Biodiversity and Cities

 Where am I?

 

No, these are not holiday snaps from my weekend away to the Brazilian Rain-forests. I was in fact looking for Biodiversity in London, at Kew Gardens. But, it transpires, I need not have looked further than my window, where a smattering of parakeets come daily to roost, or my cycle route to uni, where foxes are regularly seen (see pictures below). 

The Parakeets gather in this tree opposite my flat. Photo credit: Coskun Guclu

A fox by Euston Station, which I noticed on my way home. Photo credit: Coskun Guclu

Clearly, cities can be hosts for much unexpected biodiversity. This video unpacks the relationship of biodiversity with cities:

The bigger picture; from Expansion to consumption

Urban environments are vital to consider in discussions concerning the most threatened global planetary boundary of all, biosphere integrity(See figure 1). 

Figure 1: The 9 Planetary Boundaries as Outlined by (Steffen et al, 2015). The Green zones represent low risk, the yellow zones represent increasing and uncertain risk and the red zones represent high risk. 

Urban sprawl expansion, development of transport infrastructure, urban linked over-exploitation, air and nutrient pollution lead to habitat loss, either directly or indirectly compromising biodiversity.
Invasive mammalian predatory species introduced by humans, such as dogs, cats, pigs and rodents account for 58% of contemporary bird, reptile and mammal species extinctions, and in cities their presence puts pressure upon native species, which are already strained by the aforementioned ecosystem stressors of urban environments. Furthermore, informal expansions such as the Favellas of Rio de Janeiro and the poorly planned sprawls of American cities have impacted bio-diverse mangrove and forested regions respectively. This is further exacerbated by urban nutrient and industrial pollution and Urban Heat Island, referred to in earlier blog posts, which drive habitat loss along coastal cities and increase animal disease transmission in warming city regions. Clearly, urban development poses a threat to biodiversity in the Anthropocene, but is demonstrably part of the solution, too.

Why it matters

Urban biodiversity affords residents beneficial eco-systems services, impacting physical and mental well being, and also increasing property prices. While conservation projects such as Kew Botanical Garden are impressive and urban located, and some argue that novel urban environments may increase biodiversity in the Anthropocene, I feel it important to continue to pursue the development of biodiversity sensitive cities rather than grow complacent. Although Maxwell et al noted that agriculture and over-exploitation take precedence over urban development as the primary threats to the 8,688 threatened species(See figure 2), it must also be considered that urban dwellers consume 75% of planetary resources, and their consumption patterns ultimately drive the demand upon agriculture and over-exploitation. This is clear in the case of bush meat demand along the Congo River Basin and Europe in diaspora communities, and rapid urban expansion in south east Asia leading to heightened demand for traditional medicinal ingredients such as tiger, shark fin and and rhinoceros horns. City-based consumer activities have a huge role in affecting non-urban biodiversity as much as the destructive urban developments that restrict biodiversity in the center.

Figure 2: The biggest threats to Biodiversity, outlined by (Maxwell et al, 2016)

Looking ahead

In order to preserve the ecosystem services provided by bio-diverse urban environments, measures can be taken along a variety of parameters. Central to this approach is the acknowledgement that functional division in urban planning is problematic, and a bottom up systems focused standpoint should be adopted in nurturing and proliferating urban biodiversity. Additionally, the novel ecosystems peculiar to cities must be incorporated into this approach. Urban ecosystems may not replace the natural systems, but may still contain rare species. Urban afforestation has capacities beyond CDR, and increased under-storey vegetation by 10-30% has been found to increase native taxa by 10-140% in urban environments. Furthermore, establishing wildlife corridors has further benefits, demonstrated in this video:

By decreasing impacts of urban fringe light and sound pollution on adjacent ecosystems, proliferating habitats for native species through afforestation, mitigating urban emissions, following the suggestions of past posts in diminishing nutrient pollution, limiting and regulating housing developments and by altering consumption patterns away from livestock farming, urban biodiversity and adjacent regional biodiversity may be conserved and supported.