Epsilon Archive for Student Projects

Abstract

Around the globe, including Sweden, biodiversity is decreasing, and many invertebrate and plant species are threatened. One of the main reasons for the decline is the decrease in natural and semi-natural open grasslands due to intensified agriculture and land abandonment. Grazing has an important role in the maintenance of open grassland and has many benefits for the flora and fauna which reside in these habitats. The European Bison (Bison bonasus), Europe's largest now living land mammal, roamed Europe for thousands of years before it was declared extinct in the wild in the 1920’s. Soon thereafter the restoration efforts to bring back the European bison started and today it roams freely in Europe once more. Björkön is a 155 hectare island located in the lake Hjälmaren in central Sweden. It has been a nature reserve since 2019 and is mainly composed of open grassland, deciduous forests and wetland forests. The local authorities have made efforts to manage Björkön by grazing but it has not been enough to support the open landscape. The aim of this study was to analyse the habitat and area in relation to what criteria the European bison needs and to pinpoint possible conflicts if an introduction of the European bison would occur. To assess the current state of knowledge, a literature review regarding the European bison's preferred habitat and diet, and home range was done. In addition, maps of tree characteristics and main habitats on Björkön were created, and distance to the mainland was calculated. The habitat on Björkön seem to be beneficial for European bison, but may be too small for its regular home range. Furthermore, the distance to mainland on the north and south side of the islands is shorter than one kilometre and therefore there is a considerable risk that the European bison may reach the nearby mainland. The arable land and forests around the island are potential conflict areas because of damage to both farm crops and forests. European bison could however be beneficial when it comes to fulfil the needed grazing impact, keep the forests and open grassland clear of shrubs and overgrowth, and create a mosaic landscape that would benefit both the flora and fauna on Björkön.