Urbanization and Long-Term Forest Dynamics in a Metropolitan Region of Southern Europe (1936-2018)

Although peri-urban landscapes in Southern Europe still preserve a relatively high level of biodiversity in relict natural places, urban expansion is progressively consuming agricultural land and, in some cases, forest cover. This phenomenon has (direct and indirect) environmental implications, both positive and negative. The present study contributes to clarifying the intrinsic nexus between long-term urban expansion and forest dynamics in a representative Mediterranean city based on diachronic land-use maps. We discuss some counterintuitive results of urbanization as far as forest expansion, wildfire risk, and biodiversity conservation are concerned. Forest dynamics were investigated at two time intervals (1936-1974 and 1974-2018) representing distinctive socioeconomic contexts in the Rome metropolitan area in Central Italy. Additionally, the spatial relationship between forest cover and urban growth was evaluated using settlement density as a target variable. All over the study area, forest cover grew moderately over time (from 18.3% to 19.9% in the total landscape), and decreased along the urban gradient (i.e., with settlement density) more rapidly in 2018 than in 1936. The diversification of forest types (Shannon H index) was higher in areas with medium-density settlements, indicating a tendency towards more heterogeneous and mixed structures in rural and peri-urban woods that undergo rising human pressure. The dominance of a given forest type (Simpson's D index) was higher at high settlement density areas. Evenness (Pielou's J index) was the highest at low settlement density areas. The long-term assessment of land-use dynamics in metropolitan fringes enriched with a spatially explicit analysis of forest types may inform regional planning and environmental conservation, which could delineate appropriate strategies for sustainable land management in Southern European cities.