Expected increased number of species present

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).

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)

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)

For thousands of years the Rio Salado, also known as the Salt River, and its larger mainstem, the Gila River, served as an important perennial source of life and growth for indigenous people residing in central Arizona, including the Akimel and Piipaash (3). Today, the Salt River is an ephemeral river corridor connecting diverse urban communities across an expansive and growing Maricopa County (3). While the river is now typically defined by intermittent flow as a function of water conservation and distribution in an arid urban climate, it also has powerful flows during the Arizona monsoon season providing a diverse and unique ecosystem for the region (3). To foster the health of the River, a regional multi-decade project was initiated in 2018 called Rio Reimagined, which includes six cities and two tribal communities (1). Rio Reimagined is a planning initiative in a very early concept stage, centered around the mission to support and enhance this treasured river corridor (3). The goals of Rio Reimagined consist of connecting communities, Equitable & Sustainable Development, and Restoring and Revitalizing Healthy Rivers (3). As part of the Rio Reimagined, the City of Phoenix founded a collaborative project called Rio PHX that will help promote a 20-mile Rio Salado (Salt River) corridor as a local and regional destination that attracts positive investment for the benefit of existing/future businesses, residents, and tourists (1). The final aim with this project is to improve health outcomes for existing and future residents by address outstanding needs in the area and create opportunities for housing, employment, recreation, art, and ecological restoration (1). From May 2024 to May 2025 Rio PHX will engage in creating a community profile, an existing conditions assessment, community engagement & visioning, developing implementation strategies and drafting the master plan (1). Public hearings and final plan adoption are set to take place in fall 2025 (1).

Booterstown Marsh, the only remaining saltmarsh on the south shore of Dublin Bay, plays a crucial role in the Dublin Bay Protection Plan. As part of South Dublin Bay's protected landscape, this unique 4.3-hectare brackish water marsh provides vital environmental and educational value within an urban setting. It supports three key habitats, ranging from freshwater to saltwater, creating essential feeding and roosting grounds for an array of migratory birds. The marsh attracts numerous bird species, including Moorhen, Reed Bunting, Sedge Warbler, Teal, Snipe, Lapwing, Oystercatcher, Redshank, Dunlin, and Brent Geese, establishing it as the only bird sanctuary in South Dublin Bay.
Booterstown Marsh’s ecological significance is underscored by its inclusion in the Dún Laoghaire-Rathdown County Council’s Biodiversity Action Plan 2021-2025: Nature Recovery, Restoration & Reconnection. Managed by the Biodiversity Section of the council, this initiative focuses on protecting and enhancing Booterstown Marsh as part of a broader effort to restore natural habitats across the area. The council’s project addresses key factors in biodiversity loss—such as land use pressures, climate change, and invasive species—by implementing an annual monitoring program to prevent deterioration of critical EU Annex habitats and species.
An Taisce, a local NGO has managed the marsh reserve since the 1970s, dedicating efforts to conservation and public education. This habitat, along with other local ecosystems like the wetlands at Ballycorus and woodlands at Loughlinstown, serves as an essential natural defense against climate change, removing carbon dioxide from the atmosphere and helping stabilize local landscapes by slowing floodwaters in catchment areas.(1-6)

The Bee Park Molentargius is a project located in the Molentargius-Saline Regional Natural Park, in Cagliari. It is part of a broader effort to regenerate abandoned and underutilised urban spaces, transforming them into areas that support biodiversity, promote sustainability, and engage the local community in environmental stewardship (3,4). The primary goal of the Bee Park Molentargius project is to restore specific areas of the Molentargius Park to their original ecological and productive functions. It aims to enhance biodiversity, support sustainable agricultural practices, and promote environmental education. The project includes the creation of shared gardens and an educational apiary, designed to reclaim the park’s identity and encourage local participation in the management and preservation of this important natural resource (1,3). It was developed with financial support from the Autonomous Region of Sardinia and the European Union's Horizon Europe Framework Programme. Inaugurated in March 2024, the project is a collaborative initiative involving local citizens, institutions, and park beneficiaries. It includes various educational components, such as beekeeping and olive growing training courses, along with sensory analysis workshops for honey and olive oil. These activities are intended to educate the public while fostering a sense of community ownership and responsibility toward the park​ (1,2). The project indirectly addresses environmental hazards related to the degradation of urban green spaces and loss of biodiversity. By restoring the park’s natural and productive functions, the Bee Park Molentargius helps mitigate risks associated with urbanisation, such as habitat loss and the decline of pollinator populations, which are crucial for maintaining ecological balance and food security​ (3)

