Epsilon Archive for Student Projects

Abstract

In this study, fire-emulating tree veteranization was compared with prescribed burning in its effects on beetle communities in boreal forests. In Ejheden Ekopark in northern Dalarna, Sweden, a stand previously subjected to prescribed burning was compared with an adjacent stand where trees had been veteranized through girdling or bark stripping, with additional stem-base burns applied to selected trees in 2025. Beetle communities and habitat characteristics were assessed in 2024 and 2025, with the first sampling conducted 1-2 years after the initial restoration treatments and before the additional stem-base burns, and the second sampling conducted after the stem-base burns in the veteranized stand. Temporal changes were first compared between 2024 and 2025 for bark-stripped and girdled pine trees and for prescribed-burned trees (pine and birch). Treatment differences in 2025 were then assessed among bark-stripped, bark-stripped-and-burned, girdled-and-burned, and burned-only pine trees, as well as prescribed-burned pine and birch trees. Beetle abundance and species richness increased in the veteranized tree treatments between 2024 and 2025, with particularly large increases occurring in bark-stripped and girdled trees combined with stem-base burning. Shannon diversity also increased between sampling years but did not show treatment-specific temporal differences. By 2025, abundance was significantly higher in the girdled treatment than in the prescribed-burned treatment, while species richness no longer differed between the approaches. Reduced tree vitality was further associated with higher beetle abundance and species richness, greater char height with higher abundance, and greater deadwood availability with higher Shannon diversity. Community composition differed among stand-level restoration approaches, sampling years, and tree-treatment types, with temporal shifts being more pronounced in the veteranized stand. Moreover, pyrophilous and red-listed beetles increased between sampling years in the veteranized stand. These findings highlight the potential of fire-emulating tree veteranization, particularly when combined with targeted stem-base burning, to create heterogeneous fire-affected and deadwood-related habitat conditions utilized by disturbance-associated and conservation-relevant beetles. Veteranization may therefore complement prescribed burning within broader fire-based restoration strategies, although longer-term monitoring is needed to determine whether these responses persist and how different restoration approaches develop over time.