[CALM MUSIC BEGINS] {DAVID YETMAN} Trees cast long shadows into human history and the human brain.

They affect us in ways we do not fully understand.

No trees forge such a deep impression as California's great trees, giant sequoias, and coastal redwoods.

Trees with lingering power to influence the people who have lived among them.

And it's not just because they are the world's tallest trees.

[MUSIC FADES] {ANNOUNCER} Funding for In the Americas with David Yetman was provided by Robert and Carol Dorsey [MUSIC] The Guilford Fund.

Arch and Laura Brown.

And Hugh and Joyce Bell.

[THEME SONG PLAYING] {DAVID} The state of California has the world's largest trees the Sequoia.

It also has the oldest trees, the bristlecone pines.

It also has the world's tallest trees, redwoods.

And it is the redwoods which today provide increasing knowledge of climate and how it is changing in California, in the West, and in the world.

Coastal redwoods are found only in a narrow strip from just south of San Francisco, north, to southern Oregon.

The location of the earliest research about them is found in Tucson, Arizona.

Scientists in the last century have discovered that one of the best way for understanding the past is to study the record in tree rings, which tells us how long trees have lived, but a lot more than that.

To see the best collection of tree ring records we go to the Tree Ring Laboratory at the University of Arizona and see the Redwood Archives.

{KEVIN ANCHUKAITIS} So this is just part of the giant Sequoia collection that we have, almost entirely dedicated to the study of fire in the Sequoia, so you can see - {DAVID} And the sequoias like fire more than redwoods.

Is that correct?

{KEVIN} They have a different fire regime, but yeah, they can persist through multiple fires.

As you can see in this section of of giant sequoia, right.

So you can see these were pretty frequent fires, right?

Maybe ten years between these fires that would have moved through the the grove.

This would have been part of the natural regime that these trees experienced.

{DAVID} And redwoods don't get fires like that?

{KEVIN} It's a different type of fire So often you get a stand clearing fire or a much, more deadly fire, and then you see that re sprouting afterwards.

Well, we are the first, the oldest and also the largest and most diverse in terms of what we study here in the archive is over a century's worth of samples that different scientists have collected that give us some insights into the natural world and how it's changing.

Tree rings were sentinels on the landscape.

They were there when things happened, when storms occurred, when droughts passed through, when there was a fire.

And they record that information in their annual rings.

So the trees that we have around here and through much of the Northern hemisphere, and a good part of the Southern hemisphere, form one ring per year.

And that ring can be exactly dated to the year of formation.

And something about the width or the density or even the chemistry of that ring tells us about the climate environment in the year that ring was formed.

You know, while we see very regular rings here and exactly in the sequoia, when we look at the redwood, you can see this sort of sweeping changes from wides to narrow, you know from, maybe being able to visibly see 20 rings to maybe losing track of all of those.

And it's this aspect of their growth that makes them so hard to work with in dendrochronology.

One of the ways that people have approached this problem is instead of studying the width of the rings, is actually to look at the chemistry of the wood.

And so if you think about those environments where you encounter the redwoods, all that moisture coming off the Pacific, well, that moisture gets used by the tree to make the cellulose that becomes part of the wood.

And if you think about that water, it's carrying hydrogen but also oxygen.

And it turns out that that oxygen molecule that starts with water ends up in the wood.

And by actually going in and measuring the type of oxygen that's in there, we can start to say something about, say, fog persistence or temperature, or even drought One of their first uses was actually for something we call Dendroseismology The study of ancient earthquakes.

And the reason you can use redwoods for that is that they have populations that are growing right next to, or very close to an earthquake fault.

And then you have some that are growing further away.

And so what you can do is go to the trees that are on the fault.

You can study their rings and look for sudden changes or disturbances or even damage.

And then you go to the trees away from the fault and use those as control trees.

And if you see damage or changes in growth rates that are on the trees that are on the fault, you have a good hypothesis that that was caused by an earthquake.

And now you can date that ring and say, there was an earthquake at this site, 100, 200, 400 a thousand years ago.

{DAVID} And there would be no really good way to date that {KEVIN} No.

{DAVID} And the San Andreas fault is the best place to do that with redwoods, because its the only really major fault that's revealed there {KEVIN} Yep - Dendrochronology really allows us a way to know how frequently earthquakes occurred in the long term.

This giant sequoia sitting right in front of us here tells us that fire used to be really common in these groves, and now it's not because we started to put them out.

We changed the ecology.

I could look at a sequence of trees from almost anywhere across the west here and tell you about the history of droughts and even floods.

I could go all the way to the tree line in Alaska or Canada, or up into Siberia, and look at those 200 rings and tell you about how temperature changes both naturally and in response to CO2 emissions.

Trees tell us how things have changed in the past, how they varied, how droughts and floods came and went.

But they also give us insight into the present by comparing what happened before and what we see happening around us now.

We can really get a sense for how much we have changed climate, how much we have changed landscapes, how humans have modified environments.

Redwoods are just a fascinating species.

They're old.

They occupy these really unique niches and environments.

And so the giant sequoia, like the one behind me, tells us about a long history of droughts in the West.

It tells us about the natural regime of fires.

And then the coast redwoods really give us a unique insight into things like past earthquakes.

