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Forests and Carbon: Carbon Sequestration in Bogs and Peatlands

SPRUCE project plot enclosure, external view
Photo from SPRUCE project website
SPRUCE project plot enclosure, external view

KAXE's Tuesday Morning Show strives to take an in-depth look at some natural resource-based issues important to our region. Producer Mark Jacobs and hosts Heidi Holtan and John Latimer hope to discuss not only the problems but also highlight some creative solutions.

KAXE's Tuesday Morning Show strives to take an in-depth look at some natural resource-based issues important to our region. Producer Mark Jacobs and hosts Heidi Holtan and John Latimer hope to discuss not only the problems but also highlight some creative solutions.

The current focus, Forests and Carbon, is an issue receiving a lot of attention in recent years. In the first segment of the series, Todd Ontl chatted with John and Heidi about how forests sequester and store atmospheric carbon. Stephen Handler described potential changes in Minnesota's forests due to a changing climate in the second segment. In January, Eli Sagor from the U of M.N. discussed their information exchange efforts regarding forests and carbon. In February's episode, Meredith Cornett from The Nature Conservancy described their Natural Climate Solutions initiative. Sawyer Scherer from UPM-Blandin discussed diversity-centered forestry. Then, we covered biofuels in Minnesota's future with David Pelikan from Conservation Minnesota. Last month, we discussed carbon stored in forest products with Edie Sonne Hall. 

This week, Scott (covering for Heidi) and John cover carbon storage in bogs and peatlands with Paul Hanson, the principal investigator on the SPRUCE project in Northern Minnesota. Award-winner Mark Jacobs is the Forest and Carbon series producer and joined the conversation.

This interview has been lightly edited for clarity.


John: Up to now, we've been looking at carbon sequestration in trees and forests. But that's not really where the carbon is, is it, Paul?

Paul: Well, we're studying the spruce bog. Because peatlands occupy a small amount of the global land area but store a huge amount of the carbon in the system, our objective is to determine whether all of that stored carbon will stay put or be released back into the atmosphere under a series of warming treatments. We are funded by the U.S. Department of Energy Office of Science Biological and Environmental Research Program.

John: Bogs continue to sequester carbon all the time, correct?

Paul: Under current conditions, climate, and precipitation regimes, most of the bogs in the world are still accumulating carbon at small rates. Maybe not as much as they have been over the last 12,000 years, but they're still accumulating. Our objective is to determine whether that will still remain the case.

Mark: This is a major project with a lot of monitoring involved. Have you been able to find any good help locally?

Paul: We certainly have. We have two full-time employees that help us keep the experiment running. Both were born and raised in Northern Minnesota. They are full-time Oak Ridge National Laboratory employees. We also have a variety of folks like John who have found their way to the bog and joined the spirit of the effort.

Scott: And found his way out, too!

Mark: Obviously, this is an ongoing project, but what are some of your early results?

Paul: Well, we're now six and a half years into a decade-long project slated to be operated in its current form through the end of 2025. From the Department of Energy standpoint, the primary question is, "will the bog continue to take up carbon or lose carbon?". We found over our broad range of warming treatments that almost any level of warming leads to carbon loss. So, the peatland is now losing carbon as opposed to 10,000 years of gaining carbon. Most of that is in the form of carbon dioxide, but if it's still well-watered and flooded (as the bog is most of the time: not like last year), it also loses a considerable amount of methane.

Scott: How much of what you're studying at this particular bog can be generalized to other bogs?

Paul: The bog we're studying is considered a raised bog or ombrotrophic bog (it receives most of its water from rainfall, not underground sources). Peatlands are also occupied by free-flowing fens, which have higher nutrient contents. So, our results are specific to the raised bog and, in particular, to a black spruce/tamarack bog.

Researchers in SPRUCE bog experimental plot.
Photo from SPRUCE project website.
Researchers in SPRUCE bog experimental plot.

Scott: Why did you pick this area?

Paul: It's a long story, but we were looking for a new project in 2007 when federal funding for new projects was plentiful at the Department of Energy. We started looking for a spruce study in the high elevations of the Appalachians because they've been growing out of suitable climate growing space. That land base did not develop, but other spruce lands were available through the Department of Energy Forest Service Marcell Experimental Forest. So, a visit in 2009 started us off!

Scott: I've heard that about a third of the state of Minnesota is some form of wetland. Is that true?

Paul: I'm probably not the right person to ask, but I would say that's a fair statement. Historically, much more of the southern part of the state would have been wetlands before the agricultural lands were tiled and drained. [Editor's note: roughly 35% of the state was covered in wetland before colonization. Only half of those wetlands remain.]

Scott: Mark, you're familiar with Aitkin county. How would you describe the wetlands and bogs there?

Mark: We'd always considered Aitkin County about 50% wetland.

Scott: Okay. By the way, how's the flooding been? We've had such high water in the Mississippi drainage all spring and summer. Has there been much flooding there?

