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).
Mini Woodlands in South Dublin
The likely impacts of climate change in South Dublin County include an increased risk of flooding, more frequent summer droughts, deteriorating air and water quality, and biodiversity loss (1). To address these climate challenges, the county developed the County Development Plan 2016-2022 as part of the South Dublin Climate Action Plan, aiming to establish a comprehensive legislative and policy framework for green infrastructure (GI) planning (1).
The plan outlines various objectives, including creating a coherent, integrated, and adaptable GI network across South Dublin County. One key initiative is the establishment of native mini woodlands throughout the city, designed to form strategic links and integrate the GI Strategy’s objectives into all relevant land-use plans and development across the county (1).
The purpose of these mini woodlands is to connect green spaces across the city (minimum size of 100 sq m), sequester carbon, and promote biodiversity in suitable locations, such as built-up areas, low-grade parkland, and other zoned areas deemed appropriate (1). Given the long time required for tree growth, the project employs the Miyawaki method, planting a high density of diverse native species to create mature forests up to ten times faster than traditional plantations (2). These forests are estimated to host 20 to 100 times more biodiversity and absorb carbon up to 40 times more effectively, without the use of chemicals or fertilizers; key factors include ground preparation, planting density, and species diversity (2).
In 2022, the project held a planting day for the mini woodlands initiative on Mill Lane, where 1,200 native trees and shrubs were planted with the help of volunteers from local schools, the community, a corporate group, and the Mayor of South Dublin, Councillor Emma Murphy (2).
The plan outlines various objectives, including creating a coherent, integrated, and adaptable GI network across South Dublin County. One key initiative is the establishment of native mini woodlands throughout the city, designed to form strategic links and integrate the GI Strategy’s objectives into all relevant land-use plans and development across the county (1).
The purpose of these mini woodlands is to connect green spaces across the city (minimum size of 100 sq m), sequester carbon, and promote biodiversity in suitable locations, such as built-up areas, low-grade parkland, and other zoned areas deemed appropriate (1). Given the long time required for tree growth, the project employs the Miyawaki method, planting a high density of diverse native species to create mature forests up to ten times faster than traditional plantations (2). These forests are estimated to host 20 to 100 times more biodiversity and absorb carbon up to 40 times more effectively, without the use of chemicals or fertilizers; key factors include ground preparation, planting density, and species diversity (2).
In 2022, the project held a planting day for the mini woodlands initiative on Mill Lane, where 1,200 native trees and shrubs were planted with the help of volunteers from local schools, the community, a corporate group, and the Mayor of South Dublin, Councillor Emma Murphy (2).
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)
Nairobi River Basin Programme (NRBP)
Rapid urbanization and a population density of 6,247 people per km² have placed significant stress on Nairobi's natural resources (Ref 1). The 40-km long Nairobi River Basin, originating from the Ondiri Swamp, serves as a vital water source for the city (Ref 1, 2). However, it has suffered severe pollution from untreated sewage, solid waste, industrial contaminants, plastics, and agricultural runoff (Ref 1, 3). This degradation has had a serious impact on the ecosystem, local residents, and biodiversity (Ref 3).
To address these issues, the Nairobi River Basin Programme (NRBP), sponsored by UNEP, was launched in 1999 (Ref 4). Since then, government and non-state actors have worked together on solid waste management, riparian restoration, and wastewater control (Ref 1). The program was implemented in two phases: Phase I (2003–2006) and Phase II (2006–2009), involving stakeholders from the government, private sector, and civil society (Ref 1, 4, 5). Despite these efforts, a study from 2017 found significant tree removal along the river, and between 1988 and 2014, encroachment into the 30-meter riparian buffer zone dramatically increased, particularly between 2010 and 2014, further degrading the river’s health (Ref 1).
To address these issues, the Nairobi River Basin Programme (NRBP), sponsored by UNEP, was launched in 1999 (Ref 4). Since then, government and non-state actors have worked together on solid waste management, riparian restoration, and wastewater control (Ref 1). The program was implemented in two phases: Phase I (2003–2006) and Phase II (2006–2009), involving stakeholders from the government, private sector, and civil society (Ref 1, 4, 5). Despite these efforts, a study from 2017 found significant tree removal along the river, and between 1988 and 2014, encroachment into the 30-meter riparian buffer zone dramatically increased, particularly between 2010 and 2014, further degrading the river’s health (Ref 1).
Rimac River Landscape Project
The Rimac River Special Landscape Project, developed by the Municipal Programme for the Recovery of the Historic Centre of Lima (PROLIMA), is a municipal proposal that arose as a response to the significant degradation of the Rimac River as it passes through the historic centre of the Peruvian capital. The river has lost its character as a green corridor and potential public recreational space for citizens (1, 3). The main problems affecting the river are related to the erosion and risk of flooding of the river space, the ecological degradation of its channels and banks, the disconnection and low quality of adjacent public spaces and the urban fragmentation caused by car-oriented mobility (2). To recover its essence as an ecological green corridor, it was proposed to give back to the Historical Centre its riverside identity and to recover the water, environmental and scenic landscape. This project aims to restore the Rímac to its role as a geographical heritage and backbone of the city of Lima, creating a system of accessible and sustainable public spaces that will help to recover this water, urban and historical landscape, as well as providing a better quality of life for the residents and users of the Historical Centre (1).
