Mapping Connectivity in the Swedish Agricultural Landscape

Sammanfattning: The changes that Swedish agriculture has undergone during the 20th century has resulted in strongly increased productivity, but at the cost of more intensive environmental impacts. One of these is loss of biodiversity, which is driven by, e.g., usage of pesticides and loss and fragmentation of habitats. A vital process for resilient ecosystems is the possibility for species to move between habitats, known as connectivity. One approach to increase connectivity is through strategic perennialization in the agricultural landscape. The aim of this thesis is to map structural connectivity in agricultural landscapes in two major agricultural regions in Sweden and explore options for enhancing connectivity by strategic perennialization. Objectives include the development of a model to map structural connectivity in the Swedish agricultural landscape, identify landscapes where conditions for biodiversity can be improved by strengthening the structural connectivity, and investigate the potential to improve the conditions for biodiversity by introducing perennial crops in the agricultural landscape. The resulting model is based on circuit theory using the software Circuitscape, in which land cover is treated as electric circuits, which are assigned resistance based on the permeability of different types of land cover. The resistance in the developed model is based partly on human impact and partly on structural differences from areas of high biological values, or value cores, between which connectivity is modelled, in terms of object height- and cover. Two agricultural production areas were investigated, Skåne plains and Västra Götaland plains, as well as a testing area in Skåne county. Connectivity maps were created and analysed, and potential areas for strategic perennialization were identified. A strategic perennialization scenario was also modelled in the testing area. Since the application of the model is structural connectivity, uncertainties regarding how well it relates to functional connectivity varies between species. Structural connectivity has nonetheless been shown to facilitate functional connectivity in several aspects. No significant difference in connectivity could be found in the trial area following the introduction of strategic perennialization, but this is most likely due to assumptions behind area selection. Therefore, other approaches for identifying promising locations for strategic perennialization, based on connectivity maps, need to be explored.