Soil quality improvement

Mauritius is a biodiversity hotspot, which has been declared by IUCN as a “Centre of Plant Diversity”. 39% of plants, 80% of non-marine birds, 80% of reptiles, and 40% of bat species on the islands are reported as endemic. (4) Nevertheless, human activity keeps threatening this endemicity in Port Louis, a port city and the capital of Mauritius. The city is surrounded by a semicircle of mountains on one side and the Indian Ocean on the other. In 2006 a local NGO started implementing an initiative that focused on restoring native vegetation to the hill that harbours the capital and it's also the place of an important historical heritage, the Fort Adelaide. (2)

In 2019 at the Gullele Botanical Garden in Addis Ababa, the Ethiopian government launched a historic tree planting campaign. Over 350 million trees were planted in an ambitious move to counter the effects of deforestation and climate change. The Gullele Botanical Garden was selected as one of the 1000 sites all over the country involved in the Green Legacy Initiative, a national campaign against the effects of climate change. The United Nations estimates that Ethiopia’s forest coverage has declined drastically to a low of just 4 per cent in the 2000s from 35 per cent a century earlier. (1,2) The Botanical Garden was not selected aleatory as it is Ethiopia's only botanical garden and it is a nursery for various indigenous plant species. Its mission is to conserve and promote the Ethiopian diverse plants and tree population and it is a conservation initiative located at the northwestern tip of the Addis Ababa City Administration. The site covers an area of 1000 ha which is representative of the central plateau of Ethiopia. (3)

The project is part of a bigger initiative aimed at restoring the coastal forest near the city of Mahajanga in western Madagascar. Alongside 2 international NGOs, the community located in the bay next to the city of Mahajanga implemented the intervention with the ultimate goal being to transition the land into a protected area as part of the greater "Mahajanga Green Belt Project". The regrowing forest will form the northwestern end of the greater Mahajanga Green Belt, with the southeast meets the Ankarafantsika National Park. The project also has a gendered aspect as it aimed to employ mostly the women in the suburbs of the city. (1,3)

Xalapa is located beneath towering volcanic peaks in the Sierra Madre Oriental, and the city is crossed by at least five minor streams, seven rivers, and it has four man-made lakes and one lagoon in its territory. Its natural ecosystem represents “1% of the national forest area and hosts more than 12% of forest biodiversity” [1]. However, unplanned expansion has resulted in deforestation and the inadequate management of its waterways. In addition, forests, riparian corridors and wetlands have been cleared for agriculture and urban infrastructure. These disruptions to the environment have increased the frequency and intensity of flooding in the city [2]. To meet the environmental challenges, the United Nations Environment Programme (UNEP) and Mexico's Secretariat of Environment and Natural Resources-SEMARNAT launched an initiative as part of UNEP's multi-city CityAdapt Project, backed by the Global Environment Facility (GEF) [3]. The project focuses on four interventions to improve resilience to climate change through NbS: 1) riparian restoration along the Papas urban river; 2) ecological restoration of the Estropajo Hill; 3) installation of rainwater systems within the most vulnerable areas in Xalapa; and 4) implementation of an artificial wetland at schools [2,4].

The green belt was created not only as an aesthetic element but also to serve as the lungs of the city. The forest planting works around Nur-Sultan have been carried out since 1997 [6, 7]. The area of ​​the green belt of Nur-Sultan is 100 thousand hectares, of which 15 thousand hectares are planted within the city limits. The main idea of the project was to provide comfortable conditions for the residents of Nur-Sultan city, which would serve as a mechanism for improving air quality, mitigating climate and as a natural barrier to protect the city from dust winds and snowstorms [2, 4, 5, 6, 7]. An important aspect that was taken into consideration are the animal species of the forest, as the territory of the green belt is inhabited by foxes, hares, corsacs, white and grey partridges, roe deer, wild boars, etc [1, 2, 7, 8]. The primary importance of biodiversity efforts is assigned to the breeding of birds, especially pheasants [1, 2, 3, 4, 5], as pheasants are an element of local cultural heritage, and on the territory of the green belt, traditions and cultural events related with the pheasants are organised every year [2, 4]. The young forest should turn into an improved recreation area, a favourite pastime for city residents at any time of the year [2,7].

