Tall grass even in urban spaces to preserve biodiversity

We often talk about how important biodiversity is for natural ecosystems and for the health of gardens, where choosing different varieties or allowing small weeds to grow allows us to achieve a healthier lawn and richer soil. This discussion, however, can also be extended to urban greenery, that is, to all those places, often public, such as parks and flowerbeds, that enrich hyper-urbanized cities with a little nature. Recently, some local governments have introduced changes to the maintenance programs for urban green areas, producing significant improvements in public well-being.



The importance of urban greenery and preserving its biodiversity

Urban greenery plays a fundamental role in the air quality in large cities and, more generally, in the well-being of those who live in them. It is not just about the ability of trees to combat climate change by storing carbon dioxide, but also and above all about their ability to reduce temperatures, countering the heat typical of concrete jungles. Furthermore, the presence of green spaces in cities reduces the presence of fine particulate matter and thus mitigates pollution.

This year, many local governments in Italian cities have decided to let the grass grow a little taller than usual in parks, flowerbeds, and urban green areas. The goal of this strategy is not only to reduce maintenance costs, but also to increase the biodiversity of these environments. Among the taller blades of grass, in fact, many more species can nestle compared to the number that can live in an environment with short-cut grass. We are talking about insects, undoubtedly, but also about the plants themselves, since a frequently mown lawn prevents the production and dispersal of seeds and, therefore, the growth of different plant varieties.

With a good level of biodiversity, however, plants can effectively disperse pollen and seeds, animals find enough food, achieving the coexistence of more species and avoiding, instead, a few species from dominating the others, causing imbalances in the health of the ecosystem. Furthermore, when the grass is taller and is not immediately cut, it also gives flowers time to appear: in this way, bees, invaluable sources of life and biodiversity, can thrive. 

The variety of pollinators and all other insects is also fundamental in cities, because the decrease in their presence in urban areas causes no small problems for the balance of the ecosystem. More insects mean more variety, more pollination, but also a greater presence of species of other animals that feed on insects, causing an overall enrichment of the diversity of urban green spaces.

The positive consequences of letting the grass grow tall

There are several studies that confirm the benefits of letting the grass grow tall in urban green areas. A 2022 research by the Free University of Berlin involved observations in Europe and North America and concluded that there is a direct relationship between a low mowing frequency and a high concentration of insects. The conclusion clarified that a lower frequency of mowing not only increases the presence of insects, but also increases their biodiversity. In fact, by comparing it with data relating to urban parks with regularly cut grass, it emerged that in these places there is a predominance of insect species considered harmful, such as mosquitoes and ticks.

Increasing biodiversity also means populating cities with species of birds, mammals, or other insects that feed on mosquitoes or other dangerous or annoying insects, effectively reducing the dominance they have within urban areas.

In addition to the benefits in terms of biodiversity, letting the grass grow tall also brings other environmental advantages. For example, more abundant vegetation reduces soil erosion, absorbs a greater amount of carbon dioxide, and consequently reduces the heat of cities. 

In short, letting vegetation take up its space, and avoiding trying to fit it into orderly patterns that respond to aesthetic standards, is much more functional and useful to the environment. It is the message we try to teach with the dry philosophy, which uses the strategies of nature itself to take care of it, without the pretense of serving it according to our will.