Increasing temperature may compensate for lower amounts of dead wood in driving richness of saproxylic beetles

Abstract

Global warming and land‐use change are expected to be additive threats to global diversity, to which insects contribute the highest proportion. Insects are strongly influenced by temperature but also require specific habitat resources, and thus interaction between the two factors is likely. We selected saproxylic beetles as a model group because their life cycle depends on dead wood, which is highly threatened by land use. We tested the extent to which higher temperatures compensate for the negative effects of low amounts of dead wood on saproxylic beetle species richness (Temperature–Dead wood compensation hypothesis) on both a macroclimate and a topoclimate scale (north‐ and south‐facing slopes). We analyzed 1404 flight‐interception trap catches across Europe to test for interaction effects of temperature and dead‐wood amount on species richness. To experimentally test our findings from the activity trap data, we additionally reared beetles from 80 bundles of dead wood initially exposed at high and low elevations. At the topoclimate scale, we analyzed trap catches and reared beetles from dead wood exposed in 20 forest stands on south‐facing and north‐facing slopes in one region. On the macroscale, both temperature and dead‐wood amount positively affected total and threatened species richness independently, but their interaction was significantly negative, indicating compensation. On both scales and irrespective of the method, species richness decreased with temperature decline. Our observation that increasing temperature compensates for lower amounts of dead wood has two important implications. First, managers of production forests should adapt their dead‐wood enrichment strategy to site‐specific temperature conditions. Second, an increase in temperature will compensate at least partially for poor habitat conditions in production forests. Such a perspective contrasts the general assumption of reinforcing impacts of global warming and habitat loss on biodiversity, but it is corroborated by recent range expansions of threatened beetle species.

Climate-induced seasonal activity and flight period of cerambycid beetles in the Zselic forests, Hungary

“…Saproxylic insects are strongly influenced by temperature but also they require specific dead wood features, and thus an interaction between the two factors appears likely. Observations and experimental data corroborate that an increasing temperature compensates at least partly for the lower amount of dead wood (Müller et al 2015).…”

Effect of sun exposure on saproxylic beetle assemblages may change with topoclimate in a subtropical forest of east China

“…In a temperate forest of America, Reed and Muzika (2010) even suggested that slope aspect has little influence on the abundance and species richness of scolytid bark beetles. However, in a recent study executed in a temperate forest of southern Germany, it was suggested that flight intercept traps caught significantly higher numbers of species and individuals of saproxylic beetles in stands on warmer south-facing slopes than in those on colder north-facing slopes (Müller et al 2014). In the present study, the species richness of saproxylic beetles did not vary between WSS and CNS.…”

“…Ranius and Fahrig 2006;Lachat et al 2012). Especially, in a recent study, it was suggested that the amount of dead wood may interplay with temperature to affect the species richness of saproxylic beetles (Müller et al 2014). However, at small scales, the amount or volume of dead wood may be a poor predictor for saproxylic species richness and abundance (Schiegg 2000;Gibb et al 2006;Götmark et al 2011).…”

Saproxylic beetles in non-intervention and coppice-with-standards restoration management in Meerdaal forest (Belgium): an exploratory analysis

“…In addition to the dead-wood resource, temperature is assumed to be a crucial driver of the diversity of saproxylic beetles (Lachat et al 2012, Vodka & Cížek 2013, Müller et al 2014). Higher summer temperatures may even compensate for lower dead wood amounts (Köhler 2014, Müller et al 2014.…”

“…In addition to the dead-wood resource, temperature is assumed to be a crucial driver of the diversity of saproxylic beetles (Lachat et al 2012, Vodka & Cížek 2013, Müller et al 2014). Higher summer temperatures may even compensate for lower dead wood amounts (Köhler 2014, Müller et al 2014. Gärdenfors & Baranowski (1992) concluded that 70% of the Swedish red-listed saproxylic beetles living on oaks preferred sun-exposed habitat and only 16% preferred dense stands (while this was the opposite for beech-related species).…”