Biodiversity and ecosystem services related to green infrastructure in urban areas
Analysis of specificities and dynamics in place
context
Preserving biodiversity is one of the major challenges of the 21st century. Indeed, the expansion of areas dedicated to human activity is accompanied by numerous impacts on biodiversity but also on humans: artificialization of the soil involving more delicate management of rainwater, an increase in the effects of "island urban heat", destruction of habitats and ecological continuities and many others. According to the latest 2019 global assessment report from IPBES, the Intergovernmental Platform on Biodiversity and Ecosystem Services, more than 40% of amphibian species and about 10% of insects are threatened with extinction. Since 1900, the average abundance of local species in most major terrestrial habitats has declined on average by at least 20%. It is therefore essential in a context of crisis, whether environmental, social or health, to imagine solutions based on nature to try to reverse the not very encouraging trends presented above.
On the other hand, the flat, unused surfaces that are roofs have been widely acclaimed for the development of various forms of greening with ambitious programs such as Végétalisons Paris, Imagine Angers, Les Parisculteurs and many others. The possibility of enhancing these spaces, while improving the immediate environment of the local population, is arousing real enthusiasm, going as far as the creation of vegetable gardens accessible on the roofs. The greening of buildings, whatever their objectives, are in high demand.
With the current growth in ecological awareness, requests from local authorities but also from project promoters to be able to measure and evaluate the “ecosystem services” provided by these green infrastructures are beginning to increase. This requires evaluating the performance of an installation on different targets, and ultimately being able to quantify the “avoided costs” for the community.
However, today, biodiversity remains the poor relation when it comes to setting up indicators and researching associated ecosystem services. However, it is urgent to assess it in its entirety, to be able to protect it and set up suitable infrastructures, in particular by using the roofs for productive purposes. It is in fact a question of having criteria and thresholds concerning biodiversity allowing the establishment of a policy of incentive or obligation for the development of these infrastructures by the public authorities.
Questions
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What does the revegetation of roofs (productive or non-productive) bring to urban biodiversity?
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What are the conditions for transferring the principles of agroecology to the urban environment, particularly on different roofs (productive and non-productive), to estimate biodiversity and its dynamics?
Objectives of the post-doctorate
Realization of an exhaustive synthesis of current knowledge and realization of a methodological roadmap for the evaluation of the biodiversity of these green and cultivated roofs
The post-doctorate aims to make an exhaustive synthesis bringing together existing knowledge on the biodiversity (floristics and fauna, including soils and substrates) of green urban infrastructures (cultivated or not) such as green roofs and roofs in urban agriculture. International scientific and gray bibliography, but also synthesis of empirical knowledge via field surveys of designers and installers of green, ornamental and vegetable roofs. Tracing of a methodological roadmap to be able to characterize and assess biodiversity, particularly on productive roofs, and prepare the method for the study of a neighborhood as part of a thesis.
Step by step
Stage 1: September 2021 - June 2022:production of an exhaustive synthesis bringing together existing knowledge on the biodiversity (floristics and fauna, including soils and substrates) of green urban infrastructures (cultivated or not). See what also exists on the impact of spatial organization/urban forms on biodiversity. International scientific and gray bibliography, but also synthesis of empirical knowledge via field surveys of designers and installers of green, ornamental and vegetable roofs.
Step 2: March 2022 - August 2022: field surveys of decision-makers to identify the criteria used to assess biodiversity and identify how it is taken into account in various French cities including Paris and Greater Paris Metropolis, and with social landlords.
Step 3: Summer 2022: choice of a more precise applied research question in connection with an experiment to be carried out in the field on several roofs in Paris or the inner suburbs. To be chosen and co-constructed with landlords/local authorities and with urban farms already installed on roof terraces on various technical systems – in Paris and near suburbs - (eg: Topager, Nature Urbaine, Cultures en ville, etc.).
Step 4: September 2022 - March 2023:first experiment in the field - results published and delivered with partners (Workshops).