With urban population growing worldwide, urban areas are facing major challenges. These areas also play a global role in terms of biodiversity and human-nature relationships. Many cities around the world have settled in regions of high natural locational diversity, and therefore they often overlap with biodiversity hotspots. Urbanization can also lead to the immigration of alien species, with potentially negative consequences for biodiversity and the associated ecosystem services. Another important negative influencing factor in this context is climate change. At the same time, there is an increasing debate about the ongoing loss of human-nature relationship, which could have a crucial impact on the future management of urban biodiversity.
The immigration of alien or non-native species caused by urbanization processes can have negative effects on other species, biotic communities or biotopes – in this case called “invasive” species. As a result, we observe a homogenization of urban biodiversity in parks, gardens, and meadows worldwide, even though the total number of species in urban areas may be increasing. Heat and drought waves, adapted planting and associated equal gene pools, uniform management, and similar preferences in species selection will exacerbate this trend. The implications of this development are hardly known so far.
The provision of ecosystem services by urban biodiversity is of great importance for the urban population. A quite recent trend is often called “return of nature to the city”. City gardeners plant bee-friendly flowering plants in their gardens or on traffic islands. In the “edible city” zucchini and tomatoes are grown in public spaces. At the same time, “extinction of experience” – the progressive loss of human-nature interactions – does not only “reduce the important benefits that people gain from these interactions, but it may also undermine their support for pro-biodiversity policies and management actions, and thus play an important role in shaping the future of biodiversity”1.
Unfortunately, data and facts on urban biodiversity are neither centrally stored nor completely collected. A systematic analysis of these facts will fill knowledge gaps about the causes, mechanisms, trends, and consequences of urban species loss, “species returns”, and the dispersal of invasive species.
1Gaston, KJ, Soga, M. Extinction of experience: The need to be more specific. People Nat. 2, 575– 581 (2020) https://doi.org/10.1002/pan3.10118