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

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 communitie

Characteristic of tree cavities in sal <i>Shorea robusta</i> forest, Nepal

<p>Tree cavities are one of the key structures that influence abundance and diversity of cavity-dependent organisms in forests. The natural processes that lead to cavity formation and regulate the abundance of cavities are poorly understood, especially in subtropical regions of Asia. Surveys of tree cavities suitable for breeding birds were conducted in southern Nepal in sal <i>Shorea robusta</i> dominated forest. A cavity was defined as a hole in a tree trunk or a limb with a minimum entrance diameter of 2 cm × 2 cm, interior space, depth at least 2 cm and a solid bottom with a minimum diameter of 5 cm. Within 50 sample plots, we found 104 tree cavities. The mean height of cavity entrances (6.8 m above the ground) varied across tree species from 3.4 m in <i>Dillenia pentagyna</i> to 10.3 m in <i>S</i>. <i>robusta</i>, and was positively correlated with DBH of tree. The entrance exposures were most often to the south (38.2%), and located mainly in trunks (74.0%). Cavity entrances were very different in size, with mean smallest diameter 7.7 cm, the average depth of the cavity was 25.7 cm. Mode of cavity production (excavated or non-excavated) was best predicted by a model including diameter of cavity tree (DBH), cavity height and their interaction. Single check of cavities showed signs of use by birds in 21% of them. Excavated cavities accounted for 27.9% of all cavities, indicating that role of woodpeckers as cavity providers might be of importance for secondary users in sal forest.</p