Microclimate is a crucial driver of saproxylic beetle assemblages, with more species often found in sunny forests than in shady ones. Whether this pattern is caused by a higher detectability due to increased beetle activity under sunny conditions or a greater diversity of beetles emerging from sun-exposed deadwood remains unclear. This study examined whether sun exposure leads to higher microclimatic heterogeneity in deadwood and whether this drives beetle diversity in deadwood logs and at forest stand scale. Saproxylic beetles were sampled at the stand scale using flight-interception traps and at object scale using stem-emergence traps on deadwood logs at the same site. The variability in wood surface temperature was measured on single logs and between logs as a proxy for microclimatic heterogeneity in deadwood. Abundance in sunny forests was higher at the stand scale, and in shady forests at the object scale. The estimated number of species was higher in sunny forests at both scales and correlated positively with temperature variability on single logs and between logs at the stand scale and, albeit weakly, with temperature variability on single logs at the object scale. Gamma-diversity, and thus beta-diversity, across logs at the object scale was higher in sunny forests. These findings indicate that sun exposure promotes saproxylic beetle diversity due to higher microclimatic heterogeneity within and between deadwood logs. Our study therefore corroborates previous research demonstrating the importance of canopy cover and microclimate for forest biodiversity.

Bavarian Forest National Park Freyunger Str 2 94481 Grafenau Germany

Berchtesgaden National Park Doktorberg 6 83471 Berchtesgaden Germany

Department of Animal Sciences Chair of Zoology Entomology Research Group Technical University of Munich Hans Carl von Carlowitz Platz 2 85354 Freising Germany

Department of Biology Faculty of Science University of Hradec Králové Rokitanského 62 500 03 Hradec Králové Czech Republic

Department of Ecology Animal Ecology Faculty of Biology Philipps Universität Marburg Karl von Frisch Str 8 35032 Marburg Germany

Ecosystem Dynamics and Forest Management Group Department of Ecology and Ecosystem Management Technical University of Munich Hans Carl von Carlowitz Platz 2 85354 Freising Germany

Faculty of Biological Sciences Institute for Ecology Evolution and Diversity Goethe University Frankfurt Max von Laue Straße 13 60438 Frankfurt am Main Germany

Field Station Fabrikschleichach Department of Animal Ecology and Tropical Biology Biocenter University of Würzburg Glashüttenstraße 5 96181 Rauhenebrach Germany

Forest Nature Conservation Georg August University Göttingen Büsgenweg 3 37077 Göttingen Germany

Forest Nature Conservation Northwest German Forest Research Institute Prof Oelkers Str 6 34346 Hann Münden Germany

See more in PubMed

Alroy J (2010) Geographical, environmental and intrinsic biotic controls on Phanerozoic marine diversification. Palaeontology 53:1211–1235. https://doi.org/10.1111/j.1475-4983.2010.01011.x DOI

Bates D, Mächler M, Bolker B, Walker S (2015) Fitting linear mixed-effects models using lme4. J Stat Softw. https://doi.org/10.18637/jss.v067.i01 DOI

Birkemoe T, Sverdrup-Thygeson A (2015) Trophic levels and habitat specialization of beetles caught on experimentally added aspen wood: does trap type really matter? J Insect Conserv 19:163–173. https://doi.org/10.1007/s10841-015-9757-6 DOI

Bouget C, Duelli P (2004) The effects of windthrow on forest insect communities: a literature review. Biol Conserv 118:281–299. https://doi.org/10.1016/j.biocon.2003.09.009 DOI

Bouget C, Brin A, Brustel H (2011) Exploring the “last biotic frontier”: are temperate forest canopies special for saproxylic beetles? For Ecol Manag 261:211–220. https://doi.org/10.1016/j.foreco.2010.10.007 DOI

Bouget C, Larrieu L, Nusillard B, Parmain G (2013) In search of the best local habitat drivers for saproxylic beetle diversity in temperate deciduous forests. Biodivers Conserv 22:2111–2130. https://doi.org/10.1007/s10531-013-0531-3 DOI

