Butterflies in Swedish grasslands benefit from forest and respond to landscape composition at different spatial scales

Abstract

Context Loss and fragmentation of semi-natural grasslands has critically affected many butterfly species in Europe. Habitat area and isolation can have strong effects on the local biodiversity but species may also be strongly affected by the surrounding matrix. Objectives We explored how different land cover types in the landscape explained the occurrence of butterfly species in semi-natural grasslands. Methods Using data from 476 semi-natural grasslands in Sweden, we analysed the effect of matrix composition on species richness and occurrence. Additionally, we analysed at which spatial scales butterflies responded to matrix types (forests, seminatural grasslands, arable land and water). Results Forest cover showed the strongest positive effect on species richness, followed by semi-natural grasslands. Forest also had a positive effect on red-listed species at local scales. Responses to matrix composition were highly species-specific. The majority of the 30 most common species showed strong positive responses to the amount of forest cover within 200-500 m. There was a smaller group of species showing a positive response to arable land cover within 500-2000 m. Thirteen species showed positive responses to the amount of semi-natural grasslands, generally at larger scales (10-30 km). Conclusions Our study showed that surrounding forest is beneficial for many grassland butterfly species and that forests might mitigate the negative effects of habitat loss caused by agricultural intensification. Also, semi-natural grasslands were an important factor for species richness at larger spatial scales, indicating that a landscape consisting mainly of supporting habitats (i.e. forests) are insufficient to sustain a rich butterfly fauna.

Land-use history influence the vegetation in coniferous production forests in southern Sweden

“…Remnant grassland species that flourish after a clearcut can provide nectar and other resources for species that we normally associate with grasslands (Viljur & Teder 2018, Ohwaki et al 2018, Bergman et al 2018. A practical issue is then how targeted populations of plants can be boosted.…”

Linear infrastructure habitats increase landscape-scale diversity of plants but not of flower-visiting insects

“…grasslands that are traditionally managed by mowing or grazing, without any input of fertilizers or herbicides 1 , has been steadily declining due mostly to afforestation and silviculture occurring during the twentieth century 2 . In Sweden, traditionally managed semi-natural grasslands are one of the most species-rich habitats but the decrease in area during the last 80 to 90 years has been estimated to be around 90% 1 , 3 . Currently, the area of semi-natural grasslands of high nature value in the country is estimated to be around 2986.9 km 2 according to the Swedish National survey of semi-natural pastures and meadows (TUVA: http://www.jordbruksverket.se/tuva ; access date: 06-08-2020).…”

The importance of traditional agricultural landscapes for preventing species extinctions

“…Pérez-Sánchez et al 2020) and relationship between forest and open land (e.g. Bergman et al 2018). Also habitats other than semi-natural grasslands may contribute to such landscape level features.…”