Disused agricultural land recovers only slowly without active renaturation  measures, and not completely even after decades. This was the finding of an international team, including researchers from the Center for Biodiversity Research (iDiV), the Helmholtz Centre for Environmental Research (UFZ) and the universities of Halle-Wittenberg and Leipzig.

The team compared 17 formerly farmed grassland areas in the U.S. state of Minnesota with areas that had never been tilled. The fields had been set aside at different times from 1927 to 2015 and were analyzed up to 80 years after conversion. “We wanted to find out how quickly and how completely the farmed areas recovered their original biodiversity,” explained first author Emma Ladouceur.

According to the iDiv, abandoned fields had not fully recovered even after 80 years. Sixty-three native species had not reestablished at all, but there had been an increase in alien grasses and weeds.

The research results could help improve renaturation. “This could be done, for example, by seeding or planting species that we know won’t establish on their own in the old fields, and by managing exotic species to reduce competition with native plants,” Ladouceur said.