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Emily Kwong
You're listening to Shortwave from npr. Hey, shortwavers. Emily Kwong here. And today I have a treat for you. We are going to a microforest. If you've never heard of one, they are small, they are lush. And unlike natural forests, microforests are designed entirely by humans for urban environments. And producer Rachel Carlson went to visit one in Los Angeles recently. Hey, Rachel.
Rachel Carlson
I did. Hey. It was amazing. I had the most fun day ever. I hung out with two scientists who've dedicated themselves to planting these tiny forests to cool down cities and make them more resilient to climate change.
Emily Kwong
Okay, where did you go to see a microforest?
Rachel Carlson
Ascot Hills park, which is a park in northeast Los Angeles. It's surrounded by freeways and interstates. It's not too far from the heart of downtown la, so it's not really an area that I typically associate with lots of green space.
Damian Wollett
But you pull off the freeway and drive this way, and you see a green stamp of 10,000 square feet, and
Rachel Carlson
that's exactly what it looked like, a green stamp. That's Damian Wollett, an associate professor of biology at Loyola Marymount University. He's one of the scientists I met with who's worked on planting and maintaining this microforest for the last two years.
Emily Kwong
Okay, but what makes a microforest a forest?
Rachel Carlson
In a forest, the canopies of the trees touch one another.
Damian Wollett
You plant one tree that's just a tree, but once you start having the canopy connect, that starts to be what we imagine as a forest, where you have this kind of blockage of the sunlight. But also, a forest has layers, canopies
Rachel Carlson
of trees with layers of plants beneath them. So in that way, a microforest does simulate a natural forest. Okay, but what makes a microforest micro?
Damian Wollett
It's smaller.
Emily Kwong
Oh, so this is not like a fairy forest with tiny plants or something. This is just a forest forest that's got a small footprint.
Rachel Carlson
Yeah, yeah. Microforest can be anywhere from around 200 square feet to an acre. And the one I visited, about a quarter acre or 10,000 square feet. But it's the largest microforest in California.
Emily Kwong
So did I end the show? A trip to a small forest with big dreams and real life contributions to local biodiversity that are making it easier to live with climate change. You're listening to Short Wave, the science podcast from npr.
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Damian Wollett
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Emily Kwong
Okay Rachel, so today we are talking about microforests, which are supposed to mimic natural forests but on a smaller scale and in more urban environments.
Rachel Carlson
And people plant them? Yeah, ecologists use local plants to help restore biodiversity to the area. So for example, Los Angeles is prone to drought, so there's lots of drought tolerant native plants. In the microforest I went to like Southern California black walnut and blue elderberry, but in other places ecologists would use different types of plants.
Emily Kwong
Cool. So do microforests exist in other parts of the world?
Rachel Carlson
Yeah, there are others in the US And Damian, our biologist from earlier told me they're also popular in Europe. The original idea goes back over 50 years to Japan to an ecologist named
Damian Wollett
Dr. Akira Miyawaki and he developed the idea of these kind of tiny forest approach to restoring degraded land.
Emily Kwong
Interesting. Well, how do you even go about planting a microforest? Like, what is involved?
Rachel Carlson
Well, a forest isn't just trees. It's a bunch of different species with different roles, from roots in soil to shrubs, to those tall canopy trees that you might think of when you think of a forest. So that's how microforests are planted too, with dense layers of different kinds of plants.
Damian Wollett
So you're kind of planting a whole ecosystem at one time. Instead of waiting for nature to kind of go through succession step by step to get eventually to a forest, it's planting the whole forest at one moment.
Emily Kwong
Interesting. So why is it strategic to have plants at different heights and different layers of the forest?
Rachel Carlson
The lowest layers help keep the soil healthy, which ultimately keeps those upper layers growing. And planting a lot of plants all at once contributes to the microforest growth. And they mature faster than a traditional forest. It might be a couple decades for a micro forest instead of something like a century for a bigger forest.
Emily Kwong
Very cool. Okay, so let's go back to the microforest you visited in la. Tell me about your field trip.
Rachel Carlson
I went on a weekday. It was warm, like 75 degrees outside. But I pulled up to the park and met Damian, and he introduced me to someone else.
Damian Wollett
There's Katherine right there.
Rachel Carlson
Oh, great. Hey. Catherine Pokradouni is a horticulturist who helps plant and develop microforests like this one. We walked up a very steep hill to meet her. I was on a hike. You can't, can't talk at this point because you're breathing too heavy. That's totally fine. I know my mic's gonna catch me, like, out of breath.
Emily Kwong
Wow. This is like meeting some master gardeners or something. But of the forest.
