Relative impacts of land-use and climate change on grasshopper range shifts have changed over time

Abstract

Aim Stopping the decline of biodiversity is one of today's greatest challenges. To help address this, we require studies that disentangle the effects of the most important drivers behind species range losses and shifts. In this large-scale study, we aim to evaluate the relative impacts of changes in land use and climate on distributional changes in grasshoppers. Location Central Europe. Time period Historical (pre-1990 vs. 1990-1999); recent (1990-1999 vs. 2000-2017). Major taxa studied Orthoptera (hereafter referred to as grasshoppers). Methods We used an advanced modelling approach within the framework of spatial point pattern analysis (SPPA) to calculate distributional changes of 58 grasshopper species based on > 100,000 aggregated observational records. Historical and recent range shifts were compared among four functional groups and analysed against: (a) the species temperature index (STI); and (b) the species farmland index (SFI). Results During the earlier historical period, most species suffered from large range losses, with habitat specialists declining more than generalists with equal mobility. Range retractions were related to species with high SFI values; that is, species associated with farmland having a high natural value. In contrast, during the recent period the distribution of less mobile species generally remained stable, whereas highly mobile species even expanded their ranges, irrespective of their habitat specificity. Additionally, range expansions occurred mostly among thermophilic species; that is, those with high STI values. Main conclusions This is the first large-scale study world-wide that quantifies both historical and recent range shifts of numerous grasshopper species. Our results suggest that historical range losses were mainly caused by severe loss of semi-natural habitats pre-1990. Recently, global warming has led to range expansions of several grasshopper species. The challenge now is to ensure the persistence of species that might not be able to evade future climate change owing to the increasing lack of suitable refuge habitats in intensive agricultural landscapes.