Point location, which indicates where the NBS takes place

In the 1980s, rapid industrialization, urban population growth, and increased water usage led to severe pollution in Dianchi Lake, exceeding its environmental capacity and significantly degrading its water quality (Ref 1). This deterioration had serious effects on nearby ecosystems, including Cuihu Lake (Ref 2). Cuihu Lake (翠湖), also known as Green Lake Park, is a well-known park and body of water in the center of Kunming, Yunnan Province, China. In Cuihu lake the decline in water quality caused a sharp reduction in native species like the golden line barb, which depend on the local ecosystem for survival, pushing them to near extinction and destabilizing the entire ecosystem (ibid.).
To address this, several effective initiatives have been launched to restore Cuihu Lake’s ecosystem in recent years (Ref 2, 3). One of them was started in 2020 when a restoration project was initiated by the site's administration in collaboration with Dr. Li Weiwei’s team from the Kunming Institute of Zoology, Chinese Academy of Sciences. The project focused on creating micro-habitats and restoring the aquatic ecosystem (ibid.). Ecosystem and biodiversity restoration efforts were conducted across a 5,000 m² area on the east side of Green Lake Park, covering approximately 1/27th of the lake (ibid.).
As a result, more than 20 aquatic animal species are now thriving and contributing to water purification, while three submerged plant species cover over 50% of the project area (Ref 2, 3, 4). Bird diversity and numbers are also increasing, with species like white-breasted kingfishers, green-winged teals, and crested guinea-fowls returning to the area (ibid.). Additionally, there has been a significant improvement in water quality (ibid.).

This project, implemented in several schools across Fort-de-France in 2018, focuses on creating arboretums in schools to educate children about Martinique's native natural heritage and raise awareness of biodiversity loss. An arboretum is a curated collection of trees selected for scientific, conservation or public enjoyment.
The initiative, led by the Martinican National Botanical Conservation, is supported technically by the municipal landscaping department and administratively by the city of Fort-de-France and the Martinican School Rectorate. It includes three main activities: a seminar on Martinique's rich yet fragile botanical heritage, an excursion into a forest, and a tree planting event at schools featuring native or endangered plant species. The program has reached at least six schools in and around Fort-de-France.
(Ref. 1,2,5)

Liquid 3 is the first urban photo-bioreactor in Serbia, developed by an interdisciplinary team at the Institute for Multidisciplinary Research at the University of Belgrade (Ref. 1,2,3). Prompted by an appeal of the United Nations Development Programme (UNDP), the team was eager to find novel approaches to combat the city's severe air pollution issues while being space efficient and providing year-round benefits (Ref. 3). The key to the bioreactor are algae which are very efficient in sequestering carbon and filtering heavy metals from the air (Ref. 2). A Liquid 3 feature can be quickly set and occupies a plot of only 3 m². Some of its benefits include its ability to withstand high levels of air pollution and its ease of installation on surfaces like walkways and other sealed infrastructure (Ref. 2,3). Additionally, by design, Liquid 3 integrates amenities such as power outlets, a bench, and nighttime lighting (Ref. 1). The selected strain of algae can tolerate temperatures between 5-35°C making it deployable all year. However, monthly maintenance is required, during which the water and algae are replaced—both of which can be repurposed, for example, as fertilizers (Ref. 6).The project has received global media coverage as well as a prize for the best innovative and climate-smart solution in Serbia. Its success has prompted the installation of two more such bioreactors in Serbia, with interest coming from other countries such as Hungary and the UAE (Ref. 1,4).

The World Health Organization estimates that 80% of the population in developing countries use medicinal plants for health prevention and care, primarily in rural areas (3). These plant species have therapeutic potential in treating various diseases, and they are considered safe and effective medications with fewer side effects and affordable prices (3). In Peru, medicinal plants have historically been used to treat respiratory, gastrointestinal, and digestive ailments. To this day, they continue to be used by both native and urban communities (3).
To promote, develop, and encourage research, innovation, and technologies related to the use, preservation, conservation, and employment of medicinal and food plants, the National Center for Social and Intercultural Research in Health (CENSI) of the National Institute of Health (INS) has inaugurated its medicinal and food plant nursery located in one of its facilities (Chorrillos) in Lima (1, 3). The primary objective of this project is to adapt various species from the coast, mountains, and jungle of the country and initiate a plant production program that contributes to improving public health, environmental quality and the revitalization of the ancestral knowledge of indigenous, Amazonian, Andean, and Afro-Peruvian communities (1). Additionally, it aims to contribute to mitigating the effects of climate change by creating green areas, reducing atmospheric carbon dioxide levels through plant photosynthesis, improving soil quality, and promoting the responsible use of water resources, among others (3).
For the development of this project, the INS is working in collaboration with the International Organization for Migration to benefit not only the health and well-being of the Peruvian community but also promote the integration and care of the migrant population in the country (2).

In Lisbon's Areeiro district, Urbem, a non-profit organization, is leading the creation of a 2500m2 Miyawaki mini-forest in Casal Vistoso Urban Park. This initiative involves densely planting native species to rapidly establish a diverse, self-sustaining forest ecosystem. Supported by the Lisbon City Council, the project aims to enhance urban biodiversity, improve air quality, and contribute to climate resilience. Volunteers from the local community play a crucial role in every stage, from preparing the land to planting and maintaining the forest. Despite initial challenges, such as a 40-50% plant survival rate, the forest is expected to become self-sustaining within three years. The project focuses on environmental restoration and seeks to engage and educate the community, fostering a sense of ownership and connection to these new green spaces (Ref 1; Ref 2; Ref 3; Ref 4).

