Increased conservation or restoration of ecosystems

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.).

The Çukurova University Botanical Garden was initiated in 1972 by the Department for Landscape Architecture to protect and conserve the rich native and non-native biodiversity of the region for future generations (Ref. 5,9). Its establishment responds to the lack of Botanical Gardens in Türkiye despite the country's great diversity. The Garden also wants to offer protection for increasingly threatened species in the face of rapid and uncontrolled urbanization (Ref. 5,9). Being located close to two Deltas and an important agricultural region, the collection also aims to include a great number of wetland and agricultural species, drawing public attention to the importance of these ecosystems (Ref. 6). As such, the University invites every school in Adana to visit and participate in its ongoing educational activities and primary school children are offered hands-on gardening programmes (Ref. 1,2). Furthermore, visitors can immerse themselves and learn about various vegetation zones, including endemic maquis, where stairs, walking paths and information boards have been installed (Ref. 4). The University maintains research activities in the Botanical Garden and in on site laboratories, which regularly host interns (Ref. 4). To ensure the stready supply of plant material for landscaping and education, nurseries have been set up and in 2020 a 250 m² medicinal and aromatic plant greenhouse was added where students of the Faculty of Agriculture are trained and endemic species grown (Ref. 9,10).

The Three Mile Creek Hydrological Restoration project is taking place in one historic channel of the Three Mile Creek, located east of Dr. Martin Luther King, Jr. Avenue, and covering approximately 1,800 linear feet (Ref 3). This project, led by the City of Mobile, aims to remove sediment from the stream channel. This segment of the Creek was bypassed with a straight channel in the early 1980s to control flooding in the area, thus accelerating the accumulation of sediments in the historic channel (Ref 1).
The project's goal is to restore and maintain the natural flow to the historic channel and create a connection to the City and County's Blueway initiatives (Ref 3). This will improve habitat conditions and water quality and help to protect the area’s estuarine and marine water resources (Ref 8). It will also contribute to revitalizing the Three Mile Creek Watershed and provide increased recreational opportunities for citizens, like kayaking and canoeing (Ref 6). Construction work occurred in 2022 and 2023 (Ref 3).
The Three Mile Creek Hydrological Restoration is a key component of the Mobile Bay Shore Habitat Conservation and Acquisition Initiative, which focuses on acquiring, restoring, and preserving habitats, including riparian, wetland, and upland areas that support various fish and wildlife species affected by the environmental disasters of the Deepwater Horizon oil spill that occurred in 2010 (Ref 1). The project spans three critical areas: 450 acres within the Three Mile Creek Watershed (as detailed in this project profile), 300 acres in the Dog River Watershed, and 40 acres of bay shore property in the Garrows Bend Watershed (with the latter two areas being part of separate initiatives) (Ref 4).

The intervention of the Ecological Park of La Molina is an urban-landscape design project developed between the San Martín de Porres University, through the IVUC, the Institute of Housing, Urban Planning and Construction, and the Municipality of La Molina (7). This is the first ecological park in the city of Lima, located in a characteristic ecosystem such as Las Lomas, between 600-1000 m.a.s.l. (1). It is a natural area that is part of the hill system of Villa María del Triunfo, located in the Subtropical Coastal Desert ecoregion, and is part of the Regional Conservation Area ‘Sistema de Lomas de Lima’ (7). The City Council decided to open this space in 2022 to the public, as a 200-hectare area, designed to bring people closer to nature, through outdoor activities and environmental education about its fauna, flora and microclimates (1). Thus, citizens can enjoy a recreational area with multi-purpose spaces and sports circuits; a cultural area where workshops and an open-air amphitheatre are held; an ecological interpretation area with exhibition galleries and an interpretative route; and an administrative and control area (1). The park also envisages reforestation efforts in areas that are currently arid and infertile to convert them into green areas for the enjoyment of citizens (1). In 2023, conservation efforts were reinforced for an additional 50 hectares, due to the danger posed by encroachment and land trafficking (4).

