The importance of vegetation type, habitat patch size and isolation for the occurrence of scarce heath butterfly, Coenonympha hero, in the Värmland county

Abstract: As agricultural activities in Sweden have ceased nowadays, more and more meadows are being overgrown and planted with forest. Since natural and managed grasslands are very important to a large part of the European butterfly fauna, it is a big threat to these species when meadowlands are being planted and overgrown as it gives them less space and is fragmenting their habitats. The scarce heath butterfly, Coenonympha hero, is one of the butterfly species that is being threatened by this, and has decreased its numbers during the past years. It is protected in Sweden, where it occurs primarily in the Värmland and Dalarna regions. The purpose of this essay is to try to explain how area size, isolation and vegetation will influence populations of scarce heath butterflies in chosen patches in the Värmland province. 55 patches where the butterfly had been observed between the years 2004-2009 were included in this study. The patches were divided into four different categories depending on the vegetation, and the size of each patch along with the distance to the three closest patches was measured. The data was used for statistical analyses in Excel and SAS 9.2. Regression statistics show that there is a significant correlation between the maximum number of butterflies and the size of the patches, and between the closest patch/three closest patches set against the maximum number of butterflies. The type of vegetation seemed to have no specific importance for the butterfly populations according to this study.