Early post-fire bird community in European boreal forest: Comparing salvage-logged with non-intervention areas

Abstract

Salvage logging after disturbances in forests substantially modifies vegetation structure and dead wood availability, but empirical evidence on its impact on biodiversity, especially in European boreal forest, is sparse. In this study we investigated the short-term effect of post-fire salvage logging on species richness and abundance of birds in recently burned mixed coniferous forest. Using point counts we estimated local species composition at 49 salvaged sites and 55 non-intervention sites (burnt forest left for natural regeneration) that were not logged after a fire in south-central Sweden. Local species richness, abundance and Simpson's species diversity index were significantly higher at non-intervention sites compared to salvaged sites. Forest birds that rely on structurally complex forest stands, such as tits (Parus major, Lophophanes cristatus, Poecile montanus), robin (Erithacus rubecula), mistle trush (Turdus viscivorus) and tree-toed woodpecker (Picoides tridactylus) were mainly associated with non-intervention sites, while species that are typically linked to farm- or shrublands, such as whinchat (Saxicola rubetra), white wagtail (Motacilla alba), red-backed shrike (Lanius collurio), and meadow pipit (Anthus pratensis) were more common at salvaged sites. These results are consistent with the idea that post-fire salvage logging has an immediate impact on the bird species composition and abundance in boreal forest. We conclude that although post-fire salvage logging may be beneficial for birds occurring in open landscapes, it has negative effects for forest bird species richness and abundance, at least over the short term. To protect typical forest communities with many forest specialists of high conservation concern, we recommend reducing the extent of post-disturbance salvaging in forests of high conservation value and updating the existing management policy to restore the amount of woody debris and facilitate long-term structural complexity and biodiversity in densely stocked conifer stands. Keywords: Natural disturbance, Forest management, Salvage logging, Forest fire, Boreal forest, Bird communities