Formal coordination mechanisms to oversee project implementation and decision-making (e.g., multi-stakeholder steering committees, working groups)

The green belt regeneration project along the Byzantine Walls of Thessaloniki aims to revitalize the neglected green spaces surrounding these historic fortifications, which span 4 kilometers and are recognized as a UNESCO World Heritage site for their remarkable Byzantine architecture. The walls are located in Thessaloniki’s densely populated Upper Town, a factor that contributed to their environmental degradation. As such, the project focuses on restoring the degraded space surrounding the walls, improving the urban microclimate, and strengthening urban resilience while maintaining the area’s traditional character. By integrating heritage conservation with sustainable green infrastructure, the initiative seeks to provide both environmental and social benefits to the local community. Proposed by the Municipality of Thessaloniki and approved by the Greek government as part of a program that focuses on Central Macedonia, the project envisions a revitalized green zone along the walls, with vegetation and different types of trees being planted. However, some local families have expressed concerns, as the project involved the demolition of certain homes in the officially designated green belt area. (Refs. 1, 2, 3, 4, 14).

Two stages of a project called "Flowering roadsides" have been created along a bike road stretch measuring 6,5 km between the areas of Gunnilse and Bergum in the eastern part of the City of Gothenburg. The projects came to be through citizens' initiatives and are carried out in cooperation between the City of Gothenburg and two local NGOs: The Bergum-Gunnilse Development Association and the Gothenburg branch of the Swedish Society for Nature Conservation (Gunnilse-Bergum utveckling & Göteborgs naturskyddsförening). The first stage of the project was carried out in 2021 and focused on taking inventory of species and ecosystems along the stretch and suggesting management options to promote biodiversity. The second stage is carried out from 2022 to 2024 and focuses on implementing and evaluating alternative management options to today's conventional management. Mowing and scraping are carried out to disturb weeds and benefit meadow flowers. Sand has been placed to create a habitat for wild bees. Signs were put up along the stretch to inform the public of the initiative, and benches will be renovated to create opportunities for recreation. The project receives funding from the Swedish Environmental Protection Agency through their local nature conservation investment, LONA. The project falls under the umbrella project of "the world's longest meadow", organised nationally by the Swedish Society for Nature Conservation [Ref. 1, 3, 4]. The goal of that project is to transform 1000 km of Swedish roadsides into flowering meadows with high biodiversity richness [Ref. 2].

The Olaya Herrera neighbourhood in Cartagena has been the focus of a series of projects that involve ecological restoration, environmental education, and community resilience building. These initiatives have centred around the restoration of the Ciénaga de la Virgen, an ecologically significant but heavily degraded coastal wetland bordering the neighbourhood. The primary goals of the projects in Olaya Herrera include the restoration of degraded mangrove ecosystems, mitigation of flooding and water pollution, strengthening community participation in environmental management, and promoting sustainable urban environments (ref 1, 2). The project is led by the EPA Cartagena, which coordinates actions such as collecting solid waste, planting timber trees and ornamental plants, and restoring green spaces that had become informal dumping grounds (ref 1). It also includes a community-led initiative called Los Guardabosques de Olaya that focuses on reforestation and environmental stewardship, it involves children, youth, and local mothers in reforesting mangrove areas around the Ciénaga de la Virgen. The community has established a mangrove nursery and employs innovative waste management practices, such as installing traps in canals to prevent solid waste from entering the Ciénaga (ref 2). The project also involves the private sector in 2022, the EPA led a campaign with local companies like Konfirma, Acuacar, and Pacaribe that focused on improving environmental health through the removal of 10 cubic meters of waste, promoting healthy living environments and fostering community participation in environmental monitoring and waste management practices​ (ref 4). Also, in collaboration with community leaders and local companies, the ANDI-TRASO Alliance supports large-scale reforestation and restoration activities in the southern parts of the Ciénaga de la Virgen adjacent to Olaya Herrera. The alliance plans to plant 40,000 mangrove seedlings (ref 6).

