Central Business District / City Centre

The Mobile Tree Trail is a nature-based solutions (NBS) initiative aimed at preserving Mobile, Alabama’s urban forest while celebrating its cultural and ecological heritage (Ref 1, Ref 2). First established in the early 1990s by volunteers, the original trail featured 24 iconic trees, selected for their historical significance, environmental value, and beauty (Ref 1, Ref 2). Over the years, some trees were lost to development and storms, and the trail faded into obscurity (Ref 1, Ref 4).
From 2021, the Mobile Tree Commission, with support from The Nature Conservancy, is leading efforts to revive the trail (Ref 3, Ref 6). Activities include reviewing past entries, opening public nominations, and selecting new trees that best represent Mobile’s identity (Ref 3, Ref 4). The project emphasises inclusivity and public participation, welcoming volunteers and local input to shape a trail that evolves with the city (Ref 4, Ref 6).
Mobile faces environmental threats such as hurricanes, urban expansion, and loss of native tree cover (Ref 1, Ref 6). The revitalised trail helps address these challenges by promoting awareness, conserving old-growth specimens like the 300-year-old Duffie Oak, and maintaining vital green spaces (Ref 4, Ref 6).
The Mobile Tree Trail blends education, tourism, and conservation, enhancing urban resilience while telling the city’s story through its trees (Ref 3, Ref 6).

The stretch of the Great Lakes basin ecosystem from southern Lake Huron through western Lake Erie forms a unique urban refuge where life thrives with beauty and resilience. Known as Metropolitan Detroit, this region is where the Community Foundation for Southeast Michigan and many partners are working to create The Great Lakes Way by connecting 160 miles of greenways and 156 miles of water trails (1).
The vision for the Great Lakes Way project is to ensure that all residents and visitors of southeast Michigan—people of all ages, backgrounds, ethnicities, abilities, and interests—feel connected to the water resources, welcomed on its trails, and able to enjoy the benefits and opportunities these access points provide (1). To bring this vision to life, the project plans to link 160 miles of greenways and 156 miles of blueways, connecting people to a range of world-class freshwater, wildlife, and recreational opportunities. These include fishing areas, bird migration pathways, parks, working waterways, preserved woodlands, and restored wetlands (2).
The Great Lakes Way project connects existing assets, supports accessibility and equity, and promotes the Great Lakes Way to both residents and visitors through marketing and communication efforts (2). There are 26 points of interest that will serve as connection hubs along the Great Lakes Way (2). In Detroit specifically, the focus is on connecting 13 culturally or historically significant destinations, as well as locations known for their environmental and ecological importance or as regional landmarks (2).
Rich in world-class fisheries, migratory flyways, parks, urban centers, small towns, preserved old-growth woodlands, and restored wetlands, the Great Lakes Way offers unique experiences that can only be found here. By uniting the natural and cultural assets the Great Lakes Way designation aims to emphasize and expand the essential linkages needed to further connect this remarkable region. (2,3)

The Digital Hub, a campus in Dublin 8 offering 49,000 sq. ft. of office, studio, and workspaces for small businesses in technology, creative industries, social enterprises, and artisans, has partnered with Pocket Forests to establish Ireland’s first urban native tree nursery. Located on The Digital Hub campus, the Pocket Forests Tree Hub will grow native Irish trees, including birch, rowan, and alder, to support the planting of over 600 trees throughout Dublin 8 and beyond.
As Dublin 8 district faces a noted lack of green spaces and low tree density, as highlighted by the Mapping Green Dublin project from University College Dublin and local groups, the Tree Hub is set to address this gap. This innovative initiative aims to improve the local natural environment and bolster biodiversity in a rapidly urbanizing area.
Pocket Forests, co-founded in 2020 by Ashe Conrad-Jones and Catherine Cleary, is inspired by the Tiny Forest concept, which brings diverse native plants to small urban plots. Using permaculture methods, Pocket Forests regenerates depleted soil and creates diverse micro-forests on plots as compact as six square meters. This approach, which enriches soil and encourages biodiversity, has a unique capacity to transform urban areas into lush, green spaces, contributing to improved air quality and local ecosystems.
The Covid-19 pandemic has underscored the importance of access to nature for well-being, and The Digital Hub offers an ideal location for this first-of-its-kind urban initiative. The Tree Hub will serve as a valuable resource for greening Dublin 8, promoting community engagement, and fostering a greater connection to nature.
Beyond the nursery, Pocket Forests will run a series of six half-day workshops at The Digital Hub to educate the community on biodiversity, pollination, compost, soil health, and the importance of urban forest ecosystems. The Digital Hub’s Tree Hub boosts well-being, biodiversity, and green space for future generations. (1-5

