Informal groups with joint interests (e.g. mothers with toddlers, runners, dog walkers)

HortaFCUL is a project created and managed by the Faculty of Sciences at the University of Lisbon to raise awareness and promote the practice of permaculture as a solution to the ecological, social, and economic problems the world is facing (1). This initiative began in 2009 on the University campus through a garden, which allowed HortaFCUL to start conducting some activities that could answer some socio-environmental challenges, such as food security and sovereignty, ecosystem degradation and climate change (13), by raising awareness, teaching, and practising many aspects involved in permaculture and urban agriculture (2). Its focus has been on regenerating soil in an urban environment and creating productive landscapes for people and other beings (12). They grow different types of plants (vegetables, shrubs, trees) in different ways (swales, raised beds, greenhouses) to increase plant diversity and foster ecosystems (13).
The project is managed by students and researchers, who hold educational activities, such as courses, workshops, and dissemination activities (events, discussions, fairs, and conferences) (2). The project is organised according to a non-hierarchical sociocratic model, in which all decisions are made as a group, and where all ideas, critiques, and suggestions are seen as added value and an opportunity to improve techniques and knowledge (3). Additionally, it is open to the community, allowing anyone interested to participate and volunteer (1).
HortaFCUL is also one of the pioneering permaculture projects in operation in the Lisbon region and is now recognized as a national reference centre for permaculture (2). Since its inception, HortaFCUL has sought to be a hub that attracts people, organizations, and other initiatives, and it is currently a point of contact between different projects and associations, such as local businesses, educational institutions, and networks (5).

The Mediterranean climate in Lisbon, already characterised by low precipitation, has been further exacerbated by climate change. The city faces challenges related to biodiversity loss, urban loneliness, and climate anxiety (1). To address these issues, Lisbon's urban development plans have prioritised the re-naturalisation of urban spaces and the integration of ecological networks. Urban nature is now a central component of the city's Master Plan (2012) and other strategic agendas (1).
It is being developed by the LISGREEN project, which aims to enhance ecological connectivity and mitigate the effects of urban heat islands in Lisbon. By establishing nature-based solutions, it aims to restore forests within the city (1, 2, 3). This project encompasses different strategies, such as the RENATURA pilot project. It is a collaboration with the NGO URBEM and involves active public participation in tree planting and forest maintenance. This initiative aims to educate the community about nature, promote well-being, and mitigate extreme climate events (1), through the creation of urban forests.
The main strategy is to create fast forests using the Miyawaki method, which involves dense planting of native trees, removal of invasive plants, and intensive initial care. This approach accelerates the growth of natural forests within a short period, using native species and reducing the need for watering (1)
The first fast forest was developed in Parque Casal Vistoso within Bela Vista Park, within the Eastern Green Corridor of Lisbon. The park is being underutilised because of the lack of shade (1). Thus, this initiative encouraged volunteers to participate in tree planting and forest maintenance activities (3). The NbS intervention began with a 300m² experimental plot near the Vale da Montanha pedestrian bridge and has since expanded to a new 1,500m² plot on the opposite side of the bridge (2). Over 500 volunteers joined the effort, planting more than 3,800 trees (1)

Public spaces in Colombo are disappearing due to rising land prices, causing infrastructure issues that harm citizens' health, especially in low-income areas (3). One proposed solution to address the problems caused by rapid urbanization is the creation of community gardens, which can at least improve low-income residents' diets and immune systems and address malnutrition (3).
Considering the limited urban space for both citizens and other living beings, the organization Eco-friendly Volunteers decided to create a community garden. The Metta Garden in Colombo (1, 2) aims to bring back urban biodiversity through organic home gardening, generating healthy food for people and creating living space for many other animals and plants (2). Following the Buddhist concept of Metta (loving-kindness to all beings), it promotes walking meditation paths and facilities to experience nature using all five sensory organs (1), in addition to being a place for experiencing loving-kindness for both human and non-human living beings, seen and unseen (4, 5).
It has become a training institute for many stakeholders seeking to grow organic food and earn a better income through the high demand for organic products (2). At the same time, it serves as a biodiversity spot, attracting butterflies, bees, and other forms of wildlife to an urban environment (2).
The area is located in the middle of a semi-urbanized area, on the outskirts of Boralesgamuwa (2, 3). Maintained by a group of volunteers, it features a greenhouse and a plot of land of around 5,000 sq feet, populated with vegetable patches, a butterfly garden, flowers and rare medicinal plants (3, 4). The garden was divided into four sections representing the Buddhist elements: water, heat, air, and solid. Each section features specific plants and designs, like a pond for water, a compost pit for heat, tall plants for air, and a rock garden for solid. The layout follows a mandala design based on permaculture principles (4).

