Tree-Related Microhabitats Follow Similar Patterns but are More Diverse in Primary Compared to Managed Temperate Mountain Forests

Martin Mikoláš,Thomas Asbeck,Veronika Zemlerová,Miroslav Svoboda,Daniel Kozák,Andreea P. Spînu

doi:10.1007/s10021-021-00681-1

Martin Mikoláš, Thomas Asbeck + Show 4 more

Open Access

https://doi.org/10.1007/s10021-021-00681-1

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Abstract

The impact of forest management on biodiversity is difficult to scrutinize along gradients of management. A step towards analyzing the impact of forest management on biodiversity is comparisons between managed and primary forests. The standardized typology of tree-related microhabitats (TreMs) is a multi-taxon indicator used to quantify forest biodiversity. We aim to analyze the influence of environmental factors on the occurrence of groups of TreMs by comparing primary and managed forests. We collected data for the managed forests in the Black Forest (Germany) and for the primary forests in the Western (Slovakia) and Southern Carpathians (Romania). To model the richness and the different groups of TreMs per tree, we used generalized linear mixed models with diameter at breast height (DBH), altitude, slope and aspect as predictors for European beech (Fagus sylvatica (L.)), Norway spruce (Picea abies (L.)) and silver fir (Abies alba (Mill.)) in primary and managed temperate mountain forests. We found congruent results for overall richness and the vast majority of TreM groups. Trees in primary forests hosted a greater richness of all and specific types of TreMs than individuals in managed forests. The main drivers of TreMs are DBH and altitude, while slope and aspect play a minor role. We recommend forest and nature conservation managers to focus: 1) on the conservation of remaining primary forests and 2) approaches of biodiversity-oriented forest management on the selection of high-quality habitat trees that already provide a high number of TreMs in managed forests based on the comparison with primary forests.

Highlights

To tackle the biodiversity and the climate crisis that forests face (Schelhaas and others 2003; Hanewinkel and others 2013; Seidl and others 2014, 2017), a great number of approaches including adaptive strategies, retention forestry, close-to-nature forest management or ecological forestry have been developed (Bauhus and others 2009; Messier and others 2019; Gustafsson and others 2020; Cada and others 2020)
We aim to provide a first comparison of drivers of tree-related microhabitat (TreM) richness between primary and managed forests that 1) highlights the importance of the primary forests for the conservation of biodiversity and 2) identifies focal points for forest management to increase these habitats for the conservation of forest dwelling species
The individuals in the primary forests provided a greater richness of TreMs per living tree compared to the managed temperate mountain forests (Table 1, Figures 2, 3 and 4)

Summary

Introduction

To tackle the biodiversity and the climate crisis that forests face (Schelhaas and others 2003; Hanewinkel and others 2013; Seidl and others 2014, 2017), a great number of approaches including adaptive strategies, retention forestry, close-to-nature forest management or ecological forestry have been developed (Bauhus and others 2009; Messier and others 2019; Gustafsson and others 2020; Cada and others 2020). Remnants of primary forests deliver a unique source of information to address the question of influence of management or natural disturbances and dynamics on biodiversity (Kozak and others 2018); these remnants are rare and difficult to locate (Sabatini and others 2018; Mikolasˇ and others 2019) Another challenge in assessing differences between managed and primary forests is the comparability of datasets; for instance, the collection of data on taxonomic groups might not always be comparable across sites (Bruelheide and others 2020). To overcome this problem partially, a multi-taxon indicator beyond single-species information has been widely implemented and used for quantifying forest biodiversity, namely the standardized, hierarchical typology of tree-related microhabitats(Larrieu and others 2012, 2018; Paillet and others 2018; Asbeck and others 2020b; Basile and others 2020a; Jahed and others 2020; Asbeck and others 2021a). The hierarchical TreM typology distinguishes 15 groups of TreMs in seven forms: Cavities: woodpecker breeding cavities, rot holes, concavities, insect galleries and bore holes; Tree injuries and exposed wood: exposed sapwood and/or exposed heartwood; Crown deadwood in different forms; Excrescences: twig tangles (witches broom), cankers and burrs;

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