Abstract
Over the past decade, ecological connectivity has entered the political agenda, especially within the European transnational context. This evolution has driven the development of structural ecological connectivity and landscape permeability methodologies, such as the Continuum Suitability Index (CSI) presented here, which considers a range of anthropogenic factors that impact ecosystems. Numerous international and national projects have adopted the CSI to assess terrestrial landscape permeability on the macro-regional scale and prioritize areas for the implementation of ecological conservation and restoration measures. Although the CSI methodology has been applied several times, its sensitivity to individual factors, plausibility and ability to maintain consistency and robustness across different data sources and levels of spatial data precision have remained largely unexplored. Here, we presented the conceptual aspects of the CSI methodology, incorporating the outcomes from a literature review and expert workshops, and examined the CSI results for three projects spanning the Alps and Dinaric Mountains. Five key factors—namely, land use, population pressure, landscape fragmentation, environmental protection and topography—were identified as pivotal for analyzing landscape permeability and thus ecological connectivity. Notably, among these factors, population pressure exhibited the highest sensitivity, while fragmentation exerted the least influence on CSI outcomes. When comparing the CSI factors with data on the presence of red-listed species, the environmental protection indicator emerged as the most influential factor.
Furthermore, our investigation comparing the different projects indicated that the chosen level of detail and data sources had minimal impact on the CSI results. Collectively, these analyses highlight CSI’s adaptability and considerable potential as a versatile and straightforward applicable tool for an initial assessment of ecological connectivity at the macro-regional scale.