Landscape composition and connectivity explain butterfly use of clear-cuts in contrasting forest-farmland mosaics

Loss and intensified management of meadows, grasslands and open woodlands have caused widespread declines of butterflies in Europe. While historical forests contained dispersed open habitats as a result of windfall, wetlands, and large herbivores, many forests today are more closed and less structurally diverse through most of the forest cycle. However, temporary open habitat created by clear-cuts under rotational forestry may be used by butterflies, with their use potentially depending on connections to more permanent open habitats. In Sweden, where more than half of the land area consists of production forest with few naturally open areas, clear-cuts are ubiquitous and can provide habitat for species associated with open habitats and forest edges. We compared butterfly communities at the centre of 120 forest clear-cuts in two different Swedish regions, one with a forest-dominated landscape with little grass- and farmland (Dalarna), and one with a forest-farmland mosaic landscape (Scania). The main objective was to evaluate how butterfly use of transient, open clear-cut habitat depends on successional stage and landscape context. We combined the survey of 120 clear-cuts in 2018, 2019 and 2020 with landscape analyses. We used (i) a dbRDA to understand the drivers of community structure; (ii) GLMs to investigate the landscape and local drivers of farmland and grassland butterfly indicators; and (iii) joint species distribution models to understand how traits and phylogeny mediate species’ responses to local and landscape variables. All 14 species of the Swedish farmland indicator, and 9 out of the 12 grassland indicator species, were observed in the 120 surveyed clear-cuts. The butterfly communities differed markedly between the regions, but also with respect to the area of clear-cuts and farmland in the surrounding landscape. Most importantly, clear-cuts were used by many grassland and farmland butterfly species, with their occurrence and abundance associated with the composition of the surrounding landscape. This indicates that clear-cuts may provide functional habitats for some butterfly species, depending on their ecological requirements and the broader landscape context. Body size and larval host-plant type partly explained butterfly species distributions in clear-cuts. Our results demonstrated that use of clear-cuts is filtered by life-history traits, with the proportion of roads also associated with the occurrence of several species, highlighting the role that landscape-wide management could play for butterfly conservation even in production forests. Hence, while clear-cuts are known to have negative consequences for forest biodiversity, we show that their ubiquitous use in modern forestry could have positive incidental consequences for butterflies, with these effects depending on the broader landscape context.