Mobile Tree Trial
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).
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).
Liberties Greening Strategy
The Liberties is one of the most recognizable urban areas in Dublin and Ireland, strongly associated with old Dublin, working-class communities, and the brewing and distilling industries. While rich in history, cultural significance, and local stories, The Liberties faces numerous placemaking and quality-of-life challenges. The area continues to experience significant dereliction, a fragmented urban fabric, and a shortage of high-quality green spaces. For instance, tree coverage in The Liberties is sparse, with good-quality street trees only found in a few small areas, such as Gray St. and Reginald St., along the South Quays, Cornmarket, and near the fountain on James St. The area has approximately 1,200 trees, amounting to less than 5% canopy coverage.
In response to these challenges, Dublin City Council enacted The Liberties Greening Strategy in 2015. Building on the Liberties' Local Area Plan, this strategy aims to develop a network of new urban parks, improve access to heritage green spaces, and refurbish existing parks and play areas. It addresses multiple goals, including ecological connectivity, water management, flood risk reduction, air quality improvement, social cohesion, environmental education, and public health. This strategy is an initiative of the Parks and Landscape Services Division of Dublin City Council, in collaboration with the South Central Area Office and with input from Áit Urbanism + Landscape and Mary Tubridy & Associates.
Since its implementation in 2015, the strategy has resulted in the development of two new community parks, enhancements to several green spaces, and the greening of public spaces. It has also introduced measures to support food production in community gardens and allotments, revitalize ecosystems, strengthen water management, improve air quality, boost carbon sequestration through tree planting, divert water from the local sewer network, prevent flooding, and regulate heat. (1, 2, 3)
In response to these challenges, Dublin City Council enacted The Liberties Greening Strategy in 2015. Building on the Liberties' Local Area Plan, this strategy aims to develop a network of new urban parks, improve access to heritage green spaces, and refurbish existing parks and play areas. It addresses multiple goals, including ecological connectivity, water management, flood risk reduction, air quality improvement, social cohesion, environmental education, and public health. This strategy is an initiative of the Parks and Landscape Services Division of Dublin City Council, in collaboration with the South Central Area Office and with input from Áit Urbanism + Landscape and Mary Tubridy & Associates.
Since its implementation in 2015, the strategy has resulted in the development of two new community parks, enhancements to several green spaces, and the greening of public spaces. It has also introduced measures to support food production in community gardens and allotments, revitalize ecosystems, strengthen water management, improve air quality, boost carbon sequestration through tree planting, divert water from the local sewer network, prevent flooding, and regulate heat. (1, 2, 3)
Treetroit
Over the past century, vast portions of the world’s oldest forests have been lost to clear-cutting and managed forestry (1). Arboretum Detroit is working to counter this trend by reforesting Detroit’s urban landscape, transforming abandoned city blocks into thriving groves of trees (1). Each parcel of land features trees that showcase the unique contours and characteristics of specific species, creating a diverse urban forest mosaic across the city (1). These "forest patches" are protected, designed to mature safely for generations, offering a space of tranquility and natural beauty for all Detroiters (1).
Arboretum Detroit’s main goal is to cultivate environmental consciousness, inspiring the community to consider our interconnectedness with nature and our impact on it (1). Through their reforestation mission, they demonstrate the ecological, cultural, aesthetic, and economic value of trees, both locally and globally (1). Trees alter our environment by using their leaves to filter the air we breathe by removing dust and other particles. Deciduous shade trees cool homes in the summer and allow the winter sun to heat homes when they lose their leaves. Trees can serve as a windbreak. The more compact the foliage on the group of trees the more effective the windbreak. Their pilot project, launched on Earth Day 2019, brought these values to life. Volunteers and members planted 21 trees across the site, including species like Princeton Sentry Ginkgo, Redpoint Red Maple, Paper Birch, Cedar, Yew, and understory trees like Kousa Dogwood and Forest Pansy Redbud, enhancing the habitat for local pollinators and birds (2). The trees were arranged in trios, interspersed with native seeds, soil, compost, and glacial boulders to create a healthy and engaging environment for all (2).