"Adopt a linden tree" is a project that involved the planting and adoption of linden trees in the city of Iași, spanning from 2019 to 2023 across three editions (1 to 8). The campaign was spearheaded by the National Athenaeum of Iași, in collaboration with the Mihai Eminescu Association from Vienna (2). This initiative was launched in celebration of the Athenaeum's 100th anniversary, and it specifically chose the linden tree because of its deep-rooted symbolism in the city of Iași. The tree is not only a natural landmark but also carries cultural and historical weight, as it is closely associated with Romania’s national poet, Mihai Eminescu, who is known for his love of linden trees.
In 2019, 100 linden trees were planted, a number that was repeated in 2020. In the 2023 edition, 50 trees were added, bringing the total number of trees planted through this project to 250 (1 & 4 & 5). An important and unique aspect of the initiative is the "adoption" of the trees by volunteers who participated in the campaign. These volunteers not only lent their names to the trees but also took on the responsibility for their care, ensuring the trees' survival and growth until they reached maturity .
Volunteers were encouraged to participate, and the campaign was supported by donations from individuals, businesses, and public institutions. The municipality of Iași also contributed by providing funds, approving the initiative, and preparing the land through its subsidiary, Servicii Publice Iași S.A., reflecting strong public-private collaboration.
Beyond its cultural significance, the campaign aimed to achieve several other objectives. These included enhancing the city’s aesthetics, promoting community engagement, and improving the quality of life in Iași by contributing to cleaner air and a healthier environment . The initiative also aimed to raise environmental awareness among residents and foster a stronger sense of responsibility toward the natural world. (1-8)

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).

In an architecturally important area of Berlin, situated between the Landwehr Canal, the Kulturforum (the Berliner Philharmonie and the Berlin State Library) and the new construction on Potsdamer Platz, a combination of green and grey infrastructure has been realised to minimise the burden on Berlin’s existing water infrastructure.
Green and non-green roofs harvest annual rain, which flows through the site’s buildings and is used for toilet flushing, irrigation, and fire systems. The roofs retain and then release water to the large on-site buffer pond, which has five underground storage tanks. Next to the roofs, a series of urban ponds and connecting canals have been implemented, with a combined area of approximately 1.2 hectares. They are filled with rainwater, creating an oasis for urban life. Vegetated biotopes are integrated into the overland landscape and serve to filter and circulate the water that runs along streets and walkways. The lake’s water quality is excellent, forming a natural habitat for animals and cooling the surroundings, while fresh water usage in the buildings has been reduced. (Ref. 1; Ref. 2; Ref. 3; Ref. 6)
The project was implemented in the 1990s as part of the development of Potsdamer Platz in the wake of the reunification of Germany. Several architects collaborated on the implementation that was completely privately funded. Beyond its ecological and technical features, the site is a blue natural site in the heavily built city centre of Berlin and allows people to linger and enjoy natural features. The drainage system won several sustainability prices and is considered a successful integration of nature and technology-based mechanisms to foster climate change adaptation. As the rainwater system stores rainwater in underground tanks and ponds, the urban sewage system is relieved during heavy rain, and water can evaporate. Therefore, the small water circle is closed, and the microclimate is cooled. (Ref. 2; Ref. 6)

