Improved prevention or control of invasive alien species

The "Plan Arbre" is a tool for ecological planning and renaturation aiming to plant 308,000 trees between 2023 and 2029, sourced from the municipal nursery with seeds purchased from local suppliers (Ref 1, Ref 2). In 2023, 14,922 trees were planted, with plans to double this number in 2024 (Ref 1). The project addresses the loss of 50% of Marseille's natural spaces over the past 75 years, aiming to reverse this trend and reintroduce nature into the urban environment (Ref 2). It also tackles issues like drought and heatwaves, particularly in summer, by using trees and shrubs to cool the air, restore biodiversity, reduce air pollution, and enhance public spaces while absorbing CO2 (Ref 2).

The plan is divided into two phases. Phase I focuses on planting in Marseille's 58 parks and 273 squares and gardens, as well as around childcare centres, schools, socio-cultural centres, and sports facilities (Ref 2, Ref 3). From 2020 to 2023, various improvements were made, including playground renovations, installation of misting systems, automatic watering, and the creation of a CrossFit area (Ref 3). Phase II will involve identifying major boulevards, avenues, and streets lacking trees to enhance the urban canopy (Ref 2).
A diverse range of tree species were selected for their drought resistance, water efficiency, and ability to attract biodiversity (Ref 2, Ref 3). The project also focuses on increasing biodiversity and managing invasive species through natural methods to protect trees from pests without chemicals (Ref 3). Furthermore, the initiative includes de-impermeabilizing soils and implementing a smart irrigation system with tensiometric sensors, developed with the start-up GreenCityZen, which has saved 66% of water in two years (Ref 3). The Plan Arbre also promotes citizen participation, with 23 parks selected for community gardening projects, where ten winning associations will receive plants from the municipal nursery (Ref 1).

Phoenix is one of the hottest cities in the United States, with temperatures regularly exceeding 40°C (104°F) for more than 90 days each year. The urban heat island effect is severe here, posing a significant health risk. Many communities in Phoenix lack equal access to shade cover—often, the impact of extreme heat disproportionately affects low-income neighborhoods that lack resources for tree planting and maintenance. In contrast, wealthier areas tend to have more trees and are visibly greener, which helps reduce the heat residents experience.
To address these disparities, the City of Phoenix partnered with SRP, a not-for-profit public power utility, to launch the "Right Tree, Right Place" program in 2018. This initiative aims to bring shade relief to areas most in need, such as parks, public transit stops, and schools, while replacing older trees that interfere with SRP power lines. SRP and the city work together to identify trees that pose risks to overhead power lines, and for each tree removed, three new trees are planted—either in a different location or with a species better suited to coexist with power lines.
One of the program’s notable projects took place in West Phoenix’s Cortez Park, where 24 drought-tolerant trees from four different species were planted. This diversity helps protect the trees against pests and other natural threats, ensuring their longevity and resilience. Through initiatives like these, the "Right Tree, Right Place" program contributes to Phoenix’s larger goal of developing a robust, biodiverse urban forest. By expanding green infrastructure, the city aims to reduce local temperatures, improve air quality, and create cooler, healthier neighborhoods for all residents. (1-8)

Historically, the area of San Paolo in Cagliari has suffered from environmental degradation and illegal dumping, making it an unsightly entrance to the city. In 2022, the Città Metropolitana di Cagliari, initiated a project to transform this degraded area into a urban park featuring 7,000 new plants, including olive trees, junipers, lentisks, myrtle, rosemary, tamarisks, and Aleppo pines. Managed by the municiplaity of Cagliari, and funded by a €500,000 grant from the Ministry of Ecological Transition, this initiative will cover 4.7 hectares between Via San Paolo and the Santa Gilla Lagoon, creating a natural corridor connecting the city to the lagoon. The project aims not only to restore the land but also to enhance both metropolitan and municipal environmental requalification plans.
A multidisciplinary team, including a forestry technician, agronomist, and biologist, developed the project to ensure it is environmentally sustainable and suited to the local ecosystem.
The work on the project began in June of 2022 with land preparation, removal of invasive species, and waste collection, resulting in the clearing of over 5 tons of rubbish. By December, around 3,000 plants had already been planted, with the remaining work, including the installation of an irrigation system, scheduled for completion by January 2023. The selected plant species are fast-growing, and within two years, the shrubs are expected to reach a height of about two meters. The park is planned to open to the public in 2024, providing a new green space for walking and outdoor activities.
The San Paolo urban park project has encountered obstacles, mainly due to the expropriation of buildings, leading to legal disputes, permit delays, and a temporary halt caused by a tender-related issue. The site is currently overgrown and unused, showing clear signs of neglect. (Refs. 1, 2, 3, 4 & 5).

The Lower Salt River Restoration Project (LSRRP) is a riparian restoration initiative located along the Lower Salt River within the Mesa Ranger District of the Tonto National Forest. This collaborative project seeks to restore a section of the Lower Salt River Recreation Area that was severely impacted by the 2017 Cactus Fire. The Cactus Fire was a significant wildfire that caused extensive damage to vegetation and habitat in the area, highlighting the need for targeted restoration efforts to rebuild the ecosystem and mitigate future fire risks.
The LSRRP’s primary activities focus on removing invasive tamarisk trees, which are highly flammable and contribute to the intensity of wildfires, and planting native seedlings to reestablish local flora. By removing tamarisk trees, the project aims to create a landscape that is more resistant to fire, reducing the wildfire risk for the region. Additionally, the project supports the abundance and diversity of native plant species by removing invasive plants and planting thousands of native riparian tree species.
The restoration efforts also aim to enhance the riparian habitat by expanding two critical vegetation communities—the mesquite bosque and the cottonwood-willow gallery forest. These communities support rich biodiversity and offer essential habitats for local wildlife.
Beyond ecological restoration, the project emphasizes community involvement and awareness. It provides opportunities for the local community to participate in the project through environmental education events for K-12 students and ongoing volunteer involvement in monitoring and maintaining restored areas.
Overall, the Lower Salt River Restoration Project is a proactive effort to protect and revitalize the Lower Salt River Recreation Area, enhancing its ecological resilience and engaging the community in long-term conservation. (2-4, 6, 8, 11)

