Informal settlement or slum area

Martinique is a biodiversity hotspot, home to over 1,500 endemic plants, 70% of which are under threat from human activities. In response to these pressures, the Péyi Vert [Green Country] initiative was launched to plant endemic trees and strengthen the island's biodiversity. Beyond simply preserving species, these trees are crucial in maintaining healthy ecosystems, as they provide essential services such as carbon sequestration, shade, food for human consumption, soil decontamination, pollination, and protection against coastline erosion.
Launched in June 2020 by Entreprises et Environnement (EE), a not-for-profit business association representing 80 Martinican companies, the Péyi Vert initiative aims to plant 1 million native trees (either Martinican or Caribbean) over five years. It can be seen as a Martinique-wide strategy to adapt to and mitigate climate change. Péyi Vert facilitates connections between people who want to plant trees and Martinican companies that serve as financial sponsors. The initiative emphasizes conserving natural heritage by planting endangered species, as well as promoting native species that, while not necessarily threatened, provide valuable ecosystem services or contribute to biodiversity restoration.
Between 2020 and 2023, EE reported planting 50,000 trees (Refs 1, 4, 6, 7). Although individuals can make donations, Péyi Vert primarily seeks funding from companies looking to offset their carbon emissions or enhance their Corporate Social Responsibility (CSR). To achieve its goals, the initiative mainly collaborates with municipalities, companies, and farmers (Ref 3).

To protect the Lomas de Primavera from urban pressure and other threats, the Lomas de Primavera Ecological Association has implemented strategies for its conservation. One of the strategies this organisation has promoted is reforestation activities. Working together with the Municipality of Lima and other interested actors, they have sought to expand Lima's green spaces, improve air quality, enhance flora, and promote tourism, among other benefits (1). Lima's Municipality has supported the project by donating 20,000 trees for reforestation and to prevent land encroachment (1), social organisations and environmental activists have joint efforts to plant more than 250 trees to support the conservation efforts (2, 7).
The Lomas de Primavera Ecological Association leads the project, organizing community management efforts to conserve the Lomas de Primavera sector. This association is based in the Agrupación Familiar Primavera Lomas de Carabayllo community (2). The association's conservation activities involve collaboration with various stakeholders at different levels. Locally, it works with community leaders and organizations. At the district level, it coordinates with the Carabayllo municipality and the NGO CIDAP to improve urban conditions. The metropolitan-level collaboration includes the Municipality of Lima and the ACR 'Sistema de Lomas de Lima' for ecosystem protection and valorization. Nationally, it partners with MINAM, SERNANP, MINAGRI, UNDP, UCV, and the Network of Peruvian Lomas to enhance ecosystem services, restore degraded areas, and conduct research on the Lomas (2).
The preservation and reforestation of these ecosystems is essential, as they have social, cultural and environmental value, including the following ecosystem services: provision of genetic resources, soil formation, pollination, aesthetic services, ecotourism, food, education, and archaeological and historical services (3)

The Adana Central Park stretches along both riverbanks of the Seyhan River. The idea was first introduced by the former mayor of the city, Aytaç Durak, in the late 80s to address the need for accessible green spaces in the developing area (Ref, 2). Previously, citrus gardens and informal settlements were located on these riverbanks, which now host over 400.000 plants and 67 different tree species on an area of 33 ha (Ref. 2,5,6). In 1998 construction of the park began, which lasted until 2004 (Ref. 2,5). The park is appreciated by visitors for its aesthetically landscaped appearance and the many amenities for children, youth, relaxation and socializing (Ref. 7). The two sides of the river are connected via bridges or, alternatively, visitors can board the Venetian style gondolas to access either side (Ref. 5). In 2021, park lighting infrastructure has been extensively replaced to ensure accessibility and safety during day and nighttime (Ref. 3).

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).

The "Line Park" project in Belgrade aims to create a continuous green belt spanning 4.6 kilometres and covering over 48 hectares. As such, the project will revitalize the former railway corridor from "Beton Hala", just below the Belgrade Fortress, to the Pancevac Bridge. Inspired by notable urban parks like New York's "High Line", Moscow's "Zagrađe," and Toronto's "Rail Corridor," it will become a major recreational destination and also help to alleviate the pressures from the city's heavy air pollution and summer heat (Ref. 5, 6).
The park will be divided into ten thematic sections dedicated to aromatic plant and flower gardens, urban gardening and beekeeping, sports facilities, a newly built university campus and more. Additionally, there will be an amphitheatre and facilities for outdoor education. To further integrate green infrastructure, new buildings will have green roofs and walls (Ref. 2,5). Ultimately, the park integrates a number of amenities into the entire city.
The development of the park also introduced innovative co-creation mechanisms in terms of governance and planning. Since Belgrade is part of the multinational CLEVER Cities Initiative, the city's Secretariat for Environmental Protection suggested the use of the site as a pilot test for introducing nature-based solutions in urban planning and with diverse stakeholders' input. Several workshops, focus groups, and consultations took place between 2019 and 2021, which facilitated the diversity of ideas that have been adopted into the official construction plan (Ref. 1, 2). Despite these successes, civil society groups raise concerns over the extraordinary cost of 70 million euros, displacement of Roma communities and the interest of real estate developers that may undermine the project's original cause (Ref. 3, 8).

