Evidence for positive population-level effects of an agri-environment scheme on grassland butterflies

Many studies have reported positive effects of agri-environment schemes (AES) on species richness and abundance, but studies demonstrating demographic, population-level responses, which is the desired outcome from AES, are rare. This is at least partly due to the difficulty in distinguishing between behavioural and demographic effects in snapshot studies. Here we report positive population-level effects of environmental set-asides (currently included in the national AES of fallows in Finland) in grassland butterflies and day-active moths. We firstly identified a set of conditions that a species should meet in order to succeed in establishing a local population in an area where the focal agr…