Ecology, Transport Infrastructure and Environmental Assessment

Abstract: Transport infrastructure has a wide array of effects on ecological processes. These effects benefit certain species and might enhance or accelerate ecological processes such as colonization and dispersal, but as well extinction. The overall impact on biodiversity is however negative and several authors conclude transport infrastructure to have detrimental effects on terrestrial and aquatic communities. Planning and construction of transport infrastructure is in the EU to be preceded by an environmental assessment process, with the overall aim to prevent rather than repair potential unintended negative effects. This thesis presents two studies on transport infrastructure effects on biodiversity in the context of environmental assessment. The first study reviewed how and how sufficiently biodiversity aspects were accounted for in environmental assessment of transport infrastructure projects and plans, and identified opportunities to improve concurrent practice. The first study concluded that the treatment of biodiversity aspects has improved over the years, but that the low use of quantitative impact assessment methods, the treatment of fragmentation and spatial and temporal delimitation of the impact assessment study area remain problematic. The second study assessed the impact of the Swedish road network on biodiversity by use of existing landscape ecological metrics and GIS. The second study reconnects to the shortcomings in environmental assessment practice identified in the first study, by discussing the utility of the method in terms of applicability in environmental assessment processes. The second study identified nature types and species adversely exposed to transport infrastructure effects, and concluded that sound methodologies for biodiversity assessment can be developed using existing tools and techniques. In sum, transport infrastructure influence vast areas of the surrounding landscape, and this is not accounted for in planning and design of new transport infrastructure due to shortcomings in current environmental assessment practice. Existing tools and techniques could be used to address several of these shortcomings, and an increased use of quantitative analysis of transport infrastructure effects on biodiversity would add significantly to the quality of impact predictions and evaluations.