The project consists of 4 stages of intervention: Puente del Ejército - Puente Santa Rosa / Puente Santa Rosa - Puente Balta / Puente Balta - Límite
of the CHL to the east (5). Among the interventions that make up the Special River Landscape Project are: the renaturation of the 4 km of the Rimac River as it passes through the city, the construction of 14 parks, 7 squares, 1 tree planting project, 24 street renovation projects, 7 bridges/pedestrian walkways, 10 building rehabilitations and 2 new public facilities (4). It is planned to start implementing the project by the end of 2024 (4).
The project consists of 4 stages of intervention: Puente del Ejército - Puente Santa Rosa / Puente Santa Rosa - Puente Balta / Puente Balta - Límite
of the CHL to the east (5). Among the interventions that make up the Special River Landscape Project are: the renaturation of the 4 km of the Rimac River as it passes through the city, the construction of 14 parks, 7 squares, 1 tree planting project, 24 street renovation projects, 7 bridges/pedestrian walkways, 10 building rehabilitations and 2 new public facilities (4). It is planned to start implementing the project by the end of 2024 (4).
Green Blue Axis of Sintra, Oeiras and Amadora
The Green and Blue Axis (Eixo Verde e Azul, EVA) is an inter-municipal green corridor project connecting the municipalities of Sintra, Oeiras, and Amadora through a 15-kilometre green ecological axis along the Jamor River (Ref 2). It aims to renaturalize the river, improve water quality, and control flooding while promoting sustainable mobility through pedestrian and cycling routes (Ref 5). The project also enhances public access to green spaces and cultural heritage sites, such as the Queluz National Palace (Ref 6). EVA supports the Lisbon Metropolitan Area’s regional strategy for climate change adaptation, risk prevention, and low-carbon economy (Ref 4). Funded by the European Regional Development Fund and municipal budgets, the project has an overall investment of €11 million (Ref 1). EVA exemplifies inter-municipal cooperation, overcoming policy conflicts to achieve shared environmental, social, and economic goals, making it a model for integrated territorial development (Ref 4). The project’s long-term impact includes reduced carbon footprint and increased territorial cohesion.
The Green Rush
The project La Ruée Verte aims to create a green corridor connecting two emblematic locations for social and environmental justice: La Base Marseille and L’Après M. The route spans over 7 km and passes through La Friche de La Belle de Mai and aims to bring more nature into the city on a larger scale in a fair and equitable way (Ref 2).
Given the challenges of climate change—rising temperatures, urban heat islands, fewer trees in Marseille, and increasing urbanization—the green corridor will offer a solution to combat the suffocating effects of the city’s concrete sprawl (Ref 2). Additionally, it aims to reduce pollution peaks and improve air quality (Ref 2), increase biodiversity (Ref 2), and provide access to green spaces and places for social interaction (Ref 2).
The project also addresses the broader social crisis, with rising costs of food, housing, and transportation (Ref 2). Local solidarity is key, ensuring that all green initiatives foster community interaction and consider the urgent needs of residents, such as precarious living conditions and isolation (Ref 2). Collective participation is central to the project, ensuring that it is designed by and for residents of different neighborhoods, reflecting their realities. The project, called “La Ruée Verte,” aims to unite various citizen groups, social centers, and associations to amplify their voices (Ref 2).
The project's first phase, “La Petite Ruée,” will launch in October 2024, following a year of preparation. It will start with neighbourhood micro-projects and shared advocacy, including events and gatherings (Ref 2). The goal is to collectively think about social and climate justice and begin taking concrete actions towards popular ecology in each neighbourhood (Ref 2).
Given the challenges of climate change—rising temperatures, urban heat islands, fewer trees in Marseille, and increasing urbanization—the green corridor will offer a solution to combat the suffocating effects of the city’s concrete sprawl (Ref 2). Additionally, it aims to reduce pollution peaks and improve air quality (Ref 2), increase biodiversity (Ref 2), and provide access to green spaces and places for social interaction (Ref 2).
The project also addresses the broader social crisis, with rising costs of food, housing, and transportation (Ref 2). Local solidarity is key, ensuring that all green initiatives foster community interaction and consider the urgent needs of residents, such as precarious living conditions and isolation (Ref 2). Collective participation is central to the project, ensuring that it is designed by and for residents of different neighborhoods, reflecting their realities. The project, called “La Ruée Verte,” aims to unite various citizen groups, social centers, and associations to amplify their voices (Ref 2).
The project's first phase, “La Petite Ruée,” will launch in October 2024, following a year of preparation. It will start with neighbourhood micro-projects and shared advocacy, including events and gatherings (Ref 2). The goal is to collectively think about social and climate justice and begin taking concrete actions towards popular ecology in each neighbourhood (Ref 2).