The Thalangama wetlands are part of a network of wetland ecosystems around Colombo city that spread over 20 km2 and provide critical life support to the city. These ecosystems keep people safe from floods, cool the air, filter polluted water, provide food and medicines, and fight climate change (10). These wetlands have become an environmental protection area and a biodiversity hotspot in a rapidly urbanising environment, as they host an array of plants and animals, including the endangered fishing cat and otter (5, 10). In 2007, Thalangama Lake and its surroundings were declared an Environmental Protection Area (EPA) under the National Environmental Act (4, 5). This protected area covers approximately 118 hectares (4) and includes two man-made reservoirs: Thalangama Tank (11 ha) and Averihena Tank (3.2 ha), located just 300 meters apart (5). The area hosts floating and rooted plants, scrublands, and trees that provide habitat to up to 100 species of migratory, resident, and endemic birds throughout the year. In addition, the area supports 30 species of dragonflies, 12 species of reptiles, 10 species of mammals, and 15 species of freshwater fish (1, 4). Since the lakes and their surroundings were declared an EPA, only limited uses are permitted, such as traditional fishing and rice cultivation (4, 5). The lakes are also important for floodwater retention and have high scenic and aesthetic value, attracting many visitors, and scientific and educational activities (5, 13).
However, due to the area's rapid urbanisation, land values have increased significantly, leading to excessive landfilling and the reclamation of paddy lands for housing. This is compounded by the indiscriminate disposal of garbage and construction waste and the spread of invasive species (5). These challenges have also led to the engagement of surrounding communities in managing and maintaining it (11).

According to data from the National Institute for Space Research (Inpe), Rondônia ranks fourth nationally among the states with the highest number of detected fire outbreaks (2). In response to this issue and to restore devastated areas in the Amazon, Terra Cura was established in 2016 by resident Luana Lopes, promoting the planting of more than a thousand trees in the Porto Velho region (1). The areas benefiting from this initiative were those degraded by deforestation, causing erosion along the riverbanks (1).
This reforestation effort took place in the scenographic city of Jerusalem of the Amazon, from 2016 to 2022, a cultural and touristic complex in Porto Velho, where erosion caused by deforestation was observed along the riverbanks next to it (2). It was developed as a collaboration with the club and the founders of the Associação Clube Teatral Êxodo, who gave the space so that we could recover the land (3).
The project focused on developing an agricultural strategy known as syntropic farming, by implementing an agroforestry system. This approach seeks to reorganize and restore the natural environment, creating better conditions for planting and allowing trees to thrive. In the reforestation process, volunteers and experienced technicians worked together Additionally, the project included a nursery used for donating seedlings and for offering forestry and agro-construction courses to the community, held in the reforestation area (2).
The Terra Cura project, in addition to working on reforestation and recovery of degraded areas, promoted environmental and cultural integration at the site, promoting sustainable fairs and bazaars, training courses in ancestral practices such as soil cultivation and bioconstruction, and thematic events, bringing together artists and local communities (3). Although they were evicted from the area surrounding the scenic city of Jerusalem (5, 6), they are still active in the area.

The Prinzessinnengarten Kollektiv Berlin is a community garden in the New St Jacobi Cemetery in Berlin-Neukölln that invites people to join in gardening and experience nature. As part of open gardening days, people can participate in the design of the garden areas and gain experience in the local, ecological cultivation of useful plants. The main aim of their work is to provide opportunities for education and participation. Activities are open to everyone and range from sowing, planting and harvesting to seed production, processing and preserving vegetables, keeping bees to questions of community-based urban habitat design.The community also has its own farm shop where seeds, food and processed products are sold. (Ref. 1; Ref. 4) Numerous projects for recycling and upcycling, innovative cultivation methods, organic beekeeping, composting methods and post-fossil mobility use the Prinzessinnengarten as a platform for sustainable urban living. Artists also work in the garden with participatory methods on the question of how cities and their coexistence can be designed in a sustainable and resource-saving way. Outside the Prinzessinnengarten, offshoot gardens are set up and collaborations are developed to build nationwide and European networks. Through lectures, workshops, study visits and participatory research in the garden, we endeavour to include and further develop the topics associated with the Prinzessinnengarten in discussions and education. (Ref. 7)

The project is located on a cemetery, which has been partially closed since 2016. This means that burials are no longer carried out on the site and the existing rights of use of the 500 or so remaining graves will no longer be extended after expiry. The church association lends the land to the project in exchange for maintenance work on the surrounding grounds. (Ref. 6)

