(gentle music) - [Korena] When I climb into a tree, there's just this feeling of perspective.

You can hike to the top of a mountain.

You can climb a rock wall.

You can get up high in different ways, but there's just something about sitting on a branch where you see no other people for miles.

Just being able to look at the ecosystem that's surrounding you really puts it into scale of how large and beautiful these ecosystems are, but then it also allows you to reflect that these ecosystems are decreasing at a rapid rate.

- [Narrator] Korena Mafune is a PhD scientist from the University of Washington with a background in fungal and soil ecology.

She studies canopy soils, and her research takes her to a place few humans ever go, the tops of some of our oldest trees.

- [Korena] When you think of canopy soil, it's these thick mats that occur on tree branches, particularly in our temperate rainforests.

They are these rich organic soils.

You'll see these beautiful green mats draping off trees, but the real treasure is what's buried underneath.

- [Narrator] How did dirt get so high into these trees?

Branches in the rainforest quickly develop a moss layer, which intercepts leaves falling off the trees.

As this debris accumulates, plants, mosses and ferns grow on the limbs, eventually decomposing to create the same type of rich organic soil you'd find on the ground, except it's all suspended in the air, sometimes hundreds of feet off the ground.

- [Korena] Yes.

Amazing - [Narrator] To understand these skyward soil layers, Korena has to compare them to what lies beneath our feet.

- I always kind of look at it as there's an above half that we can see, and then there's this below ground hidden half that a lot of interactions and processes are going on in.

And so when we look at the trees above ground.

We got one of our big boys right here.

And we think about the interconnections below ground, we can start thinking about these fungal organisms or this mycorrhizal network that we have beneath our feet.

Got a mushroom right there, that looks like a Russula species.

- [Narrator] What Korena's talking about is called the mycorrhizal network.

Basically it's layers of on layers of barely visible thread-like filaments that connect trees and fungi within a forest ecosystem.

Mycorrhizal mushrooms can transfer water, carbon, nutrients and minerals through this network and can collect nutrients provided by the decomposer fungi, but even more incredibly, they can use this fungal network to communicate.

Noting its similarity to the internet, some scientists have nicknamed it the wood wide web.

- Call me a little biased, but fungi kind of rules the world.

Oh, there's a coral fungus.

The fungus and the plants are communicating, saying, "Hey, you have a surplus of this.

Can you send it over this way and help me out during a time of need?"

- [Narrator] This is where Korena turns her scientific interests skyward again.

She's investigating.

If these suspended canopy soils might provide something for the trees they can't otherwise get from the ground.

- The trees, they have the meal on the forest floor but it's kind of like a buffet, everybody's going at it.

But then the canopy soils, I like to think that they're kind of like this little snack that they can access with their advantageous rooting system.

These trees are hundreds of years old.

If canopy soils never existed in this system, would these tree species be as resilient as we see?

- [Narrator] Finding out how these snacks get delivered requires Korena to get up close and personal with each tree.

- When I get to one of the trees that I climb, I always thank that ecosystem and that tree for letting me conduct research.

Some say I have a PhD in untangling knots.

We're not actually spurring boots into this tree and climbing up the old-fashioned way, We're doing it in a way that tries not to hurt the environment or has as little impact on these old growth environments as possible.

It's like this little inchworm process.

I climb anywhere from 30 to about 80 feet into these maples.

(gentle music) - [Narrator] Once Korena is up in the tree, the real science begins.

- [Korena] So we can see the forest floor for scale.

Those ferns are giant.

- [Narrator] First she collects samples, taking care not to damage the fungi or the tree roots.

She will then run PCR tests in the lab to extract DNA and find out which kinds of fungal communities are present.

From there, she can gain insights on nutrients and soil temperature.

- [Korena] Just look at that.

That is so thick.

You see this?

We hit the jackpot.

- [Narrator] What she discovered is that canopy soils have more available nutrients for a tree than the forest floor.

- [Korena] These rooting systems were associating with a unique suite of fungal organisms that may be helping these maples be more resilient, helping them fight stressors.

- [Narrator] As climate change increases the frequency of stressors like drought, Korena hopes that the canopy soils can help both the trees and entire ecosystems weather the challenging decades and centuries ahead.

After all, these trees have survived much longer than we have.

They have a lot left to teach us, and not all of it is about science.

- When I walk into a forest, I don't only see the trees.

I see ecosystems within ecosystems, little niches within other niches, a whole ecosystem in a handful of soil, a whole ecosystem looking around me.

So it's kind of this balance of realization that these areas don't exist in many places anymore, but also the realization that where they do exist, they're so beautiful and they provide so much, not only for me personally, but to the surrounding environment.

(gentle music)