This study researched the global biodiversity of cities. It found that cities do have the ability to support biota diversity. Globally, cities show similar composition in bird and plant species within biogeographic realms. In all cities except Australia, native species are dominant. The median of bird species richness was 112.5 and 776 for plants. This represents nearly three-quarters of bird species being found in cities and two-thirds of all plant families being found in cities. However, when this study analyzed species density, it found that cities only support 25% of native plant species when compared to non-urban density. A median of 8% of bird non-urban density of bird species are found in cities.
The study went on to research the cause of low species density and found that they were largely anthropogenic. For birds, density decreased as urban land cover increased, showing the importance of green spaces within cities. For plants, species density increased as the cover of intact vegetation and city age increased.
I think that this provides a good foundation for rewilding urban areas. This study clearly shows that it is possible for a diversity of wildlife to exist in cities, but it also indicates the issue of species density. Here there is both sadness and hope. These populations can exist in cites, but how long will they? If we do not take actions such as rewilding, I fear that species density will just continue to decrease until there is nothing left. By creating more green spaces with native vegetation, we can try to reverse the main cause of decreasing bird and plant populations—urban land cover. We need to shift city planners’ thinking of destroying nature to develop into destroying old development to rebuild nature. I think that the fact that old cities with older vegetation is where plant species thrive the most is a good place to start. Rewilding takes time. If newer cities incorporate native vegetation into their landscape now, it’s value as habitat will increase as time goes on. It’s important to start creating and managing green spaces in cities now before it is too late. With this design of adding native vegetation, cities will be better able to support a rewilding effort.