Arboretum Detroit’s main goal is to cultivate environmental consciousness, inspiring the community to consider our interconnectedness with nature and our impact on it (1). Through their reforestation mission, they demonstrate the ecological, cultural, aesthetic, and economic value of trees, both locally and globally (1). Trees alter our environment by using their leaves to filter the air we breathe by removing dust and other particles. Deciduous shade trees cool homes in the summer and allow the winter sun to heat homes when they lose their leaves. Trees can serve as a windbreak. The more compact the foliage on the group of trees the more effective the windbreak. Their pilot project, launched on Earth Day 2019, brought these values to life. Volunteers and members planted 21 trees across the site, including species like Princeton Sentry Ginkgo, Redpoint Red Maple, Paper Birch, Cedar, Yew, and understory trees like Kousa Dogwood and Forest Pansy Redbud, enhancing the habitat for local pollinators and birds (2). The trees were arranged in trios, interspersed with native seeds, soil, compost, and glacial boulders to create a healthy and engaging environment for all (2).
Greening Colombo
The financial capital of Sri Lanka, Colombo, is the fastest-growing city in Sri Lanka, and as such, it is constantly changing. Most expansions in urban areas are taking place without proper planning, which can cause damage to existing pockets of forests, landscapes and green areas in and around the city (1). The environmental impacts of this rapid urbanisation include increased pollution, increased heat due to the expansion of roads/pavements, tall structures that block out light and wind and reduced biodiversity in fauna and flora (1).
To face these challenges, the Federation of Environmental Organisations (FEO) proposed a city-wide Tree Planting Campaign to create an Urban Forest Strategy in public and private lands in the greater Colombo area (1). The plan is to kick-start the program at the Borella Cemetery as it has a large land area available for planting, specifically 178062 sq meters (3). The project started to be implemented in July 2020 with the seasonal rains (1). This project aims to grow urban trees to help mitigate some of the negative impacts of unplanned and rapid urbanisation, thus making the city more resilient to these changes (1).
The trees that will be planted will be mostly native species and also exotic plants will be selected based on specific requirements (1, 3). It is also planned to have flowering plants and shrubs to encourage butterflies, bees and birds to interspace the trees (1). The new parking space near the Borella Cemetery will also be planted with deep root shading trees interspaced with flowering plants (1).
The project aimed to include a large number of stakeholders including the government, the private sector and the residents of Colombo (1). And they have also reached schools in Colombo and hope to involve environmental associations to further the cause (3).
To face these challenges, the Federation of Environmental Organisations (FEO) proposed a city-wide Tree Planting Campaign to create an Urban Forest Strategy in public and private lands in the greater Colombo area (1). The plan is to kick-start the program at the Borella Cemetery as it has a large land area available for planting, specifically 178062 sq meters (3). The project started to be implemented in July 2020 with the seasonal rains (1). This project aims to grow urban trees to help mitigate some of the negative impacts of unplanned and rapid urbanisation, thus making the city more resilient to these changes (1).
The trees that will be planted will be mostly native species and also exotic plants will be selected based on specific requirements (1, 3). It is also planned to have flowering plants and shrubs to encourage butterflies, bees and birds to interspace the trees (1). The new parking space near the Borella Cemetery will also be planted with deep root shading trees interspaced with flowering plants (1).
The project aimed to include a large number of stakeholders including the government, the private sector and the residents of Colombo (1). And they have also reached schools in Colombo and hope to involve environmental associations to further the cause (3).
Renatura pilot: Fast Forests for Lisbon
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)
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)
Gothatuwa Wetland Park
Sri Lanka, particularly its low-lying coastal areas, faces recurring flooding challenges exacerbated by climate change, coastal erosion, and urbanization (1). Wetlands have emerged as crucial ecosystems in mitigating these risks, acting as natural sponges during heavy rainfall and releasing water gradually as flood levels subside (1). Beyond flood control, wetlands play a vital role in environmental quality. Their biodiversity helps filter pollutants and chemicals from the air and water, creating a healthier environment for both humans and wildlife (1). In 2018, Colombo was designated as a Global Wetland City under the Ramsar Convention, becoming the first and only capital city to receive this recognition (1). Recognizing the significance of wetlands as nature-based solutions, international institutions have prioritized their conservation through financing programs (1), and the city has developed projects to raise awareness and involve its citizens in their protection (1). These efforts have resulted in the creation of four wetland parks in the city, that comparing to a wetland, the wetland parks have more human intervention. Thus, they are focused on different topics and activities (2): Diyasaru Park, Beddagana Wetland Park (managed by the Urban Development Authority), Kotte Rampart Wetland Park (managed by the Urban Development Authority), and the Gothatuwa Wetland Park (managed by the Sri Lanka Land Development Corporation) (2). Gothatuwa Park is the newest wetland park and it is located in the flood-prone Gothatuwa neighbourhood (1). Inaugurated in 2024, It has a recreational focus, with trails for cyclists and hikers, and together with the other wetland complex, this park is designed to make the wetlands a cornerstone of local people's lives (1). Currently, environmental education activities are carried out in the park, focusing on managing aquatic invasive plants, tree planting and solid waste collection (3).
