Decadal effects of forest fire on biodiversity and browsing: a comparison between wildfire and prescribed burning

Emelie Fredriksson

Decadal effects of forest fire on biodiversity and browsing: a comparison between wildfire and prescribed burning

Bidragets översatta titel: Långsiktiga effekter av skogsbrand på biodiversitet och bete – en jämförelse mellan naturlig brand och naturvårdsbränningar

Emelie Fredriksson

Institutionen för vilt, fisk och miljö

Publikation: Avhandling › Doktorsavhandling

4 Nedladdningar

Sammanfattning

Brandens roll som naturlig störning i boreala ekosystem har i stort sett försvunnit på grund av effektivt brandbekämpning vilket har medfört stora konsekvenser för den brandrelaterade biologiska mångfalden. Skogsbränder skapar områden med tidiga successionsstadier med stora mängder lövträd och nybildad död ved. Dessa livsmiljöer saknas till stor del i dagens skogslandskap. Nyligen har naturvårdsbränder införts som en åtgärd för att främja den biologiska mångfalden. I den här avhandlingen utvärderar jag effekterna efter brand på artsammansättning av vedlevande tickor, skalbaggar, fågel- och däggdjursarter, vegetation i fält- och buskskikt samt älgbete. Jag fann skillnader i artsammansättning bland alla taxa ett drygt decennium efter brand och en tydlig förändring hos skalbaggar åren omedelbart efter brand. Inga däggdjur eller fåglar nyttjade skogsbränderna till en högre grad jämfört med den obrända skogen, vilket tyder på att de brända områdena inte tillför så mycket i ett landskap redan präglat av habitat i tidiga successionsstadier. De obrända skogarna var även viktiga livsmiljöer för bland annat rödlistade tickor, ren och tjäder. Skogsbranden skapade unika strukturer i form av stora mängder död ved och rik fältskiktsvegetation men jag upptäckte distinkta skillnader jämfört med naturvårdsbränderna. Naturvårdsbränder påverkade inte den biologiska mångfalden hos tickor, skalbaggar, eller fodertillgången och nyttjande av älg i samma grad som naturliga skogsbränder. Därför betonar jag vikten av högre brandintensitet om naturvårdsbränningar ska efterlikna skogsbränders effekter på biologisk mångfald i större utsträckning.

Bidragets översatta titel	Långsiktiga effekter av skogsbrand på biodiversitet och bete – en jämförelse mellan naturlig brand och naturvårdsbränningar
Originalspråk	Engelska
Kvalifikation	Doktor i filosofi
Förlag	Swedish University of Agricultural Sciences
Tryckta ISBN	978-91-7760-841-7
Elektroniska ISBN	978-91-7760-842-4
Status	Publicerad - 2021

Nyckelord

Boreal forest
Coleoptera
community composition
disturbance regime
functional groups
indicator species
traits
turnover

SLU-serie

Acta Universitatis Agriculturae Sueciae

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title = "Decadal effects of forest fire on biodiversity and browsing: a comparison between wildfire and prescribed burning",

abstract = "The role of fire as a natural disturbance in northern European boreal ecosystems has largely disappeared due to effective fire suppression with large consequences for fire-associated biodiversity. Recently, prescribed burns have been introduced as a conservation action that aims to promote biodiversity. Not only fire regimes but also wildlife densities have been heavily impacted by human activities. Forest fires can result in pervasive changes with early successional forest stages, large amounts of deciduous trees, and newly formed deadwood, habitats which are largely missing in the managed boreal landscape. In this thesis, I evaluate decadal post-burn effects on community composition of wood-inhabiting polypores, beetles, bird and mammal species, vegetation differences, and moose browsing levels. I compare three unusually large wildfires in northernmost Sweden with nearby unburnt forests and five prescribed burns. I found differences in community composition among all taxa a decade after burning and a distinct turnover of beetles the years immediately postburn. No wildlife species had higher visitation frequency in the wildfire areas, suggesting that burnt areas did not necessarily add much habitat in a landscape already dominated by early successional forest stages. Unburnt forests were also important for red-listed polypores, reindeer, and western capercaillie. However, wildfire, in contrast to prescribed burning, did provide large amounts of deadwood and rich field layer vegetation impacting biodiversity and functional trait composition of beetles and polypores and changing moose forage availability and browsing levels. Thus, for prescribed burning to mimic wildfire and better emulate wildfire impacts of biodiversity, I emphasise the importance of higher tree mortality.",

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