Arthropod communities in fungal fruitbodies are weakly structured by climate and biogeography across European beech forests

Abstract

Aim:The tinder fungus Fomes fomentarius is a pivotal wood decomposer in European beech Fagus sylvatica forests. The fungus, however, has regionally declined due to centuries of logging. To unravel biogeographical drivers of arthropod communities associated with this fungus, we investigated how space, climate and habitat amount structure alpha and beta diversity of arthropod communities in fruitbodies of F. fomentarius.Location: Temperate zone of Europe. Taxon: Arthropods.Methods: We reared arthropods from fruitbodies sampled from 61 sites throughout the range of European beech and identified 13 orders taxonomically or by metabarcoding. We estimated the total number of species occurring in fruitbodies of F. fomentarius in European beech forests using the Chao2 estimator and determined the relative importance of space, climate and habitat amount by hierarchical partitioning for alpha diversity and generalized dissimilarity models for beta diversity. A subset of fungi samples was sequenced for identification of the fungus' genetic structure. Results:The total number of arthropod species occurring in fruitbodies of F. fomentarius across European beech forests was estimated to be 600. Alpha diversity increased with increasing fruitbody biomass; it decreased with increasing longitude, temperature and latitude. Beta diversity was mainly composed by turnover. Patterns of beta diversity were only weakly linked to space and the overall explanatory power was low. We could distinguish two genotypes of F. fomentarius, which showed no spatial structuring. Main conclusion:Fomes fomentarius hosts a large number of arthropods in European beech forests. The low biogeographical and climatic structure of the communities suggests that fruitbodies represent a habitat that offers similar conditions across large gradients of climate and space, but are characterized by high local variability in community composition and colonized by species with high dispersal ability. For European beech forests, retention of trees with F. fomentarius and promoting its recolonization where it had declined seems a promising conservation strategy. K E Y W O R D Sdead wood,

Climatic and vegetational drivers of insect beta diversity at the continental scale

“…Again, to date studies specifically comparing bioclimate and vegetation drivers on insect beta diversity have been sparse. Climate was not dominant in structuring composition in the case of fungus‐associated arthropods in beech forest (Friess et al, ). In other study systems, mean summer temperature was found to be the primary climatic variable driving alpine plant diversity (Baldwin‐Corriveau, ) and beta diversity of grassland and savanna plots in South Africa (Jewitt, Goodman, O'Connor, Erasmus, & Witkowski, ), and compositional and phylogenetic beta diversity of snakes in the Atlantic forest hotspot of South America (Moura, Costa, Argôlo, & Jetz, ).…”

“…Candidate mechanisms responsible for tree density effects might be that there is a threshold in resource density at which insects will begin to use the resource (Verschut, Becher, Anderson, & Hambäck, 2016). Further, there is a well-established theoretic framework for plant-herbivore interaction, in which plant traits and interactions with higher trophic groups are mediated by plant neighborhood (Underwood, Inouye, & Hamback, 2014), while tree cover at the scale of plot or forest is well known to drive insect communities in both alpha and beta diversity, probably via habitat availability and microclimatic differences between dense and open forests (e.g., Friess et al, 2019;Penone et al, 2019).…”

Small-scale spontaneous dynamics in temperate beech stands as an importance driver for beetle species richness

“…In protected beech stands, the most common wood-boring fungus is Fomes fomentarius 82 . The most abundant microhabitats in our study were wood-decay fungi, especially of the genus Fomes , which are very important microhabitats for saproxylic beetles 83 .…”

DNA metabarcoding reveals host-specific communities of arthropods residing in fungal fruit bodies

“…The most common families we identified consist mostly (Bolitophilidae, Mycetophilidae and Oppidae) or partly (Chironomidae and Cecidomyiidae) of fungivorous species [27,79,80]. However, fungivores may not necessarily be dominant, as our annotations are largely unresolved at the species level and predators could make up to a third of the faunal composition in fruit bodies [25,39]. At the order level, true flies and oribatid mites were dominant, which we expected based on earlier rearingbased studies on living fruit bodies of wood-decay fungi [17,26,27,34].…”

“…The studies that have considered all arthropods are either exploratory, i.e. not inferring community patterns based on host traits [17,26,36], or limited to one or two fungal hosts [25,35,39]. However, to get a solid understanding of the effects of host traits in the fungi-arthropod system, we need to assess arthropod communities across different hosts.…”