The Sino-Singapore Tianjin Eco-City (SSTEC) is a bilateral project between Singapore and China with a large scale private-sector involvement with the objective to "transform the 34 km2 barren, non-arable land and polluted wastewater ponds into ... a thriving city which is socially harmonious, environmentally-friendly and resource-efficient – a model for sustainable development for 350 000 residents. (1,2). The Eco-Valley is an S-shaped, 11 km green spine that runs through the whole Eco-City connecting its centre with sub-centres, all four residential districts, community spaces, multiple parks, commercial zones, and waterside areas as a scenic park providing a place for connectivity, transit, leisure and recreation for residents (1).

The city of San Salvador was built at the foot of a volcano and down its slopes, it is prone to droughts, floods and landslides. In 2020, Tropical Storms Amanda and Cristobal struck the city with torrential rainfall and gale-force winds triggering landslides and floods, causing damage to homes, infrastructure and roads, and with severe impacts on topsoil depletion affecting the fertility of economically and environmentally central coffee plantations[3].
To meet the economic and environmental challenges caused by such events, the United Nations Environment Programme (UNEP) together with El Salvador’s Ministry of Environment and Natural Resources, local organizations and coffee growers launched an project focusing on the Arenal Monserrat watershed located on the slopes of the volcano [3,4]. Through the integration of Ecosystem-based Adaptation (EbA) the initiative aim to address the effects of climate change by restoring coffee plantations and forests and digging infiltration ditches to be used as sponges to reduce flood risks for 115,000 people by 2022 [1,4,5]. The project was launched as part of the multi-city CityAdapt Project of UNEP and GEF, aiming to provide tools to local governments plan for adaptation and mitigate greenhouse gas emissions from their cities while conserving their ecosystems.

In 2015 an innovative project called the "Sweet City" (Ciudad Dulce) was launched in Curridabat. Its main goal was to bring wild spaces into 21 urban neighbourhoods of Curridabat ("spaces of sweetness") and eight corridors ("transitions") and thus linking neighbourhoods and parks through a participatory re-design approach with local stakeholders [3]. The main objective of the Sweet City model is to reintroduce biodiversity into the urban space by focusing on five fundamental dimensions: Biodiversity, Infrastructure, Habitat, Co-existence and Productivity. The interventions of this project included park improvements, sustainable drainage systems, the protection of wetlands, spring water recovery, promoting organic farming practices, and many strategies that help improve biodiversity and motivate citizen participation, finally, as ecosystem-based disaster risk reduction measures and climate change adaptation actions [1].

"The Urban forest strategy (UFS) is a central part of an innovative overarching policy framework of the City of Melbourne underpinning the city's aim to create healthy ecosystems for people and nature" in the period between 2012-2040 (1 p9). The UFS outlines a scientifically-vetted long-term process to re-nature the city with a diverse selection of urban trees and open space for and with the citizens, combining elements of an eco-managerial governance arrangement with an open and reflexive co-governance approach. (1 p11). The Strategy concentrates on 6 areas to achieve its goals: canopy cover, forest diversity, vegetation health, water quality and soil moisture, urban ecology and environmental stewardship among citizens. (1)

The Xochimilco borough of Mexico City is a World Heritage and Globally Important Agricultural Heritage System wetland site, with significant cultural and ecological importance in food cultivation and water ecosystem (1). Due to the deterioration of the area and lack of top-down initiatives for the restoration and conservation of the area, a number of grassroots initiatives trying to revive the traditional chinampa cultivation and restore the natural state of the ecosystem function and its native species such as the Xochimilco axolotl through reinvigorating sustainable practices that produce quality food and foster water supply. This NBS introduces 3 such grassroot intiatives: (a) Cooperativa Chinampayolo (b) Restauración Ecológica y Desarrollo A.C. (REDES) with its EcoQuilitl producer-consumer network and (c) Umbral Axochiatl A.C. (local community organisation). (1)