Changes in plant landscape and biodiversity levels in the Oreto River Basin (Palermo, NW Sicily)

Abstract This study reconstructs the evolution, over the past 35 years, of the plant landscape in the Oreto River Basin (Palermo, NW Sicily), an area of high ecological value included in the Site of Community Importance ITA020012. A vegetation map produced in 1990 was georeferenced and digitalized, then compared with a new land-use map generated from satellite imagery, field-checked, and classified according to the CORINE Land Cover level 3 system. The analyses show that artificial surfaces increased from 8.86% to 15.89% of the Basin, driven by urban sprawl, while agricultural land declined from 38.83% to 29.10%. Pure citrus groves decreased by 14.69 km², whereas olive groves (+ 3.89 km²) and mixed orchards (+ 5.50 km²) expanded, often in response to growing water scarcity. Natural and semi-natural areas show a slight overall increase (from 52.09% to 54.72%), despite a sharp loss of conifer reforestations (–8.17 km²) due to recurrent fires, which fostered the expansion of natural grasslands (+ 13.80 km²). The fragmentation of relict communities of Chrysojasminum fruticans , Ilex aquifolium , Ostrya carpinifolia , and Platanus orientalis , together with the decline of Carex panormitana near urban areas, highlights emerging conservation concerns. Overall, the findings underscore the urgent need for integrated policies to curb uncontrolled urbanization, prevent fires, and enhance both forest biodiversity and the traditional agricultural landscape.