Mark: I don't get to Aitkin [the city] as often as I used to. I live near Jacobson; I certainly see the river near Jacobson is pretty high along Highway 200. So, I assume Aitkin is the same. I haven't heard of any major damage or anything from people I know there, but Aitkin floods just about every year to some extent.

Scott: So, Paul, how important are bogs and wetlands in the overall scheme of carbon sequestration and carbon dioxide release? 

Paul: From the standpoint of carbon sequestration, it's more of a historical storage unit. So, they're really important because they store this vast amount of carbon. There is concern that with warming or changes in precipitation levels, conditions will cause that to be released. That would then add more greenhouse gases to the atmosphere exacerbating the climate change problem. In terms of some peatlands that have been previously drained, if they're allowed to become wet again, they could return to carbon storage conditions.

Scott: We ditched [tiled and drained] all this land up here a hundred years ago to try to make it agriculturally intensive. So, that was weakening the carbon sequestration potential of the land?

Paul: Had it been effective, it would have. The drain peatlands I'm referring to are in Great Britain and Northern European countries, where they've emphasized dramatic use of that resource: more so than in Canada and the northern lake states.

Mark: Paul, I just want to point out that in Northern Aitkin County, right on the Itasca County border, we were doing a big peatland project in terms of looking at it as a wetland bank or for carbon credits or something like that. So we did some pretty intensive surveying, and it was amazing: even though those ditches weren't functioning very well, [there was considerable] sloughing of the peat around the ditches because of decomposition over the years. If you take the water out, it does decompose.

A tuft of sphagnum moss
Photo by iNaturalist user yurii_basov
A tuft of sphagnum moss

Scott: So, what is the physical form of the sequestered carbon? Is it old, dead, rotted plants?

Paul: Yep, that's exactly right. Here in a temperate climate, it represents material that has undergone a significant amount of what we call labile carbon materials: sugars, starch, carbohydrates, and such. What's left and stored away is somewhat recalcitrant (less susceptible to decomposition). Then, the fact that it's kept cold and underwater most of the time keeps it in that stored form.

John: Paul, we have several temperature regimes that we're testing (2.25, 4.5, 6.75, and 9 degrees above ambient temperature). What sort of things are we seeing taking place in the greenhouses?

Paul: In addition to the carbon storage question, which is the Department of Energy's primary interest in the SPRUCE study, we're also very interested in getting the most 'bang for the buck'. So, we're looking at vegetation responses; the [sphagnum] mosses (the keystone species for the raised bog system) don't like warming and the air drying associated with it at all. We're seeing loss of that particular component of the peatland. Unlike the sphagnum response, shrubs tend to like it a lot. They're sort of taking over the warmest treatments. (Keep in mind that our warmest treatments go well beyond projections for climate change.) We're covering a broad range of options.

Scott: There are actually silos, aren't there? Describe the site: how many silos are there?

Paul: Think of a greenhouse; there are ten fully-constructed experimental plots...

Scott: Controlled weather places?

Paul: Exactly. We're trying to cheat current conditions to give us a glimpse of the future, whatever it might be. From the side, they look like a greenhouse, except if you were to fly over them, you'd see a big gaping hole in the top that allows rain and snow to get in. So, we don't have to artificially produce that. The walls themselves and the sort of angled frustum (conical shape) at the top give us some efficiency in keeping that warm air envelope around the ecosystem we're studying.

Aerial view of SPRUCE project enclosures
Photo from SPRUCE project website
Aerial view of SPRUCE project enclosures

John: The vegetation has changed markedly. It seems the black spruce does not like warmth.

Paul: In the very warmest treatments (+9 degrees C or 15-17 degrees F above current temperature conditions), the spruce and tamarack have both been damaged periodically, not routinely, as it turns out, by the warmest treatments. When we started the study in 2016, we had a spring freeze event where all of those warm plot plants got started. We had a really cold event, and the foliage was damaged tremendously on the larch and the spruce several weeks later (or that's when we observed it). Then, just recently, with the last heat wave we had during developmental tissues in spruce, we've seen tissue damage in several of our warmest plots, which we hadn't seen before.

John: We've seen that the new growth, the new stuff coming out, wasn't heat-hardy.

Paul: That's a good way of expressing it. That new supple developing and extending spruce branch was not prepared for the really warm conditions: we're not only talking about the heat wave we had under warming conditions, but 16 degrees F above and beyond that.

John: This brings to mind the frost damage we had in '16. Because the ambient temperature is 15 degrees C or 27 degrees F below [the temperature of the warmest plot], it takes a pretty cold day to affect the warmest plot.

Scott: Paul, is there currently any other project like this in the United States?

Paul: This is unique in terms of its size and complexity. We tried to pull off whole ecosystem warming treatments in an intact system. And in this particular case, a high-carbon system important to natural carbon storage.

