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Traditionally, it has been assumed that cultivating food leads to a loss of biodiversity and negative impacts on an ecosystem. In a recent study, researchers looked at 28 urban community gardens across California over five years and quantified biodiversity in plant and animal life, as well as ecosystem functions such as carbon sequestration (碳封存), food production, pest control and human well-being.

“We wanted to determine if there were any biodiversity and impacts on ecosystem function in those unban gardens,” says Shalene Jha, the lead author of the study in Ecology Letters. “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 by scientists about the negative effect of food production on bio diversity have been almost entirely based on intensive rural agriculture enterprises that tend to grow on one or two types of crops, often at a massive scale. Urban community gardens, private gardens, and urban farms and orchards tend to grow more types of plants in smaller areas. The new study is the first to explore the effects of urban gardens across a wide range of biodiversity measures and ecological services.

“It’s estimated that by 2030, about 60% of the world’s population will live in cities,” Jha says. “And urban farms and gardens currently provide about 15%-20% 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 support both biodiversity and local food production.”

The study also found that the choices that gardeners make can have a large impact on their local ecosystem. For instance, planting trees outside crop beds could increase carbon sequestration without decreasing food production from too much shade. And covering only within crop beds could help improve soil carbon services, while avoiding negative effects on pest control.