Abstract
Tundra ecosystems contain some of the largest stores of soil organic carbon among all biomes worldwide. Wildfire, the primary disturbance agent in Arctic tundra, is likely to impact soil properties in ways that enable carbon release and modify ecosystem functioning more broadly through impacts on organic soils, based on evidence from a recent extreme Anaktuvuk River Fire (ARF). However, comparatively little is known about the long-term impacts of typical tundra fires that are short-lived and transient. Here we quantitatively investigated how these transient tundra fires and other landscape factors affected organic soil properties, including soil organic layer (SOL) thickness, soil temperature, and soil moisture, in the tussock tundra. We examined extensive field observations collected from nearly 200 plots across a wide range of fire-impacted tundra regions in AK within the scope of NASA’s Arctic Boreal Vulnerability Experiment. We found an overall shallower SOL in our field regions (∼15 cm on average) compared to areas with no known fire record or the ARF (∼20 cm or thicker), suggesting that estimations based on evidence from the extreme ARF event could result in gross overestimation of soil organic carbon (SOC) stock and fire impacts across the tundra. Typical tundra fires could be too short-lived to result in substantial SOL consumption and yield less robust results of SOL and carbon storage. Yet, repeated fires may amount to a larger amount of SOC loss than one single severe burning. As expected, our study showed that wildfire could affect soil moisture and temperature in the tussock tundra over decades after the fire, with drier and warmer soils found to be associated with more frequent and severe burnings. Soil temperature was also associated with vegetation cover and air temperature.
Highlights
Soil organic layer (SOL) is a crucial component controlling the physical and thermal mechanisms of vegetation growth, soil decomposition, and carbon balance across permafrost-dominated landscapes of the High Northern Latitudes (HNLs; Harris 1987, Harden et al 2006, Drobyshev et al 2010, Jiang et al 2015, Trugman et al 2016)
These were lower than the 6.1 cm estimated from the Anaktuvuk River Fire (ARF) (Mack et al 2011)
Typically tundra fires can be too short-lived to result in considerable SOL consumption with substantial spatial variation and yield much less robust modeling results regarding the loss of soil organic carbon (SOC), compared to the severe combustion and extended smoldering observed on the ARF or boreal forest fires
Summary
Soil organic layer (SOL) is a crucial component controlling the physical and thermal mechanisms of vegetation growth, soil decomposition, and carbon balance across permafrost-dominated landscapes of the High Northern Latitudes (HNLs; Harris 1987, Harden et al 2006, Drobyshev et al 2010, Jiang et al 2015, Trugman et al 2016). SOL thickness is an important indicator of the SOC storage in Alaskan tundra, given their strong positive relationships (Pastick et al 2014, Baughman et al 2015). It affects the establishment and growth of boreal forests (Lafleur et al 2015, Trugman et al 2016) and alters soil temperature and moisture (Kasischke and Johnstone 2005). Soil temperature and moisture can influence the hydrological and thermal processes in the SOL and permafrost (Fisher et al 2016, Schuh et al 2017) Monitoring those can enhance our understanding of soil carbon dynamics and permafrost degradation in the Arctic
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
