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Short Wave

Why are scientists planting tiny forests in big cities?

02 Jun 2026

Transcription

Transcript generated automatically by AI and may contain errors.

Chapter 1: What is the main topic discussed in this episode?

0.031 - 19.192 Unknown

New shows, new music, new movies. Keeping up with pop culture sometimes feels like a full-time job. Thankfully, over at Pop Culture Happy Hour, it's literally our job. We break down what's actually worth watching, listening to, and pretending you already knew about. So the next time someone says, did you see that? You can say, yeah, obviously.

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19.553 - 23.477 Unknown

Follow NPR's Pop Culture Happy Hour wherever you get your podcasts.

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24.939 - 49.039 Emily Kwong

You're listening to Shortwave from NPR. Hey, Shore Wavers, 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.

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49.019 - 70.542 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. Okay, where did you go to see a microforest? Ascot Hills Park, which is a park in northeast Los Angeles. It's surrounded by freeways and interstates.

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71.003 - 79.139 Rachel Carlson

It's not too far from the heart of downtown L.A. So it's not really an area that I typically associate with lots of green space.

79.84 - 84.409 Damien Ouellette

You pull off the freeway and drive this way and you see a green stamp of 10,000 square feet.

84.507 - 87.049 Rachel Carlson

And that's exactly what it looked like, a green stamp.

Chapter 2: What are microforests and why are they important?

87.309 - 104.003 Rachel Carlson

That's Damien Ouellette, 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. Okay, but what makes a microforest a forest? In a forest, the canopies of the trees touch one another.

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104.584 - 114.312 Damien Ouellette

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. We have this kind of blockage of the sunlight, but also a forest has layers.

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114.865 - 126.323 Rachel Carlson

Canopies 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?

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126.363 - 135.738 Emily Kwong

It's smaller. Oh, so this is not like a fairy forest with tiny plants or something. This is just a forest that's got a small footprint.

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135.798 - 149.097 Rachel Carlson

Yeah, yeah. Microforest can be anywhere from around 200 square feet to an acre. And the one I visited is about a quarter acre or 10,000 square feet. But it's the largest microforest in California.

150.218 - 164.498 Emily Kwong

So today on 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 Shortwave, the science podcast from NPR.

Chapter 3: Where is the largest microforest in California located?

168.933 - 179.17 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, and people plant them.

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179.631 - 198.794 Rachel Carlson

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.

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199.374 - 199.775 Emily Kwong

Cool.

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200.055 - 215.901 Rachel Carlson

So do microforests exist in other parts of the world? Yeah, there are others in the U.S., 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 Dr. Akira Miyawaki.

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215.941 - 222.902 Damien Ouellette

And he developed the idea of this kind of tiny forest approach to restoring degraded land.

223.017 - 227.385 Emily Kwong

Interesting. Well, how do you even go about planting a microforest? Like what is involved?

227.405 - 244.738 Rachel Carlson

Well, a forest isn't just trees. It's a bunch of different species with different roles from roots and 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.

244.955 - 256.02 Damien Ouellette

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.

256.702 - 262.896 Emily Kwong

Interesting. So why is it strategic to have plants at different heights and different layers of the forest?

Chapter 4: What makes a microforest function like a natural forest?

369.034 - 388.193 Damien Ouellette

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.

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388.747 - 400.394 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.

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400.775 - 407.43 Damien Ouellette

Which prior to this microforest being planted, we had an idea that there were only 100 species being documented in the whole park.

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407.647 - 417.798 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 walking around and counting everything?

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417.918 - 439.922 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. Wait, why spider webs?

440.603 - 442.965 Rachel Carlson

Apparently they're like nature's DNA swabs.

443.426 - 459.102 Damien Ouellette

Spider webs 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.

459.082 - 468.213 Damien Ouellette

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.

468.433 - 474.02 Emily Kwong

That's so useful. Are researchers planting the spiders too to swap their webs?

Chapter 5: How do scientists choose plants for microforests?

681.711 - 685.716 Damien Ouellette

Again, the insects, the wildlife that's here...

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686.489 - 701.452 Rachel Carlson

It also helps bring people into nature. Even in the short time I was with Catherine and Damien, a few people walked by and asked questions about the micro forest. They said they love seeing the new plants in the park or asked us what kinds of trees we were looking at and even if they could help.

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703.395 - 726.744 Emily Kwong

For the love of micro forest, Rachel Carlson, thank you for bringing this to the show. Yeah, thanks, Emily. 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.

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727.445 - 745.47 Emily Kwong

Email shortwave at npr.org your question in 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 Shortwave from NPR.

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