Mapping potential natural vegetation through a quantitative and multivariate approach. The case study of Campobasso Functional Urban Area (Italy)

To provide a methodology useful for fine-scale ecological research on urban and peri-urban areas, we propose an updated approach for the Ecological Land Classification (ELC) based on Potential Natural Vegetation, tested in the Functional Urban Area (FUA) of Campobasso (Italy). We applied a divisive process, hierarchically dissecting the territory from broader to narrower land units (LU) based on environmental discontinuities with respect to bioclimate, lithology and geomorphology. Within these LU, phytosociological surveys of woodland patches representative of the current vegetation potential were homogeneously stratified. Sampled data were thus investigated by statistical clustering and Indicator Species Analysis, allowing different mature vegetation typologies to be recognised and respective relationships with environmental variables to be detected. In particular, threshold values for each environmental diagnostic feature with respect to PNV discontinuities were estimated through multivariate analyses. Finally, a detailed PNV/Environmental Land Unit map of the study area was obtained, enhancing not only the geometric but also the typological detail of the cartographic information already available at the regional and national level. By improving knowledge on mature forest ecosystems and respective environments, the approach may effectively support restoration actions in the specific case study, but can also be transferred and generalised for broader biodiversity research on urban systems, such as that on the overall Italian FUA promoted by the National Biodiversity Future Center. • Defining reference ecosystems is crucial for effective restoration • Ecological land units and PNV represent useful reference models • An updated and semi-automatic process is proposed here for their spatialisation • The process may be easily attuned to other urban context types