Common reeds under control, decided the villagers

The eutrophication of lake shores and the slowness and high cost of mowing common reed prompted the start of a project to restore the shores of the Kuokanniemi lake in Sumiainen in the summer of 2022," says Jaakko Soikkeli, project preparer.

Common reed is one of the most common plant species by lake shores. It grows and spreads rapidly through its root system and clogs up the landscape. It also impairs water flow and oxygen levels, recreational use of beaches and the value of coastal properties. When it accumulates on beaches, it causes aesthetic damage, releases greenhouse gases through decomposition and nutrients stored on the bottom back into the aquatic ecosystem.

"Common reed has spread rapidly in Finland over the last decades and is estimated to be present in coastal and lake areas on up to 100 000 hectares. It has become quite a problem," says Soikkeli.

However, there are very few riparian mowing and harvesting companies in Finland, which makes timely mowing at an affordable price difficult.

"When no good mowing and harvesting contractor could be found, a working group of villagers was formed in February 2023 to think of new solutions for removing and utilising common reed," says Soikkeli.

The aim was to develop a system that would make the mowing of aquatic plants more ecologically and economically sustainable and that would allow mowing and harvesting to be carried out simultaneously.

"At the end of July and beginning of August, the mower was already in operation and mowing in the water. Even though we were late getting started last summer, we managed to clear 10 hectares of banks," says Soikkeli.

All of the ferry's functions are electrically powered, and no hydraulics, which can be dangerous for water bodies, are used at all. The batteries are charged by solar cells and a low-power aggregate.

"Thanks to its technology, the platform is very quiet and its operation does not disturb the biota or residents of the surrounding area," adds Soikkeli.

The mowing of common reed increases biodiversity. Mowing prevents common reed from spreading and becoming too dense, helps to recycle water by increasing the aeration of the shore and promotes the growth of other plant species. Mowing increases the resilience of the ecosystem against eutrophication, reduces climate emissions and provides better habitats for different animal species. It increases recreational use of beaches and creates amenity in coastal landscapes.

"In the first phase, we received permission to dump common reed, but in the longer term we plan to use common reed in a more diverse way," says Soikkeli.

Common reed is rich in nitrogen and phosphorus and can be used as a soil improver, for example in fields. Lake reed is also a good raw material for compost and mulch.

Common reed can also be used as roofing and insulation material.

"A properly built common reed roof can last up to 100 years," says Soikkeli.

Thanks to its hollow structure, it is also an excellent insulating material. In the future, common reed can be used in energy production, composite structures, growing media and even as a material for the battery industry.

The project received funding from Metsä Group's Funding programme for Nature Projects.

"Metsä Group's funding came in handy. Product development of a brand new invention is a long-term process and takes a surprising amount of money. Thanks also to all the volunteers who gave their time to the project," says Soikkeli.

The aim is to replicate the invention in the future and save the shores of lakes in other parts of Finland.

The article originally appeared in Metsä Group's Viesti magazine 2/2024