Big Cities Kill Native Plant Life, Replace it with Invasive Species


Photo: wwarby via Flickr, CC 2.0

The world is moving into cities, and this is a good thing. Living in urban areas is more efficient -- mass transit is better, walking is easier, you tend to have less stuff, and the housing is less energy-intensive. And with a projected 9 billion people sharing the world in 2050 (7 billion right now), we're going to have to be as efficient as possible. But the migration to cities isn't all rosy. A recent study has revealed that urbanization decimates native plant life, and replaces it with invasive species. Science Daily reports:

More than half of the world's population now lives in cities, yet we know little about how urbanization affects biodiversity. In one the first studies of its kind, ecologists in Indianapolis, USA have used 70 year-old dried plant specimens to track the impact of increasing urbanization on plants. Lead by Dr Rebecca Dolan, director of the Friesner Herbarium, Butler University, the team examined 2,800 dried plants collected around Indianapolis before 1940 and compared these with plants they and their students found at 16 field sites between 1996 and 2006.
The research team found that as urbanization increased, it began registering a more significant impact on the native plant life. While it still has roughly the same diversity of plant species, 700 different ones, many of the natives have disappeared and been replaced by invasive ones that settlers have tracked in. And the invasive ones have often fully taken root and incorporated themselves into the local ecology.

The report revealed that native plant species died off at a somewhat alarming rate of 2.4 species a year, replaced by 1.4 new ones annually. Dolan's takeaway?

"This study shows that our flora is becoming less distinctive," she says.

And it highlights an important fact -- that we need to preserve our biodiversity as the world rushes towards urban areas. There's already an effort underway to link 9 huge cities in China into a single mega-city -- the scope of biodiversity loss that's apt to occur somewhere like that could be incredible. City planners should take care to map out ample green spaces and areas for native flora to thrive -- lest we transform our cities into homogeneous habitats, full of the same invasive species the world over.

More on Urbanization
Urbanization & Export-led Agriculture Now Main Causes of Deforestation
The Ecology of Cities

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