Boreal Forest Wildfire in a Changing Climate
Eckdahl, Johan LU
(2023)
- Abstract
- The boreal region contains 40% of the earth’s carbon (C) that is stored in vegetation and soils with its forests accounting for almost 30% of the terrestrial C sink. Boreal forests are experiencing some of the most rapid rates of climatic warming and increases in fire activity, threatening to release large amounts of their dense C reserves to the atmosphere. While climate and wildfire place strong controls on ecosystem function, few observations have been made regarding their potential synergistic effects. This thesis utilized 50 separately occurring summer 2018 wildfires, each paired with an unburnt control and spread across the near-entire climatic range of boreal Fennoscandia, providing the first field campaign targeting regional-scale... (More)
- The boreal region contains 40% of the earth’s carbon (C) that is stored in vegetation and soils with its forests accounting for almost 30% of the terrestrial C sink. Boreal forests are experiencing some of the most rapid rates of climatic warming and increases in fire activity, threatening to release large amounts of their dense C reserves to the atmosphere. While climate and wildfire place strong controls on ecosystem function, few observations have been made regarding their potential synergistic effects. This thesis utilized 50 separately occurring summer 2018 wildfires, each paired with an unburnt control and spread across the near-entire climatic range of boreal Fennoscandia, providing the first field campaign targeting regional-scale variation in boreal wildfire activity. It was found that climate determined the prefire quantity and structure of forest fuel, which in turn controlled both the immediate and extended fire-induced removal rates of C and nitrogen (N) to the surrounding land and atmosphere. Reorganization of ecosystem structure through wildfire burning strengthened climatic control over soil microbial community structure and nutrient cycling, with warmer regions experiencing enhanced nutrient mobilization under oligotrophic processing of remaining burnt organic soil. Greater warmth and soil fertility together stimulated growth of broadleaf overstory species under a restricted recovery capacity of previously established coniferous and ericaceous plant communities, though this transition to novel growth patterns was limited by residual, biodiversity inhibiting plant-soil feedbacks. Together these results suggest that continued climate change and wildfire can serve to remove C and nutrients from burnt boreal forests under a limited capacity for their reaccumulation. This postfire resource drain is capable of influencing longer-term patterns of ecosystem regrowth and the boreal forest contribution to the global land-atmosphere C balance that is deserving of further study. (Less)
- Abstract (Swedish)
- Den boreala regionen innehåller 40% av jordens kol (C) som lagras i vegetation och mark med sina skogar som står för nästan 30% av den terrestra C sänkan. Boreala skogar upplever några av de snabbaste hastigheterna för klimatuppvärmning och ökningar i brandaktivitet, vilket hotar att släppa ut stora mängder av deras C reserver till atmosfären. Även om klimat och skogsbränder har stark kontroll över ekosystemets funktion, har få observationer gjorts avseende deras potentiella synergistiska effekter. Denna avhandling utnyttjade 50 separat förekommande sommarbränder 2018, var och en parade med en obränd kontroll och spridda över nästan hela det klimatiska området i boreala Fennoskandien, vilket ger den första fältkampanjen som riktar sig mot... (More)
- Den boreala regionen innehåller 40% av jordens kol (C) som lagras i vegetation och mark med sina skogar som står för nästan 30% av den terrestra C sänkan. Boreala skogar upplever några av de snabbaste hastigheterna för klimatuppvärmning och ökningar i brandaktivitet, vilket hotar att släppa ut stora mängder av deras C reserver till atmosfären. Även om klimat och skogsbränder har stark kontroll över ekosystemets funktion, har få observationer gjorts avseende deras potentiella synergistiska effekter. Denna avhandling utnyttjade 50 separat förekommande sommarbränder 2018, var och en parade med en obränd kontroll och spridda över nästan hela det klimatiska området i boreala Fennoskandien, vilket ger den första fältkampanjen som riktar sig mot regional variation i boreal brandaktivitet. Det konstaterades att klimatet bestämde den prebrandmängden och strukturen på skogsbränsle, vilket i sin tur kontrollerade både de omedelbara och förlängda brandinducerade borttagningshastigheterna av C och kväve (N) till den omgivande marken och atmosfären. Omorganisering av ekosystemstrukturen genom skogsbränder stärkte klimatkontrollen över strukturen på markmikrobsamhällen och näringscykling, med varmare regioner som upplever förbättrad näringsmobilisering under oligotrofisk bearbetning av kvarvarande bränd organisk mark. Större värme och markfruktbarhet stimulerade tillsammans tillväxten av lövträd över trädgränsen under en begränsad återhämtningskapacitet hos tidigare etablerade barr- och erikoidväxter, även om denna övergång till nya tillväxtmönster begränsades av kvarvarande, biologisk mångfalds hämmande växt-markåterkopplingar. Tillsammans tyder dessa resultat på att fortsatt klimatförändring och skogsbränder kan tjäna till att ta bort C och näringsämnen från brända boreala skogar under en begränsad kapacitet för deras återackumulering. Denna resursdränering efter branden är kapabel att påverka längre mönster av ekosystemåterväxt och den boreala skogens bidrag till den globala land-atmosfär C balansen som är värd ytterligare studier. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/bca6a5fd-28b4-484d-a204-f2a13141bd36
- author
- Eckdahl, Johan
LU
- supervisor
- opponent
-
- Associate Professor Pellegrini, Adam, University of Cambridge, UK.