University of Cagliari's Green Roof
The project focused on implementing multilayer blue-green roofs in four Italian cities—Cagliari, Palermo, Perugia, and Viterbo—as part of a broader European initiative to address climate change impacts in urban environments (1,3). Spearheaded by a collaboration between multiple Italian universities and the Dutch company Metropolder, the project began in 2019 (1,3). The primary goal is to enhance urban resilience by integrating green infrastructure capable of mitigating climate-related urban hazards such as flooding and heat waves, which are increasingly severe due to climate change and urbanisation (2,3).
The multilayer blue-green roofs combine the ecological benefits of traditional green roofs with an added water storage layer, allowing them to retain rainfall and manage runoff effectively (2,3). This dual function helps reduce pluvial flooding and the urban heat island effect, while also improving thermal insulation in buildings (2,3). Each installation was planted with low-maintenance, climate-adapted vegetation, and equipped with sensors to monitor ecohydrological and thermal performance over several years (1,3). These roofs are capable of retaining up to 100% of rainfall from significant events, thereby easing the burden on urban drainage systems and contributing to climate adaptation in Mediterranean cities (2,4).
The multilayer blue-green roofs combine the ecological benefits of traditional green roofs with an added water storage layer, allowing them to retain rainfall and manage runoff effectively (2,3). This dual function helps reduce pluvial flooding and the urban heat island effect, while also improving thermal insulation in buildings (2,3). Each installation was planted with low-maintenance, climate-adapted vegetation, and equipped with sensors to monitor ecohydrological and thermal performance over several years (1,3). These roofs are capable of retaining up to 100% of rainfall from significant events, thereby easing the burden on urban drainage systems and contributing to climate adaptation in Mediterranean cities (2,4).
Iasi More Green
In 2022 an afforestation initiative was implemented near a landfill located in the Tutora commune (1 - 6). Organized by the City Hall of Tutora, the event brought together representatives from the regional government of Iasi County, the "Asociația de Dezvoltare Intercomunitară pentru Salubritate" (ADIS), and volunteers from SC Girexim SA, SC Salubris Iasi, and Edil Industri Iasi. Together, they planted 2,000 acacia saplings, donated by the Forestry Directorate of Iasi (6). The afforestation action took place under the umbrella of the regional environmental campaign "Iasi Mai Verde" (Iasi More Green), led by the County Council of Iasi. This campaign promotes a range of eco-friendly activities, including educational programs in schools, waste cleanup events, and afforestation initiatives in partnership with ADIS, while actively encouraging the support and participation of local municipalities from across the region (1, 3, & 7).
"Iasi Mai Verde" aligns with national environmental strategies such as the Ministry of the Environment's "Curățăm România" (Let's Clean Romania) and the annual Planting Forest Month (3 & 6).
On the same day, as part of the Iasi Mai Verde initiative, students from a local school in Tutora were given a practical education workshop on how waste management operates at the regional level. The students were also invited to witness the afforestation action and participate, fostering a deeper understanding of environmental stewardship (1- 5).
The newly planted trees are acting as a natural barrier, and help improve air quality by filtering dust, pollution, and waste particles originating from the nearby Tutora landfill. In turn, this contributes to better living conditions for the residents in close proximity to the landfill, enhancing both their health and overall quality of life (5).
"Iasi Mai Verde" aligns with national environmental strategies such as the Ministry of the Environment's "Curățăm România" (Let's Clean Romania) and the annual Planting Forest Month (3 & 6).
On the same day, as part of the Iasi Mai Verde initiative, students from a local school in Tutora were given a practical education workshop on how waste management operates at the regional level. The students were also invited to witness the afforestation action and participate, fostering a deeper understanding of environmental stewardship (1- 5).
