Re-surveys reveal biotic homogenization of Orthoptera assemblages as a consequence of environmental change

Aim: Biodiversity loss is a major global challenge. While population trends of vertebrates are well documented, insect declines have not been sufficiently studied and their drivers are still not fully understood. This inhibits the implementation of sensible conservation action. Repeating historical surveys can help to reveal the patterns and drivers of insect declines. Location: Central Europe Time period: 2018 to 2020 Methods: We resurveyed 199 study sites in which Orthoptera assemblages had been recorded between 1986 and 1999. Results: Our results show a significant increase in species per site (α-diversity), but simultaneously a homogenization of Orthoptera assemblages (decreasing Sorensen’s β-diversity). Highly mobile species significantly increased in site occupancy compared to species with low mobility. Some Orthoptera species showed significant altitudinal range shifts, including species with positive trends (i.e. expansion to higher altitudes) and negative trends (i.e. extinctio...