The problem of habitat fragmentation
Urban, industrial or agricultural areas, transportation corridors, and their continued growth often affect pristine natural areas and the wildlife that depends on these areas. The loss and cutting up of natural areas through these anthropogenic activities is commonly referred to as "habitat fragmentation". Transportation corridors, mostly roads and railroads, are among the main causes of habitat fragmentation. They not only cause the loss of natural habitats but also affect the quality of adjacent habitats, hinder the movement of grounddwelling animals across the landscape and increase wildlife mortality through vehicle collisions. These impacts can increase the risk of (local) extinction for certain species, especially those that are already vulnerable or endangered.
In Bulgaria plans have been developed to substantially upgrade and expand the national road and railroad networks, including five Pan-European Transport Corridors. The existing transportation corridors and the proposed extensions pose a threat to wildlife and affect the development and functionality of both a national and Pan-European Ecological Network (PEEN), including the designation and protection of NATURA 2000 sites.
It has been shown that existing and planned road and railroad networks do not necessarily inhibit the development of a coherent ecological network. However, biodiversity issues should be taken into account from the early stages of transport planning onwards. This study aims to identify and prioritize sections of the Bulgarian road and railroad network where mitigation be required and provides recommendations to avoid or mitigate the problems identified. The overall objective of the project is, in these times of extensive expansion of the road and railroad systems, to develop tools to help the Bulgarian authorities set up a national program to minimize the fragmentation effects of these transportation corridors so as to preserve biodiversity and develop a coherent and sustainable ecological network across the country.