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Do gardens foster biodiversity?

Even in urban areas, monarchs visit gardens.
Credit: Montréal Space for Life Day camps
 Même en zone urbaine, les monarques visitent les jardins.
  •  Même en zone urbaine, les monarques visitent les jardins.
  • Des apprentis scientifiques tentant d’identifier des insectes.
  • Des apprentis scientifiques dans la friche des Jardins-jeunes.
  •  Des apprentis scientifiques dans le jardin de vivaces aux Jardins-jeunes.
Do gardens foster biodiversity?

The story of a scientific experience | Summer 2021

The recipe was simple: get day camp youngsters involved and introduce them to community research. The goal was to prove scientifically that gardens promote biodiversity. Between you and me, there’s no denying that a garden promotes biodiversity in cities – but we were after some numbers.

A simple protocol

Over the summer, four cohorts from Space for Life day camps were formed to take invertebrate inventories. In total, 24 groups of animologues (9 to 10 years old) collected data on invertebrates from four different habitats. The idea was to compare the biodiversity on asphalt, on the lawn, in a flower garden and in an untended area.

Where did the idea come from to evaluate biodiversity in a wild meadow?

In May, when I was visiting the Youth Gardens, Banjo, the horticulturist in charge, introduced me to a secret corner of the Jardin botanique: an untended area. He explained to me that it was the result of an initiative aimed at letting nature do its work. In fact, an untended area is a transitional ecosystem. It’s what happens when you let grass grow. For some it’s an abandoned lawn, but for us it was a golden opportunity to evaluate the biodiversity there. Besides, an untended area comprises a space that needs no fertilizing and no watering.

The results

Based on our observations, gardens host an average of 13 species versus fewer than 3 for concrete surfaces. Overall, gardens and untended areas host two to three times more species than concrete and lawns. Even though everything was a little stage-managed (predictable), the results are indisputable: spaces where plant biodiversity is plentiful also foster animal biodiversity.

Graphic

Our results, illustrated in a graph.

How can such results be explained?

We can assume that this abundance of life is essential to the entire resulting food chain (birds, mammals, reptiles and others).

In addition, green spaces equate to food and shelter for the wildlife found there. They’re the basis of our urban ecosystems. If we wish to preserve wildlife in our cities, it’s vitally important to conserve natural habitats that are home to plants of all sorts in order to support it. Although the natural untended area hosts a little less animal life than the flower garden, our results indicate that the species we found were different in the two: more butterflies in the gardens, and more crickets in the untended area. In a way, these two habitats are complementary.

To be convincing, you need numbers

All summer I kept repeating, “to persuade people, you need to have numbers.” Now that we have them, let’s try to convince political decision-makers to develop more green spaces (of all kinds) in order to promote biodiversity.

Science, difficult sometimes, but educational!

Between the heatwaves, the storms and the tall grass that tickled, the animologues were faced with several challenges and met them brilliantly. We even caught some of them carrying on with their research right through lunch.

A big thank-you to the whole Space for Life day camps team and especially to the animologues, without whom none of all this would have been possible. I hope our experience helped develop your curiosity and your desire to preserve biodiversity!

See also

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