The Cartagena-Barranquilla Road Corridor project, led by the National Infrastructure Agency (Agencia Nacional de Infraestructura (ANI)), covers 146.7 km to enhance connectivity between Cartagena and Barranquilla (ref 2). While primarily a transportation initiative, the project stands out for its focus on environmental conservation and community development. A major goal is the restoration of ecosystems and biodiversity protection. To this end, over 40,000 mangrove seedlings have been planted in the 34.13-hectare Ciénaga de la Virgen, a vital coastal wetland in Cartagena. These mangroves play a crucial role in restoring habitats, capturing carbon, and acting as natural flood barriers, thereby safeguarding nearby communities (ref 1,4,6). The project also tackles hazards like wildlife-vehicle collisions and habitat fragmentation. Seven wildlife crossings have been built to facilitate the safe movement of species, including the endangered Blue Crab (Cardisoma guanhumi) in the Ciénaga de Mallorquín. These crossings are essential for preserving local wildlife (ref 1,7).
In terms of socio-economic impact, the project has created over 9,000 jobs and established six bioclimatic nurseries, which provide sustainable livelihoods for communities in La Boquilla, Villa Gloria, Tierra Baja, and Puerto Rey. These nurseries support mangrove restoration and offer local people opportunities to participate in planting, monitoring, and maintenance activities. This approach fosters a circular economy, empowering community members, both men and women, to engage in sustainable economic practices (ref 1,2,6).
Overall, the Cartagena-Barranquilla Road Corridor is more than a transport project; it acts as a green corridor with a comprehensive approach that combines environmental conservation, hazard mitigation, and socio-economic development.

The D'Olive Creek Restoration project is designed to address the significant environmental challenges facing the D’Olive Creek Watershed and its tributaries (Tiawasee and Joe’s Branch), primarily caused by increased urbanization. Over the last several decades, the area has experienced severe erosion, sedimentation, and habitat degradation due to stormwater runoff from new residential and commercial developments. This runoff has led to stream channel instability, loss of wetlands, and impaired water quality in both D'Olive Creek and Mobile Bay, threatening aquatic and wildlife habitats (Ref 2).
The project involves restoring degraded streams and implementing management measures to reduce the downstream impacts within the watershed. Key activities include stormwater retrofits, stream restorations, and continuous monitoring. These efforts aim to stabilize stream segments and significantly reduce sediment loading into the northeast quadrant of Mobile Bay. This is crucial for improving water quality and clarity, which is necessary for re-establishing submerged aquatic vegetation (SAV) beds that serve as critical nursery areas for shellfish and finfish (Ref 1). By using natural materials like rock and living plants, the project also seeks to create a sustainable and ecologically balanced watershed system (Ref 3).
The anticipated outcomes include enhanced water quality in D'Olive Creek and Mobile Bay, reduced erosion and sedimentation, and the restoration of vital habitats, which will contribute to the region's overall ecological health (Ref 1, 3). This restoration project is part of a broader strategy outlined in the 2002 Comprehensive Conservation Management Plan for the Mobile Bay Estuary (Ref 1).

At the beginning of the twenty-first century, Kunming’s urban planning faced major challenges, including fragmented development, environmental degradation, and limited green spaces (Ref 1). In response, the municipal government launched a series of strategic plans aimed at promoting high-quality urban development and environmental restoration.
Baisha Lake was identified as a key area in these strategies, with plans for Baisha Lake Park first highlighted in 2017 (Ref 2) and reaffirmed in the "Opinions on Supporting High-Quality Development in Kunming" in 2021 (Ref 2). To implement parts of this broader strategy, the government entered into public-private partnerships. In 2018, land development rights for parts of East Baisha Lake were granted to Dahua Group, on the condition that 40% of the area be reserved as green space and that ecological restoration efforts be undertaken (Ref 3, 4).
The Eastside Baisha Lake Park project, launched by Dahua Group in February 2023 (Ref 3, 5), is thus one component of this larger government-led urban renewal effort. The project follows the city's planning framework of “one lake, six zones, 46 scenic nodes” and includes 55 hectares of green space, with 40% designated as parkland. By the end of 2023, 6.5 hectares had been completed, and the south bank of the park opened to the public in September 2023 (Ref 3, 6).
The broader East Baisha Lake area's development was originally planned by the state-owned Kunming Urban Construction Company, but land rights were later transferred to Dahua Group. Thus, while a private developer is leading the construction, the project remains a part of Kunming’s publicly driven strategy to restore the lake and enhance urban livability.

