How Will Future Forests Survive Climate Change?

Forests are the lungs of our planet. Not only do they absorb carbon dioxide and create oxygen, they also regulate temperature, absorb rainwater to help prevent flooding and provide critical habitat for the majority of the world's land-based plant and animal species. But the trees that make up forests are increasingly endangered. Enter reforestation: replanting new forests to replace the old ones. For the past century, the United States Forest Service has helped to replant new forests and manage existing ones. As scientists face the ongoing threat of climate change, they're developing new strategies, including one that tries to predict the future. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave http://plus.npr.org/shortwave. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:00Speaker 00

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• 0:12Emily Kwong?

  You're listening to Short Wave from NPR.

• 0:19Emily Kwong?

  Hey, Short Wavers. Emily Kwong here. And today, I am joined by producer Hannah Chin.

• 0:24Speaker 02

  Hello.

• 0:25Emily Kwong?

  For a story about forests.

• 0:27Speaker 02

  It's muddy out here.

• 0:28Emily Kwong?

  OK, Hannah, you reported this story from somewhere that sounds pretty wet. Are you in a forest right now?

• 0:36Speaker 02

  I am not in a forest, but I did report this story from somewhere that is wet, which is my home state of Oregon.

• 0:41Emily Kwong?

  Nice.

• 0:42Speaker 02

  We drove out on a rainy day to the US Forest Service's Dorina Genetic Resource Center. It's located in Cottage Grove, which is this small town that's a couple hours' drive from Portland. And the day I visited, the crew was pretty busy. We're putting 10 fir bags here. So let's see, I got six, seven, eight, nine, 10. That's how many fit in this bag.

• 1:06Emily Kwong?

  Packing up hundreds of baby Douglas fir trees into plastic bags and then big cardboard boxes.

• 1:13Speaker 02

  And then I'm putting it in the pile here. Right now, we're counting 67 per box.

• 1:20Emily Kwong?

  So this is Michelle Osgood. She's the assistant horticulturist here at Dorina Genetic Resource Center. And she and her crew are taking all of these seedlings out of the greenhouse.

• 1:29Speaker 02

  So we're taking each tree out of its cell that it's been growing in for about, I don't know, eight months or so, and putting them in these bags into these boxes that are going to be frozen for a couple of months before they get outplanted.

• 1:44Emily Kwong?

  They're going to freeze these little baby trees?

• 1:46Speaker 02

  Yeah, it's so that they can keep the trees in storage until the ground is, like, ready to plant. Right now, they're dormant, so they're not really growing. They're kind of sleeping right now. And then we'll put them into a deep sleep in the freezer for a couple of months. And then they'll wake up and they'll be out in nature and start growing again.

• 2:03Emily Kwong?

  They're like deep-sleep princess tree popsicles.

• 2:07Speaker 02

  Deep-sleep princess seedling popsicles, but yeah, basically.

• 2:13Emily Kwong?

  What are these seedling popsicles for?

• 2:15Speaker 03

  OK, so you already know that forests are really important for the ecosystem, right?

• 2:20Emily Kwong?

  Oh, we depend on them. I mean, trees generate oxygen, they trap CO2, they absorb water to help prevent flooding, they regulate temperature, they're like critical habitat for animals.

• 2:32Speaker 03

  Yeah, right. But they're in danger due to things like overharvesting and increasing wildfires. So that's why we need reforestation, replanting new forests to replace the old ones. So Emily, these seedling popsicles are part of a reforestation master plan that the Forest Service is carrying out across the West Coast. It's a plan that looks into the future to help our forests survive increased heat, changing weather patterns, and other potential threats that they might face.

• 3:02Emily Kwong?

  So today on the show, reforestation reimagined. How scientists are working to change the trees we plant and where we plant them in the race against climate change. You are listening to Short Wave from NPR.

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• 4:37Emily Kwong?

  Okay, so humans have been reforesting or planting new trees to compensate for losing old ones for a long time. I mean, this was happening in ancient China as early as 1122 BCE.

• 4:46Speaker 03

  Which is really cool.

• 4:46Emily Kwong?

  But large-scale reforestation, like what you're talking about, really began with the establishment of the US Forest Service in the late 19th and early 20th century, more than 100 years ago. So this is kind of a new project in some way.

• 5:01Speaker 03

  Yeah, I guess compared to China, it is relatively new. But if you do the math, we've been replanting trees for easily more than a century.

• 5:09Emily Kwong?

  Yeah.

• 5:10Speaker 03

  But that doesn't necessarily mean it's a simple process.

