Collaboratrici e collaboratori

Insect community records are strongly influenced by the timing of sampling (e.g. season, weather) and the location of sampling (e.g. elevation, land use). However, we still poorly understand how the combination of these factors affects communities of insects such as moths. We analysed a vast moth community dataset from Switzerland, collected by a single expert over a period of 50 years, containing data on 2.8 million moth individuals (1045 species) and covering the entire annual cycle. We used regression models to relate moth community characteristics (total abundance, species richness, biomass) to season, weather, elevation, and land use (landscape composition). Total abundance, species richness, and biomass showed a clear bimodal seasonal cycle with peaks in early spring and in summer. The different peaks reflected peaks of moth species with different overwintering stages, for example the spring peak was driven by species overwintering as pupae or adults. Moth abundance, richness, and biomass also increased with increasing temperatures at the time of sampling and increased further when precipitation events occurred around warm sampling nights. We also found increases along the elevational gradient and with increasing forest cover. We show how land use, elevation and weather shape moth communities, and that overall community characteristics such as total abundance have distinct peaks across the season. It is therefore important that studies of spatio-temporal changes in moth communities take into account all these factors, such as the under-sampling of early-season communities that often occurs in sampling campaigns.