Artificial phenomenon of spatial fragmentation, which can or could prevent one or more species from moving as they should and could in the absence of a fragmentation factor.
The presence of obstacles, particularly linear obstacles linked to road and communication networks (paved or stabilised ground, guardrails, barriers or fences along them, vehicle traffic) is particularly detrimental to the proper movement of plant and animal species.
Watercourses are also confronted with this phenomenon. Indeed, rivers and streams are living environments that are shaped around the water and sediments they carry, and which transform their beds, thus creating rich and diverse habitats for flora and fauna. Many animal species use them to reach areas that are favourable for their reproduction, growth, feeding or refuge. The free movement of living organisms and the smooth natural transport of sediment is one of the major challenges of the European Water Framework Directive. However, the structures installed in riverbeds (weirs, bridge rims, bushings, dams, etc.), whose height can vary from a few dozen centimetres to several metres, are likely to alter the migration of aquatic species and the diversity and quality of the natural habitats available.
In January 2020, more than 101,500 structures were inventoried.