John: We've talked about carbon dioxide, are there other gases coming out that we should note?

Paul: The other gas that's very important is methane gas. It's produced when the bog is flooded, and there's no oxygen in that stored peat zone. Under those conditions, there's a variety of biochemical processes that some of my collaborators would be better suited to talk about. The bottom line is: that when it's warmer and flooded, we get more methane out of the system. That's important because methane is 30 times more powerful as a greenhouse gas than carbon dioxide, even though there's a lot more carbon dioxide out there.

John: 30 times more effective at holding heat in?

Paul: Yeah, the ability to retain heat, not in terms of carbon units. Interestingly enough, however, because of the very, very dry year we had last year, we saw the very interesting phenomenon that the methane release disappeared. With the dry conditions we had, the water tables dropped to about minus 70 to minus 80 centimeters below the surface of what we call the 'hollows' in the peatland. That allowed all of that upper peatland to be aerated. Once it's aerated, it shuts off the methane [producing] microbes.

Mark: Let's assume the project ends in a few years, and your results are similar to what you have right now. Will recommendations be coming out of this? What can we do to reverse that, other than just reducing greenhouse gas emissions?

Paul: Well, the role of the Department of Energy researcher is to provide information and results; in our case, results across a range of temperatures for the public and the policymakers to make decisions about where to move forward. What we're learning from the SPRUCE study is that any amount of warming is causing carbon release from peatlands. That needs to be factored into full carbon budgets that can inform the relationship between natural carbon cycles and anthropogenic or manmade carbon components.

Interior view of SPRUCE project plot
Photo from SPRUCE project website
Interior view of SPRUCE project plot

Scott: Has it occurred to you from your research that there might be some effective way for humans to artificially intervene in containing methane or carbon?

Paul: Well, that goes beyond my area of expertise: I think that's the bottom line. The magnitude of our appetite for fossil fuels to feed our electrical and power needs is very, very large compared to the natural cycles. And although the natural cycles are very large as well, they're highly dynamic. My job is to understand a key component of those cycles so it can be factored into solutions that other people might propose for carbon sequestration and storage.

Scott: Mark, in other programs on this topic, we've talked about how trees sequester carbon just by growing and being trees. Is the suggestion of 'plant more trees' not up to the task of making a dent in carbon emissions?

Mark: Well, it would depend on how many trees, and that's the discussion we have quite a bit. It can certainly take up some of the slack. I think we have to be careful because we don't want prairies or savannahs planted [with trees that would change the landscape]: we gotta put the right trees in the right places to be really effective and make a bit of a dent in it.

Scott: Yeah. And, we think of the tropical rainforests being harvested on other continents and wondering, 'is that still going on and adding to the problem?'.

Mark: Yeah, I think it is. Deforestation is mainly conversion for agriculture. We have to look at ourselves as consumers and consider, 'are we contributing to the demand causing this deforestation?'.

Scott: Good point, Mark. Thanks a lot for joining us again this morning and producing this series on forests and carbon. Paul, thanks for coming to the studios this morning. Is there any way people can learn more about the SPRUCE project?

Paul: Yeah, we have a website.

Scott: What about visitors? Would it be hard to accommodate them?

Paul: Within our website, there's a virtual tour where people interested in learning more about the site can go. There are contact points for scheduling visits and tours: we do that from time to time on schedule or impromptu.

Scott: All right, thanks a lot! When the project's over, what will you do with John Latimer?

John: Bury me in the bog, I hope. Cut a slit in the peat and slide me in!

Paul: Well, that'll be a sad day.

Scott: Oh geez. Well, thanks a lot, Paul!

Paul: My pleasure!

Heidi Holtan is KAXE's Director of Content and Public Affairs where she manages producers and is the local host of Morning Edition from NPR. Heidi is a regional correspondent for WDSE/WRPT's Duluth Public Television’s Almanac North.
As a mail carrier in rural Grand Rapids, Minn., for 35 years, John Latimer put his own stamp on a career that delivered more than letters. Indeed, while driving the hundred-mile round-trip daily route, he passed the time by observing and recording seasonal changes in nature, learning everything he could about the area’s weather, plants and animals, and becoming the go-to guy who could answer customers’ questions about what they were seeing in the environment.
Charlie Mitchell (she/they) joined KAXE in February of 2022. Charlie creates the Season Watch Newsletter, produces the Phenology Talkbacks show, coordinates the Phenology in the Classroom program, and writes nature-related stories for KAXE's website. Essentailly, Charlie is John Latimer's faithful sidekick and makes sure all of KAXE's nature/phenology programs find a second life online and in podcast form.

With a background in ecology and evolutionary biology, Charlie enjoys learning a little bit about everything, whether it's plants, mushrooms, or the star-nosed mole. (Fun fact: Moles store fat in their tails, so they don't outgrow their tunnels every time conditions are good.)