When you think of wetlands, you probably think of marshy areas around lakes and rivers. But there are also wetlands in the damp forests of the Pacific Northwest. And those wetlands can be very important for storing carbon and helping to slow climate change. Researchers in Washington are mapping the forested wetlands of the West. Natalia Mesa, Editorial Fellow for High Country News, joins us to talk about the effort, and the importance of wetlands, which she recently wrote about.
Note: This transcript was computer generated and edited by a volunteer.
Dave Miller: From the Gert Boyle Studio at OPB, this is Think Out Loud. I’m Dave Miller. When you think of wetlands, you might think of marshy areas around lakes and rivers, perhaps the US Southeast. But there are also wetlands in the damp forests of the Pacific Northwest, and a new study found that they are more extensive than scientists previously thought. Natalia Mesa is an editorial fellow for High Country News. She recently wrote about this and she joins us now. Natalia, welcome.
Natalia Mesa: Thank you for having me.
Miller: You note that more than 50% of the wetlands in the lower 48 states have disappeared since European settlement. What are the biggest reasons for this?
Mesa: Wetlands have historically been prime targets to build farms and towns, both of which are super water hungry. The main drivers of wetland loss have shifted over time. Back in the day, it was draining and converting wetlands to farmlands and pastures. But in the past century or so, urban development has also become a huge driver of wetland loss.
Miller: And this loss is increasing?
Mesa: That’s right. A new report by the US Fish and Wildlife Service found that wetland loss has sped up in the last decade or so, which is extremely concerning. We’re still draining wetlands and converting them to agricultural land. But factors like warming due to climate change are also likely speeding up wetland loss.
Miller: Why are wetlands so important? I mean, what’s lost when wetlands dry up?
Mesa: Oh man, it’s hard to overestimate the importance of wetlands. Wetlands provide a ton of benefits for both humans and wildlife. They’re really important habitats. More than 10% of all species and 15% of endangered species rely on wetlands. Wetlands also provide flood protection to nearby areas. They are water quality improvers, they can slow shoreline erosion. Without all of these, we would see species decline and decline in human health. They also store a lot of carbon and are a really important tool to fight climate change. Even though they are only about 6% of the world’s land surface, they contain 20% to 30% of the carbon stored in soil.
Miller: Why have wetlands in the west been so hard to map in the past?
Mesa: There are certain types of wetlands that have been hard to map in the past. To make maps of wetlands, scientists use satellite imagery. But the problem with that is that some wetlands are in forests and literally covered by the tree canopy. Some wetlands are also ephemeral, meaning they’re only flooded at certain times, or they have water flowing underneath the soil that isn’t visible to satellites, and we have a lot of those forests in the Pacific Northwest. So it’s possible that we’re missing a lot of these forested wetlands. And that’s one of the reasons why they don’t appear on federal or state maps.
Miller: That was part of the impetus behind this new research that you recently wrote about. What did these researchers have to do for this study?
Mesa: The study that I covered was trying to map out forested wetlands and quantify the amount of carbon they stored. It was conducted by researchers at the University of Washington’s College of the Environment. And to map out these wetlands … specifically in the Hoh Rainforest, they used a cool technique called “Lidar” to map the areas from the sky. This technique is able to see through the tree canopy and give them a picture of what’s underneath. But that’s only part of the story.
They also needed to go out into the field and validate that what they were seeing was actually a wetland, and also collect data on how much carbon is stored in the wetlands. To do that, they went out into the Hoh Rainforest. That meant hiking into these really remote areas and bushwhacking and driving on these dirt roads in the middle of nowhere. And once they were there, they dug a hole in the ground and lugged that soil back to the lab to measure the carbon. So it was a lot of work.
Miller: What did they find?
Mesa: They found a lot of unmapped wetlands. They found an almost 300% increase in the land area covered by wetlands in the Hoh Rainforest. And they found that overall, these hidden wetlands are also super carbon-rich. They store five times more carbon than scientists previously estimated, and could be a really important tool to fight climate change.
Miller: In 2016, a federal study concluded that wetlands in the west held about 6% of the total carbon stored by the wetlands of the lower 48 states. This new paper suggests that that was an underestimate, but by how much?
Mesa: We don’t really know the answer to that yet. But the really exciting part of the study is that they developed a tool to figure out how much carbon is likely in other forested wetlands, so that future studies will be able to map the carbon in the west and the extent of wetlands in the west more accurately. This is something that they can easily transfer to other forests in the Pacific Northwest.
Miller: Will this finding lead to a different land or wetland management plan in the Hoh Rainforest on the Olympic Peninsula? Will people treat this area differently now?
Mesa: I think so. Washington is actually doing pretty well in terms of wetland conservation. We have state laws that explicitly protect wetlands and now that these wetlands are on the map, hopefully land managers can make decisions about how to protect them.
Miller: That is based on state law, but what did a recent US Supreme Court ruling mean for the preservation of wetlands at the federal level?
Mesa: The Supreme Court ruling, “Sackett v EPA,” basically took away protections from millions of acres of wetlands and weakened the Clean Water Act. The justices, based on no available science, redefined wetlands as “waters that have a continuous surface connection to another body of water.” And there’s a pretty rock solid scientific consensus that that’s not a good definition of a wetland. Like I said, some wetlands flow beneath the surface, some are only around seasonally. But the good news is that the Biden administration has made it a priority to conserve wetlands and states are starting to pass laws that explicitly protect them.
Miller: Are there other areas in the Northwest that researchers know they want to study next?
Mesa: The study was conducted on only a small region in the Northwest. There are acres and acres, tens of millions of acres of wetland in Washington, Oregon and Alaska, that still need to be mapped. But these researchers are also interested in studying these areas over time, and figuring out how factors like deforestation and climate change impact these wetlands, which now they can do because they have a more accurate and useful baseline of the amount of carbon stored.
Miller: Natalia, thanks very much.
Mesa: Thank you.
Miller: Natalia Mesa is an editorial fellow for High Country News. Her recent article focused on new research that found more extensive forested wetlands in the northwest than were previously known about.
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