Brackebusch AP (1975) Gain and loss of moisture in large forest fuels. USDA Forest Service, Research Paper INT-173

Chao A, Jost L (2012) Coverage-based rarefaction and extrapolation: standardizing samples by completeness rather than size. Ecology 93:2533–2547. https://doi.org/10.1890/11-1952.1 PubMed DOI

Chao A, Gotelli NJ, Hsieh TC et al (2014) Rarefaction and extrapolation with Hill numbers: a framework for sampling and estimation in species diversity studies. Ecol Monogr 84:45–67. https://doi.org/10.1890/13-0133.1 DOI

Clarke A, Gaston KJ (2006) Climate, energy and diversity. Proc R Soc B Biol Sci 273:2257–2266. https://doi.org/10.1098/rspb.2006.3545 DOI

De Frenne P, Zellweger F, Rodríguez-Sánchez F et al (2019) Global buffering of temperatures under forest canopies. Nat Ecol Evol 3:744–749. https://doi.org/10.1038/s41559-019-0842-1 PubMed DOI

De Frenne P, Lenoir J, Luoto M et al (2021) Forest microclimates and climate change: importance, drivers and future research agenda. Glob Change Biol 27:2279–2297. https://doi.org/10.1111/gcb.15569 DOI

Elston DA, Moss R, Boulinier T et al (2001) Analysis of aggregation, a worked example: numbers of ticks on red grouse chicks. Parasitology 122:563–569. https://doi.org/10.1017/S0031182001007740 PubMed DOI

Gossner MM, Wende B, Levick S et al (2016) Deadwood enrichment in European forests—which tree species should be used to promote saproxylic beetle diversity? Biol Conserv 201:92–102. https://doi.org/10.1016/j.biocon.2016.06.032 DOI

Grove SJ (2002) Saproxylic insect ecology and the sustainable management of forests. Annu Rev Ecol Syst 33:1–23 DOI

Haddad NM, Tilman D, Haarstad J et al (2001) Contrasting effects of plant richness and composition on insect communities: a field experiment. Am Nat 158:17–35. https://doi.org/10.1086/320866 PubMed DOI

Hagge J, Leibl F, Müller J et al (2019) Reconciling pest control, nature conservation, and recreation in coniferous forests. Conserv Lett 12:e12615. https://doi.org/10.1111/conl.12615 DOI

Heidrich L, Bae S, Levick S et al (2020) Heterogeneity–diversity relationships differ between and within trophic levels in temperate forests. Nat Ecol Evol 4:1204–1212. https://doi.org/10.1038/s41559-020-1245-z PubMed DOI

Jost L (2010) The relation between evenness and diversity. Diversity 2:207–232. https://doi.org/10.3390/d2020207 DOI

Krah FS, Seibold S, Brandl R et al (2018) Independent effects of host and environment on the diversity of wood-inhabiting fungi. J Ecol 106:1428–1442. https://doi.org/10.1111/1365-2745.12939 DOI

Leutner B (2018) Space for communities: quantifying data requirements for remote sensing based habitat modeling. Julius-Maximilians-Universität Würzburg

Liu S-S, Zhang G-M, Zhu J (1995) Influence of temperature variations on rate of development in insects: analysis of case studies from entomological literature. Ann Entomol Soc Am 88:107–119. https://doi.org/10.1093/aesa/88.2.107 DOI

Möller G (2009) Struktur- und Substratbindung holzbewohnender Insekten, Schwerpunkt Coleoptera—Käfer. Dissertation at Freien Universität Berlin. Freie Universität Berlin

Müller J, Brustel H, Brin A et al (2015) Increasing temperature may compensate for lower amounts of dead wood in driving richness of saproxylic beetles. Ecography (cop) 38:499–509. https://doi.org/10.1111/ecog.00908 DOI

Müller J, Ulyshen M, Seibold S et al (2020) Primary determinants of communities in deadwood vary among taxa but are regionally consistent. Oikos 129:1579–1588. https://doi.org/10.1111/oik.07335 DOI

Oksanen AJ, Blanchet FG, Friendly M, et al (2020) The vegan package. Community ecology package. http://cran.r-project.org/

