Planting trees isn’t enough. Here’s why we need tiny man-made forests

On a single day in 2019, Ethiopia famously planted 350 million trees. The same year, Turkey planted 11 million of its own.

It’s no exaggeration that tree-planting has taken root around the world as a popular fix for the climate crisis through campaigns like the Trillion Trees initiative and Bonn Challenge, but are these efforts missing the forest for the trees? (Terrible pun intended.)

Just as fast as tree-planting has taken hold, so has the backlash. Some scientists argue these “tree plantations” lack the ecological diversity of old-growth forests, and improper planting of trees can also lead to lots of dead trees. Up to 90 percent of the saplings planted in Turkey in 2019 were dead by 2020, according to The Guardian.

To save the planet and restore ecosystems, a new book argues we shouldn’t settle for simply planting trees. Instead, we should start planting forests. Well, mini-forests, specifically. And not just in rural areas, but in parking lots and on roadsides in urban communities around the world.

“It’s a really powerful way for people to connect with nature,” says Hannah Lewis, the author of Mini-Forest Revolution, available for pre-order now and releasing on June 9.

“The whole system is self-sustaining.”

Lewis, who has an M.S. in sustainable agriculture and sociology, extensively researched renowned Japanese botanist Akira Miyawaki’s innovative method of planting a small forest of native plant species as a way of restoring ecosystems before starting a mini-forest in her own community in France.

In an interview, Lewis tells Inverse how the Miyawaki method can save ecosystems around the world — and why it’s better than simply planting trees. Even though Miyawaki passed away last year, his teachings live on in her book and in the countless mini-forests inspired by his ecological teachings.

This interview has been edited and condensed for clarity.

How did your background in sustainability lead you to research mini-forests?

I was working in a sustainable community food system for a number of years before I discovered Biodiversity for a Livable Climate, which was addressing the climate crisis by restoring and preserving ecosystems.

That’s when I discovered the Miyawaki method. That was a project in Nantes, France, not too far from where I live. They were planting 200-square-foot dense native forests as a response to a road expansion near their home. It clicked with me because they're not just planting trees, they're actually planting a native ecosystem. One small group of people can restore an ecosystem.

What is a mini-forest and why are they so important?

A mini-forest is a small ecologically robust forest that can be planted by communities in parks and cities, in schoolyards and churchyards, and beside busy roads. It’s flipped traditional landscaping on its head. You get more biodiversity and a different appearance. It’s a dense band of multi-layer trees as opposed to the elegant but less ecologically useful line of single species down the side of the street.

When you have degraded land in cities and rural areas, if you leave it alone for 100 years or more, we would start seeing small plants that live short lives. Dandelions or something like that. After that, you get larger, longer-living species with deeper roots. Then you get shrubs and pioneer trees, and, eventually, the vegetation is increasingly larger, longer living, and more shade-tolerant. Young plants can grow up in the shade of those forests and continue the succession.

So in that sense, you've created a stable ecosystem. After about three years, the whole system is self-sustaining and does not need any maintenance or assistance from humans.

Why is planting mini-forests better than simply planting trees?

The Miyakwai method physically protects the plants. He plants more densely in places where there's more wind or harsh weather. The plants protect each other from the harsh wind, kind of in a way that penguins in the Arctic huddle in a circle to shield each other from the harsh winds. Plants can do that too. If you have just one tree constantly battered by the wind without anything else around protecting it, that tree is going to be really stressed and it's not going to grow well. It will also lack the microclimate that's created when you have lots of trees growing together and you have that canopy. If you’re going through a drought, you'll have a bit of resistance within the forest system because you've created a microclimate that can maintain some of the humidity.

Why are mini-forests attractive to urban communities?

It’s a really powerful way for people to connect with nature. For one thing, you can involve the whole community. When you plant using the Miyawaki method, you're using really young plants. They're just a foot or two high, and you don't have to dig really deep holes. Even a five-year-old or an older person can pick up these lightweight plants and dig a hole to put them in.

It also helps people connect to nature. Miyawaki always made a point to help deepen people’s awareness of the plants native to the area. He had a planting festival and began each festival with a naming ceremony. One person would hold up a plant and say its name, and then everybody would repeat the name three times. Identifying the plants and knowing what grows together is a really enriching experience.

How do you identify the appropriate species to plant in a given area?

That is the central question of the Miyawaki method. What he looked at was the Shinto shrines in Japan. A Shinto shrine was established as part of a new town and the forest was left standing as a place where the gods could live. It was forbidden to cut down those areas. Those sacred forests exist today and they have distinct vegetation.

Whenever [Miyawaki] would plant a forest, he would look for a sacred forest in the area. Then he would map plant those same species. We don't have sacred forests in the U.S., to my knowledge, but you could just look at the most natural forests in the area and see what species are there.

Should preserving older forests take precedence over creating mini-forests?

Absolutely. The Miyawaki method is just a way to try to catch up. If we had all the forests still standing, we wouldn't need to catch up. The most important thing is to keep the older trees. They store so much carbon. They're supporting the habitat. Think about the number of leaves that a giant old tree has compared to a new sapling. It's a lot more photosynthetic surface so it's drawing down a lot more carbon.

One interesting way the Miyawaki method fits well with the idea of preserving existing forests is that you can improve the connectivity between the existing ecosystems. If you have several mini-forests in a city arranged in a strategic way between larger ecosystems, you can facilitate a movement of species between those ecosystems.

You can’t have an ecosystem in isolation. It’s much more healthy when it’s connected to other ecosystems so animals and plants can move and migrate and forage and mix with other populations genetically.

What’s your favorite example of a mini-forest?

One really moving story was the Yakama Nation. They worked with the residents of a correctional facility who were dealing with really intense problems of addiction and other issues.

The idea was to work with people in a way that helps connect them to their cultural heritage by knowing the names of plants and knowing how they’ve been used for generations. And using that as a way to help people work through their personal challenges. It’s not just a physical thing. It’s also a cultural and emotional process of connecting with nature.

In the book, you talk about how you were initially met with some resistance from community members. How did you work to address their concerns?

When I first approached the city, I was just one person, and it surprised the city council. They were concerned about the roots and bothering the infrastructure. So then I teamed up with a newly established environmental organization and they liked the idea. They took it on as a project and I joined their board. So then we had more of a team. It’s never a good idea to try to plan a community project as one single individual — that's bound to fail.

Going back to the city council, we were able to show them this is something that had been adopted in Paris and other parts of our region. As soon as we found a site that didn't compete with other potential uses for land, people seemed okay with it. It was also right next to a little hiking trail so it would even enhance that experience.

How can mini-forests help people think more deeply about their community's role in alleviating the climate crisis?

We're a little team of people in this small town saying, “Let's plant a forest.” It was a really new idea so we had to explain why the heck we should build a forest in a town. That allowed us to start talking about what’s at stake if we continue losing so much biodiversity globally. That area is going to increasingly see drought. Having vegetation there maintains humidity in the soil.

If it inspires other communities, or if the people in town think it's a cool idea and plant more, then symbolically, it could have a much greater impact locally, regionally, or, eventually at the global level.