"Rain garden" along the October 28th street in Thessaloniki
The 28th of October Street (28ης Οκτωβρίου) was one of the most neglected streets on the eastern side of Thessaloniki, completely devoid of trees despite its central importance. Additionally, the street suffered from severe flooding during heavy rainfall. In 2011, the Municipality of Thessaloniki, in collaboration with Konstantinos Zervas, the Deputy Mayor for the Environment, Quality of Life, and Free Space, proposed a redevelopment project aimed at transforming the street through the planting of trees and the installation of flower beds that would function as rain gardens (Refs 3, 5). This initiative was part of the "Integrated Green Cities" action, which falls under the European territorial cooperation program Greece-Bulgaria 2007-2013 (Refs 1, 2, 3, 6).
To achieve the dual goals of sustainable rainwater management and urban beautification, decorative trees were planted in specially constructed bioretention tree stands. These stands, along with the flower beds, were designed to collect rainwater, which would then be used to irrigate the trees along the road and the plants forming the rain gardens. Rainwater was gathered from the road surface, pavements, and the gutters of apartment buildings through these bioretention systems (Refs 1, 2). This sustainable water management solution significantly reduced rainwater runoff, improved water quality, and enhanced the area’s aesthetic appeal (Refs 2, 6, 7).
To achieve the dual goals of sustainable rainwater management and urban beautification, decorative trees were planted in specially constructed bioretention tree stands. These stands, along with the flower beds, were designed to collect rainwater, which would then be used to irrigate the trees along the road and the plants forming the rain gardens. Rainwater was gathered from the road surface, pavements, and the gutters of apartment buildings through these bioretention systems (Refs 1, 2). This sustainable water management solution significantly reduced rainwater runoff, improved water quality, and enhanced the area’s aesthetic appeal (Refs 2, 6, 7).
Revitalizing the Huveaune river and its biodiversity
The project to revitalize the Huveaune River and its biodiversity is taking place in Aubagne, a city within the Marseille Metropolitan area. For a long time, the river received little attention, constrained by urbanization, and was even covered for several hundred meters. Urbanization and the construction of a road have made the floodplain more susceptible to flooding (Ref 2). The initiative aims not only to restore the Huveaune and its environment but also to strengthen the connection between residents and the river (Ref 1) while reducing flood risk as a critical objective (Ref 1).
The challenge is transforming the area into a higher-quality environmental space with resilient ecosystems. A diagnostic conducted during the project's design phase revealed the site's degraded state, including the presence of invasive species, steep banks unsuitable for riparian vegetation, poor waterway conservation, and disrupted ecological continuity (Ref 2).
Key actions include revitalizing the river and its biodiversity, removing artificial banks, and creating new meanders to give the river a more natural shape. Diversifying flow patterns will create habitats for aquatic and fish species by varying water heights and flow speeds. This involves increasing the river's sinuosity and varying the width of the minor riverbed (Ref 2). Additional steps include planting trees and shrubs adapted to the Mediterranean climate with low water needs (Ref 2). To bring residents closer to the river, plans include creating walking and cycling routes, sports equipment, educational panels, and useful visitor facilities such as benches, water points, and restrooms (Ref 3).
The challenge is transforming the area into a higher-quality environmental space with resilient ecosystems. A diagnostic conducted during the project's design phase revealed the site's degraded state, including the presence of invasive species, steep banks unsuitable for riparian vegetation, poor waterway conservation, and disrupted ecological continuity (Ref 2).
Key actions include revitalizing the river and its biodiversity, removing artificial banks, and creating new meanders to give the river a more natural shape. Diversifying flow patterns will create habitats for aquatic and fish species by varying water heights and flow speeds. This involves increasing the river's sinuosity and varying the width of the minor riverbed (Ref 2). Additional steps include planting trees and shrubs adapted to the Mediterranean climate with low water needs (Ref 2). To bring residents closer to the river, plans include creating walking and cycling routes, sports equipment, educational panels, and useful visitor facilities such as benches, water points, and restrooms (Ref 3).
Restoration of the green area on Lago Avenue
The Recovery of Green Area on Avenida del Lago is a group of activities aimed at restoring and preserving the ecological integrity of green space within an urban setting. This project involves multiple stakeholders, including the "Establecimiento Público Ambiental" (EPA) Cartagena, "Fundación Verde Que Te Quiero Verde", Asopopa, and local businesses such as Crepes and Wafles and Centro Comercial Caribe Plaza. The primary focus is environmental restoration, sustainable urban mobility, and public space recovery (ref 1). The project aims to rehabilitate the degraded green spaces along Lago Avenue by enhancing urban greenery, restoring mangrove ecosystems, and improving public access and mobility. It also focuses on reducing pollution, preventing informal waste disposal, and raising environmental awareness among local communities and businesses. These activities align with broader efforts to promote ecological sustainability and enhance urban resilience (ref 1, 3). Since 2020, activities have included the planting of trees, mangroves, and other native vegetation in the green spaces of the avenue. Regular clean-up campaigns have been organized to remove solid waste, and community education programs have been conducted to promote environmental stewardship (ref 2). Previously, Lago Avenue was an area plagued by pollution and homelessness, and with the project, the intention is to gradually transform the area into a wooded area or productive park (ref 2).