In 2022, the municipality of Cagliari launched a project to revitalize Viale Trieste, one of its avenues, by redesigning its roads and pedestrian areas and adding new green spaces. The project covers approximately 1,300 meters and 36,500 square meters, and will be completed in two phases, each focusing on different sections of the avenue. With a budget of 12 million euros, funded by municipal, national, and EU resources, the aim is to transform Viale Trieste into a vibrant, accessible, and attractive space for everyone.

The renewal will introduce new green spaces and improved drainage systems to enhance soil permeability. As part of this, some trees will be relocated to other areas of the city to address root issues and improve survival rates. Dead or unstable ficus trees will be removed, while 79 new trees will be planted. Older ficus trees will be relocated to city parks, with younger ones planted along the avenue to prevent pavement damage and promote sustainability. The project also includes upgrading water supply and drainage systems to manage stormwater more effectively, reducing the risk of flooding and improving sustainability. Public lighting will be modernized, with new street lamps and dedicated lighting for pedestrian and bicycle paths to make the area safer and more welcoming after dark.

However, the community has expressed concerns about the project, citing safety issues, delays, disruptions, and poor communication from officials. There is also significant opposition to replacing the historic ficus trees, valued for their environmental and historical significance, with Chinese pear trees and younger ficus (Refs. 1, 2, 3, 4, 5, 6, 11, 16).

The Upper Detroit Riverfront Habitat and Parks Restoration Project aims to restore and enhance vital fish and wildlife habitats along the Detroit River. This initiative seeks to rehabilitate approximately 30 acres of upland and shoreline habitats within Riverfront-Lakewood East Park, A.B. Ford Park, and Mariners Park (all located alongside the river), covering nearly one mile of the Detroit River and its shorelines.
Key outcomes include improving approximately 1,000 linear feet of existing shoreline along the Detroit River by incorporating native wetland edges and fish spawning shelves into the restoration efforts. The project also plans to enhance around 2,000 linear feet of canal shoreline and 800 linear feet along Fox Creek to create or improve habitats for fish and herpetological species. In Riverfront-Lakewood East Park, 28 acres are targeted for the establishment or enhancement of native vegetation to support birds, mammals, and pollinators. If feasible, the creation of about 7 acres of wetlands, along with shallow and deep-water habitats, is also part of the vision.
The project is guided by the City of Detroit's 2017 Parks and Recreation Improvement Plan and represents part of a broader strategy to revitalize the city’s green spaces after years of underfunding. With renewed commitment, the city has allocated nearly $12 million to enhance neighborhood parks, particularly in areas that have lacked investment over the past decade.
However, the project was temporarily halted in 2020 due to high water levels causing flooding in the adjacent neighborhood. As of 2024, it remains on hold while the City of Detroit conducts a flood mitigation study. Despite this delay, the project remains a critical step toward fostering community stewardship and creating sustainable green spaces that improve the quality of life for all Detroit residents.
(Ref. 1, 4, 5)

The City of Gothenburg's policy for park and street trees was updated in 2016 and has the overarching aim to maintain and develop the ecological, historical, social and economic values of the city's trees and tree environments. Trees are described as having ecological, historical, cultural and economic values. They can provide ecosystem services such as habitat and biodiversity, air quality improvement, flood prevention, heat mitigation, recreation and aesthetic values [Ref. 1].

The policy applies to all trees in the streets, squares, and parks within the municipality but not to natural environments such as forests at the city's edge. Further, the policy is mostly relevant for municipality employees whenever they make decisions that will affect trees or tree-covered areas, such as zoning/planning and construction projects. Other actors in the city, such as private real estate or construction companies, are not required to follow the policy but are encouraged to consider it. The policy formulates sub-goals and guidances regarding the preservation of existing trees (prioritising large and old ones), the planting of new trees, the maintenance of trees, protection during construction work and finally, the taking down of trees, including compensation measures. The policy's direct effects is an expected improved management of trees within the municipal organisation. This may have further indirect benefits in the form of increased ecosystem service provision when the policy affects other projects [Ref. 1, 2].