Effect of forest management on temperate ant communities

Martin M. Gossner,Michael E. Grevé,Jörg Hager,Wolfgang W. Weisser,Peter Schall,Heike Feldhaar

doi:10.1002/ecs2.2303

Martin M. Gossner, Michael E. Grevé + Show 4 more

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https://doi.org/10.1002/ecs2.2303

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Abstract

AbstractHuman management of ecosystems can have direct or indirect effects on species communities. How species communities are affected by management is a key question in ecology and nature conservation. As keystone taxon, changes in ant communities can have sustained consequences for entire ecosystems. In forests, management has been shown to have an overall negative effect on ant communities in tropical and a positive effect in boreal forests. However, in temperate forests, it is unclear what components of forest management affect ant communities and how. This study explores the direct and indirect effects of forest management on the taxonomic and functional diversity of ant communities in 150 temperate forest stands in three regions in Germany. Using a multi‐model inference approach and structural equation models, we analyzed the effects of 18 variables, including variables of forest management, forest structure, arthropod diversity, and biomass, as well as abiotic factors, on ant species richness, abundance, and functional trait diversity (Rao's Q) based on morphological (FDM) and life‐history traits (FDLH). In total, we found 28 ant species occurring on 120 plots. Main direct effects of forest management on ant abundance and species richness were caused by tree species selection, measured as dominant tree species. The main positive indirect effect was mediated by a reduced canopy cover with an increasing proportion of oak and pine, resulting in a higher temperature amplitude. Due to the low number of species in two regions, we analyzed functional diversity for the most ant species diverse region only. FDLH was affected positively by tree harvesting and negatively by structural complexity. FDM showed no response to forest management, potentially due to the low morphological diversity of temperate forest ants. Our results show that forest management practices in temperate forests strongly impact ant community structure. This can be beneficial for ants if management reduces the canopy cover, either by tree harvesting or by changing the tree species composition toward shade‐intolerant tree species. To promote ant diversity as key taxon for maintaining ecosystem processes in forest ecosystems, we suggest to integrate forest stands with more open and warmer conditions in future management strategies.

Highlights

Land-use and management intensification is a major threat to biodiversity (Allan et al 2014), leading to local species loss and homogenization of communities across trophic levels
This study explores the direct and indirect effects of forest management on the taxonomic and functional diversity of ant communities in 150 temperate forest stands in three regions in Germany
Using a multi-model inference approach and structural equation models, we analyzed the effects of 18 variables, including variables of forest management, forest structure, arthropod diversity, and biomass, as well as abiotic factors, on ant species richness, abundance, and functional trait diversity (Rao’s Q) based on morphological (FDM) and life-history traits (FDLH)

Summary

Introduction

Land-use and management intensification is a major threat to biodiversity (Allan et al 2014), leading to local species loss (alpha diversity; Newbold et al 2015) and homogenization of communities (loss of beta diversity; Gossner et al 2016) across trophic levels. In temperate European managed forests, which cover more than 30% of the European land surface, native broad-leaved forests have partly been replaced by more productive conifer forests which comprise shorter rotation cycles (Ru€ther and Walentowski 2008) This contributed to a decrease in species richness across multiple taxa (Paillet et al 2010, Buse 2012) and to changes in structural and functional composition of arthropod communities (Finch and Szumelda 2007, Pohl et al 2007, Gossner et al 2013). Admixing additional broad-leaved tree species, especially in conifer forests, is suggested to increase habitat heterogeneity and biodiversity in even-aged forests (J€akel and Roth 2004) Their positive effects on biodiversity have recently been questioned (Schall et al 2018a)

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