“El Chamizal is a site of significant sociocultural importance and a key part of the identity of the people of Juarez. It is frequently visited by over 200,000 people seeking a space for recreation and enjoyment.” Located along the Rio Bravo/Grande river, El Chamizal is a park and a riparian area (Ref 2). Despite its popularity, the park has been suffering three decades of irregular management by the Municipal Government of Juárez and is facing issues such as accelerated desertification, soil degradation, and biodiversity loss. (Ref.2)

To counteract some of these challenges, in February 2024, the Secretariat of Environment and Natural Resources (Semarnat) and the National Commission of Protected Natural Areas (Conanp) designated El Chamizal Park, spanning 327 hectares, as a Zone of Ecological Restoration (ZER) (Ref 1).

The restoration plan involves dividing the park into four distinct zones, each with specific recovery actions (Ref 1; 2). Zone A, covering 107.3 hectares, is designated as a conservation area where reforestation with native species must commence. Zone B, which spans 47.8 hectares, also requires reforestation with native plants. Zone C, encompassing 12.7 hectares, consists of flooded or floodable plains that must remain in their current state. However, the surrounding ecosystem in this zone needs restoration with native aquatic plants to aid in stormwater purification. Zone D, at 159.8 hectares, contains existing infrastructure—such as buildings, installations, and communications—that must remain unchanged (Ref 3, p. 96). The project proposal is still awaiting implementation.

Sourced from Northern Worcestershire, the River Stour has played a significant role in the industrial heritage of Birmingham and the Black Country (Ref 1). It consists of 11 Water Framework Directive water bodies and multiple tributaries, spanning 200 km in length (Ref 2, 3). Once a pristine Salmonid river that powered the Industrial Revolution, rapid industrialization severely impacted the river, leaving it heavily polluted with sewage (ibid.).
Initiated by the Birmingham and Black Country Wildlife Trust (BBCWT) in 2021, the Love Your River Stour (LYRS) project focuses on Dudley and Wolverhampton, aiming to transform the River Stour and its surrounding green spaces into a beautiful, wildlife-rich source of pride for local communities and to create a corridor for wildlife to thrive through the heart of the Black Country (Ref 4).
Phase 1 of the project was completed in June 2023, bringing significant improvements along the river (Ref 5, 6, 7, 8). In Phase 2, the project will extend to a stretch running through Cradley Heath and Lye (Ref 7, 8). This initiative is funded by the UK Government's Green Recovery Challenge Fund.

In September 2018, a new didactic itinerary on invasive alien species was inaugurated in Cagliari's botanic garden. The initiative has been initiated in order to raise awareness and share important legislative and scientific knowledge on the matter (Refs. 1, 2 & 3). It has been curated by Life ASAP, which is an EU co-funded project focused on targeting the introduction of animal and vegetal alien species in Italian territory (Refs. 4 & 5). The initiative in the botanic garden focuses on a 13-pannels pathway through the garden, which will guide visitors towards the discovery of the issue of the introduction of alien invasive species on the territory. The goal is to attract the population's attention to the topic through a sensorial and interactive experience. In fact, the panels are easy to understand, colorful, and accompanied by explanatory images and bas reliefs. Children and youngsters can also participate in a laboratory called "the alien's identikit," according to which they have to recognize the newly learned alien species around the garden (Refs. 1, 2 & 3). This Path represents the first (and only) permanent space dedicated to biological invasion processes and invasive alien species in the network of Italian Botanical Gardens. (Ref.2).
Therefore, the project, in collaboration with the University of Cagliari, promotes education for all ages on the risks and consequences of such an underestimated problem and aims to educate citizens on how their actions can prevent the phenomenon from spreading further (Refs. 1, 2 & 3).

The Circle Forest project, led by Arboretum Detroit in partnership with Detroit Future City, is transforming a vacant lot the size of a football field in the Poletown East neighborhood into a green space. Once used as a dumping site, the area is being revitalized with 200 native trees, including oak, elderberry, white pine, and juniper. Supported by local groups like Detroit Audubon, Singing Tree, and the US Fish and Wildlife Service, the project aims to improve environmental quality and provide better access to nature for residents. Since 2019, over 120 trees have been planted, with plans to develop a native meadow. This initiative offers a space for recreation and reflection, benefiting the local community, including a nearby nursing home and rehabilitation center. Beyond ecological restoration, Circle Forest fosters connections to indigenous knowledge and respects the wisdom of the original stewards of the land. (Ref.1, 2)

The mangrove area of Morne Cabri, located in the municipality of Le Lamentin and sharing the bay of Fort-deFrance, is the largest mangrove area in Martinique. Since 2011, the municipality has led efforts to understand and better manage the area (Ref 1). The natural regeneration of the mangrove is threatened by fresh water run-off (from waste and rainwater), invasive species and pollution. However, it is an important protection against extreme weather events, operates as a carbon sink for the island and provides recreational activities (Ref 1). The municipality has led several initiatives supported by volunteers, local businesses, national subsidies and private donations (See: Ref 2, 3, 4, 11).