From individual wetlands to multifunctional wetland landscapes

How wetlands are designed has a major impact on both the environment and the people living nearby.

“The construction and restoration of wetlands can serve many different purposes: increasing biodiversity, removing nutrients, storing carbon, creating recreational areas, or regulating water flows,” says Pia Geranmayeh, researcher at the Department of Aquatic Sciences and Assessment at SLU.

“But it’s difficult to design a single wetland that provides all these ecosystem services at once.” 

Different goals require different solutions:

“To effectively remove nutrients, a wetland must be located in agricultural areas and have a certain size. On the other hand, a wetland intended to promote biodiversity should be placed near other aquatic environments so that species can spread, and it needs to be designed in a completely different way. Conflicts of interest can sometimes arise – for instance, wetlands that efficiently remove nutrients may also emit greenhouse gases, and if nutrient-rich topsoil is left during biodiversity restorations, it may worsen water quality.”

The goal is to balance these interests:

“After optimizing the design for a primary purpose, we try to enhance synergies and reduce conflicts. In this way, we can create a multifunctional wetland landscape – where the entire landscape is optimized based on local conditions,” says Geranmayeh.

Wetland research

Wetlands have been created and restored with government funding since the 1990s. Initially, the focus was on reducing nitrogen runoff and algal blooms in Laholm Bay. Later, the need to control water flows and reduce phosphorus losses was added. After the dry summer of 2018, the climate perspective also became central.

Despite major investments, few long-term and comprehensive measurements have been made of the wetlands’ effects. Today, the responsibility often lies with individual researchers, which leads to short-term follow-up – even though the benefits of wetlands change over time. There is therefore a need for long-term, coordinated measurements that capture the full variation of the ecosystem.

“We have measured, for example, greenhouse gases in some wetlands, and biodiversity in others – but not everything in the same wetland. That means we can’t see how the functions interact,” says Martyn Futter, researcher at the Department of Aquatic Sciences and Assessment.

In the ongoing project PuddleJump, SLU is measuring 20 wetlands in Uppsala, Enköping, and Östhammar. For the first time, they are being analyzed from multiple perspectives at once.

The project is being conducted in close collaboration with municipalities, authorities, and political scientists. Interviews and workshops with municipal project coordinators have revealed several challenges: long processing times, lack of long-term funding, and limited expertise in certain areas when the work is carried out alone – especially in smaller municipalities.

“Many municipalities lack resources and networks to share experiences. We support them with tools and advisory manuals,” says Pia Geranmayeh.

SLU has developed a national online map showing where wetlands provide the greatest benefits for nutrient removal. If a landowner wants to build a wetland where the purification potential is low, the purpose should instead be to support biodiversity or manage water flows. Researchers are now developing a new mapping tool that identifies locations in forests where water can be stored – for example, in old drained wetlands rather than on farmland.

“Uppsala planned to flood agricultural land to protect the city center, but that leads to nutrient leakage and eutrophication. Our tool shows alternative forest locations where water can be stored without negative side effects,” says Martyn Futter.

Citizen science and the next steps

A new feature in PuddleJump is the participation of citizens in research. By helping to observe plants, monitor water levels, and measure water clarity, more data is collected while participants’ understanding of wetlands increases. They also provide valuable information about recreational values that complement the scientific data.

Sampling in the 20 wetlands is now nearing completion. This fall, all collected data will be analyzed to give a clearer picture of how the wetlands of the future can benefit both nature and society.

“We need to see wetlands as parts of a larger landscape system, not as isolated units, and continue to follow up on both benefits and side effects. Only then can we optimize their function and create sustainable solutions for the future,” concludes Martyn Futter.