Monitoring of butterflies within a landscape context in south-eastern Sweden

Abstract

SummaryMonitoring of butterflies is often directed only towards grassland fauna. Species associated with other habitats, as well as the impact of the surrounding landscape, are often neglected. The aim with this study was, in contrast, to perform and evaluate a landscape-based monitoring method for butterflies in diverse habitats and more specifically (i) to evaluate the impact of environmental variables on butterfly abundance, (ii) to compare the distribution of butterflies in different habitats, and (iii) to analyse data from the study with the aim of improving the method. Eight randomly placed study sites (750 m x 750 m) located in south-eastern Sweden were used. The vegetation composition (tree cover, percentage of coniferous and deciduous forest, shrubs, dry, mesic, damp and wet land) inside the squares was analysed using aerial photos and habitats along transects were categorized in the field. The butterfly composition varied depending on the landscape composition. Tree cover had the largest impact on butterfly abundance with a negative relationship between abundance and increasing tree cover. The most species-rich habitats were other grasslands (abandoned fields and fallows), clear-cuts, semi-natural grasslands, and bogs, each habitat also harbouring unique species. Clear-cut was the habitat harbouring the highest abundance and other grasslands the highest diversity of butterflies. Semi-natural grasslands, where the nationally-based monitoring of butterflies in Sweden currently is being performed, constitutes <1% of the total land area in Sweden, indicating a current bias in monitoring directed towards only a part of the species pool. The landscape-based kind of monitoring presented here can, if performed regularly, increase our knowledge of how 3 structural changes of landscape affect butterflies and thereby improve conservation efforts.

Drivers of species richness and abundance of butterflies in coffee–banana agroforests in Uganda

“…In this study, both the abundance and diversity of butterflies increased with increasing amount of semi-natural habitats per square kilometre. Similarly, in southeastern Sweden (Jonason et al 2010), butterfly species richness (not the abundance) was found to be positively related to increasing tree cover in the farm landscape. Apart from land use and farm management methods or farming practices (Weibull and Östman 2003), vegetation structure, quality of the matrix surrounding an agricultural habitat (Binzenhöfer et al 2008;Summerville et al 2008), diversity and types of habitats (Dessuy and de Morris 2007;Ngai et al 2008;Kumar et al 2009), landscape heterogeneity and habitat connectivity (Davis et al 2007) are important factors determining occurrence, movements, population dynamics, seasonality, persistence and longterm survival of Lepidoptera faunal communities in the agricultural landscapes (Dennis 2003;Greza et al 2004;Chay-Hernández et al 2006;Kivinen et al 2008;Öckinger and Smith 2008;Pickens and Root 2008;Stasek et al 2008;Dover and Settele 2009;Brückmann et al 2010).…”

History matters: Impact of historical land use on butterfly diversity in clear-cuts in a boreal landscape

“…However, the same pattern does not appear to exist for grassland remnants in the less studied boreal landscape, with no apparent relationship between butterfly diversity and the amount of semi-natural grasslands in the landscape (Bergman et al, 2008). Recent studies have emphasised the importance of the surrounding matrix in explaining differences in the effects of habitat fragmentation between landscapes (Phiter and Taylor, 1998;Rickets, 2001;Jules and Shahani, 2003;Dennis and Hardy, 2007;Jonason et al, 2010).…”

Flower abundance and vegetation height as predictors for nectar-feeding insect occurrence in Swedish semi-natural grasslands

“…Hence, this confirms the proposition by Bergman et al (2014) that this grassland specialists group is truly relying on grassland which does not seem to be the case for larger group of grassland-dependent species. Members of the latter group can be found not only in grassland but in several types of "marginal" habitats (Jonason et al, 2010;Ibbe et al, 2011;Berg et al, 2011;Korpela et al, 2015;Blixt et al, 2015). Franzén and Nilsson (2008) stressed the importance of flowerrich habitats for red-listed pollinating insects and Wallis de Vries et al (2012) identified flower abundance as a crucial factor responsible for widespread decline in butterfly richness.…”