ASSESSING INFORMAL TRAIL NETWORKS IMPACTS ON PROTECTED AREAS LANDSCAPES: A CASE-STUDY FROM PORTUGAL

Visitor-created informal trails, sometimes referred to as "social trails", represent an important threat to the visitor experiences and natural resources of recreational areas by removing vegetation, moving wildlife, altering the hydrological cycle, introducing invasive species and fragmenting landscapes. This paper presents the preliminary stage of a project that intends to develop the current understanding of informal trails and their potential impacts on protected natural landscapes. The methodological approach has its application in a Portuguese protected area, the Arrabida Natural Park, and consists of three sub-steps: (1) collection of GPS-based data from a webshare service based on a WebGIS and a spatial analysis using a geographic information system; (2) an on-site visual survey of informal trails using condition class assessment method; and (3) an assessment of the diversity of trail-based fragmentation across the area using landscape fragmentation metrics to summarize the relative impacts on a landscape scale. When using the proposed approach it will be possible to produce a comprehensive coverage of information with reasonably high accuracy about the absolute and relative levels of impacts from informal trails at the landscape scale (fragmentation indices) and at the local scale (trails condition assessment).