These four square kilometers in western Arkansas used to be a cattle ranch.

But today, they’re home to more  than 300,000 freshly planted trees. Makeovers like this one are a promising tool to address Earth’s climate crisis.

Our planet could absorb a huge amount of he heat-trapping carbon we’ve been pumping into the atmosphere if we could just put it into trees. But as simple as it sounds, rebuilding  a healthy forest is way more complex than just scattering some  acorns and crossing your fingers. So let’s look at what it actually  takes to transform farmland back into natural paradise, and how just a  little help from us can go a long way. [♪INTRO] This episode was made in partnership with HHMI Tangled Bank  Studios, and their documentary Wild

Hope: Mission Impossible,  a story that explores why the journey to perfect plant-based meat is an endeavor of planetary proportions. Watch it now, streaming free here on YouTube. Researchers have identified restoring forests around the globe as a major player in absorbing the carbon that’s in the atmosphere right now. Which means that while we need to explore several different avenues to get us  out of the climate crisis, we can get surprisingly  far just by planting trees.

And that’s why scientist Pat Brown is filling these fields in Arkansas with saplings. Pat is probably best-known for creating the Impossible Burger back in 2016, and now he’s looking at how we can  turn land cleared for cow pastures back into forests that absorb the  maximum possible amount of carbon. The problem with regrowing forests is that there’s no one, perfect way to do it.

See, when a forest forms naturally, it goes through different stages of development, called forest succession. It starts with small plants popping up from seeds. Then, as early generations of  these first plants alter the soil, bigger plants take hold and create some shade.

Finally, shade-loving species arrive. And as the years go by, they grow a thick canopy, and the forest becomes stable and mature. The thing is, this process unfolds  slowly, over decades or centuries.

And in the meantime, all the different plant and animal species that eventually make up the forest ecosystem gradually  start to come and go again. So, getting all the pieces  to fall into place just right isn’t straightforward, especially  if you’re trying to move fast. It’s kind of like building a house: You can’t call in the electrician  before you’ve poured the foundation.

Stuff has to happen in  order. Same goes for forests. But if we did want to move at a quicker pace, what exactly is the best way to plant a forest? hat’s what scientists like  Pat Brown want to find out.

Here on this land, he’s researching  three different approaches to try and create a system that  other researchers can follow. They’re asking questions like: Should we let nature take its  course, or give it a hand? And just what kind of hand does nature need?

On one section of land,  his team is doing nothing — they’re just letting the land grow wild. ut on two other sections,  they’re trying something called active regeneration, where they  plant new forests themselves. On one of these sections, they planted around 30 different species of native trees. The goal here is to kickstart  the growth of a diverse forest with plants that  naturally thrive in the area.

The downside is that it’s still not especially fast compared to doing  nothing, and they won’t know how well it even works until they see the results. On the final section, they planted timber species that are specifically known for growing fast. This approach might not  restore the original ecosystem, but it’s cheaper, and it’ll speed up the growth of big trees that can take in a lot of carbon.

And the team hopes that jumpstarting  the formation of a shady environment might even allow  native species to take hold faster. Bottom line: Every kind of active  regeneration has its pros and cons, if we’re looking for the best  way to capture carbon quickly. But one drawback they all share  is that it takes a lot of time and resources to plant a forest from scratch.

You usually have to raise trees  in nurseries for a few years, then plant them one by one. And  that’s not always practical. So, surprisingly, some scientists  think that Pat’s first approach — just leaving the land alone — is actually the best thing  we can do to regrow forests.

After all, nature will usually  return to areas we leave be, no matter how badly we’ve messed them up. I mean, just look at the abandoned  city of Pripyat, a few decades after the explosion of the nearby  Chernobyl nuclear power plant. Hundreds of healthy, mature trees  now dot the landscape there.

Or the whole island of Puerto Rico.  In the late 1940s, only 6% of the island was forested, compared to  95% at the time of European contact. But by the 1950s, farmers  abandoned most of this land as the island’s economy shifted away from farming. By the end of the 20th century, Puerto Rico’s lush forests were bouncing back.

This is called natural regeneration. And the obvious perk is that it’s cheap, because all you need to do is… nothing. The downside is that these  re-wilded forests usually aren’t identical to the  ecosystems they left behind.

It can take decades or even centuries for species to return in their original numbers. But some studies have found that,  for certain types of forests like tropical ones, natural  regeneration can both work better and restore more biodiversity  compared to active regeneration. The trick is figuring out when and  where that’s actually true, though.

Because sometimes, land can  be caught in a human-caused feedback loop it simply can’t  recover from on its own. For instance, in the Sahel region of Africa, land that had been cleared for agriculture and construction materials became  overrun with grazing animals. Whenever small plants started to grow back, the grazing animals ate them.

And as the land got more and more barren, it became harder and harder for any  would-be forest to gain a foothold. In other places, such as  deforested parts of South India, invasive species took hold on deforested land and crowded out the native  plants that lived there before. So, sometimes there comes a  point where we need to step in.

It’s all about figuring out which  way is best for the situation. But fortunately, replanting an entire forest from scratch isn’t the only way  to break the feedback loop. Since the 1970s and even before,  conservationists have been exploring a middle ground between  natural and active regeneration.

It’s called assisted natural regeneration. In this approach, you’re not just leaving the land completely to its own devices,  but you’re not planting the whole forest yourself  either. You’re assisting.

And that can take a lot of different forms. In Burkina Faso, which is part of  that barren region of the Sahel, a conservation organization  called newTree restored several square kilometers of forest just by building fences to keep out browsing animals. Meanwhile, in the Bandipur  Tiger Reserve in South India, conservationists helped a forest  recover by creating little trenches and pools to catch  water and moisten the soil.

That made it easier for seeds  to sprout and spread roots, and it also attracted animals  that helped spread those seeds. Within several years, the area had  already made a significant recovery, with native grasses, trees, and animals returning. Unfortunately there’s no  playbook that can tell us exactly how to bring back all the  forests we’ll need to absorb the vast amount of carbon we humans  have added to the atmosphere.

But the good news is, there  are many ways to do it. And maybe someday, there will be  a playbook that maps out a plan. We just need more research, like the type Pat Brown is collecting in Arkansas, in order to find the best methods  that work in each ecosystem – whether planting trees by hand, or  letting nature do most of the work.

Our challenge is just to figure  out what’s holding nature back in each location, and what  we can do to help it along. Because the sooner we can save forests, the sooner they can help save us. This video was inspired by  HHMI Tangled Bank Studios’ documentary Wild

Hope: Mission Impossible. Watch the Wild Hope series right here on YouTube – or follow @wildhopetv on  Instagram to discover more stories about scientists and  changemakers working to restore biodiversity around the globe. Change is closer than you think. [♪OUTRO]