A green area was turned into a "reuse park" to save trees, bushes and other plants that had to be moved from elsewhere due to construction work. The project resulted from constructing the new business school at the University of Gothenburg, where circular economy initiatives are being tested. Plants that would have to be removed from that site were moved to the park at Medicinareberget temporarily. They will later be replanted elsewhere on campus, saving money and reducing the environmental impact of buying new plants. The lead actor in the project is the public real estate company Akademiska Hus, which owns and manages the affected parts of the university campus. The reuse park was established in 2021, and it's implied that it can continue to function as a storage site for plants from different construction locations. The project is highlighted as a learning opportunity for how the reuse of plants can be implemented in future construction projects. The project is connected to the regional initiative Återbruk Väst within the national platform CCbuild, which promotes circular solutions in the construction centre [Ref. 1-5].

According to the FAO, in 2022, 16.6 million Peruvians faced moderate or severe food insecurity, representing an increase of 1.5 million compared to the previous year (3). This situation was exacerbated by the health crisis, inflation, and job losses, leaving three out of ten Peruvians in poverty in 2021. The situation was particularly critical in Metropolitan Lima and Callao, with 14% of families reporting difficulties in acquiring protein-rich foods due to their precarious economic situation (2).
In response to this food crisis, the Municipality of Lima implemented the "Lima te Cuida" (Lima Takes Care of You) initiative, in which residents from vulnerable areas got training to create urban gardens and produce organic compost to help the community kitchens in these areas become self-sustainable (1, 2). An example of this initiative is the community garden in A.H. Villa Mosha in San Juan de Lurigancho, where a community garden has been built, and community members have been trained in small-scale planting, cultivation, care, and harvesting of various foods (2).
This initiative has been supported by the MUSA project "Mujeres Unidas por la Seguridad Alimentaria y Ambiental" (Women United for Food and Environmental Security) as part of the project "Alimentando a Lima desde Adentro" (ALDA) (Feeding Lima from within), which has had an impact in eight districts of Lima to strengthen food security (3). In addition to promoting urban agriculture, the project seeks to influence public policy through training and development of proposals to promote urban agriculture at the local level (4).

The Gårda pilot rain garden has been constructed as part of the research project Innovative Rain Gardens at Chalmers University of Technology in Gothenburg. In addition to causing flooding, runoff rain water in urban environments can be contaminated with microplastics, organic pollutants and metals which can spread into the natural environment. Yet, most of the storm water in urban environments is not treated. The purpose of the Innovative Rain Gardens project is to research the ability of a pilot rain garden to treat such pollution. The project acknowledges the function of a rain garden to prevent flooding, but in this study only the pollution treatment potential is investigated. The pilot rain garden was constructed next to the E6 highway in central Gothenburg [Ref. 1-4]. It includes several different bioretention filters where selected plants are grown in filters containing different materials such as biochar, ash and soil [Ref. 2, 3]. Results so far show that the use of rain gardens can significantly reduce pollution. However, further research is needed to determine the long term function of the bioretention filters and the potential of scaling up the NBS. The project is funded by the Swedish Research Council for Sustainable Development (Formas), IMMERSE - Implementing Measures for Sustainable Estuaries, an Interreg project supported by the North Sea Programme of the European Regional Development Fund of the European Union, and COWIfonden (private foundation) [Ref. 1-3].

Baštalište is an organic community garden initiative located in the town of Slanci, some 20 minutes from the city centre of Belgrade (Ref. 3). It is one of the first initiatives of its kind in Serbia, emerging after organizations such as WWOOF Serbia and the Belgrade Flower Festival, along with activists and citizens, united with the goal of growing vegetables for their own needs. Additionally, they aimed to highlight the numerous neglected and abandoned urban spaces in the city that could be repurposed in this manner (Ref.1). Even though more and more people would like to join Baštalište, the community has been struggling to grow beyond their original plot of 1800 m2, shared between some 30 people of mixed demographics (Ref. 3). They have turned to the municipality to provide more such spaces for urban community gardening but their appeals bear little success (Ref. 2,3). Despite their spatial constraints, the initiative remains open to anyone who would like to visit and help while being financed by membership fees (Ref. 1,2,3). The initiative hopes to eventually scale this type of activity, drawing inspiration from the example of Zagreb, where over 2,000 garden communities were established within 2.5 years after the city decided to repurpose its neglected areas (Ref. 2).

Peru is classified as one of the 17 most biodiverse countries in the world, so biodiversity and its conservation are important national aspects (2, 3, 4). However, one-third of the native flora currently assessed is threatened (3, 4). Thus, the creation of the Botanical Garden represents the opening of a space to learn about, study and conserve the national flora by strengthening Peruvian society's awareness of its value (4, 5).
The Botanical Garden is in its early stages of development and is not open to the public yet, but its development and implementation have the support of several associations such as the British Council, Concytec, the Ministry of Environment, the Ministry of Culture, the British Embassy and the Asociación Pro Jardín Botánico Nacional de Lima (1). The initiative has been incorporated as part of the Bicentennial City project of the Ministry of Environment in Ancon (6).
The implementation began in 2021 on a 10-hectare plot of land donated by the Universidad Nacional Agraria La Molina (UNALM) in Lima (3), and it will be carried out in several stages. An Inter-Institutional Committee has been established to oversee its development (3). In addition, it is planned to extend the idea of botanical gardens to other regions of the country, creating a network that will allow the conservation and study of flora in different contexts (4, 5), as the purpose of its development is to condense in one place all the biological richness of the country (7).
With this project, they aim to strengthen the conservation of plant species, the generation of inputs for education, and as a source of cultural spaces and for the well-being of its citizens, among others (1, 2). The Botanical Garden is intended to house a select sample of the more than 25,000 species in Peru, emphasising those that are endemic, threatened and of social, cultural and economic relevance (8).