Linking species assemblages to environmental change: Moving beyond the specialist-generalist dichotomy

Environmental changes due to land use developments, climate change and nitrogen deposition have profound influences on species assemblages. Investigating the dynamics in species composition as a function of underlying traits may increase our understanding of ecosystem functioning and provide a basis for effective conservation strategies. Here, I use a broad array of species traits for butterflies to identify four main components of associated traits. These reflect the spatial use of the landscape, abiotic vulnerability, developmental rate and phenology, and food specialisation, respectively. The first three trait components each contribute to determine Red List status, but only the developmental rate and phenology component is related to recent population trends. I argue that the latter component reflects the environmental impact of nutrient availability and microclimate, as affected by nitrogen deposition. This perspective sheds a new light on ongoing changes in community composition. Thus, a multidimensional view of trait associations allows us to move beyond the simplistic specialist–generalist dichotomy, renew our view on species-specific studies and help in setting new priorities for conservation