Highly dynamic post-fire bird assemblages in a European boreal forest landscape under two management scenarios

Abstract

Wildfires are key natural disturbances in boreal forests, yet increasing fire frequency under climate change, together with salvage logging and silvicultural treatments, raises concerns for biodiversity conservation. Although post-fire avian succession is well studied in North America, it remains poorly understood in European boreal forests. We examined bird assemblage dynamics over six years following the largest Scandinavian forest fire in two centuries (13,100 ha, south-central Sweden, 2014). Roughly half of the burned area was left for natural regeneration, while the remainder was salvage-logged and replanted, enabling direct comparison of bird assemblage trajectories under contrasting management options. Standardized point counts at 103 sites (2015–2020) recorded 14,371 individuals of 98 species. Ordination analyses showed persistent differences between naturally regenerating and salvage-logged sites, with no convergence over time. Naturally regenerating areas supported stable assemblages dominated by forest species associated with complex woody structures, whereas salvage-logged sites hosted more dynamic communities dominated by open-habitat and edge-associated species. Species richness increased gradually in both habitats, with continuous turnover of indicator species, especially in salvage-logged areas. Rarefaction indicated higher pooled richness in salvage-logged sites; however, landscape-level simulations showed that total richness was maximized when both management types occurred in similar proportions. Our results demonstrate that post-fire bird communities in European boreal forests are dynamic and strongly shaped by management. Naturally regenerating burns provide essential habitat for forest specialists, while salvage-logged areas contribute transiently to open-habitat diversity. We conclude that mixed management—retaining at least 30–40% of large burns for natural succession while permitting some salvage logging—best sustains regional avian diversity under increasing wildfire regimes.