Scotty Creek 2.0: a boreal peatland complex recovering from a recent late-season wildfire (October 2022)

by Oliver Sonnentag, Université de Montréal; Haley Alcock, Université de Montréal; Kyle A. Arndt, Woodwell Climate Research Center; Susan M. Natali, Woodwell Climate Research Center; Matteo Detto, Princeton University. 

The number of active flux towers in Canada’s Arctic-boreal region north of 60 deg N is limited to a dozen sites (Pallandt et al., 2022). Two active flux towers in this vast region are in the headwater portion of Scotty Creek, a ca. 150 km2  basin ca. 60 km south of Fort Simpson, NT, in the Dehcho region, home of the Łı́ı́dlı̨ı̨ Kų́ę́ First Nation. Eddy covariance and supporting measurements at Scotty Creek have been made since 2013 and 2015 at the landscape and ecosystem scale (AmeriFlux ID: CA-SCC, https://tinyurl.com/mvzj2w5r, and CA-SCB, https://tinyurl.com/57sxsd6w, respectively). CA-SCC measures fluxes originating from the boreal peatland complex, comprising forested permafrost peat plateaus and thermokarst wetlands, compared to CA-SCB, which is nested in the flux footprint of CA-SCC and only measures fluxes originating from a thermokarst wetland (Figure 1a). 

A decade of nested flux measurements at Scotty Creek has shown that permafrost thaw and associated wetland expansion across the Dehcho region have neutralized the net ecosystem carbon balance of the thawing boreal peatland complexes. The net ecosystem carbon balance quantifies the net carbon sink-source strength of ecosystems and landscapes by considering atmospheric carbon fluxes (i.e., mostly carbon dioxide and methane), including those caused by disturbances (e.g., wildfires) and carbon transported laterally by water moving across and through ecosystems (Chapin et al., 2006). Interannual variability in the net ecosystem carbon balance at Scotty Creek is largely controlled by differences in net carbon dioxide fluxes due to increased and reduced photosynthesis with wetter and drier years causing Scotty Creek to act as net carbon dioxide sink and source, respectively (Lhosmot et al., in revision, Sonnentag et al., in preparation).

Figure 1: a) Nested eddy covariance measurements at Scotty Creek comprising an ecosystem tower (CA-SCB, brown footprint area in the inset) located within the footprint of a landscape tower (CA-SCC, green footprint), b) and c) original CA-SCC destroyed by wildfire (October 2022), and d) rebuilt CA-SCC (March 2023). Photo credits: Mason Domenico

In October 2022, a late-season wildfire destroyed CA-SCC (http://bit.ly/4kjLDDr), but not CA-SCB (Figures 1b & c). The wildfire ripped through dry forested permafrost peat plateaus whereas the thermokarst wetlands were mostly unaffected. In addition to CA-SCC, the wildfire also destroyed the Scotty Creek Research Station, the first and only Indigenous-led research station in Canada. Under the leadership of the Łı́ı́dlı̨ı̨ Kų́ę́ First Nation (https://tinyurl.com/2bj43peb), the Dehcho First Nations took over the lease for the research station from Wilfrid Laurier University in August 2022. 

Driven by the urgent need to better understand the complex interactions between permafrost thaw, wildfire activity, and surface-atmosphere interactions, CA-SCC was rebuilt within a few months and reinstrumented in March 2023 (Figure 1d), making CA-SCC the only flux tower site that has measured pre- and immediate post-fire fluxes in the Arctic-boreal region. This reconstruction was made possible through the generous financial support of multiple institutions and scientific communities, including Permafrost Pathways (Woodwell Climate Research Center, Woods Hole, MA), Can-Peat (University of Waterloo, Waterloo, ON), IVADO (Montréal, QC), the Łı́ı́dlı̨ı̨ Kų́ę́ First Nation, the National Science Foundation RAPID program (Washington, DC) and AmeriFlux (Lawrence Berkeley National Laboratory, Berkeley, CA). The original, pre-fire CA-SCC flux system comprised a LI-7700 (LI-COR Inc., Lincoln, NE) and an EC150 gas analyzer with a CSAT3A sonic anemometer (both Campbell Scientific Inc., Logan, UT). After the fire, the CA-SCC flux system was rebuilt (March 2023) with a LI-7500DS (LI-COR Inc.) and a LI-7700 gas analyzer and a Gill WindMastre Pro sonic anemometer (Lymington, Hampshire, UK). Additionally, a loaner flux system (IRGASON; Campbell Scientific Inc.) provided by Ameriflux was installed thanks to the Rapid Response Systems program (March 2023-March 2026). This loaner flux system helps guarantee continuity of the pre-wildfire flux record and offers a comparison of two co-located eddy covariance systems in this unique ecosystem setting (Figure 2).

Figure 2: Intercomparison of latent heat flux (LE), sensible heat (H) flux, friction velocity (u*), and net carbon dioxide flux (Fc), obtained with the two co-located flux systems at CA-SCC (March 2023 to August 2024).

