Talk Impact of linear transport infrastructures on ecological continuities and landscapes: comparison and connection of tools and methods
  • Alexandra Locquet
    Bio statement : Alexandra Locquet is a student in geography; she is graduated with a Geography degree and a first year of Master Environment at Paris 1 Panthéon-Sorbonne University. She is currently student in the second year of a “Bioterre” Master (Biodiversity Territory Environment) at Paris 1 Panthéon-Sorbonne University. She had the opportunity to work on the ecological continuities and movement species issues during various work experiences and as part of her studies.
    Country : FR
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  • Richard Raymond
    Bio statement :
    Country : FR
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Linear transport infrastructures (high-voltage power lines, motorways) impact the landscapes and fragment the natural environment, which influence the circulation of species and requires facilities or management measures to restore ecological continuities.

To this end, while studying the territory of the Regional Natural Park of the Ardennes in France, we considered the different tools and methods for analysing, on several scales, the impact of transport infrastructures on the landscape and ecological continuities. Thank to those researches we succeeded to identify spaces where ecological continuities should be restored or created. The issue here is to compare two different methods, a habitat-centred approach and another centred on species, to obtain a complete reading of the whole territory.

The “habitat” method is based on an evaluation and a rating of all environments in the territory. The rating is assigned according to several criteria that evaluate the ecological quality of elements. These criteria vary according to the type of element studied (linear or surface). The ratings are added to obtain the final score of the element studied, which makes it possible to assess its quality (proven, strong, weak ecological potential) and to prioritize the various elements which constitute a landscape. The “species dispersal” method simulates the potential displacement of indicator species starting from the reservoirs of biodiversity. This method is based on the maximum cost a given species can incur when moving, depending on the types of environment crossed. These are modelled in the form of a grid in which each cell corresponds to a type of environment to which a resistance coefficient is assigned: the harder it is to cross over, the higher the coefficient will be.

These methods were developed using bibliographic searches and a GIS tool which was completed by the creation of data sets (field information and picture interpretation).

We show the advantages and limits of each approach. The “habitat” method makes it possible to prioritize natural elements and to see if high ecological quality areas are impacted by infrastructures, which provides a fairly accurate reading of the landscape. The “species dispersal” approach provides an analysis adapted to the animal being studied and a dynamic reading of the ecological network. It emphasizes the impact of infrastructures on the movement of species. However, this method does not integrate one-off elements, and crossing linear and surface data is not obvious under GIS. Both methods are dependent on the data quality, which can lead to bias.

We also reveal that these two methods can effectively be used complementarily to assess the impact of infrastructures on both habitats and species. We have used it on several scales (municipal and multi-municipal) with certain limits because on too large a scale the first method is no longer readable.They can also be used to evaluate the effectiveness of actions intended to restore ecological continuity and to integrate transport infrastructures with the landscape (wildlife passages, hedges and groves under power lines...). They can be implemented on any territory.

fragment; circulation of species; ecological continuities; territorial analysis; ecological quality; ecological network; movement of species