A spatial ecological assessment of fragmentation and disturbance effects of the Swedish road network

• Loss and degradation of habitat are primary effects of the Swedish road network.
• Natural grasslands + southern broadleaved forest were most exposed to road effects.
• Forest species with high area demands were most prone to be adversely impacted.
• The quantitative approach has high potential for use in environmental assessment.

Transportation infrastructure has a wide range of effects on ecological processes, which result in both positive and negative impacts for biodiversity. However, the treatment of biodiversity in planning and environmental assessment have been criticized, especially regarding habitat loss and fragmentation effects, the low use of quantitative methods and that of assessments being descriptive rather than analytical and predictive. The aim of this study was to assess the impacts of the Swedish road network by spatial modelling of road effects, to explore potential impacts of fragmentation and disturbance effects of roads on habitat networks for selected ecological profiles, and to discuss the utility of applying quantitative methods for environmental assessment purposes. Habitat and landcover data was used for creating habitat networks for six ecological profiles. Fragmentation and disturbance effects were modelled in GIS and FRAGSTATS was used to quantify ecologically important landscape metrics on habitat amount and connectivity. The results showed that natural grasslands and southern broadleaved forest were substantially more exposed to road effects in Sweden, compared to old coniferous and trivial broadleaved forest. Furthermore, habitat loss was a main consequence of road effects, and forest species with high area demands were most prone to be adversely impacted. Suggestions on method development in order to increase the quality of the analysis methods for environmental assessment are discussed. The potential is seen as high for use of quantitative ecological methods to generate baseline environmental information as well as coarse predictions on likely consequences of development options, useful for environmental assessment.