Contents lists available at ScienceDirect Forest Ecology and Management journal homepage: www.elsevier.com/locate/foreco Both natural and anthropogenic microhabitats and fine-scale habitat features of managed forest can affect the abundance of the Eurasian Wren Łukasz Piechnik a, ⁎ , Przemysław Kurek b , Mateusz Ledwoń c , Jan Holeksa b a W. Szafer Institute of Botany, Polish Academy of Sciences, Kraków, Poland b Department of Plant Ecology and Environmental Protection, Adam Mickiewicz University, Poznań, Poland c Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Kraków, Poland 1. Introduction Microhabitats are fine-scale habitat features frequently related to specific plants, vegetation and soil structures (Fuller, 2012). The mi- crohabitats of forest ecosystems are responsible for a considerable share of their biodiversity and complexity (Winter and Möller, 2008; Michel and Winter, 2009; Larrieu et al., 2018). Forest microhabitats increase the biodiversity of plants, fungi (Fritz and Heilmann-Clausen, 2010; Nordén et al., 2004), invertebrates (Stockland et al., 2012) and verte- brates (Van der Hoek et al., 2017). Vertebrates take advantage of fine- scale habitats such as ground litter, field layer vegetation, coarse woody debris, brush piles, hollow trees and uprooted trees, which provide them with shelter, a food base and breeding sites (Regnery et al. 2013; Kellner and Swihart, 2014). Fauteux et al. (2012) found that some species of rodents and shrews were highly abundant in plots with high volumes of late-decay-class stumps and early- and well-decayed logs in managed and unmanaged boreal forests. Regnery et al. (2013) found that the Common Pipistrelle Pipistrellus pipistrellus was positively af- fected by volume of canopy deadwood, diversity of tree microhabitats, and density of Cerambyx cavities. Birds also take advantage of forest microhabitats; that has been studied mostly in the context to such structures as old, dying and uprooted trees, fallen logs and tree hollows (Wesołowski, 2007; Regnery et al., 2013; Maziarz and Broughton, 2015; Van der Hoek et al., 2017). For example, the presence of old rough-barked trees favours the Middle Spotted Woodpecker Den- drocoptes medius, a bird that feeds on invertebrates living in fissured bark (Stachura-Skierczyńska and Kosiński, 2016); hollows in snags are needed by secondary cavity nesters such as the Nuthatch Sitta europaea and Eurasian Pygmy Owl Glaucidium passerinum (Wesołowski and Rowiński, 2004; Barbaro et al., 2016). Natural forest microhabitats that provide good conditions for birds are the main focus of this type of research (Wesołowski and Martin, 2018). Most of those studies concentrate on microhabitats typical of old-growth forests (Barbaro et al., 2016; Bouvet et al., 2016; Wesołowski and Martin, 2018). Much less is known about how an- thropogenic microhabitats associated with managed forests affect birds. An increasing number of studies show that forest microhabitats such as road edges, wood piles or drainage ditches can increase the diversity of various groups of organisms, including vascular plants and amphibians (Lugo and Gucinski, 2000; Suislepp et al., 2011; Zielińska et al., 2016). It has been found that the presence of forest roads and patches of thinned stands favours some bird species (Hagar et al., 2004; Šálek et al., 2010). However, the effects of having a high number of anthro- pogenic microhabitats formed as a result of forest management prac- tices (e.g. brush piles, drainage ditches) are still unknown. Relationships between forest microhabitats and birds have been documented mostly in the context of forest structure and tree related microhabitats (Mahon et al., 2008; Müller et al., 2009; Wesołowski and Martin, 2018). However, it is well known that several groups of Northern Hemisphere birds such as Galliformes (Teuscher et al., 2013), forest waders (Duriez et al., 2005) and some small passerine birds (Batáry et al., 2014) are associated with the understory layer. For in- stance, the presence of the Hazel Grouse Tetrastes bonasia (Galliformes) was strongly correlated with bilberry and ravines (Kajtoch et al., 2012), and the Eurasian Woodcock Scolopax rusticola (forest wader) chose places with lush shrubs and low-branched understory (Braña et al., 2013). Small passerine birds (e.g. Blackbird Turdus merula, European Robin Erithacus rubecula, Blackcap Sylvia atricapilla) are most frequently found in forests that have many uprooted trees and fallen logs or dense plant cover (Urban and Smith, 1989; Remm et al., 2006; Wesołowski et al., 2018). In our study we assess the relationships between the abundance of microhabitats and fine-scale habitat features (hereinafter: micro- habitats) in the forest understory of a managed forest and the density of breeding Eurasian Wrens Troglodytes troglodytes. The Eurasian Wren is a small passerine bird living mostly in the lowest forest layers. It is widely distributed across Eurasia. Although the microhabitats related to its occurrence are known to some extent, the statistical relationship be- tween the abundance of microhabitats and the abundance of the Eurasian Wren has hardly ever been tested (Wesołowski, 1983; Waterhouse et al., 2002). Here we consider four natural microhabitats common in forest ecosystems: fallen logs, upturned root plates, high https://doi.org/10.1016/j.foreco.2019.117695 Received 15 April 2019; Received in revised form 7 October 2019; Accepted 13 October 2019 ⁎ Corresponding author. E-mail address: l.piechnik@botany.pl (Ł. Piechnik). Forest Ecology and Management 456 (2020) 117695 0378-1127/ © 2019 Elsevier B.V. All rights reserved. T