Penone C, Allan E, Soliveres S et al (2019) Specialisation and diversity of multiple trophic groups are promoted by different forest features. Ecol Lett 22:170–180. https://doi.org/10.1111/ele.13182 PubMed DOI

Pouska V, Macek P, Zíbarová L (2016) The relation of fungal communities to wood microclimate in a mountain spruce forest. Fungal Ecol 21:1–9. https://doi.org/10.1016/j.funeco.2016.01.006 DOI

Schmidl J, Bussler H (2004) Ökologische Gilden xylobionter Käfer Deutschlands. Naturschutz Und Landschaftsplanung 36:202–218

Seibold S, Bässler C, Brandl R et al (2015) Experimental studies of dead-wood biodiversity—a review identifying global gaps in knowledge. Biol Conserv 191:139–149. https://doi.org/10.1016/j.biocon.2015.06.006 DOI

Seibold S, Bässler C, Brandl R et al (2016) Microclimate and habitat heterogeneity as the major drivers of beetle diversity in dead wood. J Appl Ecol 53:934–943. https://doi.org/10.1111/1365-2664.12607 DOI

Seibold S, Hagge J, Müller J et al (2018) Experiments with dead wood reveal the importance of dead branches in the canopy for saproxylic beetle conservation. For Ecol Manag 409:564–570. https://doi.org/10.1016/j.foreco.2017.11.052 DOI

Seibold S, Rammer W, Hothorn T et al (2021) The contribution of insects to global forest deadwood decomposition. Nature 597:77–81. https://doi.org/10.1038/s41586-021-03740-8 PubMed DOI

Seidl R, Thom D, Kautz M et al (2017) Forest disturbances under climate change. Nat Clim Change 7:395–402. https://doi.org/10.1038/nclimate3303 DOI

Senf C, Pflugmacher D, Zhiqiang Y et al (2018) Canopy mortality has doubled in Europe’s temperate forests over the last three decades. Nat Commun 9:4978. https://doi.org/10.1038/s41467-018-07539-6 PubMed DOI PMC

Stokland JN, Siitonen J, Jonsson BG (2012) Biodiversity in dead wood. Cambridge University Press, Cambridge DOI

Sverdrup-Thygeson A, Birkemoe T (2009) What window traps can tell us: effect of placement, forest openness and beetle reproduction in retention trees. J Insect Conserv 13:183–191. https://doi.org/10.1007/s10841-008-9141-x DOI

Taylor LR (1963) Analysis of the effect of temperature on insects in flight. J Anim Ecol 32:99. https://doi.org/10.2307/2520 DOI

Thom D, Sommerfeld A, Sebald J et al (2020) Effects of disturbance patterns and deadwood on the microclimate in European beech forests. Agric for Meteorol 291:108066. https://doi.org/10.1016/j.agrformet.2020.108066 DOI

Ulyshen MD (ed) (2018) Saproxylic insects: diversity, ecology and conservation. Springer International Publishing, Cham

Vodka S, Konvicka M, Cizek L (2008) Habitat preferences of oak-feeding xylophagous beetles in a temperate woodland: implications for forest history and management. J Insect Conserv 13:553–562. https://doi.org/10.1007/s10841-008-9202-1 DOI

Vogel S, Bussler H, Finnberg S et al (2020a) Diversity and conservation of saproxylic beetles in 42 European tree species: an experimental approach using early successional stages of branches. Insect Conserv Divers. https://doi.org/10.1111/icad.12442 DOI

Vogel S, Gossner MM, Mergner U et al (2020b) Optimizing enrichment of deadwood for biodiversity by varying sun exposure and tree species: an experimental approach. J Appl Ecol. https://doi.org/10.1111/1365-2664.13648 DOI

Zellweger F, De Frenne P, Lenoir J et al (2020) Forest microclimate dynamics drive plant responses to warming. Science 368:772–775. https://doi.org/10.1126/science.aba6880 PubMed DOI

Trapping liquids may bias the results of beetle diversity assessment

Quantifying wood decomposition by insects and fungi using computed tomography scanning and machine learning