The ReDuna project, initiated in 2014, focuses on restoring the sand dune ecosystem in Costa da Caparica (Almada) in response to severe coastal erosion exacerbated by sea-level rise and winter storms. It aims to strengthen the resilience of dunes to environmental pressures while restoring ecological balance. Actions include sand nourishment, the installation of willow sand fences, and the planting of 100,000 native species. Community engagement was a key factor, involving local residents, NGOs, and schools in maintenance and replanting efforts. The project has been successful, with significant biodiversity recovery, establishing deep-rooted vegetation, and stabilising the dunes. Ongoing monitoring and adaptive management are central to its strategy, ensuring long-term sustainability. The ReDuna project serves as a replicable model for similar coastal protection initiatives globally (Ref 1).

The intervention of the Ecological Park of La Molina is an urban-landscape design project developed between the San Martín de Porres University, through the IVUC, the Institute of Housing, Urban Planning and Construction, and the Municipality of La Molina (7). This is the first ecological park in the city of Lima, located in a characteristic ecosystem such as Las Lomas, between 600-1000 m.a.s.l. (1). It is a natural area that is part of the hill system of Villa María del Triunfo, located in the Subtropical Coastal Desert ecoregion, and is part of the Regional Conservation Area ‘Sistema de Lomas de Lima’ (7). The City Council decided to open this space in 2022 to the public, as a 200-hectare area, designed to bring people closer to nature, through outdoor activities and environmental education about its fauna, flora and microclimates (1). Thus, citizens can enjoy a recreational area with multi-purpose spaces and sports circuits; a cultural area where workshops and an open-air amphitheatre are held; an ecological interpretation area with exhibition galleries and an interpretative route; and an administrative and control area (1). The park also envisages reforestation efforts in areas that are currently arid and infertile to convert them into green areas for the enjoyment of citizens (1). In 2023, conservation efforts were reinforced for an additional 50 hectares, due to the danger posed by encroachment and land trafficking (4).

The Horta Nova Urban Park, located in the Carnide parish (Lisbon), is a recently inaugurated green space that combines horticulture with community recreation. The Carnides neighbourhood is characterised by an inspiring history of overcoming hardship, with residents turning food shortages into opportunities by cultivating community gardens since the 70s. Currently, "the neighbourhood continues to be an example of solidarity, innovation and community spirit" (Ref. 2). In 2013, as a response to food scarcity caused during the post-Troika economic crisis, a group of local residents created an unauthorised vegetable garden overnight, on previously derelict space in the neighbourhood. Only in 2021 did the local authorities officially recognise the vegetable gardens, which since 2013 had operated under an informal agreement (Ref. 3). With the official establishment of the horticultural park, in addition, the park has a newly planted broad lawn, an open-air gym, and a dedicated dog park, creating a versatile space for residents (Ref 3).
Currently, this park features 80 vegetable plots, each with a dimension of 100 m2 per plot, attributed by the municipality through an official application process (Ref. 1). The park is a great reflection of the neighbourhood’s resilience and its history of small-scale citizen-oriented agricultural production that began as a response to social difficulties (Ref 1, 2).

Named after the former Mexican president Lázaro Cárdenas, this green corridor project stretches over 4,5 km throughout one of the most densely populated areas in Belgrade. It was first built in the 1970s, connecting the building blocks 45, 44 and 70 of Novi Beograd, but has deteriorated since then (Ref. 4,9). Given the fact that close to 40.000 people live in the area which its highly vulnerable to climate change, action was taken to fully reconstruct the corridor for the benefit of local and surrounding residents (Ref. 3,4).
The project was implemented in three phases, according to the three blocks adjacent to the construction site starting in 2019. During the third implementation phase in 2022, however, major delays occurred due to disagreements with the local neighbourhood association "Common Action Block 70 and 70a", which demanded to be taken into consideration in the project's design (Ref. 2,5). Despite some cooperation between the responsible authority (Greenery Belgrade) and the association, demands could not be met (Ref. 5). In the end, the project was carried out as originally planned by the authorities, with a delay of approximately one year. Ultimately, the green corridor provides ample amenities for sports (bicycle lanes, basketball courts, playgrounds, etc.) and recreational activities (benches, chess area) as well as low-barrier infrastructure for all age groups (Ref. 9).
The project was initiated by President Aleksandar Vučić and supported by the current mayor of Belgrade, Šapić, who both have roots in the district (Ref. 4,6).