Located in the Lima district of San Isidro - the heart of commercial activity in Peru - the Real Dos Tower is a prime office building in the Centro Empresarial Real de San Isidro. It was inaugurated in 2018, and it is distributed over 23 levels (14 floors and 9 basements) and enjoys a landscaped green roof (1162 m2) at the crown of the building and numerous outdoor vertical gardens at full height (2365 m2) on the three main fronts (1, 4). This project was a finalist in the 2018 Mipim Awards, considered the ‘Oscars’ of world architecture, and stood out for its architecture and design, due to its attributes of innovation and sustainability (2).
This building has managed to create harmony between design and efficient use of resources. It is characterised by a glass façade with colourful movable shutters and symbolic Peruvian designs (2, 3, 6). It has green walls on the three main fronts, four daylight fronts and a roof garden (2). The architect, Jean Nouvel, worked together with ARVE Peru on the overall landscape plans for the Real Dos tower (1, 3).
This is part of the façade remodelling project of the Camino Real Towers in the Real Business Centre, led by the real estate company Grupo Centenario (1, 2, 3, 4, 5, 6). This overarching Project has sought to develop 4,475 m2 of vertical gardens and roof gardens, which have a technified irrigation system to generate efficiencies in water use, meeting the plants' water requirements in the different seasons of the year. Their implementation helps to filter CO2 and renew the O2 in the office complex.
The ARVE group describes these actions as conducive to creating thermal barriers and sound insulation, a better environment for rest, work and entertainment and increasing property value (7)

Tirana's urban development has set a new record in 2022, when more than 1.8 million square meters of new buildings were constructed (Ref. 5). This rapid development increased the need for accessible urban green areas. At the Tulla Urban Farm, a wide audience is trained to create those green areas in their yards, balconies and roofs with the added benefit of growing produce for their own needs (Ref. 1,2,5). This practice of food autonomy is deeply rooted in Albanian culture but has been lost in urban settings where concrete has taken over the city (Ref. 1). Tulla Urban Farm addresses this issue by providing an inclusive space for people of diverse backgrounds to come together and experience urban gardening first hand under the guidance of professionals from the Agricultural University of Tirana (Ref. 2,3). In these "urban agricultural schools", workshops, seminars and discussions are held to re-cultivate traditional agro-cultural practices and knowledge that will benefit the participants, many of which are from marginalised backgrounds (Ref. 1, 4). All these activities are facilitated through the rooftop greenhouse of the Tulla Cultural Center, which harbours over 300 plants (Ref.1). As such, Tulla Urban Farm not only provides a space for experiencing and learning about plants but also for social interaction and building a community that also addresses more serious issues such as mental health in a society that faces high rates of unemployment (Ref. 1).
The project had received inital funding from the German GIZ in 2022 and won the Cultures of Resistance Award through which it financed the first two years of its programme and enabled free participation at the urban agricultural school for all participants (Ref. 2,4).

Lima is the capital of the region with the lowest coverage of green spaces. According to the World Health Organisation (WHO), a city should have at least 9m2 of green space per inhabitant. Lima is just over 3m2 square metres, which means a deficit of almost 60 million square metres. In this context, actions from the public and private sectors are essential to add this type of space to the city. In response to this need, Grupo Centenario carried out a green project on one of its plots of land in San Isidro, where real estate projects will be developed (1, 2, 3, 4).
A square was built with a green area with wild and low-consumption species, knocking down the walls that surrounded the land for years, turning it into a place for everyone to see and use (1, 2, 3, 4). The Choquehuanca Square was built to contribute to the community and make it a better place to live. It is located on a plot of land that was previously enclosed by walls, converting it into an area of 3,945 m2 with a green space that occupies 70% of the square (1, 2, 3). This is a temporary project, as the green space was opened while projects are being developed on this land (1, 2, 3).

Masthuggsparken is a planned park in the Masthuggskajen district, which is undergoing development and construction. The park will measure about 2000 m2, and serve as a green oasis and meeting place for locals. It will have ameneties such as benches and areas for play, and a noise barrier against a large nearby road. The park will connect to the adjacent square and street, making it accessible to visit. The street will be renovated to have more trees and plants, increasing green connectivity in the district. The park will be surrounded by trees and other plants, which are planted to promote biodiversity and be adapted to a changing climate [Ref. 1-5, 7]. The park is at a low point, where up to 800 m3 of stormwater will flow during heavy rainfall, reducing flood risk in the surroundings [Ref. 1, 2, 6]. The Masthuggskajen district has a sustainability program, establishing goals for green environments which the park will contribute to. Green areas should be accessible to the entire district and provide ecosystem services such as rainwater management, climate adaptation, biodiversity and recreation. The program was created by the City of Gothenburg in collaboration with construction companies active in the area and was supported by Citylab Action, a national competence program in sustainable urban development [Ref. 7]. The City of Gothenburg is the primary responsible for the park, which will be constructed between 2025 and 2026 [Ref. 1, 2, 4].