Long considered biological deserts, cities are known to contain fewer species than the undeveloped lands they replace, and often fewer than the modified landscapes that surround them. However, urban areas also support substantial numbers of native species, including some uncommon and threatened species. While there is a large body of research documenting biodiversity patterns in cities, relatively little attention has been paid to the links between cities and their surrounding landscapes. Here, we use Silicon Valley as a case study to evaluate the potential for this highly modified urban center to contribute to regional resilience and biodiversity. Drawing from urban ecology literature from around the world, we develop a conceptual framework for how cities affect biodiversity and resilience. We apply this framework to Silicon Valley to ask under what conditions, in which types of locations, and for which types of species, cities are likely to benefit regional biodiversity.
Results/Conclusions
We show that the unique abiotic and biotic conditions in cities can create opportunities for biodiversity support. We identify factors such as rare habitats, altered climate regimes, productivity, and resource bases, as well as altered community structure and species interactions that create unique opportunities for species to escape from threats faced elsewhere, using examples from Silicon Valley. Drawing from historical ecology and contemporary vegetation data, we identify habitat types and features (including patches of willow groves and valley oak ecosystems) that have persisted in the urban landscape, and are unique in the region. Using avian biodiversity data from the citizen science tool eBird, we compare the urbanized valley to the surrounding agricultural and protected open spaces to identify species that have the potential for support in cities. We discuss implications of this work for urban design and planning, and highlight how alterations to cities in the future could affect their ability to contribute to regional biodiversity and resilience.