Urban gardens promote biodiversity and human well-being

Until recently, scientists have assumed that cultivating food leads to biodiversity loss and negative impacts on a variety of ecosystems. However, according to a new study led by the University of Texas at Austin, community gardens and urban farms positively affect biodiversity, local ecosystems, and human well-being.

The researchers examined 28 urban community gardens across California during a period of five years and measured plant and animal biodiversity, along with ecosystem functions such as pollination, food production, carbon sequestration, pest control, and human well-being.

“We wanted to determine if there were any tradeoffs in terms of biodiversity or impacts on ecosystem function,” said study lead author Shalene Jha, an associate professor of Integrative Biology at UT Austin. “What we found is that these gardens, which are providing tremendous nutritional resources and increasing well-being for gardeners, are also supporting incredibly high levels of plant and animal biodiversity. It’s a win-win.” 

Previous assumptions about the negative effects of food production on biodiversity have been largely based on intensive rural agriculture enterprises which usually grow only one or two types of crops at massive scales. By contrast, urban community gardens, private gardens, and urban orchards and farms tend to grow more types of crops in smaller areas, thus supporting biodiversity and ecosystem services.

“It’s estimated that by 2030, about 60 percent of the world’s population will live in cities. And urban farms and gardens currently provide about 15-20 percent of our food supply, so they are essential in addressing food inequality challenges. What we’re seeing is that urban gardens present a critical opportunity to both support biodiversity and local food production,” Jha explained.

In addition, the scientists found that the choices urban gardeners make can have significant impacts on local ecosystems. For instance, planting trees outside crop beds can increase carbon capturing without damaging or limiting pollinators or decreasing food production from too much shade, while mulching only within crop beds could help improve soil carbon services without any negative effects on pest control or pollinators.

“By quantifying the factors that support a diverse suite of ecosystem services, we highlight the critical role of garden management and urban planning for optimizing biodiversity and human benefit,” the authors concluded.

The study is published in the journal Ecology Letters.

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By Andrei Ionescu, Earth.com Staff Writer

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