Regulation of built environment

Tempelhofer Feld stands as an innovative green solution in the heart of Berlin, addressing several issues of environmental justice, biodiversity, and urban resilience. Within the S-Bahn ring, only one in 20 residents lives in areas well-served by green spaces, and districts like Neukölln, Kreuzberg, and Tempelhof would face even greater scarcity without this vast expanse. Many residents in these neighborhoods lack access to private green spaces such as gardens or balconies. Without nearby parks, people are compelled to travel to other districts, exacerbating the congestion of green spaces and increasing local traffic.
Since its opening in 2010, Tempelhofer Feld has provided Berlin with over 300 hectares of open, green, leisure, and recreational space, making it one of the largest urban open spaces globally. Once the site of bustling air traffic, it is now a sanctuary for activities such as skating, strolling, gardening, picnicking, birdwatching, kiteboarding, and more. These wide-ranging uses showcase its transformation into an accessible, multifunctional green space that serves as a social equalizer, particularly for disadvantaged neighborhoods, a significance amplified during the Covid-19 pandemic.
The field is not just a recreational haven but also a vital ecological refuge. With over two-thirds of its area designated as green space, it hosts diverse ecosystems, including extensive natural meadows, lawns, and protected habitats for birds and other species. Certain areas are closed to the public to preserve these sensitive environments, emphasizing the balance between human activity and ecological conservation. Since 2019, animal landscape keepers, including around 100 resident sheep, have contributed to sustainable land management practices, promoting biodiversity and ecological health (Ref. 2).
Managed collaboratively by political, administrative, and societal actors, the site exemplifies integrated citizen participation in urban planning. (Ref. 3)

The City of Gothenburg's policy for park and street trees was updated in 2016 and has the overarching aim to maintain and develop the ecological, historical, social and economic values of the city's trees and tree environments. Trees are described as having ecological, historical, cultural and economic values. They can provide ecosystem services such as habitat and biodiversity, air quality improvement, flood prevention, heat mitigation, recreation and aesthetic values [Ref. 1].

The policy applies to all trees in the streets, squares, and parks within the municipality but not to natural environments such as forests at the city's edge. Further, the policy is mostly relevant for municipality employees whenever they make decisions that will affect trees or tree-covered areas, such as zoning/planning and construction projects. Other actors in the city, such as private real estate or construction companies, are not required to follow the policy but are encouraged to consider it. The policy formulates sub-goals and guidances regarding the preservation of existing trees (prioritising large and old ones), the planting of new trees, the maintenance of trees, protection during construction work and finally, the taking down of trees, including compensation measures. The policy's direct effects is an expected improved management of trees within the municipal organisation. This may have further indirect benefits in the form of increased ecosystem service provision when the policy affects other projects [Ref. 1, 2].

The "Há Vida no Meu Bairro" project is an innovative urban initiative led by the Lisbon City Council aimed at transforming the city into a "15-minute city." This concept ensures that all essential urban functions, such as commerce, green spaces, education, sports, culture, health, and social support, are within a 15-minute walk from residents' homes. The project promotes neighbourhood identity, quality of life, active mobility, and the development of safer, more comfortable public spaces. By integrating these elements, the initiative seeks to create multifunctional neighbourhoods where daily needs can be met locally, reducing dependence on cars and enhancing pedestrian accessibility (Ref 1).
Lisbon's approach is both city-wide and neighbourhood-specific, with pilot projects being developed in collaboration with the city's 24 parishes. These projects focus on improving public spaces and pedestrian mobility, reinforcing the city's commitment to sustainability and community engagement (Ref 2). The initiative also emphasizes the importance of public participation, encouraging residents to contribute to the design and development of their neighbourhoods and enhancement of local identity and green spaces (Ref 3).

The pilot project in Bairro Padre Cruz, Carnide, Lisbon, is a groundbreaking initiative aimed at enhancing women's safety in public spaces and improving access to public transport. Launched in June 2024, this project stems from extensive consultations with local women to address their specific security concerns (Ref1). It involves strategic interventions like better lighting and the relocation of bus stops to safer areas, ensuring a more secure environment for women (Ref4). A key element of the project is the greening of the area through tree planting and the creation of more harmonised public spaces, contributing to a more pleasant and welcoming neighbourhood (Ref2). Funded by the Recovery and Resilience Plan (RRP), this initiative aims to foster greater inclusivity and safety in urban design, with completion expected by 2025 (Ref4).

The "Jardim do Eucaliptal" (Eucalyptus Garden) in Benfica is undergoing extensive renovations to improve its facilities and usability. Over time, the intensive urbanization of this neighbourhood has not left many traces of the historic eucalyptus forest typical of this area, but this urban park actively protects and maintains these old and heavy-trunk eucalyptus trees, growing amidst the park's more recent vegetation (Ref. 3). In the last few years, several trees have fallen, causing considerable damages to buildings and vehicles in the nearby area (July 2023), and leading to residents demanding financial compensations for damages and for the Lisbon City Council (CML) to take action for mitigating future problems (Ref. 5).
The renovation project implementation, expected to last six months, includes refurbishing the children's playground, sports field, toilets, and amphitheatre, along with introducing a dog park and outdoor exercise equipment (Ref 1). The park, originally part of the Quinta das Palmeiras de Guerreiro Galla forest, remains a crucial green space in the area despite extensive urbanization (Ref 2). These renovations, with a budget of 180,000 euros, also address the maintenance of public street furniture, the pavement, and lighting infrastructure, ensuring that the park meets the growing needs of the local community (Ref 3). These activities aim to meet the growing needs of the local population and improve these urban green spaces so that the community can enjoy them to the fullest. (Ref. 4).

