Since the confinement, the town halls of certain cities let grow their lawns. It is an opportunity to allow flora and fauna to develop and thus to promote biodiversity. A choice made in particular by the Parc de Bercy, where Europe 1 visited.

Tall lawns, 20 or 30 centimeters in big cities, it's an unusual sight. If nature takes back its rights, it is with the agreement of the municipal authorities who let the lawn grass grow well beyond the usual sizes. In addition, 43% of the municipalities questioned during confinement say they are ready to put the mower away for the long term. The objective: to promote biodiversity.

Biodiversity promoted by confinement

In the Bercy park, 14 hectares in the heart of Paris, some walkers, returning since Saturday, are surprised and thought that "it was due to confinement, that there was less maintenance". However, in Paris as in Versailles, Strasbourg or Arcueil, the municipality deliberately lets grow certain lawns. By this means, the blades of grass go up in seed, make flowers which attract and feed insects which are then used as meal for the birds.

This is bearing fruit: this year, the tits are in their third litter, while the bad years, it's only one. The calm of confinement, more abundant food and mild weather thus favored the reproduction of animal species.

"A return from nature"

In the alleys of Bercy Park, some nettles even reach almost a meter high. Far from being a simple weed, as Philippe Jacob, the manager of the Paris biodiversity observatory explains, "it's a return to nature, it's a plant that we don't have a lot, but a lot of insects. "

The example of these benefits of nettles is particularly visible for butterflies. In particular, "a cohort of butterflies, called small tortoises, which will lay eggs specifically on nettles and whose caterpillar only eats the leaves of nettles" explains Philippe Jacob.

Letting nettles grow therefore favors these colorful butterflies. A new habit to take but which does not worry the walkers of the park, "we have the impression of being a little bit in the fields, we are used to a very clear lawn but I think we will quickly get used to. "