Bat responses to changes in forest composition and prey abundance depend on landscape matrix and stand structure

Jérémy S P Froidevaux,Luc Barbaro,Jérôme Molina,Olivier Vinet,Antoine Brin,François Calatayud,Laurent Larrieu,Yves Bas

doi:10.1038/s41598-021-89660-z

Abstract

Despite the key importance of the landscape matrix for bats, we still not fully understand how the effect of forest composition interacts at combined stand and landscape scales to shape bat communities. In addition, we lack detailed knowledge on the effects of local habitat structure on bat-prey relationships in forested landscapes. We tested the assumptions that (i) forest composition has interacting effects on bats between stand and landscape scales; and (ii) stand structure mediates prey abundance effects on bat activity. Our results indicated that in conifer-dominated landscapes (> 80% of coniferous forests) bat activity was higher in stands with a higher proportion of deciduous trees while bats were less active in stands with a higher proportion of deciduous trees in mixed forest landscapes (~ 50% of deciduous forests). Moth abundance was selected in the best models for six among nine bat species. The positive effect of moth abundance on Barbastella barbastellus was mediated by vegetation clutter, with dense understory cover likely reducing prey accessibility. Altogether, our findings deepen our understanding of the ecological processes affecting bats in forest landscapes and strengthen the need to consider both landscape context and trophic linkage when assessing the effects of stand-scale compositional and structural attributes on bats.

Highlights

Despite the key importance of the landscape matrix for bats, we still not fully understand how the effect of forest composition interacts at combined stand and landscape scales to shape bat communities
In mixed forest landscapes (i.e. ~ 50% of deciduous forests), bat activity was higher in stands with a higher proportion of coniferous trees
Our results indicated that the positive effects of mixing conifer and deciduous trees at the stand level on bat activity changed according to the dominant forest composition in the surrounding landscape

Summary

Introduction

Despite the key importance of the landscape matrix for bats, we still not fully understand how the effect of forest composition interacts at combined stand and landscape scales to shape bat communities. We tested the assumptions that (i) forest composition has interacting effects on bats between stand and landscape scales; and (ii) stand structure mediates prey abundance effects on bat activity. The carrying capacity of these new forest patches highly depend on their quality[3] which is partly determined by their structure and composition (here defined as the degree of mixture between coniferous and deciduous tree species). These two forest attributes are known to be key drivers of species diversity and are considered as the most practical biodiversity indicators for forest management planning[4]. Bats are especially sensitive to both fine-scale and coarse-grained variation in forest c omposition[34] because of the large range of various resources they need to exploit both daily and across their annual life cycles, i.e. for roosting, commuting, foraging, swarming, and mating[35]

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Conclusion