Carbon loss from boreal peatland wildfires greater than purported: insights from high resolution lidar and field data
Abstract
A vital carbon sink, boreal peatlands in western Canada store a disproportionate amount of the global soil carbon relative to their area. As potential evapotranspiration is the dominant hydrological process, these peatlands are sensitive to climatic shifts and are widely observed to be drying with climatic change. Concurrently, wildfire extent, severity, and frequency are increasing in this region. Carbon loss as a result of peat combustion can influence the global carbon-climate cycle, such that there is potential for a shift in these peatlands from carbon sink to source. Despite the importance of boreal peatlands in the global carbon budget, there are substantial uncertainties as to peatland depth of burn (DOB) and subsequent carbon loss during wildfire. DOB can be highly variable, a condition which is often not accounted for due to methodological limitations. Accessibility and time constraints may limit the capacity of field measurements to account for wide spatial variability, laboratory experiments lack generalizability to natural settings, and optical remote sensing cannot account for DOB. High resolution, time-series lidar data can be used to overcome these limitations by spatializing pre- and post-fire ground surface elevations.
This study uses pre- and post-fire high-resolution lidar data, in combination with field data, to quantify spatial variability of carbon loss during a 2016 boreal wildfire (Horse River Wildfire). Field data collection, including GPS validation, vegetation surveys, and peat sample collection, was done coincident to lidar missions. We quantify DOB by creating a difference elevation model from pre- and post-fire lidar data and analyze peat samples for bulk density and carbon content. While this research is ongoing, results suggest that average DOB and carbon losses, respectively, are 19 cm (SD = 10) and 2.7 kg/m2 (SD = 1.4) within peatlands (n = 200); 54 cm (SD = 24) and 20.6 kg/m2 (SD = 9.1) along peatland edges (n = 50); to a maximum of 108 cm (n = 250) and 55.6 kg/m2. These values are greater than those previously reported, suggesting that carbon losses from boreal peatland wildfires are underestimated. This supports the need for more accurate quantification of carbon loss from peat fires to better understand the role of boreal peatlands in the global carbon-climate cycle.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B33B..02N
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCES