Congruent patterns of functional diversity in saproxylic beetles and fungi across European beech forests

Abstract

Aim Beech forests comprise a globally unique temperate forest type in Europe. The dominance of beech in these forests developed during the ongoing post‐glacial northward re‐colonization, concurrently with intensified forest use by humans. We investigated how these two processes together with climate shaped the patterns of functional diversity of two major species groups involved in wood decomposition and whether functional diversity is determined on the local or regional species pool level. Location European beech forest distribution range. Taxon Saproxylic beetles and fungi. Methods We analysed records of 532,496 saproxylic beetles of 788 species and 8,630 records of 234 saproxylic fungal species based on sets of traits similar to both groups. We tested how space, climate and landscape composition affect trait‐based functional diversity on local and regional scales. Using structural equation modelling, we tested whether functional diversity is shaped on the local or regional scale. Results The response of local functional diversity of both saproxylic beetles and fungi followed a highly congruent pattern of decreasing functional diversity towards the north, with higher elevation and accounted for overall geographical gradients with higher temperature, while increasing with higher precipitation. Structural equation modelling revealed that local functional diversity is determined by community changes operating on the level of the regional species pool. Main conclusions Our findings suggest that the functional diversity patterns of saproxylic organisms in European beech forests are mainly determined on the regional scale and driven by anthropogenic and biogeographical processes. To conserve the variation and hotspots of functional diversity in beech forests, activities have to focus on a broad spatial and climatic range of sites throughout Europe, including the primeval forests in the east, as started by the UNESCO World Heritage selection of “Ancient and Primeval Beech Forests of the Carpathians and Other Regions of Europe”.

A Comparison of the Formation Rates and Composition of Tree-Related Microhabitats in Beech-Dominated Primeval Carpathian and Hyrcanian Forests

“…Our finding of site-and region-specific differences in TreM dynamics and composition in both World Heritage areas complements earlier reports of beech forest diversity. Moreover, in the design of measures directed at conserving the overall diversity in beech forests, this study supports a research approach based on regions that differ in their soil, climate, and tree mixtures, rather than on different local stands within a single region [45,59].…”

“…Primeval temperate forests serve as an important reference baseline for integrative management strategies [38]. Studies of beech forests have focussed on their stand structure [23,24,29]; the amount and composition of deadwood [39]; and the composition of fungi, bryophytes [40][41][42], and beetles [34,[43][44][45]. By contrast, the composition and dynamics of TreMs in natural forests of European and Oriental beech remain poorly explored.…”

Primary determinants of communities in deadwood vary among taxa but are regionally consistent

“…Spatial distance played a role only for saproxylic beetles and spiders, but not for microbes (fungi and bacteria), and even for both arthropod taxa, space played only a minor role. Fungi and saproxylic beetles are often inter‐related in deadwood ecosystems (Weslien et al 2011, Thorn et al 2015, Jacobsen et al 2018, Hagge et al 2019a, Seibold et al 2019). However, the variation in the beetle assemblages could not be explained by adding fungal composition to the beetle model (not shown).…”

Dispersal ability, trophic position and body size mediate species turnover processes: Insights from a multi‐taxa and multi‐scale approach

“…For example, among the determinants of community assembly at larger spatial extents, geographical distance (neutral processes) was shown to be more important than environmental factors (niche process), as demonstrated in pan‐European vs. country‐wide analyses (Keil et al., 2012; Qian et al., 2005). However, recent studies have shown regional effects with an explicit spatial clustering, such as the effects of biogeographical history on local assemblages over a continental spatial extent in Europe (Hagge et al., 2019; Jiménez‐Alfaro et al., 2018). These observations demonstrate the importance of resolving spatial structure into multiple spatial scales in studies on species turnover.…”