City ecologist says taller grass does not mean more ticks

City ecologist Merle Karro-Kalberg has said taller grass does not automatically mean more ticks, ERR reported in its Vikerraadio programme Ökoskoop. She said urban ecology is not about leaving all grass uncut, but about giving less dominant plants a chance to support biodiversity.

Karro-Kalberg described Maarjaväli, a large green area in Tartu between Physicum and the current Konsum store, as a testing ground for urban biodiversity. The area was used as allotments by city residents in the 1990s before it was transferred to the University of Tartu. The university has mowed it annually, and it now has a relatively species-rich community.

The University of Tartu is working with the city of Tartu on the Rohering project, which tests different ways of restoring biodiversity in urban areas. At Maarjaväli, these include less frequent mowing, establishing meadows and habitat fences, and creating donor patches using seeds collected from nature.

Sheep maintain part of the area, while cattle have also been introduced this year. Karro-Kalberg said the animals had been well received by city residents.

Karro-Kalberg said urban green spaces were once mainly created for visual appeal and recreation. Today, she said, biodiversity loss is one of the main environmental problems. Frequent mowing favours only a few plant species, while plants such as nettles are important to several butterfly species and thistles provide food for many pollinators.

She stressed that urban ecology does not mean leaving every area uncut. Spaces for playing ball and having picnics are still needed, but the balance has shifted too far towards closely mown lawns. Such lawns are sometimes called green deserts because they support few plant species and offer little to pollinators.

Karro-Kalberg said she had not found a single tick at Maarjaväli. There is no scientific evidence that taller grass or hay immediately means more ticks, she said. People who are especially concerned about ticks can mow a metre-wide strip along paths and avoid walking into tall grass.

At the same time, mowing remains necessary, she said. If land is left completely uncut in Estonia, it will eventually become scrubland and then spruce forest. Biodiversity also requires sunnier areas, and meadows should be mowed once or twice a year.

After mowing, the cut vegetation should be left on the ground for a couple of weeks so that seeds can fall, then collected and removed. Otherwise, a new layer of decomposing material forms, allowing only stronger plants to grow through it.