Rachel Carlson
It was.
Emily Kwong
And you said that Damian and Catherine have been working on this particular microforest since 2024. So it's two years old?
Rachel Carlson
Yeah, they just celebrated its second birthday. And another amazing thing about a microforest compared to a much larger forest is the size allows researchers like Damian and Catherine to use it as a science experiment.
Emily Kwong
Yeah. You said the microforest is like a quarter of an acre?
Rachel Carlson
Mm, 10,000 square feet. And right next to it, there's another plot of land exactly the same size, except it's brown, it's filled with invasive weeds. Catherine and Damian aren't planting anything there, so they can directly compare the plots and see what kinds of insects and birds and other critters show up. To each one.
Emily Kwong
Oh, and study the biodiversity when you create a forest with native plants.
Rachel Carlson
Yeah.
Damian Wollett
Every two weeks, going back and forth between the two of them, counting how many insects we're finding, what birds are there, what lizards are moving through there. We find some cool field mice, some spiders, all sorts of neat things that we find here in the microforest that aren't over there in the control plot,
Rachel Carlson
all frolicking in the midst of hundreds of trees, shrubs, and other native plants they've cultivated. And Catherine and Damien have seen around 100 different animal species in all just in the microforest, whereas.
Damian Wollett
Which, prior to this microforest being planted, we had an idea of that there were only 100 species being documented in the whole park.
Emily Kwong
It's the place to be, this microforest. It's bringing the party. How are these scientists tracking the biodiversity, though? Are they. Are they walking around and counting everything?
Rachel Carlson
Partially, yes. They're using a few different methods, though. Damien's lab has mapped out the entire microforest and given each plant a GPS coordinate. And they use drones to measure plant growth, plant volume, and see which species are doing well together and which ones aren't. They also use spider webs to track different animals moving through the microforest.
Emily Kwong
Wait, why spider webs?
Rachel Carlson
Apparently they're like nature's DNA swabs.
Damian Wollett
Spiderwebs are kind of a filter for the air. And as animals move through their environment, they're shedding skin cells and metabolic waste that floats in the air that sticks to the spider web. So then we came out here, we collected spider webs and washed the DNA off those spider webs, and then got an idea of what are all the animals moving through here within the last 24, 48 hours using genetic tools.
Emily Kwong
So useful, our researchers planting the spiders, too, to swab their webs?
Rachel Carlson
No, it's just the spiders that naturally show up, and the researchers don't interfere. Aside from studying the webs, Damian says one of his students came up with the idea.
Emily Kwong
I always knew spiders would make good scientists.
Rachel Carlson
Okay, agree.
Emily Kwong
And what have they found out?
Rachel Carlson
They've been able to use those webs to figure out what other kinds of animals are hanging out in the microforest, which is especially helpful for ones that are nocturnal or just harder to spot on their walkthroughs.
Damian Wollett
We had a barn owl that I've never seen in there, and it's definitely flying through the area at night. And we're picking up a signature of that being here.
Rachel Carlson
Bats, too.
Damian Wollett
So it just gives us a more full Picture of how is this really behaving like a forest? It's not just when we're conveniently here. It's all hours of the day and night.
Rachel Carlson
And they also use human community scientists in addition to their spider scientists. Damien's lab developed an app where park visitors can help collect data. And they've had over 150 or so. People use their phones to scan QR codes attached to the plants to help measure their growth.
Damian Wollett
We don't use tape measures. We just say, well, how tall are you? And they kind of estimate the height. We look for signs of flowers or seeds or herbivory. And also, is it alive?
Rachel Carlson
Damian stood next to a Southern California black walnut tree to show me.
Damian Wollett
Stand next to a few of them and you can see they're taller than me.
Rachel Carlson
How tall are you?
Damian Wollett
So I'm just under 6 foot. So that's a little bit higher.
Rachel Carlson
Yeah.
Damian Wollett
Some of the elderberries down there are over 10 foot, which is incredibly fast when you think about how long it takes for a plant in Southern California
Rachel Carlson
to grow in comparison. He told me he has a black walnut tree in his backyard that's nearly a decade old, but it's not as tall as this one.
Emily Kwong
He sounds like a proud parent.
Rachel Carlson
He kind of was.
Emily Kwong
He's like, look how tall my tree grew.
Rachel Carlson
He actually hugged the tree at one point, which was maybe my favorite part of the whole day.
Emily Kwong
So at the risk of not seeing the forest for the trees, how would you say overall is the health of the totality?
