Urban gardens, because they are a mine of biodiversity

Urban gardens, because they are a mine of biodiversity

Urban gardens

The rivalry between urban and rural areas has deep roots. But an expanding movement, accompanied by a new scientific field, is progressively eroding this gap, seeking to bring more countryside to the city. So-called rurbanization promises to secure a greater share of locally grown food, beautify the urban environment and even reduce temperatures during heat waves.

The trend also subverts the old assumption that growing food would harmful to biodiversity, because the deforestation of land to be used for agriculture requires the elimination of native plants and animals. Ecologist Shalene Jha of the University of Texas at Austin says this idea is based on observations of rural agriculture, where large industrial crops of corn or wheat can have catastrophic effects on ecosystems. However, this is not the case for urban agriculture, city gardens and smaller green spaces.

Assisting biodiversity

In a recent article published in the journal Ecology Letters, Jha and his colleagues have shown that urban gardens can actually increase biodiversity, especially if those who tend them focus on planting native species, which attract native insects such as bees. “It doesn't matter how big or small the garden is. It is the practice of cultivating the landscape – and the decisions regarding vegetation and land cover – that ultimately determine the plant and animal biodiversity in that place,” explains Jha.

The ecologist's team analyzed the biodiversity of twenty-eight urban gardens in California over a five-year period, discovering very active ecosystems that have increased the diversity of species in the area. In California gardens, the researchers found predators such as birds and ladybugs — which feed on the insects that devour crops and thus help increase yields — and an abundance of pollinators such as bees, which in turn benefit from the variety of crops and increase plant productivity. This means that urban gardens not only produce food for people, but also for other species: "They actually support incredibly high levels of plant and animal biodiversity" , highlights Jha.

One of the challenges of urban agriculture is that it requires intensive manual work: you cannot drive a combine harvester into town at harvest time. From an ecological perspective, however, this restriction is actually a blessing. Since all the work is done by hand, urban farmers can grow any type of plant next to each other, thus increasing the yield.

Multi-pronged benefits

In another study published this month in the journal Agronomy for Sustainable Development, a team of researchers surveyed seventy-two urban farming sites in France, Germany, Poland, the UK and the US. “We see quite diverse growing spaces that often grow a huge variety of crops, as well as non-food products,” says study author Jason Hawes, an environmental sustainability researcher at the University of Michigan. On average, the sites grew twenty different crops. “Many people also grew flowers for fun, and in community gardens flowers are planted to make the space more pleasant – explains Hawes -. This kind of thing contributes to local biodiversity".

This biodiversity strengthens urban ecosystems against pests, which would instead have an easy life with a monoculture: "Suddenly you have an imitation of what happens naturally in terms of insect predation because if you build it, they will come" – thus extending the food supply for local pollinators. While native plants are best at attracting native animals, pollinators can make do with even an imported tomato plant. "I'm a huge fan and advocate of native plants, but I'm an even stronger advocate of growing with a purpose” – says Jennifer Bousselot, horticulturist at Colorado State University, who studies the p practice of rooftop cultivation and did not participate in any of the new studies –. And believe it or not, most pollinators are able to adapt".

Bees, in particular, particularly appreciate well-designed urban gardens, especially if they are rich in ornamental flowers. In the past, several Research has shown that bee-related diversity can be higher in cities than in surrounding rural areas.It is counterintuitive, but the floral diversity of an urban garden can be greater than that of a wheat or corn field.

And while they may appear unsightly to the human eye, bees definitely appreciate brown patches of earth.Unlike honey bees that live in beehives, the vast majority of species are solitary and many dig into the earth for shelter A piece of land in a garden offers them a habitat. Bees also hate open spaces, where birds, dragonflies and other predators roam: "It's like they have a giant target on their back that says 'Eat me,'" says biologist Gerardo Camilo, who studies urban bees at the University of Saint Louis but was not involved in the studies. If you leave your garden a little messy, bees will have places to hide as they hop from flower to flower. "There is a message for everyday gardeners to grasp: with  minimal effort, a big change can be made," Camilo points out.

But there are still limits to what an individual urban farmer can do. A bee must first be able to reach a home garden. For this reason, cities need to have chains of green spaces – with some exposed land and untidy vegetation – for insects to travel safely. "The neighborhood surrounding your garden should be inviting to bees, so as to offer them a route to work," says Camilo.

The future of food

This type of solution requires collective urban actions and planning, but guarantees chain benefits. Greenery absorbs rainwater, for example, mitigating urban flooding. Plants also release water vapour, drastically lowering temperatures, which in cities are much higher than in rural areas due to the preponderance of concrete. Green spaces are also great for mental health. Food waste can end up directly in urban gardens in the form of compost, reducing reliance on synthetic fertilizers, which are terrible for the planet. Finally, city gardens are able to produce food closer to the place of consumption, reducing the emissions associated with the transport of products.

It is increasingly evident that crops in urban areas can be much more productive compared to rural farms. For some vegetables, such as cucumbers, yields can be up to four times higher. This is largely due to the fact that urban farmers tend their crops by hand, an activity that requires a lot of effort but also creates jobs.

The spread of more vegetable gardens in cities, however, it comes with challenges. First of all, finding land for urban agriculture is not cheap. Furthermore, urban gardens need water, which is always a particularly precious commodity; rainwater harvesting systems would be ideal, but cities could also build infrastructure to channel rainwater into green spaces.

Bringing more agriculture to urban areas must become a priority: more than half of humanity now lives in cities, a share that according to forecasts will rise to 5 billion people by the end of the decade. "Urban gardens produce 15-20 percent of our global food supply, and this number is growing. And therefore their value, not only in terms of food production, but also in terms of plants and supporting animals, is increasingly important,” comments Jha.

This content originally appeared on sportsgaming.win US.

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