Xenopoulos introduced the paper by Zolkos,et al, 2002 by opining that Arctic regions are disproportionally affected by climate change, resulting in increases in wildfire frequency. Wildfires can profoundly affect the biogeochemistry of tundra ecosystems. In these permafrost environments, postfire effects include large amounts of nutrients and carbon released into aquatic ecosystems, and changes in vegetation and hydrology. But these changes are not uniform across the Arctic landscape. A more concrete understanding of the role of the Arctic landscape and its mosaic of land features is needed to further our knowledge of wildfires in northern ecosystems.
Map of the Yukon-Kuskokwim Delta in Alaska outlining in red the outer border
of wildfires that occurred in 2015. The yellow points are the aquatic ecosystems
that were sampled (Zolkos et al. [2022])
Zolkos et al. [2022] address this gap by measuring changes in surface and pore water chemistry variables across landscape gradients within streams, lakes, and fen and peat ponds, of the Yukon-Kuskokwim Delta, Alaska, following high wildfire activity in 2015. In general, wildfires reduced organic carbon and CO2 in surface water but increased inorganic constituents and nitrogen cycling. Response and recovery to wildfire depended on landscape characteristics. Aquatic environments found in higher elevation and within smaller watersheds revealed enhanced carbon cycling due to their strong linkages with their terrestrial surroundings. Lower in the landscape, enhanced nitrogen cycling along stream riparian corridors was the major response to wildfire.
Zolkos and 8 co-authors summarized that warming at northern high latitudes is expected to increase wildfire activity, permafrost thaw, and hydrologic connectivity. Yet, contrasting evidence for wildfire effects on aquatic biogeochemistry hinders a more concrete understanding of potential future changes to northern ecosystems, especially in delta environments, where land-freshwater linkages are strong.
To address this, the authors made ∼400 measurements of hydrochemistry within the Yukon-Kuskokwim Delta, Alaska, following high wildfire activity in 2015. Variation in hydrochemistry among five aquatic environments—peat plateau ponds, fen ponds, fen channels, lakes, and streams—was more strongly associated with watershed characteristics (e.g., land-freshwater linkages) than wildfire. However, wildfire consistently affected some parameters. For instance, dissolved organic carbon and CO2 were lower in burned watersheds, likely from combustion of organic matter, whereas, pH, specific conductance, and nitrogen were higher, reflecting solute release from combusted organics.
Multi-year measurements (2015–2019) allowed us to assess post-fire variation in hydrochemistry among lakes and fen ponds, and indicate that ecosystem response and recovery to wildfire depend on watershed characteristics. Results indicate that increasing tundra wildfire at northern high latitudes could drive multi-year shifts toward stronger aquatic inorganic nutrient cycling. Across broader spatiotemporal scales, variation in terrain characteristics is likely to underlie wildfire effects on aquatic ecosystems.
[The original working URL: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022JG006891 ]
[In addition, two related papers are also included:
"Lightning in Alaskan Tundra Ignites Most Fires", which includes the Seward Pennisula: https://eos.org/editor-highlights/lightning-in-alaskan-tundra-ignites-most-fires
and
"Aquatic Plants May Accelerate Arctic Methane Emissions," https://eos.org/articles/aquatic-plants-may-accelerate-arctic-methane-emissions ]
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