Landscape effects on butterfly assemblages in an agricultural region (original) (raw)
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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, semi-natural 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.
The Influence of Landscape Structure on Butterfly Diversity and Movement
2015
Schneider, C. 2003. The influence of landscape structure on butterfly diversity and movement in grasslands- A comparison of two agricultural areas in Southern Sweden. Doctoral dissertation. ISSN 1401-6249, ISBN 91-576-6432-3. The objective of this thesis was to investigate the influence of habitat and landscape factors on butterfly diversity and movement in grasslands. The studies were carried out in two agricultural areas in Southern Sweden that differed in landscape structure, including habitat amount and field size. The results show that both habitat characteristics and landscape structure influenced species numbers and abundance of butterflies in grasslands. The amount of adjacent forest, flower abundance, field size and estimated nutrient levels were factors identified as influencing butterfly species composition. Mark-release-recapture experiments with two grassland butterflies (meadow brown, Maniola jurtina L. and scarce copper, Lycaena virgaureae L.) indicated that these spe...
Journal of Insect Conservation, 2014
This study investigates how butterfly communities are influenced by habitat and landscape factors in forest-dominated landscapes. The abundance and species richness of butterflies were determined in 22 semi-natural meadows located in north-eastern Estonia. A correlation analysis, partial least squares analysis and stepwise forward-selection multiple regression analysis were applied for habitat parameters and the surrounding landscape at four spatial scales, i.e., 250, 500, 1,000 and 2,000 m radius. We found a positive correlation between the proportion of forest and total butterfly species richness at a 250 m radius scale. Contrary to expectation, the amount of meadow area in the surrounding landscape negatively influenced butterfly species richness and abundance. Our results emphasise the importance of both the surrounding landscape and habitat characteristics for butterfly species richness. Because butterfly communities are composed of individual species with different habitat requirements, diverse habitats and landscape configurations should be applied in insect conservation and management.
Biodiversity and Conservation, 2008
A widespread decline in biodiversity in agro-ecosystems has been reported for several groups of organisms in Western Europe. The butterXy fauna was studied in 60 selected semi-natural grasslands in a coniferous-dominated boreal landscape in south-eastern Sweden. The aim was to investigate how butterXy assemblages were aVected by the amount of semi-natural grasslands in the surrounding landscape. Furthermore, we wanted to determine if semi-natural grasslands in boreal landscapes harboured species otherwise declining in other parts of Europe. For each study site, the amounts of semi-natural grasslands in the landscape within radii of 500, 2,000 and 5,000 m were studied. Nine local habitat factors were also recorded. Only the amount of semi-natural grasslands within a 5,000 m radius could explain a signiWcant part of the variation in butterXy composition, but there was no clear relationship between the amount of semi-natural grassland and butterXy diversity. Instead, this study showed that local habitat quality was very important for butterXy diversity at individual sites. Flower abundance, sward height and herb composition were the most important local factors. Patches surrounded by a small amount of semi-natural grasslands had high butterXy diversity, contrary to expectations. This may be explained by the fact that forest habitat provides a matrix with several features suitable for butterXies. The butterXy fauna was rich in species representative of low-productivity grasslands, species that are declining in other countries in Western Europe.
Journal of Insect …, 2007
Indicator classifications help us to focus on the most relevant groups of species in monitoring the effects of land use changes on biodiversity. We studied changes in distribution area of 74 butterfly species preferring one of the three common habitats of boreal agricultural landscapes: semi-natural grasslands (35 species), arable field margins (7) and forest edges (32). Using extensive atlas data from four time periods during the last 50 years in Finland, we quantified trends in the occupancy of the species in 10 km grid squares, and classified them into four classes: declining (23), stable , increasing and fluctuating species. Trends among the species favouring three habitats were different: 60% of the species of seminatural grasslands had declined, whereas 86% of the species typical of open field margins had increased. An increase also predominated in species associated with forest edges. Declining and increasing species differed in three ecological characteristics: increasing species were more mobile, utilized a wider range of habitats and, based on their larval host plants, lived in more eutrophic habitats than declining species. Species overwintering as adults showed more positive trends in occupancy than species overwintering as eggs, larvae or pupae. Observed trends in occupancy are in good agreement with long-term changes in land use and habitat availability in Finland: a long-continued decrease in the area of semi-natural grasslands and an increased amount of open forest edges and clearings due to modern forestry during the past 50 years.
High cover of forest increases the abundance of most grassland butterflies in boreal farmland
Insect Conservation and Diversity, 2017
High cover of forest in the landscape matrix has been shown to weaken the negative effects of habitat fragmentation on grassland butterflies. No studies have however focused on examining species‐specific responses of grassland butterflies to forest. The data from 3 years of butterfly monitoring in Southern Finland were used to test whether the amount of forest cover in the surrounding landscape affected the abundance of grassland butterfly species in semi‐natural grasslands, field margins, and forest edges. More than half of the studied species benefitted from high cover of forest. Species with the strongest preference for forested landscapes were Lycaena virgaureae, Argynnis adippe, Argynnis aglaja, and Boloria selene, which probably find suitable resources in herbaceous habitats at forest edges and clearings. Several small‐sized species were positively affected by surrounding forest cover in field margins but not in the other habitat types. Although field margins are suboptimal ha...
Monitoring of butterflies within a landscape context in south-eastern Sweden
Journal for Nature Conservation, 2010
Monitoring 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 to: (i) evaluate the impact of environmental variables on butterfly abundance; (ii) compare the distribution of butterflies in different habitats; and (iii) analyse data from the study with the aim of improving the method. Eight randomly placed study sites (750 m  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 categorised 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), clearcuts, 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 o1% 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 form of monitoring presented here can, if performed regularly, increase our knowledge of how structural changes of landscape affect butterflies and thereby improve conservation efforts.
2009
Metapopulation theory predicts that species richness and total population density of habitat specialists increase with increasing area and regional connectivity of the habitat. To test these predictions, we examined the relative contributions of habitat patch area, connectivity of the regional habitat network and local habitat quality to species richness and total density of butterflies and dayactive moths inhabiting semi-natural grasslands. We studied butterflies and moths in 48 replicate landscapes situated in southwest Finland, including a focal patch and the surrounding network of other semi-natural grasslands within a radius of 1.5 km from the focal patch. By applying the method of hierarchical partitioning, which can distinguish between independent and joint contributions of individual explanatory variables, we observed that variables of the local habitat quality (e.g. mean vegetation height and nectar plant abundance) generally showed the highest independent effect on species richness and total density of butterflies and moths. Habitat area did not show a significant independent contribution to species richness and total density of butterflies and moths. The effect of habitat connectivity was observed only for total density of the declining butterflies and moths. These observations indicate that the local habitat quality is of foremost importance in explaining variation in species richness and total density of butterflies and moths. In addition, declining butterflies and moths have larger populations in well-connected networks of semi-natural grasslands. Our results suggest that, while it is crucial to maintain high-quality habitats by management, with limited resources it would be appropriate to concentrate grassland management and restoration to areas with well-connected grassland networks in which the declining species currently have their strongest populations.