas where moisture levels may be suitable for new growth and permit the peatland to naturally regenerate. Spreading unburnt or mildly burnt moss into fire break gaps may also be useful for restoration.

This study examined how wildfire burn affected the capacity of S. fuscum and S. magellanicum sphagnum moss to hold water and regenerate. Continuing to monitor moss regrowth over several seasons at the wildfire-impacted regions of Morewood bog would provide comparative-species data on resilience over time. A 5-year study could evaluate how variations in environmental factors, like temperature and precipitation, affect peatlands recovery, as changes in these conditions could influence water uptake, regrowth, and overall peatland resilience after wildfire damage. Expanding the study to additional species at Morewood could help identify the most resilient species for restoration efforts in wildfire-affected peatlands.

I am very grateful to Dr. Elyn Humphreys, Professor at the Department of Geography and Environmental Studies at Carleton University, for her wonderful mentorship during the research, for the Mer Bleue bog field trip, and for her help in collecting peat samples from both sites.

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