The Cinturón Verde de Independencia initiative is a pilot intervention that seeks to plant an urban forest in the lower middle-class district of Independencia (1) in the northern part of the urban territory (3). Here, 19% of the population lives in high-risk conditions, settled on steep slopes, and threatened by landslides (3).
It is part of a broader planning strategy that involves proposals engaging different levels of government (4). This project seeks to afforest the district's hillsides to improve the environment, reduce air pollution, improve the quality of life of its inhabitants, manage waste, regulate shade, control erosion, increase wild biodiversity, and provide spaces for environmental education (2). The Independence Green Belt is linked to a wide range of plans, projects, and decrees that have been developed by actors at different levels of government since 2016 (4). It works hand in hand with the EBA Lomas programme and seeks to create a green belt along the Lomas-city interface, which acts as a buffer zone for this sensitive ecosystem and creates a protective boundary against the expansion of irregular human settlements while providing a space for environmental awareness (2).
This program was developed by a consortium of multiple private, public, national, and international parties with strong community support (3). In two phases, an urban forest park of 4,800 of native trees irrigated with treated wastewater has been planted. During the first phase, PREDES planted 3,300 trees with USAID support in 2015, and another 1,500 were recently planted by PERIFERIA (consultants) (3).
The Independencia Green Belt occupies the hill areas of the district of the same name and relates to a possible metropolitan-scale buffer belt.
Its boundaries take advantage of the seven Sustainable Ecotourism Forest Parks (PFES) in the District Municipality of Independencia (MDI), as well as 115 hectares of the Amancaes Lomas (4). It aims to conserve 400 hectares (4).

Phoenix faces substantial challenges related to extreme heat, air quality, and social inequity (1-11). The Phoenix Tree Equity Pledge, launched in 2021, is a comprehensive city-wide initiative focused on addressing urban tree inequity and reducing the effects of extreme heat, especially in communities most vulnerable to these conditions (1-12). Partnering with American Forests, the country’s oldest conservation nonprofit, the initiative aims to achieve “tree equity” by 2030, ensuring all neighborhoods receive the benefits trees offer (1).
To reach this goal, the city will focus on enhancing tree coverage in underserved neighborhoods through the development of a Residential Tree Equity Accelerator, which plans to plant 20,000 trees across 25 neighborhoods by 2030 (1-12). By utilizing the Tree Equity Score developed by American Forests, the city can monitor progress, identify areas of need, and measure the impact of these projects (2-4, 9, 11).
To foster public engagement, the initiative will collaborate with residents, businesses, and local organizations to support tree-related projects, raise awareness of the benefits of trees, and promote tree stewardship (1, 4, 15). Additionally, the project aims to create green opportunities within the community by establishing supportive policies and regulations for tree planting and care and by creating pathways to green jobs (1, 7-9, 13-14). Recognizing that heat affects communities unequally, the Tree Equity Pledge seeks to increase canopy coverage in targeted neighborhoods, improving air quality, reducing the urban heat island effect, and enhancing overall community health (1, 7-9, 13-14).

The Ciénaga de la Virgen is a coastal wetland (cienaga) located on the north side of the border of the city of Cartagena, separated from the sea by La Boquilla's sandy beach. It has a maximum width of 4.5 km, a length of approximately 7 km, a water body area of about 22.5 km², and depths of up to 1.6 m. It is connected to the city's canal system (ref 1). The recovery project of la Cienaga de la Virgen, led by EPA Cartagena, is proposed as a strategy to address the issues affecting the water body, local communities, the economic activities that depend on it, and the ecosystems that regulate the water cycle and provide multiple services, many of them essential, with an integrated and global management approach based on the basin as the unit for planning and resource management (ref 14). Some of the main problems of the wetland are related to illegal settlements on its shore, as well as illicit dumping of waste, pollution by wastewater from the illegal settlements and deforestation of mangroves (ref 4). Key activities include stopping illegal occupation by relocating established families, improving roads, promoting reforestation, encouraging social participation, managing wastewater, and enhancing tidal systems (ref. 1 and 15).
Alonside the EPA, other stakeholders involved include the regional authority "Regional Autonomous Corporation of the Canal del Dique" (Cardique), with jurisdiction in the rural area, and Cartagena Mayor's Office, and the local community, involved in all the stages of the plan thanks to the “mesas de governance” or "governance tables", discussion spaces where different actors participate in the decision-making (ref 2).

The new 6.5-hectare Anita Berber Park has been created on the site of the former St Thomas cemetery, between Tempelhofer Feld and Hermannstraße. It is named after the dancer Anita Berber, who herself was buried there in 1928. The cemetery was unused and out of use for several years and became accessible to the public through the intervention. (Ref. 3; Ref. 6) The construction period was preceded by a public participation process in which the facilities and design were developed together with the users. The redesign of the space was conducted by a landscape architecture office (Henningsen Landschaftsarchitekten PartG mbB) and financed by the German Federal Government (Ref. 1). The new park, which was planned and financed as a compensatory measure for the construction of the A100 urban highway, increases the quality of local recreation in the densely populated district of Neukölln. (Ref. 2; Ref. 6) An important goal was to achieve high species diversity in the park while preserving its valuable trees and shrubs. The park also offers multiple spots for rest and play as well as a zone for free running dogs. (Ref. 2; Ref. 6)
The park features wooden climbing structures and an old collection of trees with hollows, along with bushes and shrubs. These areas often accumulate rubbish, highlighting the ongoing waste management issues the park has faced since its renovation (Ref. 4).

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).