With a population of approximately 11 million inhabitants, the Rhine-Ruhr agglomeration is one of the largest urban agglomerations in Europe. The Ruhrgebiet is a core, densely populated area of this agglomeration with a long industrial history, primarily driven by the rapid development of its mining industry throughout the 19th century.
However, following the abandonment of the majority of its mines in the latter half of the 20th century, the region experienced major socio-economic and environmental changes. Whilst the extensive space made available in these former industrial sites has opened up potential for urban nature restoration, it comes tied with diverse visions for nature in urban environments from various stakeholders and societal groups.
In this wildE case study, teams from Wageningen University and Biologische Station Westliches Ruhrgebiet are navigating these approaches towards nature in order to create and implement possible scenarios for rewilding that could turn the former industrial sites into flourishing urban nature – nature which could mitigate the impacts of climate change in the region whilst simultaneously satisfying the demand for ecosystem services from the local community.
Mining in the Ruhr: from boom to bust
The Ruhr region was the heart of industrialisation in Germany for over 100 years. The abundance of natural deposits of coal and iron ore found in the area, as well as its location near a well-developed transport system made up of rivers, canals and railways, attracted numerous coal and steel production companies to the region.
Because of these natural resources, the Ruhr experienced great economic expansion from the 19th century onwards. This economic growth, centred around coal mining and coal based industries such as steel production, provided jobs and prosperity to the growing population in the region, and attracted migrants from all over the continent.
By the late 1950s, however, the region’s industries began to decline as international market forces increased international competition. Between 1955 and 1980, the number of coal workers decreased from 480,000 to 143,000, and by the final mine closure in 2018, less than 4,000 workers remained.
The decline of mining and related heavy industries resulted in socio-economic challenges such as increases in unemployment and poverty. However, as the region transitioned towards a more diversified economy there were also benefits for people and nature as previously high levels of air and water pollution decreased dramatically as a result of new technologies and industrial decline.
Letting nature take control in post-industrial sites
Following this economic transformation, many of the region’s industrial sites were abandoned. This led to a patchwork of urban and industrial ecosystems which have spontaneously rewilded, including abandoned mining areas, brownfields and heavy industry sites, so-called industrial nature.
These abandoned areas have high potential for rewilding in a highly urban context and on “unusual” sites. A shared characteristic across all the sites is the human-induced alteration of the areas, marked by the dominance of industrial waste materials such as slag, ash, dust, sludge, construction debris, and tailings. The soils of former blast furnace sites, mines, and coking plants show significant differences in their physical and chemical properties compared to natural soils. This influences species composition and vegetation growth.
Due to the varied site conditions and distinct temporal ecological succession, a high level of biotope diversity has emerged on the abandoned sites, ranging from raw soils with pioneer vegetation to tall shrub and bush communities, and even industrial forests. The open habitats on these derelict sites are particularly important as refuges for heat-loving species that thrive in nutrient-poor environments. These habitats support numerous rare and endangered species, such as Centaurium pulchellum, Carlina vulgaris, Oedipoda caerulescens, Epidalea calamita, and Charadrius dubius. The unique site conditions also favour the establishment of neobiota, which, due to their ecological traits, are especially well-suited for pioneering colonisation. Species like Dittrichia graveolens and Apera interrupta are among the characteristic species of industrial landscapes, alongside the aforementioned native species.
Many of these sites are undergoing natural forest regeneration due to the lack of human intervention to them, while others continue to maintain open grassland or shrubland habitats.
Rewilding for people and for nature
As this work is being carried out in such a densely populated region, it is critical to understand the impact that rewilding may have for those living in the region. Thus, a key aspect of the Ruhr case study is the understanding of the socio-political aspects of rewilding in an urban area with rapid socio-economic changes.
Through engagement with diverse stakeholder and societal groups, the case study investigates the distinct, and in some cases competing, views of nature and land management, as well as the different perceptions and recreational practices in the area to create a vision for rewilding that is beneficial to both nature and local communities, and that maintains the region’s cultural heritage.
What does this mean for climate mitigation?
Rewilding in the Ruhrgebiet is particularly important as areas that were once big drivers of climate change (through coal mining) are now turning into urban “forests”, which can help to mitigate the impacts of climate change for the local population and nature. By restoring nature in these areas, the case study will help contribute to combating the urban heat island effect.
From a natural science perspective, this also highlights the interconnection between rewilding and more active conservation management. To do so, it is necessary to understand the potential and trajectories of natural development of the sites, and to study the species that have adapted to live in these areas, especially in changing climate conditions. Natural processes may also help to decontaminate some of the soils which were contaminated by mining activities in the area, thus providing a cost effective approach to remediation.
In the longer term, by working at a variety of research sites on the theme of industrial nature, the Ruhr case study will enable future monitoring of ecological processes in the area to unlock the potential of other potential rewilding sites and to enable nature to continue to restore itself in the future.