BiodiverCity? Or the great urban extinction?


Have you ever stood in a city and wondered what it was built on top of? Woodland, marshes, fields? There's no doubt the building of ancient cities combined with modern urban sprawl has taken its toll on global plant life, but a new study has found out to what extent.

A team of scientists* looked at plant extinction rates of 22 cities around the world and their findings – reported in Ecology Letters - shed light on the potential harm our ever-growing cities have on native plant populations.

It’s a simplistic notion that if we replace nature with a building then it is immediate;y detrimental to flora and fauna. But, understanding the history of the development may give us clues of how to work with the grain of nature and not against it and provide opportunities for nature to flourish among our tower-blocks and shopping districts.

flowers and towerblocks

Cities can be green and pleasant

© Landlife

The study looked at three types of city development alongside the available botanical knowledge.

cartoon of city evicting plant by chris bisson

Is the growth of global cities causing plant extinctions?

It soon became clear that cities in the first two categories had suffered more extinctions than the last and in the first case this is almost certainly due to the persistent long-term landscape change. In type II cities, such as New York, where less than 10 per cent of the original vegetation remains - high extinction rates can be attributed to the sheer lack of space. In some modern cities that still retain large – above 30 per cent – vegetative cover then the extinction rates were much lower. However, this type of city is becoming increasingly rare as modern planning techniques try to squeeze more and more buildings into smaller and smaller spaces.

Of the type III cities San Diego still possesses over 60 per cent native vegetation cover and has only lost 11 species from the record and a similar situation can be found in Durban, South Africa. These figures might give us a clue as to how we could, and perhaps should, design our cities.

bus driving past wildflowers in liverpool

Creative conservation. One way to restore nature to cities?

© Landlife

By combining large areas of native plants, connected to prevent isolation, and utilising the tools of restoration ecology, plants and people can live hand in hand. And in Liverpool in the UK this is happening. Landlife are working with communities to restore wild flowers to bleak city-scapes. They call it Creative Conservation and it is a visually and mentally inspiring future that many other organisations, and indeed cities, could take a lead from.

*Hahs et al. (2009) Ecology Letters 12: 1-9

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