What is it about?

Boreal peatlands are a significant component of the global carbon cycle. Responsible for delivering dissolved organic carbon (DOC) into the freshwater ecosystem, the peatlands strongly influence the chemical composition and food web structure of aquatic ecosystems. However, these high-latitude peatlands are experiencing disturbances like wildfires and permafrost thaw, which are aggravated by climate change. To understand the effects of permafrost thaw and wildfires on DOC from up close, authors conducted incubation experiments on near–surface porewater (groundwater trapped in soil or rocks) from western Canadian peatlands. They studied the variation in microbial and photochemical degradation as well as porewater chemistry in different seasons. The authors observed that wildfire decreased the variability in DOC chemical composition, whereas permafrost seemed to increase it. These between-site differences became more pronounced during spring. The incubation experiments also led them to conclude that since peatlands are connected to the downstream aquatic ecosystem, disturbances linked to climate change have the potential to largely affect downstream carbon cycling.

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Why is it important?

The globally significant soil carbon stores of boreal peatlands contribute to a large portion of DOC exported to the Arctic Ocean. The change in soil DOC composition caused by the disturbances increases the mineralization of organic carbon into CO₂. This in turn leads to a microbial and photochemical imbalance in aquatic ecosystems. To realize the true effect of climate change, wildfires, and permafrost thaw on downstream nutrient and carbon cycles, we need a better understanding of the contributing sources and their associated temporal variabilities. KEY TAKEAWAY: High-latitude terrestrial environments like the boreal peatlands are hydrologically connected with larger aquatic ecosystems like oceans. The change in their hydrology and vegetation due to permafrost thaw and wildfire incidents exasperated by the climate crisis creates a cascading effect on the global carbon balance landscape.

Read the Original

This page is a summary of: Lability of dissolved organic carbon from boreal peatlands: interactions between permafrost thaw, wildfire, and season, Canadian Journal of Soil Science, December 2020, Canadian Science Publishing, DOI: 10.1139/cjss-2019-0154.
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