If biodiversity rose, would you even notice?

Many people say they’d like to see more biodiversity in their city parks and gardens. But a study suggests that when new species do appear, urbanites remain oblivious to the improvements.

The researchers conducted their experiments at 14 public gardens in Paris, each roughly 1 hectare. In some of the gardens, the team took steps to increase biodiversity such as turning lawns into flowerbeds, sowing seeds, planting starflower to draw pollinators, encouraging the growth of plants that support butterflies, and adding nest boxes for birds.

The researchers then surveyed the gardens to see if biodiversity had actually improved. They recorded bird sightings and sounds, captured butterflies, and took pictures of flowers. The team also interviewed 1,116 people who regularly visited the gardens to find out whether they valued biodiversity and had noticed the changes.

The garden improvements worked: 14 new flowering plant species grew, and the number of pollinator and bird species increased by 49 percent and 26 percent, respectively. However, visitors “neither noticed this diversity nor the changes we implemented”, the team reports in Biological Conservation. Even though 57 to 89 percent of respondents said they wanted a variety of flower, tree, and bird species in the gardens, their estimates of the number of species didn’t change much after the biodiversity improvements. Estimates of flower diversity went up only if the gardens had offered opportunities for the public to learn about biodiversity and the recent improvements, such as activity days and signs.

Visitors might not be very interested in nature or might simply lack the knowledge to pick up small details in the gardens, the team speculates. It’s possible that city-dwellers have been separated from nature for so long that they don’t recognize a good thing when they see it. So urban planners can’t assume that improving parks will foster more environmentally-conscious attitudes. “Efforts to increase people’s conservation awareness in cities may thus be in vain unless we gain a better understanding of those aspects that people may notice,” the authors conclude. Roberta Kwok | 11 February 2014

Source: Shwartz, A. et al. 2014. Enhancing urban biodiversity and its influence on city-dwellers: An experiment. Biological Conservation doi: 10.1016/j.biocon.2014.01.009.

Image © Piotr Marcinski | Shutterstock