Urban biodiversity: from ecology to landscape planning

The installation of nature in the city is a goal that municipalities are increasingly proclaiming, and city dwellers are also increasingly demanding a different living environment. Scientists are also demonstrating the benefits of greening the city: the services rendered are numerous, and the city would appear to be livable only thanks to the presence of plants that provide not only ambiance and refreshment, but also a whole range of regulatory functions, such as air cooling and rainwater management. The positive impact on human health has also been clearly demonstrated. All these arguments militate in favor of the development of nature in the city, even if certain designers and decision-makers are putting the brakes on this enthusiasm, and if many city dwellers remain intent on cleanliness, which is not always reconcilable with too much vegetation.

But today, the idea is to develop functional biodiversity, i.e. a set of species that have relationships with each other. Biological diversity is an asset in terms of resilience, and by taking ecological processes into account, we can give a certain form of stability to the whole. The aim is therefore to get closer to the way ecosystems function, either by protecting them as best we can in a new urban context, or by recreating new ones that are home to horticultural and local species. The aim is not only to protect local biodiversity and aim for system sustainability, but also to integrate the city more fully into a regional ecology.

This perspective implies a different approach to nature in the city, which until now has mainly been the subject of landscaping where aesthetics take precedence, or the subject of a choice of species linked to an expected service (cooling, for example). It raises questions not only about planting and the management of parks and gardens, but also about architecture (how should buildings be greened?) and urban planning (how should the built and the unbuilt be organized?).

New design and construction strategies, and new research into "neo-ecosystems", are underway to achieve these goals, but already several experiments by local authorities are making it possible to move beyond simply greening the city towards integrating biodiversity and the ecological processes that underpin it (species dispersal, for example).