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- Ibáñez, Theresa Simona, et al.
(author)
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Effects of Soil Abiotic and Biotic Factors on Tree Seedling Regeneration Following a Boreal Forest Wildfire
- 2022
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In: Ecosystems. - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 25, s. 471-487
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Journal article (peer-reviewed)abstract
- Wildfire disturbance is important for tree regeneration in boreal ecosystems. A considerable amount of literature has been published on how wildfires affect boreal forest regeneration. However, we lack understanding about how soil-mediated effects of fire disturbance on seedlings occur via soil abiotic properties versus soil biota. We collected soil from stands with three different severities of burning (high, low and unburned) and conducted two greenhouse experiments to explore how seedlings of tree species (Betula pendula, Pinus sylvestris and Picea abies) performed in live soils and in sterilized soil inoculated by live soil from each of the three burning severities. Seedlings grown in live soil grew best in unburned soil. When sterilized soils were reinoculated with live soil, seedlings of P. abies and P. sylvestris grew better in soil from low burn severity stands than soil from either high severity or unburned stands, demonstrating that fire disturbance may favor post-fire regeneration of conifers in part due to the presence of soil biota that persists when fire severity is low or recovers quickly post-fire. Betula pendula did not respond to soil biota and was instead driven by changes in abiotic soil properties following fire. Our study provides strong evidence that high fire severity creates soil conditions that are adverse for seedling regeneration, but that low burn severity promotes soil biota that stimulates growth and potential regeneration of conifers. It also shows that species-specific responses to abiotic and biotic soil characteristics are altered by variation in fire severity. This has important implications for tree regeneration because it points to the role of plant-soil-microbial feedbacks in promoting successful establishment, and potentially successional trajectories and species dominance in boreal forests in the future as fire regimes become increasingly severe through climate change.
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| 2. |
- Ibáñez, Theresa Simona
(author)
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Wildfire in Swedish boreal forests - Impacts of fire severity and salvage logging on tree seedling regeneration and the belowground system
- 2022
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Doctoral thesis (other academic/artistic)abstract
- Wildfires are projected to occur more frequently and become more severe as the climate warms. The increasing release of carbon to the atmosphere from more severe fires may contribute to climate warming, and thus initiate a positive feedback loop. Following wildfire, salvage logging is a common management practice, but the impact on soil and vegetation may vary depending on fire severity. Hence, it is important to understand how wildfire severity and salvage logging affect soil abiotic and biotic properties and tree seedling regeneration. Also, in the future, forest recovery from fire and salvage logging may be affected by climate warming. In this thesis, I have conducted laboratory and greenhouse experiments to investigate the abiotic and biotic effects of fire severity and post-fire management on biomass production of Betula pendula, Picea abies and Pinus sylvestris seedlings regenerated from seeds and associated soil processes. Further, I have performed a mesocosm field experiment to investigate the impacts of fire severity, salvage logging and experimental warming on P. abies and P. sylvestris nursery seedlings in situ, and undertaken field measurements of soil N transformation rates and C fluxes in stands of varying fire severity and management. This thesis shows that the effect of fire severity on the soil system is stronger than that of salvage logging and that the impact of salvage logging on forest regeneration varies depending on fire severity; these effects can further be directly or indirectly altered by experimental climate warming. This thesis also shows that the effect of soil abiotic and biotic properties following fire on tree seedling regeneration are species specific. Altogether, it contributes with new fundamental knowledge about the interactive effects of multiple drivers of seedling regeneration and soil processes in the post-fire boreal forest landscape. The conclusions of this thesis can be applied, in combination with other research, in decision making about management of boreal forest following wildfire.
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