Planting Oxygen in the Community is an initiative initiated by the medical company Antibiotice S.A., one of the largest drug producing company in Romania, with headquarters in Iasi. The initiative involves an annual tree plantation campaign that has been carried out over the past four years. Originally implemented in cooperation with the municipality of Iași, the campaign is now independently managed by the medical company Antibiotice S.A. The selected planting area is located adjacent to the company headquarters in Iași and consists of undeveloped grassland.
Throughout the campaign, a total of 1,175 trees and 6,000 shrubs have been planted, including species such as oaks, lindens, and maples. The initiative has engaged 310 volunteers from the company to assist with the planting efforts.
The campaign aims to achieve several goals: rehabilitating green spaces, protecting the environment, reducing carbon emissions, mitigating the effects of climate change, and providing cleaner air for future generations. Additionally, it seeks to enhance the company’s environmental impact and foster social interaction among employees by reconnecting them with nature.
(1-8)

The Grand Parc des Aygalades project involves the creation of a 14-hectare metropolitan park (connecting Aygalades Park with Bougainville Park and François Billoux Park) that will connect the northern neighbourhoods of Marseille to the port located further south (Ref 1). This project is part of the green conversion of Marseille's northern districts, historically among the most disadvantaged areas in France (Ref 1). The Grand Parc des Aygalades project will enhance the city's greenery, reduce flood risks, create cool zones, restore and develop biodiversity, and significantly improve residents' quality of life and air quality (Ref 1, Ref 2). The environmental and social challenges include reconnecting the populations of these neighborhoods to green spaces, services, education, sports opportunities (Ref 2).
The park project includes redesigning urban infrastructure to improve rainwater absorption and reduce flood risks, addressing the issue of impermeable and artificialized soils that exacerbate flooding during heavy rainfall (Ref 1). It also involves renaturing a 17-kilometre-long stream currently buried under railway tracks, improving flood management and rainwater drainage (Ref 1, Ref 4). The project will also convert a heavily degraded former industrial site, requiring the rehabilitation of polluted soils (Ref 1). Additionally, creating green corridors aims to mitigate the heat island effect, particularly severe in these northern districts due to the high concentration of buildings and concrete surfaces, and the lack of green spaces. Public participation will be encouraged through information meetings, thematic workshops, and an online platform for submitting ideas and feedback (Ref 4).

Eliseo Collazos is located in the coastal desert ecosystem of the Lomas or ‘fog oasis’, an area that receives less than 10 mm of rainfall per year. Vegetation cover is of particular importance in the hills surrounding Lima, as it provides critical solutions to erosion, landslides and soil degradation in the ecologically degraded ecosystem of the Lomas. However, this ecosystem is facing risks from urbanisation, illegal mining and agricultural practices, resulting in the lack of the delicate mist-fed greenery for which the Lomas are known (2). This has led to increased particulate matter in the air due to exposure to sand and wind, aggravating respiratory diseases such as tuberculosis, which is prevalent in Lima's informal communities (2).
Low-income communities have inhabited this area, forced to migrate from the rainforest, highlands and city to the desert slums (4), who have only been able to settle in these landscapes with little access to resources, prone to disaster risk, little public investment in infrastructure and little access to green spaces (2). As a result, these communities live in poor conditions (1). For this reason, in 2013, the University of Washington, under its Urban Informal Communities Initiative programme (1), initiated a participatory project that sought to address the challenges faced by the inhabitants of this area (1, 2). In a series of participatory workshops, residents identified greenspace and food security as top priorities in their community; the Gardens, Greenspace and Health project responds to these priorities as an initial step towards the expansion of greenspace, agriculture and ecological restoration in and around the Eliseo Collazos community (2, 4).
Although individual families constructed them, the front yard gardens contribute to a shared public realm and community greening (4). The general project also involved the installation of fog catchers and the creation of common recreational spaces (4).

As part of France's New National Urban Renewal Program (NPNRU) and its strategy to enhance urban quality of life, the Urban Integrated Farm in Desclieux was established in 2021, with a particular emphasis on urban agriculture.
This project is implemented by the Centre de Culture Populaire Ypiranga de Pastinha Martinique (CCPYPM or Ypiranga Martinique) in collaboration with the city of Fort-de-France and is located in the socioeconomically disadvantaged Ravine-Bouillé neighborhood. It aims to create a farm on a 2-hectare former military site that previously housed fuel cisterns connected to the French Navy at Fort Saint-Louis. Since falling into disuse in the 1990s, only the reinforced concrete structures remain.
The farm will feature various activities, including a composting zone, a café, a beehive, a botanical trail, a play garden, and areas for crop and animal production. Additionally, it will house a decontamination and materials library and a public living space for community use. Overall, this site aims to serve educational, recreational, and socioeconomic purposes, enriching the local urban ecosystem.
Even though the intervention commenced in 2021 it has encountered several challenges since 2022 due to administrative hurdles. The implementers are currently awaiting temporary authorization to proceed. The primary obstacle remains the development and execution of a comprehensive soil decontamination plan. (Ref 2; 3; 4)

