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researcher portrait

Johan Eckdahl

Researcher in boreal wildfire

researcher portrait

Climatic variation drives loss and restructuring of carbon and nitrogen in boreal forest wildfire

Author

  • Johan A. Eckdahl
  • Jeppe A. Kristensen
  • Daniel B. Metcalfe

Summary, in English

The boreal forest landscape covers approximately 10% of the earth's land area and accounts for almost 30 % of the global annual terrestrial sink of carbon (C). Increased emissions due to climate-change-amplified fire frequency, size, and intensity threaten to remove elements such as C and nitrogen (N) from forest soil and vegetation at rates faster than they accumulate. This may result in large areas within the region becoming a net source of greenhouse gases, creating a positive feedback loop with a changing climate. Meter-scale estimates of area-normalized fire emissions are limited in Eurasian boreal forests, and knowledge of their relation to climate and ecosystem properties is sparse. This study sampled 50 separate Swedish wildfires, which occurred during an extreme fire season in 2018, providing quantitative estimates of C and N loss due to fire along a climate gradient. Mean annual precipitation had strong positive effects on total fuel, which was the strongest driver for increasing C and N losses. Mean annual temperature (MAT) influenced both pre-and postfire organic layer soil bulk density and C: N ratio, which had mixed effects on C and N losses. Significant fire-induced loss of C estimated in the 50 plots was comparable to estimates in similar Eurasian forests but approximately a quarter of those found in typically more intense North American boreal wildfires. N loss was insignificant, though a large amount of fire-affected fuel was converted to a low C: N surface layer of char in proportion to increased MAT. These results reveal large quantitative differences in C and N losses between global regions and their linkage to the broad range of climate conditions within Fennoscandia. A need exists to better incorporate these factors into models to improve estimates of global emissions of C and N due to fire in future climate scenarios. Additionally, this study demonstrated a linkage between climate and the extent of charring of soil fuel and discusses its potential for altering C and N dynamics in postfire recovery.

Department/s

  • Dept of Physical Geography and Ecosystem Science
  • BECC: Biodiversity and Ecosystem services in a Changing Climate

Publishing year

2022

Language

English

Pages

2487-2506

Publication/Series

Biogeosciences

Volume

19

Issue

9

Document type

Journal article

Publisher

Copernicus GmbH

Topic

  • Climate Research

Status

Published

ISBN/ISSN/Other

  • ISSN: 1726-4170