Winners and losers over 35 years of dragonfly and damselfly distributional change in Germany

Abstract

Recent studies suggest insect declines in parts of Europe; however, the generality of these trends across different taxa and regions remains unclear. Standardized data are not available to assess large-scale, long-term changes for most insect groups but opportunistic citizen science data is widespread for some taxa. We compiled over 1 million occurrence records of Odonata (dragonflies and damselflies) from different regional databases across Germany. We used occupancy-detection models to estimate annual distributional changes between 1980 and 2016 for each species. We related species attributes to changes in the species distributions and inferred possible drivers of change. Species showing increases were generally warm-adapted species and/or running water species while species showing decreases were cold-adapted species using standing water habitats such as bogs. We developed a novel approach using time-series clustering to identify groups of species with similar patterns of temporal change. Using this method, we defined five typical patterns of change for Odonata, each associated with a specific combination of species attributes. Overall, trends in Odonata provide mixed news since improved water quality, coupled with positive impacts of climate change, could explain the positive trend status of many species. At the same time, declining species point to conservation challenges associated with habitat loss and degradation. Our study demonstrates the great value of citizen science data for assessing large-scale distributional change and conservation decision-making.

Effects of Landscape Patterns and Their Changes to Species Richness, Species Composition, and the Conservation Value of Odonates (Insecta)

“…This is very important, especially for species associated with certain types of climax habitats, such as raised bogs, fens, and some other types of late successional habitats. These species are among the species with the most negative trends in occurrence [ 36 ]. The main causes of the decline of these species are not only the degradation of natural habitats but also desiccation and other negative changes associated with global climate change [ 3 , 18 ].…”

Assessing extinction risk across the geographic ranges of plant species in Europe

“…Regular updates of Red Lists could also result in dynamic maps of a species geographical threat status and allow the monitoring of conservation success, recovery actions and biodiversity trends. To bolster national Red Lists and shorten time spans between assessments, the recent upsurge of citizen science activities could be leveraged to inform temporal trends of species more regularly (Bowler et al, 2021). Taken together, such a process of data integration could enable better cross‐national collaboration and coordination (Kühl et al, 2020), which could greatly accelerate extinction risk assessments globally.…”

Ecological drivers of Odonata beta diversity in arid and semi‐arid regions of the Central Plateau of Iran

“…This result has important implications for predicting the effect of ongoing climate change and global warming on the composition of Odonata assemblages. In response to climate change, assemblages are predicted to become increasingly composed of warm‐dwelling species and species with high dispersal ability than cold‐dwelling species and species with poor dispersal ability (Termaat et al ., 2015; Assandri, 2020; Bowler et al ., 2020). On the other hand, global warming could increase the frequency and severity of droughts (Dai, 2013), and as the surface water becomes increasingly scarce, species with bivoltine or semi‐voltine life cycles would have a lower chance to complete their larval stages (Hering et al ., 2010), so species assemblages will change in favour of vagrant species that can quickly recolonise habitats.…”