In Phoenix, many residents live in dead zones with little or no access to fresh food. These zones are called 'food deserts,' which represent a low-income area with low access to a grocery store (3). Out of the 43 food deserts identified by the city, 18 are fully or partly in south Phoenix (2-3). In 2017, Two researchers from Arizona State University’s School of Sustainability and Leuphana University Lüneburg in Germany began exploring the idea of creating a sustainable food forest cooperative in Phoenix to provide fresh, healthy food, supporting local entrepreneurs, and promote environmental sustainability (1). The project's development team spent months immersing themselves in the world of food forests, by exploring different types of community gardens, discussing preferred characteristics, anticipating local challenges, and identifying potential collaborators (1). As a result, The Food Forest Cooperative was established and planted roots in a 0.5 acre (0.20 ha) plot within the Spaces of Opportunity Community Garden in 2022 (1). This food forest engages the local community by offering educational opportunities around the value of culturally relevant, whole fruits and vegetables, medicine making, and learning about the many uses of edible/medicinal plants (4). The Food Forest Cooperative as a multi-generational project that members preserve for their children, and their children’s children (2). The intention behind the project is to address food insecurity in south Phoenix and empowering the community to take ownership of it and reconnect with their ancestors through the land and food (2). Through the Cooperative, members can contribute different skills, from administrative work to manual labor to community education and traditional medicine (2). It was created to empower community members and challenge the patterns of our food system through the blending of environmental, social and economic goals (4).

The "Plan Arbre" is a tool for ecological planning and renaturation aiming to plant 308,000 trees between 2023 and 2029, sourced from the municipal nursery with seeds purchased from local suppliers (Ref 1, Ref 2). In 2023, 14,922 trees were planted, with plans to double this number in 2024 (Ref 1). The project addresses the loss of 50% of Marseille's natural spaces over the past 75 years, aiming to reverse this trend and reintroduce nature into the urban environment (Ref 2). It also tackles issues like drought and heatwaves, particularly in summer, by using trees and shrubs to cool the air, restore biodiversity, reduce air pollution, and enhance public spaces while absorbing CO2 (Ref 2).

The plan is divided into two phases. Phase I focuses on planting in Marseille's 58 parks and 273 squares and gardens, as well as around childcare centres, schools, socio-cultural centres, and sports facilities (Ref 2, Ref 3). From 2020 to 2023, various improvements were made, including playground renovations, installation of misting systems, automatic watering, and the creation of a CrossFit area (Ref 3). Phase II will involve identifying major boulevards, avenues, and streets lacking trees to enhance the urban canopy (Ref 2).
A diverse range of tree species were selected for their drought resistance, water efficiency, and ability to attract biodiversity (Ref 2, Ref 3). The project also focuses on increasing biodiversity and managing invasive species through natural methods to protect trees from pests without chemicals (Ref 3). Furthermore, the initiative includes de-impermeabilizing soils and implementing a smart irrigation system with tensiometric sensors, developed with the start-up GreenCityZen, which has saved 66% of water in two years (Ref 3). The Plan Arbre also promotes citizen participation, with 23 parks selected for community gardening projects, where ten winning associations will receive plants from the municipal nursery (Ref 1).

North Bull Island is a national nature reserve located in Dublin Bay on the north side of Dublin. Supporting both local and migratory wildlife, the area holds several nature conservation designations. It is designated as a special amenity area for its aesthetic and recreational value and forms an integral part of the Dublin Bay Biosphere. The Island, with its 5 km beach located within the capital city and close to the city center, serves as a unique and important public amenity. (1)
The Island is estimated to attract up to 1.4 million visitors annually, including walkers, swimmers, beachgoers, birdwatchers, nature enthusiasts, kite-surfers, and various other interest groups from the local area. Additionally, it is a popular destination for schools, universities, and visitors from Ireland and abroad who come to experience accessible examples of ecological succession across nationally and internationally significant habitats, and to learn about the intricate stories that make North Bull Island Nature Reserve central to a UNESCO Biosphere Reserve and part of a global network of Biosphere Reserves. (1)
The Island and Nature Reserve are managed by the Parks, Biodiversity, and Landscape Services of Dublin City Council in collaboration with the National Parks and Wildlife Service. Dublin City Council has prepared an Action Plan for North Bull Island for 2020-2025 to implement the objectives of the North Bull Island Management Plan 2020. The North Bull Island Oversight Forum, which represents a range of stakeholders, monitors the action plan’s implementation (2). The goal is to conserve the island's environmental qualities and scientific significance while balancing its recreational and amenity value for the benefit of the local community and visitors (8).