• 5:14Speaker 05

  It's funny, reforestation, a lot of times, I think the general public, myself included before I got into this, you know, you think you put a tree in the ground, it's just, it's gonna grow, right? Turns out that's not the case. A lot of times, we put things in the ground and they die. And it's the same thing for tree seedlings as well.

• 5:29Speaker 03

  This is Rob Slayzak. He's a researcher with the US Forest Service. And he says because growing tree seedlings is so complicated, foresters try to really maximize the seedling's chance of survival. That involves things like nurturing the seedlings for longer before planting them, or planting the trees more spaced out so that they don't compete for resources. And maybe most importantly, planting local.

• 5:51Speaker 06

  We've learned that over many, many years in forestry, that seeds, they have learned to adapt to their local situation. So if you move that seed, it might do okay for a few years, it might not, it might grow for a while, it might die later. Something will cause it to not succeed.

• 6:10Speaker 03

  This is Lisa Nguyen. She's the manager of the Durinna Genetic Resource Center now. But before that, she was working with the Forest Service as a silviculturist, which just means she does tree and forest management.

• 6:21Emily Kwong?

  It sounds like she's echoing that idea that Rob brought up earlier of planting local. So keeping seeds in a certain area because they're adapted to that local environment.

• 6:32Speaker 03

  Yeah, exactly. But Lisa's been working in forest management and conservation for a long time. And in that time, the speed of climate change has really shifted. And foresters are trying to figure out whether this local approach to planting trees needs to shift too.

• 6:49Speaker 06

  Now, well, the climate is changing, right?

• 6:54Speaker 06

  Now we are looking at, is that seed even adapted to that spot anymore?

• 6:58Speaker 03

  So in the time that it takes for a seed to be harvested and then planted and then start growing, foresters are realizing the growing conditions in its home might have changed. Right, like it's so much warmer or drier that the seed's previous adaptation may no longer be advantageous under climate change. Exactly. And Rob told me this too.

• 7:17Speaker 05

  We're dealing with more severe droughts, just more harsh conditions in general. So it's just the seedlings need more of a leg up to kind of get established.

• 7:24Speaker 03

  Seedlings might face drier or more humid conditions. They might need to weather unprecedented heatwaves. And there's just a bunch of potentially changing conditions that endanger these trees. And that's a real problem for forest management. They're going through the same things we are, these poor trees. Yeah, exactly. But foresters have come up with a way of tackling it. And this is the project that Rob's leading, the same project that you heard Michelle and her crew packing up those baby tree popsicles for. It's called the Experimental Network for Assisted Migration and Establishment Silviculture, or E-Names for short. I love an acronym.

• 8:02Speaker 03

  What makes E-Names so experimental, though? Okay, Emily, would you believe me if I told you that they were looking into the future? Um, no.

• 8:14Speaker 03

  Okay, fair. I will let the experts explain. Here's Lisa.

• 8:18Speaker 06

  We have a thing called Seedbot Selection Tool. That is a tool that our geneticists developed, and it was really about helping silviculturists figure out what seed to select that's appropriate for what site. And it helps them look at maps and spatially, and it has the breeding zones in there. It has all the species in there.

• 8:37Speaker 03

  This tool is online, and it provides multiple different climate models. Each focuses on slightly different things so that silviculturists can make the most informed decision for their specific forest.

• 8:47Speaker 06

  And so you can run this climate model and look at what does that seed mean in 50 years? What does it mean in 75 years?

• 8:54Speaker 03

  Basically, which of these seeds will grow well in the future climate of this location. All right, so it sounds like what they're doing is estimating the future of specific areas and then using this seed lot selection tool to make an educated guess about what seeds may do well in that hypothetical future. That's what the ENAIS project is doing. It's experimenting with these seed selections, projecting different scenarios for what the climate will look like in the future, and then planting trees accordingly. So you heard them packing up Douglas firs in the beginning of this episode, but they've also planted other species, right? They've got instant cedar, Jeffrey pine, ponderosa pine, sugar pine, western larch, ton of different trees in places all over Oregon and Washington.

• 9:36Speaker 05

  The way in which the experiment works, we're testing essentially four kinds of types of seed sources at each site. And so we test the historic seed that would have existed there historically, the current seed that would exist there under the current climate, and then we project out to the future climate and then end of century climate.

• 9:52Speaker 03

  This sounds very science fictiony. I mean, very cool, but how can you accurately plant future seeds? In reality, Rob says it's pretty straightforward.

• 10:02Speaker 05

  All we're doing is we're matching what that future climate is with a different spot that's currently on the landscape. So as long as we match up some of those climate variables, like mean cold month temperatures, a very common one we use, or a summer heat moisture index are two really common variables that we use for seed lot selection. We're just matching them in space from what's predicted in the future to what currently exists on the ground.