Rachel Carlson
It's pretty good. And they've measured it in a few different ways. One way is to look at how many plants have survived since they were first planted. And Damian and Catherine say there's an average of over 89% survivorship for the plants now, which is pretty good. And that's one big measure of success. Another is the plant's ability to exclude weeds without humans like Damian and Catherine having to intervene.
Emily Kwong
Oh, how is the forest keeping weeds at bay on its own?
Rachel Carlson
So the control plot is filled with weeds, but in the microforest, it's a different story. We're crowding out the space with the plants that we do want so that
Damian Wollett
the plants we don't want really don't
Rachel Carlson
have much of a foothold. And that's something that we're already observing. Between year one and year two, it's probably been like an 80%, if not more reduction of weeds inside this space. So that microforest density helps keep weeds at bay. And we know that because scientists are comparing it to the control plot.
Emily Kwong
Got it, got it, got it, got it. Is the microforest also contributing to, like carbon sequestration? You know, removing carbon dioxide from the air.
Rachel Carlson
Yeah. And that leads to improved air quality and soil health. And for this microforest, Damien says it's pulling out one metric ton of carbon per year.
Emily Kwong
Dang.
Rachel Carlson
His lab expects that to increase to over 50 metric tons of carbon dioxide per per year in the next two decades. And that's more than the emissions of 10 SUVs.
Damian Wollett
Okay.
Emily Kwong
This micro force is doing its part.
Damian Wollett
Plus it's cooling the neighborhood. It's providing food again, the insects, the wildlife that's here.
Rachel Carlson
It also helps bring people into nature. Even in the short time I was with Catherine and Damian, a few people walked by and asked questions about the microforest. They said they loved seeing the new plants in the park or asked us what, what kinds of trees we were looking at and even if they could help.
Emily Kwong
For the love of microforest, Rachel Carlson, thank you for bringing this to the show.
Rachel Carlson
Yeah, thanks, Emily.
Emily Kwong
If you liked this episode, follow us on the NPR app or your podcasting platform of choice and check out our Nature Quest series, which is inspired by listener questions about the environment and how the planet is changing. If you have a question, send it to us. We'll investigate. Email shortwavepr.org your question and a voice memo and your name and location. This episode was produced by Hannah Chin and edited by our showrunner, Rebecca Ramirez. Tyler Jones, Check the facts. Jimmy Keeley was the audio engineer. I'm Emily Kwong. Thank you for listening to Short Wave from npr.
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Host: Emily Kwong (NPR)
Producer/Guest: Rachel Carlson
Guests: Damian Wollett (Associate Professor of Biology, Loyola Marymount University); Catherine Pokradouni (Horticulturist)
Date: June 2, 2026
Length: ~15 minutes
This episode explores the innovative concept of "microforests"—tiny, densely planted forests within urban environments—designed to boost biodiversity, fight climate change, and bring nature into cities. Through a field visit to Ascot Hills Park in Los Angeles, the team investigates what makes a microforest unique, how it’s built, its impact, and the creative scientific methods used to study it.
Manual Counts: “Every two weeks, going back and forth between the two...counting how many insects we're finding, what birds are there...” – Damian (07:44)
High-tech Methods:
Cool Findings:
Weed resistance: Dense, healthy growth crowds out weeds, as opposed to the control plot that’s weed-choked. (12:02)
Carbon sequestration:
Other benefits:
Emily Kwong (joking about scale):
"Oh, so this is not like a fairy forest with tiny plants or something. This is just a forest forest that's got a small footprint." (02:10)
Damian Wollett (on planting strategy):
"You're kind of planting a whole ecosystem at one time. Instead of waiting for nature to kind of go through succession step by step to get eventually to a forest, it's planting the whole forest at one moment." (05:40)
Rachel Carlson (on field day):
"I was on a hike. You can't, can't talk at this point because you're breathing too heavy. That's totally fine. I know my mic's gonna catch me, like, out of breath." (06:53)
Emily Kwong:
"He sounds like a proud parent." (11:07)
"He's like, look how tall my tree grew." (11:09)
On spider web DNA:
Rachel Carlson: "Apparently they're like nature's DNA swabs." (08:55)
Emily Kwong: "I always knew spiders would make good scientists." (09:39)
On community science:
"They've had over 150 or so people use their phones to scan QR codes attached to the plants to help measure their growth." (10:14)
Microforests are a promising urban solution for biodiversity, climate adaptation, and community connection. Through dense, multi-layered plantings tailored to local ecosystems, these tiny forests replicate natural processes, thrive quickly, support wildlife—and inspire both scientists and city dwellers to reimagine the possibilities for greening our cities.