Environmental quality

Zollverein is an abandoned colliery and coking plant near the center of Essen in Germany (Ref. 6). Since 1993 the mining here stopped, and the site was turned into a derelict area, so nature could win back its territory. Most of the railway tracks and the smaller industrial leftovers are now covered with moss, grass, and weeds (Ref. 4). After the site was recognized as a World Heritage Site in 2001, it started being developed as a multifunctional cultural, tourist and recreational center keeping and developing biotopes that emerged over time (Ref. 11).

While Hamburg has already had an impressive green infrastructure, it is now (since 2013) implementing an interconnected green network that will cover the 40 % of its area and support commuting by bicycle, recreation and climate change resilience. The project is planned to be completed by 2034. (Reference 9) The project aims to connect the two green belts, parks, recreational areas, cemeteries and animal habitats to each other with green paths and with the already existing “green axes” leading from the agglomeration to the urban core. The green network could not only absorb more CO2 but also prevent flooding by soaking up an increased amount of rain- and seawater caused by storms. (Reference 1, 2). An extensive network of cycle paths is also being built as part of the project. (Reference 2)

In 2016, the project facilitated the revitalization and development of green areas in Dąbie (by an urban part of the Vistula River) to create the Dąbie Park. The park had been a neglected vacant green space with randomly scattered former playground facilities. The initiative involved greenery management and creation (bushes, trees, flower meadows), building new sports facilities (running/cycling paths, a basketball field), new infrastructural solutions (new water drainage system, a viewpoint) and creating a safe and modern space for children in a playground surrounded by large trees which provide shadow. The modernization and revitalization of the park infrastructure and local greenery have made the green riverbank area accessible to the public [1,4,5].

A 21-kilometer regional cycle and footpath between the cities of Essen, Mülheim am der Ruhr and Duisburg was developed from the former unused railway route of the Rheinische Bahn. The path was landscaped to ensure the comfort of pedestrians and cyclists. Part of the route passes through Emscher Park and become a full-fledged part of the green infrastructure of Essen (Ref. 1).

The Newton and Arkwright roof, buildings of the Nottingham Trent University campus, holds one of the region’s largest sedum roofs, which spans its way 2,500m² across the building, creating a home for 13 varieties of sedum, insects, songbirds and a new colony of honey bees, creating a trio of hives over all campuses (ref. 1). A 150m2 bank surrounding the building is unmown in order to promote biodiversity and attract pollinating insects in the summer months. Green-walled gates was also part of the implementation activities of this project. (ref. 5).

It started with the “Let’s Plant for the Earth, Let’s Plant for Murcia” project, as Murcia’s committed to the United Nations Billion Trees Campaign. The city of Murcia committed itself in 2008 to plant 12 000 trees around the urban fabric through a series of action projects. The target was exceeded in 2010 with a total of 23 576 trees pledged and planted toward the campaign (Ref. 1).
In 2020, after having surpassed their 12,000 planted trees goal, Murcia has the new goal of planting 100,000 trees by 2030. It is a long-term project that the municipality committed itself to make (Ref. 5, 2020a).

The “Cities Dare Wilderness” project is part of the overall Hanoverian program of “More Nature in the City”, a new future-oriented approach to green spaces in urban areas. The aim of the project is to bring wilderness back to the city by increasing urban biodiversity, strengthening nature in the city and making it habitable for its inhabitants. For fulfilling these goals, eleven sites were chosen (some parts of the city park Eilenriede, some currently intensively cultivated areas or some derelict small gardens), in which different methods have been tried out, like planting local woody plants, grazing, and the implementation of interpretive trails. The development of the flora and fauna in the new wilderness is now being observed and investigated. The first step in the wilderness was made on a meadow along the course of the Fße in the Badenstedt which was fenced. It was made available for cattle to graze and influence the new growth of shrubs through feeding preferences (Reference 1, 2). The flowering meadows have attracted a variety of species. The rich habitat resulting from the project has attracted songbirds, hedgehogs, butterflies and some of the 67 bee varieties endemic to the state of Saxony (Reference 10).
Campaigns for environmental education are regularly offered in order to involve the population in the process of wilderness development. The series of “Wilderness Concerts” were organized, a “wilderness woodlice” was installed in one of the project areas (Mittlefield), and handicraft activities have been regularly offered, in addition to excursions and guided tours (Reference 8). Citizen science is also part of the project through the iNaturalist app that allows the community to record observations of the flora and fauna in the area (Reference 9).
The project is financed by the Federal Ministry for the Environment, Natura Conservation and Nuclear Society. Two other cities, Frankfurt am Main and Dessau-Roßlau is also involved as model cities. (Reference 1,2)

In 2014, the Marseille Provence Métropole Urban Community commissioned five new stormwater retention basins in order to preserve the quality of coastal waters and reduce the risk of flooding (Ref. 4). In the past, in the event of severe thunderstorms the sewage networks became saturated and a portion of the water was then directly discharged into the sea without going through the sewage treatment plants (Ref. 1). This is seen as "one of the most important documents of recent years in terms of environmental protection. It foresees in the next 5 years, 185 million euros of major works" (Ref. 1).

When the national German railway company shut down parts of the former East station of Leipzig and its tracks in 2012, citizens developed an idea for its secondary use and came up with the concept of the "Parkbogen Ost" which represents a 5-kilometre long circle of bicycle lanes, footpaths and outdoor space surrounding the East of Leipzig. The city of Leipzig recognized its potential to connect the Eastern Leipzig with the city centre and developed the strategy further by issuing a "Masterplan Parkbogen Ost" as the base for a step-wise implementation of the project in 2013 (Ref. 5).

The Chirita dam is the drinking water reserve of Iasi. The lake is protected by law, with bathing or fishing prohibited. In 2013 it was cleaned and sanitized since it became an area where many people used to dump their house residues. As such a national campaign sponsored by an NGO having social responsibility claims implemented this NBS, which meant cleaning the shores of the lake (1).