This project involves collaboration among government, private, and educational entities focused on developing an agroforestry initiative that integrates economic activity, labor market integration, and educational opportunities for young children at the “Foyer de l’Espérance” [school and child welfare center] in Fort-de-France. The objective is to plant 1,500 cacao trees on the Foyer's premises by 2025. These trees will serve as pedagogical support for teachers and children. Planting activities commenced in 2022, and the first cacao pods are expected to mature in 2-3 years. Subsequently, these pods will be processed and transformed by the Martinican Lauzéa chocolate factory under the brand “Chocolat de l’Espérance” (Refs 2; 4).
The idea for this project emerged in June 2022 when young students engaged in a discussion about cocoa farming with Thierry Lauzéa during "Business Thursdays," organized by “Espérance Formation Insertion.” These meetings allow young beneficiaries to explore the business world and discuss their career paths with professionals. During one of these sessions, the young participants inquired about the origins of the cocoa used in Lauzéa's chocolates, leading to the concept of producing cocoa for the Frères Lauzéa company (Refs 3; 5).

The Gnomes Project was launched to breathe new life into the abandoned Dublin City University (DCU) Community Garden, transforming it into a thriving urban micro-farm. Led by three friends—Martin, Jason, and Shane, collectively known as "The Gnomes"—the initiative grows pesticide-free, organic produce for the local community while championing regenerative farming practices.
The Gnomes employ bio-intensive agriculture, a sustainable approach designed to maximize yield from small spaces while maintaining biodiversity and enriching soil health. This method supports long-term productivity by promoting crop diversity, improving soil quality, and reducing dependence on external inputs through a closed-loop system.
The project’s journey began in 2015 when Jason and Martin enrolled in DCU's horticulture program and saw potential in the overgrown community garden. Shane joined as a volunteer in 2016, and by 2017, the trio had formalized their efforts to revitalize the garden. In 2019, they registered their business and began growing over 30 types of crops, eventually selling their produce through local farmers’ markets and small businesses.
Working tirelessly to restore the garden, The Gnomes cleared debris and removed invasive weeds using organic methods, transforming the area into a productive micro-farm. After negotiating with the university, they secured a lease for a 10,900 sq.-ft. plot (approximately 1/4 acre), with access to water. This space became the foundation for their bio-intensive, small-scale farming model, enabling them to grow quick-yield, high-value crops that thrive in limited spaces.
Some of their 20+ crops include a variety of leafy greens, herbs, tomatoes, cucumbers, zucchinis, green beans, onions, carrots, beetroots, baby turnips, apples, and recently added microgreens.
The Gnomes Project demonstrates the potential of urban farming, combining sustainable agriculture with community engagement. (2-5, 7-10)

This project aims to increase water retention capacity in the landscape around urban areas and promote biodiversity by restoring wetlands and natural streams in the forested areas on the island of Hisingen in northern Gothenburg. Many wetlands and streams in the area have been drained or otherwise affected by human activity, reducing biodiversity, increasing the risk of floods and droughts and causing greenhouse gas emissions from peatland. The goals of the project are to reduce the risk of floods downstream, reduce the effects of dry periods, increase groundwater infiltration and benefit species living in and around wetlands and streams in the forest [Ref. 1-3]. The Swedish Anglers Association has initiated the project in cooperation with the City of Gothenburg and the environmental engineering company Miljöteknik I Väst AB [Ref 1]. The project's first stage is a continuation of an earlier project to make an inventory of wetlands and their status [Ref 1, 2]. For the second part, 6,9 ha of wetlands and streams on land owned by the city were restored [Ref. 1, 3]. The project will lead to further efforts in wetland restoration around Gothenburg [Ref. 2, 4].

The Fenkell Stormwater Project in the Brightmoor neighborhood of Detroit is an initiative led by the Detroit Water and Sewerage Department (DWSD) to mitigate the impact of heavy rain events on the local sewer system. By transforming 92 Detroit Land Bank Authority (DLBA) parcels into 24 bioretention gardens, the project aims to significantly reduce street flooding and basement backups in the area. These gardens, spread across approximately 50 acres of mostly vacant land, utilize permeable soils and landscaping techniques to absorb excess rainfall, which helps prevent the overloading of the city’s combined sewer system. This is particularly important in reducing combined sewer overflows (CSOs), which occur when the system's capacity is exceeded during heavy rains, leading to untreated stormwater and sewage being discharged into the Rouge River.
The project is expected to manage and treat about nine million gallons of stormwater annually, making a significant impact on both the neighborhood’s infrastructure and the environment. In addition to the bioretention gardens, the project includes the partial removal of Blackstone Street between Keeler and Midland streets to further enhance stormwater management.
Community engagement has been a critical component of the project, with residents of Brightmoor and Minock Park participating in meetings to share their preferences for the types of trees, plantings, and other features. The DWSD will maintain the gardens under its Green Stormwater Infrastructure (GSI) program, which already includes 19 other similar projects across the city. The project is currently in the construction phase and is expected to be completed by the end of 2024, modernizing Brightmoor’s stormwater infrastructure and providing long-term environmental and community benefits.
(Ref.1-3)