Journal of Insect Conservation 5: 163–171, 2001. © 2001 Kluwer Academic Publishers. Printed in the Netherlands. The influence of landscape grain size on butterfly diversity in grasslands Christine Schneider 1 & Gary L.A. Fry 2 1 Department of Landscape Planning Alnarp, Swedish University of Agricultural Sciences, P.O. Box 58, S-23053 Alnarp, Sweden (phone: +46 40 41 54 34; fax: +46 40 46 54 42; e-mail: christine.schneider@lpal.slu.se) 2 Department of Landscape Ecology, Norwegian Institute of Nature Research, P.O. Box 736 Sentrum, N-0105 Oslo, Norway (phone: +47 23 35 5111; fax: +47 23 35 5101; e-mail: gary.fry@ninaosl.ninaniku.no) Received 25 January 2000; accepted 27 March 2001 Key words: butterfly diversity, grassland management, grain size, landscape pattern, Sweden Abstract The relationship between butterfly diversity and both habitat and landscape variables was studied in two areas of southern Sweden. The habitat quality of the grasslands was similar in the two study areas but the landscape pattern differed in grain size and amount of grassland and forest. Using a transect survey method, a total of 3341 butterflies were observed and 30 taxa identified. We found that both habitat and landscape variables influenced the butterfly diversity of the investigated grasslands. Species composition differed markedly between the two study areas. A study area with a fine-grained landscape pattern, a high cover of semi-natural grassland and many forest edges had twice as many butterfly species but half the number of individuals compared with a coarser-grained study area with larger grasslands widely spread in a matrix of arable fields. The results of our study indicate that both habitat quality and landscape pattern have to be considered when developing conservation strategies for grassland butterflies. Introduction The rapid decline of butterflies in large parts of Europe has caused concern in recent decades (see, for exam- ple, Thomas 1991; Pullin 1995; Thomas 1996). The qualitative changes in grassland management related to the abandonment or intensification of agriculture are seen as some of the most important factors responsible for the decline of grassland butterflies (Erhardt 1985; Erhardt & Thomas 1989; Berglind 1990). Although the effects of changes in grassland quality on indi- vidual butterfly species have been extensively stud- ied, especially in Britain (BUTT 1986; Thomas 1991; Warren 1993; Oates 1995), comparatively few studies have analysed the relationship between grassland qual- ity and butterfly diversity (Erhardt 1985; Erhardt & Thomas 1989; Dolek 1994; Dolek & Geyer 1997; Jeanneret et al. 1999). The results of landscape ecological research have forced us to consider the influence of landscape pattern on species diversity (Hanski 1999). Several authors have shown that the landscape context of habitat patches is an important factor influencing butterfly diversity (Oates 1995; Steffan-Dewenter & Tscharntke 1997; Jeanneret et al. 1999). The aim of this study is to identify habitat and landscape factors that affect butterfly diversity in two grassland areas in Southern Sweden and thus to con- tribute to the knowledge base required to develop grass- land management strategies. The study is part of a larger research programme on grassland management (Gustavsson 1995). Study areas and methods Study areas This study was carried out in two areas in southern Sweden (Figure 1a,b). Study area A is situated 10 km