Increased number of species present

Established in 1996, the United Nations Office at Nairobi (UNON) is the UN's official headquarters in Africa, located just 9.7 km from the heart of Nairobi. In line with the UN's global sustainability goals, the office took significant steps to reduce its environmental footprint as it expanded. According to the United Nations Environment Programme (UNEP), buildings contribute to a third of global energy use and are major sources of greenhouse gas emissions. To address these issues, new buildings were designed to prioritize energy and water efficiency, with a focus on sustainability.
Completed in 2011, the new headquarters reflect the UN's broader commitment to reducing greenhouse gas emissions. The design includes 6,000 m² of solar panels, rainwater harvesting systems, energy-efficient lighting, and natural ventilation, making the complex energy-neutral and water-efficient. It generates as much solar energy as it consumes, supporting over 1,200 staff members. Additionally, the project carefully preserved indigenous trees and created micro-ecosystems within the interior gardens, further aligning with the UN’s environmental mission.
By embedding these green features, the UNON complex serves as a model for sustainable development in urban settings, echoing the UN’s efforts to combat climate change and promote ecological resilience globally. (Ref. 1, 2, 3, 4)

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).

The project ‘Planting the Future and Cultivating Life’ aims to create an ecological corridor in the city by reforesting an area of 28 hectares, under the direction of the Porto Velho City Council. It encourages citizen participation in tree planting activities or the management of green areas. To this end, the municipality is carrying out tree planting programmes in parks, squares and along public roads, encouraging citizens to get involved in this endeavour by actively participating in tree planting actions, caring for trees already on their property or raising awareness of the importance of these actions. (1) They seek to involve organisations such as schools, colleges, companies, associations and public organisations to increase the community's and young people's interest in responsible practices and positive attitudes to value and preserve the environment (1).
To achieve this goal, the Porto Velho city council organised a tree-planting day on October 23rd 2023, where 31,000 tree seedlings of native and fruit trees were planted in the Park Passarela Espaço Alternativo (1, 7). This was done with the support of the Municipal Secretariat of Environment and Development (1). This activity is part of the project Virada Ambiental, which seeks to promote the planting of native trees in municipalities across the country, raising awareness of the importance of planting native species and training municipal civil servants and the general public (3, 5). The National Confederation of Municipalities also supports this project and aims to mobilise society to encourage the planting of native trees to rescue biodiversity and recover environmental services, favouring social welfare by promoting tourism, and outdoor sports activities (6), providing shade, protecting the soil and combating high temperatures (2).

In Sjöhåla, west of Kungälv, an abandoned pasture on a wet meadow by the coast was restored by reintroducing grazing, clearing bushes and reeds, digging ponds and renovating stone walls. The aim was to increase biodiversity in the area and to promote the production of local organic meat. Additionally, the project made it easier for visitors to pass through the area for recreational purposes. The project was carried out by the municipality of Kungälv and the non-profit organisation Omställning Kungälv, and involved other local associations, farmers and citizens. It was funded through the "Local nature conservation investment" by the Swedish Environmental Protection Agency. As a result of the project, the area is more accessible, and many species of plants, insects, and birds have been found. [Ref. 1-3]

The John Michuki Memorial Park was transformed from a vast dumpsite in 2008 and established in honor of John Michuki, the Environment Minister during the Kibaki administration, in 2012. Michuki garnered admiration and accolades for his enthusiasm and determination to clean and preserve the environment (Ref 1, 2). Situated along the Nairobi River, the park serves as a historically rich recreational facility (Ref 3).
However, several issues arose after the park was transferred to the county administration in 2013 (Ref 2). A section of the Nairobi River flowing through the park experienced severe environmental degradation due to illegal discharges and poor waste management, negatively impacting the riparian ecosystem and biodiversity (Ref 4). Additionally, the park became a refuge for drug users, street children, and thieves, with stray dogs posing safety threats in the area (Ref 1, 2).
As the first project within the Cleaning Up Kenya Campaign, the restoration of Michuki Memorial Park was launched in 2020 by the government (Ref 5). The park is now managed by the Kenya Forest Service (KFS) following a directive from the national government (ibid.). With funds from the treasury, a perimeter fence was erected, a 2.4 km walkway was constructed, and 4,200 seedlings and 6,357 indigenous trees were planted, along with the establishment of a nursery (Ref 1, 6). A total of 20,000 tons of solid waste were removed (Ref 6). Additionally, a community forest association was formed to ensure community engagement (Ref 2).

The Ballymun City Farm project began as a grassroots initiative when local residents envisioned turning an underutilized green space into a vibrant community resource. Though initially rejected by the City Council, the project’s supporters recognized its potential to contribute to Ballymun’s environmental, social, and economic regeneration. With a vision to create something unique for the area, the farm was designed to foster community engagement, environmental education, and local sustainability. Over time, it has grown into more than just a recreational space—it has become a symbol of community resilience, offering people of all backgrounds and abilities a place to connect, learn, and grow together (4).
Situated on 6.6 acres provided by Dublin City Council, the farm aims to strengthen community bonds, enhance civic involvement, and combat social exclusion and isolation. It serves as both an educational and recreational space, providing opportunities for people of all abilities and backgrounds to engage with environmental topics, organic food production, native breed conservation, and traditional crafts. It is envisioned that the farm will include a designated ornamental garden, consisting of shrubs, flowers, grasses and bulbs, which will become a focal point for community activities/gatherings. In addition, we plan to install raised vegetable beds, fruit bushes.
Through urban food production and community gardens—effective tools for educating schoolchildren and engaging youth—the farm addresses the gap between food production and consumption, helping to increase appreciation for local food. Investments in green infrastructure like Ballymun City Farm also support urban and regional development, including the creation of jobs. (1, 2)

