A Prescriptive Spatial Model for Assessing Cumulative Effects on Natura 2000 Sites: The case study of the Metropolitan Area of Messina (Sicily)

Spatial Decision Support Systems (SDSS) have provided Decision-Makers with powerful, complete, and engaging tools to support planning for a long time. The landscape is a fragile system to be evaluated from diverse perspectives, considering its multidimensional characteristics. Landscape metrics are indices of landscape structure used to describe landscapes’ composition and spatial distribution. They can be applied at different scales to analyse individual landscape elements based on size, shape, number, etc., describing the arrangement of features and the degree of diversity. The Landscape Metrics allows the planning to be integrated within the landscape system following more inclusive criteria - conceived as a common standard of judgments for the evaluation - and metrics, i.e. several patches per class (NPC), Edge Density (ED), Shannon Diversity Index (SHDI), Connectance Index (CI), Contrast Class Edge (CCE), etc. In this work, we assess cumulative impacts on Natura 2000 sites within the Municipality of Messina. It intends to prefigure a decision support tool to evaluate the safeguarding of biodiversity through the conservation of natural habitats and wild flora and fauna through the landscape metrics approach combined with spatial multi-criteria analysis. Starting from the environmental problems that characterise the territory of Messina, included in the Natura 2000 network, four objectives to be pursued have been identified: • Ensuring the conservation of habitats; • Defining indications on the prohibition of building permits; • Managing regulatory/organisational issues; • Quantifying and analysing the land and habitat consumption rates in the Natura 2000 network. Furthermore, the proposed methodology has been structured to assess plans or projects’ cumulative effects on the National Interest Site, verifying the interferences through landscape metrics referred to as Edge Density (ED) and Connectance Index (CI).