Green Spaces along Linear Transport Infrastructures can provide services to the human society. It occurs through ecological processes that are taking place within these spaces. What are these services? Is it possible and is there an interest in modifying these services? The study offers a preliminary assessment of ecological services produced by natural habitats of these infrastructures green spaces.
The study is based on a concrete example. The site study is a short section of a highway (around 3 km), in the south of Tours, a city in the center of France. This road is going through different kind of landscapes: woods, open farmland and peri-urban area.
Due to the inaccessibility of infrastructures green spaces (especially for security reason), we didn’t take cultural and provision services into account. Therefore, we considered that only regulation types of ecological services are likely to be present along Road and Rail Infrastructures. The study concerned the following ecosystem services: air quality regulation, local climate regulation, erosion prevention, pollination, biological control.
The second stage was the quantitative assessment in biophysical and economic terms. We selected values per biome based on accepted valuation method. We also used the InVEST Tool for pollination and erosion prevention services.
Values provide a rough estimate of the services produced by the green dependences of the infrastructure. Considering the uncertainties which surround their determination, they can only be used for information purpose. So, the study shows that there is a spatial variability of these services within these Green Spaces. It is highly dependent upon the landuse and to a lesser extent upon the surrounding environment. In economic terms, the total value is estimated around 600 €/year/ha (value which is probably underestimated since only few services were evaluated). Even if this value is low, it would represent nearly 200 million Euros per year in France (for 340.000 ha of green dependences –source Union Routière de France, 2007). Therefore, even as an indicative value, it illustrates the stakes associated to green dependences, which are often forgotten.
Furthermore, the study highlights the need for research to quantify the services produced at a local scale.
The study then explores factors that could modify the production of ecological services. Factors can vary based on management and maintenance, but also landscaping practices.
It shows that new skills can be developed for a landscape design of ecosystem services. The anthropocentric approach of ecosystem services also considers that project managers can rely on actions promoting certain services for an eco-design of their infrastructure, better social acceptability and possibly an economic optimization of their project.
Ecosystem Services; Transport Infrastructure; Green Spaces; Landscape Design; Eco-design