Sitting under that big oak tree in your backyard, you likely notice the support and shade it offers. It’s a place to rest in the summer months and appreciate colorful foliage in the fall. Its branches also provide entertainment as you listen to the birds sing and watch the squirrels rustle. And as you take a deep breath, clean air fills your lungs. The tree is providing you with what’s known as ecosystem services, free of charge.

Ecosystem services, also known as natural capital, are the direct and indirect benefits that natural systems provide for human wellbeing and quality of life. This includes tangible benefits, such as food, fresh water, and flood control, as well as cultural benefits such as aesthetic value, recreation opportunities, and mental health.

Our natural resources are worth something, arguably a lot. Dr. Robert Costanza’s 1997 publication in Nature prompted economists to place value on such services in an effort to better understand the true value of our ecosystems and thereby make better decisions. The tricky part is figuring exactly how much that something is, in the form that people care about: dollars and cents.

Economists use a variety of methods to determine the value of an ecosystem. Entrance fees tell economists how much people are willing to pay to enjoy State Parks. Waterfront housing prices show how much people are willing to pay to enjoy a lake. And the cost to treat water at treatment plants tells economists how much money is saved when a wetland purifies water instead.

Each method is slightly different and warrants different numbers. Yet, the idea remains the same. Nature is worth something, and it is a lot.

Ecosystem Service Provided by Wetlands

High-quality wetlands are some of the most significant producers of ecosystem services, particularly for water-related functions. Wetlands trap nutrients in soils, reduce greenhouse gas emissions, and purify water. They play a major role in stormwater management and flood risk reduction. And they are home to a long list of plant and animal species. “You’ve got your birds, soils, amphibians, fish, a lot of things like dragonflies and butterflies, [wetlands] just have everything,” says Tom Bernthal, Wetland Monitoring and Assessment Coordinator at Wisconsin DNR.

Bernthal has dedicated his career to wetlands. “I like [wetlands] because I like to do things that the rest of the world doesn’t already know about. And then once you get into them, into the better-quality wetlands, they’re just really cool.”

Wisconsin’s wetlands provide over $3.3 billion dollars in economic benefits to the state each year.

Wetlands provide more services than almost any other ecosystem. Globally, the annual value of swamps and floodplain wetlands is estimated at over $25,000 per acre. In the Midwest, a similar analysis found wetland value to be over $1.6 million per acre each year. These two estimates differ based on which services were considered. The more services, like clean air, the economist considers, then the higher the value. In both studies, the economic value of wetlands was higher than that of any other inland land cover type, including forests.

When considering services like flood protection, waste treatment, water regulation, gas and climate regulation, recreation, and habitat, Wisconsin wetlands provide over $3.3 billion dollars in economic benefits to the state per year.

Of course, not every wetland shares the same price tag. “Being smarter at how we restore wetlands is, in part, to spend the most money on the projects that are going to give the most bang for their buck,” says Bernthal. “I think it’s important to demonstrate the value of the ecosystem services that wetlands, in general, are providing… But when you say an individual wetland, that’s when I get a little nervous.”

Assigning a monetary value to a specific wetland can be extremely subjective. If trying to argue for the protection of the Waubesa Wetlands, for example, it’s very difficult to put value on things like aesthetic beauty or peace and tranquility. These things clearly matter, but are hard to quantify. Clean air may be valued higher than watching a squirrel, but by how much?

Rather than arguing over exact dollars and cents, ecosystem valuation should be considered one tool in the toolshed. “Nothing on its own is going to be sufficient,” says Bernthal.

Assessing Ecosystem Services in the Waubesa Wetlands

In partnership with CARPC and the Wisconsin DNR, graduate students in UW-Madison’s Water Resources Management program completed a report that assesses land use impacts in the Waubesa Wetlands watershed. This 2018 report highlights how analyzing ecosystem services can be a valuable tool for informing management decisions.

The Waubesa Wetlands, one of Wisconsin’s Wetland Gems, is a diverse complex of wetlands on the southwestern toe of Lake Waubesa. Two inlet streams, Swan and Murphy’s Creeks, flow through the City of Fitchburg and the Town of Dunn into the State Natural Area. Concern over future development’s potential impact on the streams and wetlands spurred creation of a Technical Advisory Committee in 2017.

With guidance from the Committee, the UW–Madison project monitored stream water quality, modeled potential future land use and climate change scenarios, and engaged watershed residents. The study team also completed an ecosystem services assessment for the Swan Creek corridor, which highlighted the importance of wetlands for wildlife habitat, flood and stormwater storage, groundwater provision, and water quality protection.

The assessment determined that wetlands in the Swan Creek corridor provide many services beneficial to humans and uphold the overall ecological integrity of the downstream Waubesa Wetlands. Understanding the services provided by this system helped the team set restoration priorities and identify the potential impacts of urbanization in the Waubesa Wetlands watershed.