The newly planted trees are acting as a natural barrier, and help improve air quality by filtering dust, pollution, and waste particles originating from the nearby Tutora landfill. In turn, this contributes to better living conditions for the residents in close proximity to the landfill, enhancing both their health and overall quality of life (5).
Canal restoration in Cagliari
The Cagliari Canal project is an initiative aimed at revitalizing and transforming the urban and natural landscape of the Cagliari Metropolitan Area in Sardinia. The project is rooted in the city's strategic metropolitan plan and seeks to restore and enhance the navigability of the Terramaini-La Palma canal, which had become disused and neglected over time (3,4). The primary goal of the Cagliari Canal project is to develop a connected, innovative, and sustainable urban environment by re-establishing the canal as a green and blue infrastructure (2). It aims to provide alternative, sustainable mobility options, improve connectivity between municipalities, and enhance the natural and urban environments. It strives to foster a sense of community by creating a shared space for residents and integrating modern amenities that align with environmental sustainability (1,4). It involved a highly participatory process, emphasizing community involvement from the initial planning stages. The Metropolitan Authority of Cagliari, in collaboration with local stakeholders, launched a series of consultations to gather public input on the canal's design and function(3). These consultations were part of a broader initiative called LabMet, the Metropolitan Laboratory for Innovation, which facilitated the collection of ideas and feedback (1). The project was partly developed in response to the increasing environmental challenges faced by Cagliari, including the need to adapt to climate change. The canal's revitalization is seen as a key measure for enhancing the city's resilience to climate-related risks, such as flooding and heat waves(1). By restoring the canal and its surrounding areas, the project aims to mitigate these risks through improved water management, reducing pollution, and the creation of green spaces that can absorb excess rainwater and provide cooling effects (2)
Greening of Berlin's historic heart
Located between the Rotes Rathaus, Karl-Liebknecht-Straße, Nikolai Quarter, Spreeufer and the television tower, the old founding centre of Berlin is one of the capital's most important urban open spaces. This open space between the TV tower and the Spree is being redesigned on the basis of an international open space planning competition and many years of public participation. With further development, this touristically significant location in the historic centre of Berlin will undergo a climate-resilient redesign and upgrade with great design and functional quality. (Ref. 1)
The listed areas of the Rathausforum and the Marx-Engels-Forum will in future be connected to form a continuous ribbon of open space that runs from Alexanderplatz to the Spree. Central areas will be unsealed and green spaces will be created that can be used in a variety of ways, which will also be attractive places to spend time and improve the microclimate. Trees and shrubs will be planted on already existing and new green areas. The aim is to respectfully consider the numerous visible and hidden historical references and at the same time transform the site into a sustainable urban open space that combines a high quality of recreation, sustainability and culture. Next to plants, a new rainwater management system is being implemented that stores rainwater and uses the created green spaces to evaporate water. Playgrounds and a water fountain are further additions to a new recreational area. (Ref. 3; Ref. 4; Ref. 5)
The project is characterized by a years-long participation process. Around 10.000 citizens participated in feedback rounds, workshops, dialogues, and information sessions in which they could voice they wishes and ideas for the area. The project is implemented and organized by the state-owned company Grün Berlin, which engage with various stakeholders since 2015. Preparations for the construction start in late 2024 and the project is expected to be finished in 2030. (Ref. 5; Ref. 9)
The listed areas of the Rathausforum and the Marx-Engels-Forum will in future be connected to form a continuous ribbon of open space that runs from Alexanderplatz to the Spree. Central areas will be unsealed and green spaces will be created that can be used in a variety of ways, which will also be attractive places to spend time and improve the microclimate. Trees and shrubs will be planted on already existing and new green areas. The aim is to respectfully consider the numerous visible and hidden historical references and at the same time transform the site into a sustainable urban open space that combines a high quality of recreation, sustainability and culture. Next to plants, a new rainwater management system is being implemented that stores rainwater and uses the created green spaces to evaporate water. Playgrounds and a water fountain are further additions to a new recreational area. (Ref. 3; Ref. 4; Ref. 5)
The project is characterized by a years-long participation process. Around 10.000 citizens participated in feedback rounds, workshops, dialogues, and information sessions in which they could voice they wishes and ideas for the area. The project is implemented and organized by the state-owned company Grün Berlin, which engage with various stakeholders since 2015. Preparations for the construction start in late 2024 and the project is expected to be finished in 2030. (Ref. 5; Ref. 9)
