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Abstract

Prescribed burning is used as a conservation tool in Fennoscandia to create and restore fire-associated structures and processes, aiming to benefit biodiversity. However, knowledge on when and where prescribed burns should be applied to be most efficient in terms of promoting biodiversity is lacking. In this thesis I examine how stand and landscape characteristics, weather, season and time since burning influences the outcomes of prescribed burns. I studied saproxylic fungal communities in spruce dominated stands in Finland 16 years after burning. I inventoried deadwood, basal area, potential fires-scars and seedling regeneration in 32 prescribed burn sites in Sweden. In 23 of the 32 sites, I surveyed saproxylic beetles. My results show that prescribed burn outcomes vary considerably among sites. I found that burning forests with high spruce proportions can create large volumes of deadwood, facilitate deciduous tree regeneration and promote red-listed saproxylic fungi. The red-listed fungi were present 16 years after burning, but not in previous inventories, highlighting the importance of long-term studies. Burning forests as opposed to clear-cuts benefited different types of saproxylic beetles, suggesting that these burn types are not interchangeable but instead complementary. Beetle species richness was also positively correlated to the proportion of protected forests in the landscape. The composition of the surrounding landscape should therefore be considered when planning burns. Weather and season differed between prescribed fires and wildfires, with wildfires occurring in drier weather conditions and later in the summer. Several Fire Weather Indices were positively correlated with the amount of deadwood created and establishment of deciduous seedlings. But in comparison to wildfires, few sites had high values of either, indicating that many burns are suboptimal in terms of creating structures and processes that benefit biodiversity. Burning later in the season when the ground is drier may be one way to improve outcomes. My results demonstrate that the conservation value of prescribed burns can be improved by more carefully considering forest type, landscape context, weather and seasonal factors.

Keywords

Prescribed burning; Conservation; Saproxylic species; Deadwood; Restoration; Boreal forests; Naturvårdsbrand; Naturvård; Vedlevande diversitet; Restaurering; Dödved; Boreal skog

Published in

Acta Universitatis Agriculturae Sueciae
2025, number: 2025:35
Publisher: Swedish University of Agricultural Sciences

SLU Authors

UKÄ Subject classification

Forest Science

Publication identifier

  • DOI: https://doi.org/10.54612/a.7r7ltu7875
  • ISBN: 978-91-8046-470-3
  • eISBN: 978-91-8046-520-5

Permanent link to this page (URI)

https://res.slu.se/id/publ/132975