According to the FAO, in 2022, 16.6 million Peruvians faced moderate or severe food insecurity, representing an increase of 1.5 million compared to the previous year (3). This situation was exacerbated by the health crisis, inflation, and job losses, leaving three out of ten Peruvians in poverty in 2021. The situation was particularly critical in Metropolitan Lima and Callao, with 14% of families reporting difficulties in acquiring protein-rich foods due to their precarious economic situation (2).
In response to this food crisis, the Municipality of Lima implemented the "Lima te Cuida" (Lima Takes Care of You) initiative, in which residents from vulnerable areas got training to create urban gardens and produce organic compost to help the community kitchens in these areas become self-sustainable (1, 2). An example of this initiative is the community garden in A.H. Villa Mosha in San Juan de Lurigancho, where a community garden has been built, and community members have been trained in small-scale planting, cultivation, care, and harvesting of various foods (2).
This initiative has been supported by the MUSA project "Mujeres Unidas por la Seguridad Alimentaria y Ambiental" (Women United for Food and Environmental Security) as part of the project "Alimentando a Lima desde Adentro" (ALDA) (Feeding Lima from within), which has had an impact in eight districts of Lima to strengthen food security (3). In addition to promoting urban agriculture, the project seeks to influence public policy through training and development of proposals to promote urban agriculture at the local level (4).

Lima is grappling with significant challenges driven by climate change, and one of the pressing issues is the shortage of green spaces. According to the PLAM 2035 report, Lima offers only 3.1 square meters of green area per inhabitant, well below the World Health Organization's recommendations (2). Moreover, food insecurity is on the rise, with Peru leading the region in this crisis (4). Compounding these issues is the lack of coordination among state actors tasked with addressing the country's food crisis (2).
In response to these challenges, the Energy Network of Peru (ISA REP) has been running the "Huertos en Línea" project since 2004 in the districts of Villa María del Triunfo and San Juan de Miraflores as part of its corporate social responsibility initiatives (2, 3, 6). This project aims to establish community gardens that promote environmental awareness, reduce pollution in these affected areas (1, 2), provide food for vulnerable populations, and create income-generating opportunities through the sale of surplus produce (1, 6). The gardens are strategically located in power grid easement strips, which are often plagued by encroachment, burning, and waste accumulation—issues exacerbated by poverty, extreme poverty, and weak social organization in these areas (5, 6).
Originally planned with an annual development and growth strategy up to 2011, the project has been extended year by year and has now been active for nearly two decades. Beneficiaries continue to receive technical and material support, and the number of community gardens has grown. In 2019, the initiative expanded to include two bio-gardens in the Trujillo districts of La Esperanza and El Porvenir (7, 9). The project has contributed to improving soil quality, recycling and transforming waste, enhancing landscape aesthetics, reducing burning and waste accumulation, and implementing drip irrigation systems.

Trénelle-Citron, located north of downtown Fort-de-France and separated by the city bypass, La Rocade, was originally established in the 1940s by Black Martinicans migrating from rural areas. Today, the neighborhood faces significant economic and social challenges. In 2016, young residents from the neighborhood alongside a local NGO launched a grassroots initiative to improve their community. They transformed a former municipal quarry, which had deteriorated into an informal dump, into a thriving shared urban garden, benefiting the local population. This project, based on traditional ecological gardening techniques and the cultivation of native crops, aimed to revitalize Trénelle-Citron—a densely populated area grappling with social exclusion, a shortage of green spaces, and limited economic opportunities for its youth (Ref 2).

The garden, developed on municipal land with guidance from the Ypiranga Martinique NGO, support from the local school, and collaboration from various stakeholders, now plays a vital role in the area. It raises awareness about agroecology, offers socioeconomic opportunities, promotes healthier lifestyles, and fosters social connections among residents. Spanning approximately 1,000 m², the site includes an office, a covered area, tool storage containers, market garden plots, a composting area, and a chicken coop managed by a local resident (Ref 7). In Martinique, such shared urban gardens are increasingly seen as important tools for sustainable development (Ref 5).