Cities and biodiversity

Biodiversity occurs at multiple scales, from site to citywide to regional to global. At the urban level, how a city is designed, planned, and managed can have significant impacts upon its region and other parts of the world. Just as the collective outputs of farmers, industries, and municipalities from 40% of the North American continent have created an aquatic dead zone in the Gulf of Mexico about the size of the state of Connecticut. The Gulf of Mexico is one of the most productive commercial fishing regions in the world, and this hypoxic zone displaces the shrimp, oysters, and fish that feed a global market. Similarly, the collective actions of a city’s property owners impact its levels of urban biodiversity. We all know the drivers of loss of biota in urban systems, but how can we think about it at a municipal scale? Authors de Oliveira, Balaban, et al discuss this in their article entitled "Cities and biodiversity: Perspectives and governance challenges for implementing the convention on biological diversity at the city level" (Biological Conservation  144, 2011). In it, they outline six avenues of improving biodiversity at the municipal scale: 1) development and implementation of proper housing and infrastructure policies; 2) provision of a good network of urban green spaces and functional aquatic habitats, 3) support of sustainable productive uses of biodiversity in urban areas; 4) improvements in public transportation and more compact cities; 5) increase the awareness among urban residents and decision-makers, and 6) stronger links with national and international networks. They make the case that cities can make significant strides in biodiversity levels for the following reasons:

• Cities can be an efficient form to protect biodiversity. Municipalities that reduce sprawl and their development footprint maximize more space for forests, agricultural lands, and biodiversity.
•  Cities are involved in policies to tackle global problems. The development of a City Biodiversity Index by the Conference of Parties to the Convention on Biological Diversity (CBD) created a ranking system for biological health in urban areas.
• Urban residents tend to be more educated and environmentally sensitive.
• Policies can be more effective at the city level scale.
• There are opportunities for a win-win situation between biodiversity conservation and other benefits. Areas for biodiversity conservation are similar zones for other ecosystem services.
• Convergence of movements on biological diversity and urban planning. Urban planning is more accepting of including biological components, just as biologists are more accepting of the biological relevance of urban areas.

There are definitely some challenges to enacting policies and gaining community acceptance of increasing biological services in urban areas. But as this report concludes, “cities are fundamental players to achieve the objectives of the CBD, as most of the world population lives in cities today and many of the important decisions that affect biodiversity are made in cities.”