A recent meta-analysis study carried out by researchers from Freie Universität Berlin has demonstrated that properly managing green spaces in cities can have a positive effect on the abundance and diversity of insects living there. A research team led by biology professor Jens Rolff discovered that mowing green spaces twice a year or less proved particularly beneficial to flying insects such as butterflies and bees. In the study, the researchers compared data from several countries. This included data from Freie Universität’s “Blühender Campus” (Campus in Bloom) project. In particular, this meta-analysis showed that flying insects and species that live in upright vegetation profited most from a reduced mowing regime. The results demonstrated that a more insect-friendly approach to green space management did not lead to an increase in perceived pest species that, for example, damage plant roots or cause stings. Rather, these insects occurred less frequently in the “wilder,” less manicured areas. The study was published in the international journal Urban Forestry and Urban Greening.

“The global decline in insect populations has reached alarming proportions,” warns Sophie Lokatis, coauthor and key player in establishing the “Blühender Campus” initiative. She also emphasizes that this is an issue that is not restricted to the agriculture industry – insects also rely on green spaces in urban areas and towns. Jens Rolff adds, “In Berlin alone, public green spaces account for thirty percent of the total area. This means that they have huge potential for protecting biological diversity. And that’s not even counting private gardens.” The study makes it clear that even simple, cost-effective landscaping measures can contribute toward promoting insect diversity.

“While many studies have already been carried out on the subject, the variety of approaches often makes it difficult to draw comparisons,” explains Anja Proske, first author of the study. Proske completed her master’s degree at Freie Universität in 2021 and now works as a biodiversity specialist for the Deutsche Wildtierstiftung (German Wild Animal Foundation). “However, in the end, we were able to integrate twenty-eight studies from Europe and North America into our research, allowing us to generate conclusive results.”

“The results of our study also show that not all types of insects benefit equally from the measures,” says Lokatis. “Here on campus, we are experimenting with different types of upkeep measures. For example, we are leaving large areas to their own devices over the winter months.” It is clear that many public and private green spaces in cities have the potential to contribute toward protecting insect life, notes Professor Rolff.

“This study illustrates that, with the ‘Blühender Campus’ initiative and a campus-wide effort to implement a more insect-friendly mowing regime, Freie Universität is on the right track when it comes to protecting biodiversity,” says Andreas Wanke, director of the Unit for Sustainability & Energy Management at Freie Universität. “We can act as a good example.”

Online Publication

Anja Proske, Sophie Lokatis, Jens Rolff (2022) Impact of mowing frequency on arthropod abundance and diversity in urban habitats: a meta-analysis, Urban Forestry & Urban Greening
https://doi.org/10.1016/j.ufug.2022.127714

Contact

• Prof. Jens Rolff, Freie Universität Berlin, Institute of Biology, Tel.: +49 (0) 30 838 54893, Email: jens.rolff@fu-berlin.de