Landscape fragmentation in Europe: a comparative analysis

Landscape fragmentation (LF) has been acknowledged as one of the main causes of biodiversity loss. The phenomenon consists of large-scale transformation of habitat patches in smaller fragments that tend to be more isolated over time. LF can be due to transport and mobility infrastructures (TMIs), and affects local climatic conditions, habitat quality, and isolation of animal and plant species. The literature supplies scholars with various indicators able to quantify the ecological impact of LF. In this work, we assess and compare LF in four landscape units (LUs) of approximately the same surface area –two LUs in Wales (the UK) and two in Sardinia (Italy)- belonging to quite different ecological and institutional European contexts. We apply the Barrier Fragmentation Index (BFI), which takes into account the barrier effect of road infrastructures with reference to the perception of the hedgehog (Erinaceus europaeus L), a target species quite common in both the countries. We also measure LF through the Urban Fragmentation Index (UFI), which appreciates the effect of urbanized areas. While measuring the BFI, we consider the number of patches, the length of TMIs traits without discontinuities such as bridges and tunnels, the perimeter and area of the LUs, and the probability of barrier effect that varies according to the type of TMIs. We quantify the UFI taking into account area of the LUs and the extent and perimeter of urbanized areas. We measured the highest values of BFI and UFI, respectively, in the ‘North East Wales’ (299733.70) and in ‘South East Wales’ (7.06). We registered the lowest values of the same indicators in the inner mountainous LU ‘Limbara’ (1441.57 for BFI, and 0.24 for UFI), in Sardinia. These results are a clear sign that coastal and more populated LUs are the most fragmented. These indications are key for planners and decision makers towards proper courses of actions toward defragmentation.