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Julia Kelly. Photo.

Julia Kelly

Researcher

Julia Kelly. Photo.

Boreal forest soil carbon fluxes one year after a wildfire : Effects of burn severity and management

Author

  • Julia Kelly
  • Theresa S. Ibáñez
  • Cristina Santín
  • Stefan H. Doerr
  • Marie Charlotte Nilsson
  • Thomas Holst
  • Anders Lindroth
  • Natascha Kljun

Summary, in English

The extreme 2018 hot drought that affected central and northern Europe led to the worst wildfire season in Sweden in over a century. The Ljusdal fire complex, the largest area burnt that year (8995 ha), offered a rare opportunity to quantify the combined impacts of wildfire and post-fire management on Scandinavian boreal forests. We present chamber measurements of soil CO2 and CH4 fluxes, soil microclimate and nutrient content from five Pinus sylvestris sites for the first growing season after the fire. We analysed the effects of three factors on forest soils: burn severity, salvage-logging and stand age. None of these caused significant differences in soil CH4 uptake. Soil respiration, however, declined significantly after a high-severity fire (complete tree mortality) but not after a low-severity fire (no tree mortality), despite substantial losses of the organic layer. Tree root respiration is thus key in determining post-fire soil CO2 emissions and may benefit, along with heterotrophic respiration, from the nutrient pulse after a low-severity fire. Salvage-logging after a high-severity fire had no significant effects on soil carbon fluxes, microclimate or nutrient content compared with leaving the dead trees standing, although differences are expected to emerge in the long term. In contrast, the impact of stand age was substantial: a young burnt stand experienced more extreme microclimate, lower soil nutrient supply and significantly lower soil respiration than a mature burnt stand, due to a thinner organic layer and the decade-long effects of a previous clear-cut and soil scarification. Disturbance history and burn severity are, therefore, important factors for predicting changes in the boreal forest carbon sink after wildfires. The presented short-term effects and ongoing monitoring will provide essential information for sustainable management strategies in response to the increasing risk of wildfire.

Department/s

  • MERGE - ModElling the Regional and Global Earth system
  • BECC - Biodiversity and Ecosystem services in a Changing Climate
  • Centre for Environmental and Climate Science (CEC)
  • Dept of Physical Geography and Ecosystem Science

Publishing year

2021-05-24

Language

English

Pages

4181-4195

Publication/Series

Global Change Biology

Volume

27

Issue

17

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Soil Science

Keywords

  • 2018 drought
  • boreal forest
  • carbon fluxes
  • climate change
  • compound disturbance
  • forest fire
  • forest floor
  • harvesting
  • salvage-logging

Status

Published

ISBN/ISSN/Other

  • ISSN: 1354-1013