Can urban gardeners benefit ecosystems while keeping food traditions alive?

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From: University of Illinois at Urbana-Champaign 
Published April 6, 2016 06:51 AM
http://news.aces.illinois.edu/news/can-urban-gardeners-benefit-ecosystems-while-keeping-food-traditions-alive

When conjuring up an image of a healthy ecosystem, few of us would think of a modern city. But scientists are increasingly recognizing that the majority of ecosystems are now influenced by humans, and even home gardens in urban landscapes can contribute important ecosystem services.
“Ecosystem services are the benefits that ecosystems provide to humans. In a natural ecosystem, these are things like natural medicinal products or carbon that’s sequestered by forest trees. In an urban context, it would be similar types of things. For example, shade from trees provides microclimate control to keep us more comfortable,” explains University of Illinois landscape agroecologist Sarah Taylor Lovell.

Lovell and her colleagues investigated the ecosystem services and disservices provided by home food gardens in Chicago, adding a cultural dimension by looking at gardening practices in specific ethnic communities. In an earlier study, they found a high density of food gardens in Chicago were in African American, Chinese-origin, and Mexican-origin communities.
The team visited and interviewed nearly 60 households across the city, noting the types and relative abundance of the edible plants, ornamental plants, and trees in each garden.
“The number of species grown across all of the gardens was comparable to the number of species found in a remnant native prairie near Chicago,” Lovell reports. “But the vast majority of garden species were not native to the region.”
The number of plant species in an area can have a direct impact on insects, birds, and other wildlife, but non-native crops may not benefit wildlife in an urban context to the degree that native plants might. The researchers identified additional consequences to urban food gardens in terms of ecosystem services.
“Most of the gardeners were using synthetic fertilizers to really optimize production,” Lovell explains. “In doing so, they were increasing some nutrients to a level that could lead to runoff and contamination of surrounding environments. We also identified a tradeoff between needing sunlight for your vegetable garden and preferring a treed habitat for microclimate control. Gardeners would sometimes remove trees or reduce the level of shade and shrubs.”
Despite these issues, the researchers noted that urban gardens play an important role in the cultural lives of gardeners and may lead to greater food security where fresh produce is not easily available.