• 10:25Speaker 03

  It's not a perfect system. Rob says there's uncertainty in the climate model projections and uncertainty in the climate variables they're using to match space and uncertainty in how far they transfer the seeds. I mean, this hasn't really been done before, so it's not like they have a ton of things to compare it to. But the idea is that if you live in a place that has Douglas firs and gets really cold winters now, but is projected to get milder winters in the future, and then I live in a place that also has Douglas firs, but already gets milder winters right now, then hypothetically, I could send you some of the seeds from Douglas fir trees where I live, the ones that already adapted to milder winters, so you could plant them.

• 11:04Emily Kwong?

  Does that make sense? Totally. So that we have any Douglas fir trees at all in the future of my area.

• 11:09Speaker 03

  Right. Except if you were robbed, then you'd actually send the seeds to Dorina Genetic Resource Center, and then they would sprout the seeds and plant them and grow the baby seedlings first.

• 11:18Emily Kwong?

  And turn them into popsicles, different flavors, ponderosa, larch, and ship them around Oregon and Washington?

• 11:23Speaker 03

  Exactly.

• 11:24Speaker 05

  You're generally moving it from a climate that it was historically adapted to, that it evolved under. And then you're moving it to a climate that you think is going to exist in the future at a given location. And that's, yeah, that's assisted population migration, also referred to as assisted gene flow. But it's sticking within the existing habitat range of that species. And so it's generally considered less risky than like assisted species migration, where maybe you're moving a, you know, a species far outside of its natural range.

• 11:52Speaker 03

  So they're moving the population around, but still staying within the overall species range. That way, they're hoping to avoid the risk of introducing new potentially invasive species while still benefiting from the natural individual adaptations that trees already have.

• 12:07Emily Kwong?

  That's really smart. Okay. So where are we at in this project? It sounds like it's early stages. So do we have any sense of how it's all going?

• 12:16Speaker 03

  They only started planting sites last year. But right now, the plan is to do a first year measurement after each site is planted, and then to check in on each site every five years. Rob says he's committed to leading it for at least the next 20 years, and he's hopeful it could continue for even longer. Because the Forest Service has a history of really committing to long-term growth experiments, like the Doug for Heredity Study that launched back in 1912.

• 12:39Speaker 05

  Where they were planting different populations. There was this understanding that, you know, based on how those trees evolved under the given set of conditions in which where the population existed, they would perform better than trees that evolved under a different set of conditions. And so now we're just using the concept to spin it on its head.

• 12:56Speaker 03

  I mean, Emily, some of the trees that were planted as part of the Doug for Heredity Study are still around, right? It's been over a century. And there's still stuff that we're learning from these same trees.

• 13:06Emily Kwong?

  Wow, that's pretty cool. Because you don't often hear about experiments lasting more than a decade or two. I mean, They're working on time scales of up to, I imagine, like a century. And if they are successful, you know, if this experiment goes well, these tree babies you saw earlier could grow up to outlive both of us.

• 13:27Speaker 03

  No, totally. And if these trees make it, they'll need to survive all of these different climate scenarios all along the way, which, again, kind of scary, kind of impressive, kind of optimistic. Lisa talked about it, too.

• 13:41Speaker 06

  You look at different milestones. If you look out 25 years, what does it look like? If you look out 50 years, 100 years, what does it look like? And you have to know, you have to take into account now, because you have to have seedling survival. But you also have to take into account if that tree's going to be there for 100-plus years, you know, do you want seed that was adopted 100 years ago? You have to find that balance, right?

• 14:05Emily Kwong?

  But they're creating a future where perhaps forests are standing and these trees have a chance. And that's pretty cool. Gives me some hope.

• 14:12Speaker 03

  Yeah, me, too.

• 14:15Emily Kwong?

  Hannah Chen, thank you so much for bringing us this story.

• 14:17Speaker 03

  Thanks for having me, Emily.

• 14:23Emily Kwong?

  Make sure you never miss an episode of Short Wave by following us on the podcasting platform you're listening to right now. If you have a science question, send us an email at [email protected]. This episode was produced by Jessica Young and it was edited by our showrunner, Rebecca Ramirez. Tyler Jones checked the facts and Jimmy Keely was the audio engineer.

• 14:43Speaker 03

  Beth Donovan is our senior director and Colin Campbell is our senior vice president of podcasting strategy. I'm Hannah Chen.

• 14:50Emily Kwong?

  And I'm Emily Kwong. Thanks for listening to Short Wave, a science podcast from NPR.

• 15:18Speaker 00

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