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Mowing urban lawns less intensely increases biodiversity, saves money and reduces pests - British Ecological Society

Researchers from the University of Quebec at Trois-Rivieres have found that reducing the intensity of lawn mowing in urban spaces leads to increased biodiversity, economic savings and reduced presence of allergy-triggering weeds. The results are published in the British Ecological Society journal, Journal of Applied Ecology.

An experimental site comparing the ecological effects of intense mowing (R) with low impact mowing (L) in Trois-Rivieres, Canada. Dr Chris Watson.
An experimental site comparing the ecological effects of intense mowing (R) with low impact mowing (L) in Trois-Rivieres, Canada. Dr Chris Watson.

The researchers combined data across North America and Europe using a meta-analysis, a way of aggregating results from multiple studies to increase statistical strength. They found strong evidence that increased mowing intensity of urban lawns – which included parks, roundabouts and road verges – had negative ecological effects, particularly on invertebrate and plant diversity. Pest species, on the other hand, benefitted from intense lawn management.

“Even a modest reduction in lawn mowing frequency can bring a host of environmental benefits: increased pollinators, increased plant diversity and reduced greenhouse gas emissions. At the same time, a longer, healthier lawn makes it more resistant to pests, weeds, and drought events.” said Dr Chris Watson, lead author of the study.

The issue with regular lawn mowing is that it favours grasses, which grow from that base of the plant, and low growing species like dandelion and clover. Other species that have their growing tips or flowering stems regularly removed by mowing can’t compete. Allowing plant diversity in urban lawns to increase has the knock-on effect of increasing the diversity of other organisms such as pollinators and herbivores.

The effect of intense lawn mowing on pest species was the least studied aspect of the research the authors looked at, featuring in seven datasets across three studies in Eastern Canada. However, in all of these studies they found that intensive lawn mowing resulted in an increase in the abundance of weeds and lawn pests.

Read the paper: Watson CJ, Carignan-Guillemette L,Turcotte C, Maire V, Proulx R. Ecological and economicbenefits of low-intensity urban lawn management.J Appl Ecol. 2019;00:1–11. doi.org/10.1111/1365-2664.13542