Nature in Cities
Four of the top twenty French urban areas are located in Provence-Alpes-Côte d'Azur (Aix-Marseille, Nice, Toulon and Avignon). Today, 92% of the inhabitants of Provence-Alpes-Côte d'Azur live in urban areas.
In the departments of Bouches-du-Rhône, Var and Alpes-Maritimes, nearly half of the population lives in towns of more than 50,000 inhabitants, notably in coastal areas (3 out of 4 inhabitants are concentrated on 10% of the territory according to INSEE). In Provence-Alpes-Côte d'Azur, urban concentration is a societal fact that it is imperative to take into consideration when addressing issues of lifestyle, risk, adaptation and climate impact.
Historically, housing in the Mediterranean region has always been sparsely dispersed, with villages and towns characterized by compact housing. In the Provence-Alpes-Côte d'Azur region, this concentration increased until the 1990s, before decreasing under the effect of peri-urbanisation and the deconcentrating of the population towards peripheral centres.
The city has thus become a real environmental issue. Geographic and demographic densification as well as artificialization due to the construction of the city can exacerbate the impacts of climatic variations and create particular natural dynamics. With a view to reinvestment in town and city centers, the quality of public spaces and the place of nature in the city are essential levers.
Indeed, nature in the city is a response to the crossroads of immediate and longer-term issues: issues of beautification and pacification of the living environment, social issues of providing public spaces and ecological amenities, issues of maintaining ordinary biodiversity and an urban green and blue grid, issues of adaptation to climate change and resilience in the face of risks.
Fostering nature in cities means rethinking urban development from a "win-win" perspective, where the preservation of ecosystems and the urban green and blue grid is accompanied by services rendered and regulatory functions, particularly climate regulation.
A social demand for welcoming public spaces
Essential to the functioning of the City, public spaces are the places where collective, urban and civic life is expressed, where diverse populations come together.
The design and redevelopment of quality public spaces is understood as a project aimed at welcoming the diversity of populations and uses, in a rest area designed to promote conviviality, comfort, well-being and safety, but also a space allowing nature-based solutions to the challenge of adapting the city to climate change.
Nature in the city
Nature in the city corresponds to a strong social demand, especially in the city centers dominated by collective housing. Equal access of the inhabitants to green spaces is one of the issues to be considered in planning and urban development choices, in order to ensure a balanced distribution of nature areas accessible to the public.
In its ecological functions, nature in the city relies on a diversity of public and private spaces, through parks, squares, squares, collective gardens and courtyards. It develops along traffic routes or through the renaturation of wasteland or watercourses.
However, not all urban spaces lend themselves to greening, and it is on a case-by-case basis, depending on the ecological context, the geography of the area and the wishes of the inhabitants, that projects can be developed.
The urban green and blue grid consists of networking all the nature areas in the city and of re-establishing connections between nature areas in the heart of the urban fabric and the green envelopes in the suburbs. The urban planning documents should encourage the restoration or recreation of certain travel routes that have been altered or modified by previous developments, which should be renatured to accompany the evolution of urbanization.
A necessary adaptation of urban spaces to climate change
According to climate projections, the regional territory will see its average summer temperature rise significantly, with more frequent and intense heat waves (and probably air pollution episodes) throughout the territory, increasing the risk of the development of urban heat islands in cities.
These summer climatic conditions will generate thermal discomfort that will be detrimental to the quality of life and the overall attractiveness of the territory, as well as increased health risks for vulnerable populations (particularly the elderly, whose numbers will increase sharply), in a current context of cities' unsuitability to extreme heat.
The challenge is therefore to preserve the quality of life of the population and the attractiveness of urban spaces in the face of periods of high heat by improving the thermal comfort of buildings (new and old) and the overall climatology of urban spaces, while limiting the development of electric air conditioning, which has a negative impact on the development of measures to reduce urban overheating.
It is therefore strategic in the planning documents to work on the adaptation of these areas to more extreme conditions in order to reduce the risk of development of urban heat islands, limit thermal discomfort and finally preserve the residential and tourist attractiveness of the region by working on the climatology of urbanized spaces.
This is why, in the SOUTH region, the SRADDET, in its objective 37 "Seek the quality of public spaces and promote nature in the city" and a specific rule LD2-OBJ37 encourages the maintenance and development of nature in the city and promotes the functioning of an ecological network of all these spaces, in order to form functional green and blue frames in the urban environment.
It is essential that the planning documents include landscape plans which contribute to the definition of a green and blue grid based on pre-existing structures (hydraulic networks, wooded areas).
SRADDET also invites local authorities and development stakeholders to design projects that optimize the services provided by nature in the city, particularly in the search for adaptation to climate change and resilience to risks. Thus, nature spaces promote thermal comfort by reducing urban heat islands and contribute to reducing CO2 emissions and air pollution.
SRADDET also encourages the application of biotope coefficients (CBS) to define a minimum proportion of non-waterproofed surfaces.
For further information
« Climat et ville : interactions et enjeux en Provence-Alpes-Côte d’Azur » - GREC PACA – juin 2017 GREC-SUD – Tous nos cahiers thématiques en un seul clic (grec-sud.fr)
« Provence-Alpes-Côte d’Azur, une région face au changement climatique » - GREC PACA – novembre 2015 GREC-SUD – Tous nos cahiers thématiques en un seul clic (grec-sud.fr)
Aménager avec la nature en ville - Des idées préconçues à la caractérisation des effets environnementaux, sanitaires et économiques, juin 2017. Ouvrage. FEIX Isabelle, MARQUET Sarah, THIBIER Emmanuel. ADEME. http://www.ademe.fr/amenager-nature-ville
Faire la ville dense, durable et désirable Agir sur les formes urbaines pour répondre aux enjeux de l'étalement urbain, février 2018. Guide pratique. I Care & Consult, ADEME. http://www.ademe.fr/faire-ville-dense-durable-desirable
Ecosystèmes dans les Territoires -Cahiers techniques de l'AEU2 Réussir la planification et l'aménagement durables, janvier 2015. Guide pratique. ADEME. Pdf, Epub . http://www.ademe.fr/ecosystemes-territoires
Climat et Energie / Cahiers techniques de l'AEU2 -Réussir la planification et l'aménagement durables: https://www.ademe.fr/climat-energie
Outil ARBOCLIMAT: http://www.arbre-en-ville.fr/arboclimat/