Alexandria is a city with a special charm, known for its beaches and gardens that act as the lungs through which the city breathes, and are considered a haven for its people (1). Unfortunately, in the last ten years, there has been a decrease in green space due to urban expansion and the establishment of Commercial and profitable projects (1). To address the lack of green space in the city, The Governor of Alexandria has stressed the continued efforts to develop, beautify and plant the squares and turn them into attractive civilized facades, as part of Egypts 2030 vision which aims to move towards a greener city and reduce the effects of climate change. (2). To encourage redevelopment of public green spaces, The Governor launched the “Alexandria shines with its squares” competition in 2023, where the top three neighborhoods with the best redeveloped squares would receive a prize of up to EGP 50,000 [928.45 EUR] (6). The First Al Montazah neighborhood participated in the competition by redeveloping Sidi Bishr Mosque Square (2-5). The 700 meter square was completely upgraded with solar energy, a new irrigation system to conserve water, modifications to the sewer network, and planting the garden with plants that suit the environment (3). The greening activities included planting 400 sticks of various crops in the upgraded square (4).

The PARC Rain Garden project in Plymouth, Michigan, is an innovative initiative led by the Plymouth Arts and Recreation Complex (PARC) and Friends of the Rouge, aimed at addressing stormwater management and enhancing local environmental quality. Supported by a $400,000 grant from Michigan’s Department of Environment, Great Lakes, and Energy (EGLE) through its Nonpoint Source Program, this project will involve the construction of over 31,500 square feet of rain gardens located on the property of Plymouth Arts and Recreation Complex (PARC). These gardens are designed to filter up to 240,000 gallons of stormwater per rainfall event, preventing runoff from entering local waterways like the Tonquish Creek. The rain gardens will also mitigate flooding, reduce pollution, and create a more stable water flow in the Rouge River watershed, which is heavily impacted by urban development.
In addition to their environmental benefits, the rain gardens will provide aesthetic and ecological value to the PARC campus. The plantings, featuring native Michigan species, will create habitats for pollinators such as bees, butterflies, and birds, complementing the existing beehives on the PARC rooftop. The project aims to showcase the feasibility of integrating green infrastructure into routine construction, encouraging its adoption in other urban areas and residential spaces.
Ultimately, the PARC Rain Garden project will not only improve stormwater management but also serve as a model for sustainable urban development, enhancing the landscape while fostering environmental stewardship in the Plymouth community.
(Ref.1,2)

Chandler Park, a historic park in Detroit constructed in the 1800s, underwent multiple expansions from 1922 to 1950 to include amenities such as a pool (later converted into a water park), a golf course, and public green spaces. In 2013, an expert panel recommended constructing a 2.5-million-gallon marshland within the park to provide a unique recreational and educational feature and incorporate green infrastructure principles for improved stormwater management. Completed in December 2019, the Chandler Park marshland was a collaborative project between The Greening of Detroit and the Chandler Park Conservancy, designed to enhance Green Stormwater Infrastructure (GSI) across 200 acres.
The marshland manages 2.5 million gallons of stormwater, substantially reducing the load on Detroit’s combined sewer system and minimizing basement flooding during heavy rains. Engineered with rain gardens, bioswales, and a pump system circulating up to 4 feet of water, the marshland fosters a balanced ecosystem with higher oxygen levels, benefiting local flora and fauna.
With 4,500 native plants, the marshland supports diverse wildlife, including migrating birds, turtles, frogs, pollinators like bees and butterflies, and natural mosquito predators. This project not only contributes to flood mitigation but also improves water quality by capturing stormwater and allowing pollutants to settle.
Additionally, the marshland provides a foundation for future environmental education, with plans to add an outdoor classroom and public learning spaces. The use of native plants ensures low maintenance and sustainability, requiring minimal water and fertilizers. By creating new habitats and recreational areas, the Chandler Park Marshland promotes biodiversity, environmental education, and community engagement, while alleviating urban runoff’s impact on Detroit’s sewer system.
(Ref.1-3)

The Panke is a watercourse that rises outside Berlin and reaches the urban area of the city, flows through the districts of Pankow and Mitte and flows into the Berlin-Spandau Ship Canal in Wedding. The length of the Panke is around 29 kilometres. Almost the entire length of the Panke in Berlin (around 17.6 km) is to be renaturalised - on the section from the state border in the north of Berlin to its confluence with the Berlin-Spandauer-Schifffahrtskanal (BSSK). The Panke is currently a small watercourse that has been heavily remodelled by humans. In large parts of the watercourse, the banks have been straightened like a canal and reinforced with sheet piling, among other things. Existing riverbed drops and weirs prevent fish from travelling unhindered through the watercourse. Studies on water body (structural) quality, typification and other biological quality characteristics have shown that the Panke has poor status values in the majority of Berlin's sections, e.g. in terms of the fish population. The negative assessment results are primarily attributed to the lack of habitat and structural diversity, the lack of passability of the watercourse and, in some cases, high nutrient loads. (Ref. 1)

The restoration of the river was initiated by the State Berlin, following the European Water Framework Directive. The central aim is to implement flood plains and recreate the pre-straightened water course, to ensure space for flooding, habitats for more diverse flora and fauna, increase water flow for better water quality and create a site for recreation in a densely built city. (Ref. 1; Ref. 2) The project started back in 2003 and is expected to be finished in the 2030s (Ref. 2; Ref. 7).