Natural regeneration determines wintering bird presence in wind-damaged coniferous forest stands independent of postdisturbance logging

Abstract

Natural disturbances in European production forests are undesired from an economic perspective but are important drivers of biodiversity. The removal of damaged timber to restore economic value is accompanied by negative effects on various species groups, particularly breeding bird communities, and can hinder natural regeneration. However, little is known about the effect of postdisturbance logging on bird assemblages in winter when temperatures are low and food resources are unpredictable. We conducted fixed-radius point counts of wintering birds in forest stands logged or unlogged after windthrows and in mature forest stands to test our predictions that bird species densities and abundances (i) are lower in postdisturbance logged stands and (ii) depend on the amount of natural regeneration, (iii) which differs between logged and unlogged stands. Our generalized linear mixed model did not support the expected differences in bird abundance or species densities between postdisturbance logged and unlogged stands but indicated that mature forest stands harbor the highest bird abundances and species densities. The number of regenerated coniferous trees significantly positively affected wintering bird abundances in both postdisturbance logged and unlogged stands. Hence, the number of coniferous trees appears to be a main predictor of wintering bird presence.Résumé : Les perturbations naturelles dans les forêts commerciales européennes ne sont pas souhaitables d'un point de vue économique, mais elles constituent d'importants rouages de la biodiversité. La récupération du bois endommagé pour restaurer la valeur économique a des effets négatifs sur plusieurs groupes d'espèces, en particulier sur les communautés d'oiseaux nicheurs, et elle peut nuire à la régénération naturelle. Toutefois, on connaît peu les effets que les coupes de récupération après une perturbation naturelle peuvent avoir sur les assemblages d'oiseaux en hiver, quand les températures sont basses et les ressources alimentaires imprévisibles. Nous avons effectué des dénombrements d'oiseaux d'hiver par points d'écoute à rayon fixe dans des peuplements forestiers récoltés et non récoltés après un chablis et dans des peuplements forestiers mûrs pour tester les prédictions que la densité des espèces et l'abondance des oiseaux (i) sont plus faibles dans les peuplements récoltés après une perturbation et (ii) dépendent de la quantité de régénération naturelle (iii) qui diffère entre les peuplements récoltés et non récoltés. Notre modèle linéaire mixte généralisé n'a pas confirmé les différences prédites dans l'abondance des oiseaux ou la densité des espèces entre les sites récoltés et non récoltés, mais il a indiqué que les peuplements forestiers mûrs ont la plus grande abondance et la plus forte densité d'espèces d'oiseaux. L'abondance de la régénération de conifères a eu un effet positif significatif sur l'abondance des oiseaux d'hiver dans les peuplements perturbés tant récoltés que non récoltés. Il semble donc que le nombre de tiges de conifères soit un im...

Impacts of salvage logging on biodiversity: A meta‐analysis

“…Nevertheless, several forest‐dwelling bird species depend on snags, cavities or natural regeneration in post‐disturbance forest stands. The removal of such legacies by salvage logging can cause a loss of associated bird species and consequently an overall lower number of bird species in logged areas (Hutto & Gallo, ; Werner, Müller, Heurich, & Thorn, ). Although the overall number of bird species decreased less strongly than, for instance, the number of saproxylic beetle species (Figure a), bird species that depend on post‐disturbance habitat characteristics are often of high conservation interest.…”

Effects of natural disturbances and salvage logging on biodiversity – Lessons from the Bohemian Forest

“…They should remain untouched during salvage-logging operations as they can provide shelter and food for assemblages of winter resident bird species, such as the Goldcrest (Regulus regulus) (Werner et al, 2015). Likewise, large mature spruce trees with tall crowns should be able to survive bark-beetle outbreaks as important biological legacies in bark-beetle affected areas (Jakus et al, 2011).…”

Resilience impacts of a secondary disturbance: Meta‐analysis of salvage logging effects on tree regeneration

“…The lack of overall salvage logging effects in our meta‐analysis could be related to the mutual cancellation of its effect on different mechanisms related to regeneration. For instance, after windthrow in temperate forests, salvage operations may destroy some seedlings but stimulate the growth of the remaining ones in an environment of reduced competition (Royo et al, 2016). After fire in Mediterranean pine stands, salvage logging can increase tree seedling mortality due to greater abiotic stress but simultaneously increase seedling densities through the dissemination of seeds through the dragging of tree remnants (Marañón‐Jiménez et al, 2013).…”

“…Beyond its direct effects on seedling or sapling survival, salvage logging can also impact tree regeneration by increasing microclimatic stress (Marañón‐Jiménez et al, 2013) and reducing mutualistic interactions such as mycorrhization (Beck et al, 2020) and seed dispersal (Leverkus & Castro, 2017). However, salvage logging could also enhance regeneration through mechanisms such as soil scarification, increased irradiance and seed dissemination during logging operations (Peterson et al, 2009; Royo et al, 2016). Ultimately, the effect of salvage logging can depend on the identity, timing and intensity of each of the two disturbances (i.e., the natural one and salvage logging), on plant traits associated with regeneration (Peterson et al, 2009), or on the time‐scale over which effects are measured (Macdonald, 2007).…”

“…In spite of the significance of salvage logging in both forest management and ecology, we are not aware of previous reviews that quantify its effects on tree regeneration. Previous reviews are either qualitative or focused on a particular ecosystem and disturbance type (Rodríguez Martínez et al, 2013; Royo et al, 2016; Taeroe et al, 2019).…”