A group of scientists did a fascinating experiment: They proved that adding more plants to even tiny, mangy little urban greenspaces can massively boost their biodiversity.
In 2016 they honed in on a small, 200-square-meter greenspace in downtown Melbourne — a place that is "adjacent to a major road, surrounded by large buildings, and embedded in a dense urban matrix." It wasn't exactly a verdant paradise; in fact it only had two gum trees.
They added twelve more indigenous plant species, then monitored what happened over the next four years.
The insect diversity exploded: In a year there were five times as many insect species, and two years after that, there were seven times as many as at the beginning. Better yet, most of the insects were indigenous, so it wasn't a case of the new plants attracting invasive species. (Their paper on the experiment is here.)
The upshot is that we clearly ought to be adding far more locally-appropriate plant-life to urban greenspaces. Given that insect populations are globally — and disastrously — on the decline, this is one awfully easy and probably not-that-expensive way to help out, at scale, around the world.
"I can't think of any drawbacks," says Mata. "On the contrary, the indigenous plant species require less water and don't require fertilisers." Now they have grown to cover most of the ground, there is also no more need for weed control, he says.
"This report demonstrates the ability of healthy plant and fungi communities to provide the building blocks for ecosystems abounding with biodiversity," says Ian Dunn, head of UK conservation charity Plantlife, which has been campaigning to boost wild flowers and wildlife simply by encouraging individuals and city officials to mow lawns, parks and road verges less often, or to mow at better times.
(CC-2.0-licensed photo of street flowers in Tel Aviv via RG in TLV's Flickr feed)