The revitalized nested flux tower infrastructure at Scotty Creek—Scotty Creek 2.0—marks a renewed commitment to advancing climate science in Canada’s Arctic-boreal region and to contributing flux data from a remote location to AmeriFlux and related repositories (e.g., Virkkala et al., 2025, See et al., 2024). For the first time, Scotty Creek 2.0 provides a unique opportunity to investigate how wildfire-accelerated permafrost thaw influences surface-atmosphere interactions in a boreal peatland complex undergoing post-wildfire recovery (Figure 3). In addition, Scotty Creek 2.0 will co-develop new knowledge to better support the communities of the Dehcho region to adapt to changing local (e.g., subsistence activities and cultural practices), regional (e.g., watershed water balance), and global ecosystem services (e.g., carbon storage). 

Figure 3: High-resolution (1.7 cm) RGB drone imagery (50 ha) of the headwater portion of Scotty Creek including the CA-SCB (ecosystem) and CA-SCC (landscape) flux towers for nested eddy covariance measurements of carbon, water and energy fluxes: a) pre-fire, b) first year post-fire, and c) second year post-fire. Drone imagery credit: Antoine Caron-Guay.

Quite surprisingly, post-fire (2023 and 2024) net carbon, water and energy fluxes from CA-SCC were not significantly different in direction (i.e., no obvious wildfire-related switch from net carbon dioxide sink to source) and magnitude (e.g., no obvious wildfire-related increase in net carbon dioxide source strength) than pre-fire fluxes (2013 – 2022). The lack of immediate wildfire impact on net carbon, water and energy fluxes may be due to contributions from mostly unburned thermokarst wetland contributions (CA-SCB) to landscape-scale fluxes (CA-SCC, Helbig et al., 2016, 2017a, 2017b). These preliminary findings highlight the importance of capturing disturbance impacts on landscape and ecosystem carbon, water and energy fluxes, and the need for continued and expanded monitoring of these fluxes as fire regimes expand and intensify.

References

Chapin, F.S., Woodwell, G.M., Randerson, J.T. et al.  (2006). Reconciling carbon-cycle concepts, terminology, and methods. Ecosystems, 9(7), 1041–1050. https://doi.org/10.1007/s10021-005-0105-7

Lhosmot, A., Hould Gosselin, G., Helbig, M. et al. (2024). Multi-scale water balance analysis of a thawing boreal peatland complex near the southern permafrost limit in western Canada. Hydrology and Earth System Sciences Discussions. https://doi.org/10.5194/hess-2024-367

Helbig, M., Wischnewski, K., Kljun, N. et al. (2016). Regional atmospheric cooling and wetting effect of permafrost thaw-induced boreal forest loss. Global Change Biology, 22(12), 4048–4066. https://doi.org/10.1111/gcb.13348

Helbig, M., Chasmer, L.E., Desai, A.R. et al. (2017a). Direct and indirect climate change effects on carbon dioxide fluxes in a thawing boreal forest–wetland landscape. Global Change Biology, 23(8), 3231–3248. https://doi.org/10.1111/gcb.13638

Helbig, M., Chasmer, L.E., Kljun, N. et al. (2017b). The positive net radiative greenhouse gas forcing of increasing methane emissions from a thawing boreal forest-wetland landscape. Global Change Biology, 23(6), 2413–2427. https://doi.org/10.1111/gcb.13520

Pallandt, M., Jung, M., Arndt, K.A. et al. (2024). High-latitude eddy covariance temporal network design and optimization. Journal of Geophysical Research: Biogeosciences, 129(19), e2024JG008406. https://doi.org/10.1029/2024JG008406

See, C.R., Virkkala, AM., Natali, S.M. et al. Decadal increases in carbon uptake offset by respiratory losses across northern permafrost ecosystems. Nature Climate Change 14, 853–862 (2024). https://doi.org/10.1038/s41558-024-02057-4

Virkkala, A.-M., Rogers, B.M., Watts, J.D. et al. (2025). Wildfires offset the increasing but spatially heterogeneous Arctic–boreal CO₂ uptake. Nature Climate Change, 15(2), 188–195. https://doi.org/10.1038/s41558-024-02234-5

Acknowledgements

Rebuilding the flux tower infrastructure Scotty Creek (“Scotty Creek 2.0”) was a group effort. We gratefully acknowledge the support of the Dehcho First Nations, particularly the Łı́ı́dlı̨ı̨ Kų́ę́ First Nation, for their support of our research activities on their traditional land. O.S. acknowledges the generous support through TED Audacious for Permafrost Pathways, the United States National Science Foundation Office of Polar Programs (award number 2316114), the Canada Research Chair and NSERC Discovery Grants programs, IVADO, and AmeriFlux. Scotty Creek 2.0 is part of Can-Peat: Canadian peatlands as nature-based climate solutions (https://uwaterloo.ca/can-peat). This project was undertaken with the financial support of the Government of Canada. Ce projet a été réalisé avec l’appui financier du gouvernement du Canada. Thanks to Wayne McKay (W&L Emporium), Gil Bohrer (Ohio State University), Gabriel Hould Gosselin (Université de Montréal), and William Quinton and Mason Dominico (both Wilfrid Laurier University). 

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