- organization
- alternative title
- Boreal Skogsbrand i ett Föränderligt Klimat
- publishing date
- 2023-11-26
- type
- Thesis
- publication status
- published
- subject
- keywords
- boreal forest wildfire, carbon emissions, nutrient cycling, nitrogen, microbial community, plant community, climate chnge, secondary succession, Sweden, Fennoscandia, biodiversity, boreal skogsbrand, koldioxiduttsläpp, näringscykling, kväve, mirkobiellt samhälle, växtsamhälle, klimatförändring, sekundär succession, sverige, Fennoskandien, biologisk mångfald
- pages
- 183 pages
- publisher
- Department of Physical Geography and Ecosystem Science, Faculty of Science, Lund University
- defense location
- Pangea, Helgonavägen 5, Lund.
- defense date
- 2024-02-14 10:00:00
- ISBN
- 978-91-89187-32-0
- 978-91-89187-31-3
- project
- Patterns and mechanisms in post-fire recovery of major forest ecosystem services and functions
- language
- English
- LU publication?
- yes
- id
- bca6a5fd-28b4-484d-a204-f2a13141bd36
- date added to LUP
- 2023-11-26 10:09:16
- date last changed
- 2024-01-12 13:22:55
@phdthesis{bca6a5fd-28b4-484d-a204-f2a13141bd36,
abstract = {{The boreal region contains 40% of the earth’s carbon (C) that is stored in vegetation and soils with its forests accounting for almost 30% of the terrestrial C sink. Boreal forests are experiencing some of the most rapid rates of climatic warming and increases in fire activity, threatening to release large amounts of their dense C reserves to the atmosphere. While climate and wildfire place strong controls on ecosystem function, few observations have been made regarding their potential synergistic effects. This thesis utilized 50 separately occurring summer 2018 wildfires, each paired with an unburnt control and spread across the near-entire climatic range of boreal Fennoscandia, providing the first field campaign targeting regional-scale variation in boreal wildfire activity. It was found that climate determined the prefire quantity and structure of forest fuel, which in turn controlled both the immediate and extended fire-induced removal rates of C and nitrogen (N) to the surrounding land and atmosphere. Reorganization of ecosystem structure through wildfire burning strengthened climatic control over soil microbial community structure and nutrient cycling, with warmer regions experiencing enhanced nutrient mobilization under oligotrophic processing of remaining burnt organic soil. Greater warmth and soil fertility together stimulated growth of broadleaf overstory species under a restricted recovery capacity of previously established coniferous and ericaceous plant communities, though this transition to novel growth patterns was limited by residual, biodiversity inhibiting plant-soil feedbacks. Together these results suggest that continued climate change and wildfire can serve to remove C and nutrients from burnt boreal forests under a limited capacity for their reaccumulation. This postfire resource drain is capable of influencing longer-term patterns of ecosystem regrowth and the boreal forest contribution to the global land-atmosphere C balance that is deserving of further study.}},
author = {{Eckdahl, Johan}},
isbn = {{978-91-89187-32-0}},
keywords = {{boreal forest wildfire; carbon emissions; nutrient cycling; nitrogen; microbial community; plant community; climate chnge; secondary succession; Sweden; Fennoscandia; biodiversity; boreal skogsbrand; koldioxiduttsläpp; näringscykling; kväve; mirkobiellt samhälle; växtsamhälle; klimatförändring; sekundär succession; sverige; Fennoskandien; biologisk mångfald}},
language = {{eng}},
month = {{11}},
publisher = {{Department of Physical Geography and Ecosystem Science, Faculty of Science, Lund University}},
school = {{Lund University}},
title = {{Boreal Forest Wildfire in a Changing Climate}},
url = {{https://lup.lub.lu.se/search/files/165690564/e-spik_ex_Johan.pdf}},
year = {{2023}},
}