We can actually date how frequently large earthquakes occurred on major faults in California.

And it also is starting to reveal how changes in fog and moisture are modifying these really special environments.

{DAVID} We choose to begin in the heart of Redwood Country.

Eureka, California.

Most of the remaining old growth redwoods are protected in national and state parks.

To the north and to the south.

The redwoods are here thanks to an unusual combination of factors.

The moist air masses that originated in the Gulf of Alaska come banging in here for at least six to eight months a year and the mountains that were created by the tectonic forces created a situation where the moist air arrives, it goes up, the redwoods intercept it, and they get over 100 inches of rain a year in some places.

It's a combination that makes perfect conditions for the redwoods to grow at three, four, five feet a year.

It's an astonishing phenomenon, which makes the redwoods the tallest and among the largest trees in the world.

[MUSIC ENDS] [BIRD SINGS] {DAVID} Along a large stretch of the Pacific Ocean in Redwood Country.

The action of plate tectonics has thrown up a big mountain range called the King Range.

It cuts off a big portion of heavily populated California.

That part of the Pacific is so rough that no highway has been built in there, at least no high speed highway, and it's sort of cut off from the rest of the state.

So it's called the Lost Coast.

It is a very rough and different part of California, but in its own way, it protects a lot of the redwoods inland from the ravages of big storms blowing in from the Pacific.

The Lost Coast extends for sixty miles.

It's a completely undeveloped stretch of coastline.

We can see the action of the plates bringing parts of terrain hitting the North American plate, going underneath, and these pieces all be scraped off over the millions of years that the plates are running into each other.

Continuing to raise these mountains to the east.

That gives us the Lost Coast As we go along the coast it becomes really clear why it is lost, because there are just no places for harbors.

There are no marinas.

And one of the reasons is you could build a Marina, but it would be so difficult to get there that there would be no point to it.

The mountains basically cut off the access to Highway 101 and all the main North-South routes in California So the coast is lost because it's well, lost.

[MUSIC PICKS UP THE PACE] [WAVES CRASHING] {DAVID} Highway 101 in California goes right through Redwood National Park.

That was not by design, but by the way the park was actually formed.

And it's sort of a sad chapter of American history.

There was a strong impetus back in the 1960s to save the old growth redwoods.

The lumber companies strongly opposed any creation of the national park.

And so it was really public interest, environmental interest, Native American interest to save the old growth redwoods, which have such an incomparable value and never can be replaced.

The redwoods are found only in this narrow strip, northern California, near the ocean and inland, and extreme southern Oregon.

Nowhere else.

[MUSIC ENDS] Highway 101 passes directly through Jedediah Smith Redwoods State Park In California, in the northern part, The redwoods state parks and and national parks are administered jointly.

The redwoods are so important that there is no division between state and local, and here we can see why a view unlike anywhere else in the world, The rainfall in Jedediah Smith's State Park is the highest in all of the Northern California or Oregon coast, probably up to 120 inches of rain a year.

For that reason, the trees become truly massive.

[RAIN FALLING] It's not just the colossal size of these trees, but also their age and the role that they play in bringing other organisms that live with them and help tie up carbon and make the air cleaner.

When you breathe the air in this redwood forest, there's a purity about it that I never experienced elsewhere.

[LIGHT RAINFALL] Most trees pump the water up from the ground, but if you're a tree that's 350 feet tall that takes a heck of a pump.

These trees have learnt to take in the moisture from the top and bring it down, and make it much easier to distribute that water to their system that needs it all the time.

[ACUSTIC GUITAR BEGINS] {DAVID} This uh- very nice diorama that the Forest Service - Park Services have set up to show that the redwoods are - have been inhabited for thousands of years by native peoples, and uh- they were forcefully evicted from their homelands by settlers who came in and by logging companies, by agriculturalists.

And now, centuries later we're understanding how important they were.

[CALM MUSIC] {BARRY MCCOVEY JR.}

So this is a really important place for- to Yurok people and Yurok culture.

During colonization, there was a huge rush here to get the timber out.

So the stream used to meander through the valley here, through the through meadows.

It was completely pushed over against the side and channelized.

Most of this area was covered with concrete.

Erased what was here.

Poisoned the landscape, destroyed the creek, ruined the fishery.

So many fish depend on this healthy stream.

The people depend on those fish.

There was mills built all over this entire region during that period, and it did a lot of damage to this area.

You know, we slowly kind of got moved out of these areas, out of our traditional villages and into non-native settlements Redwood trees are a cornerstone of Yurok cultures.

People in general are dependent on these trees.

The bugs in the stream will suffer.

The fish will suffer.

The elk will suffer.

The bears.

Orcas out in the ocean will suffer from impaired redwood forest.

[MUSIC CUTS] [TRUCK RUMBLING] {DAVID} With the discovery of gold in Northern California, the most available wood is redwood.

Although it's not ideal for building houses, it is excellent to provide for parts of the houses that would normally decay because it doesn't decay like other woods.

The access to those forests were so easy that they became the target of lumbermen everywhere.

and 95% of the old growth forests are now gone.

[TENSE MUSIC BEGINS] {STEVE MIETZ} Here at Redwood National and State Parks, the league and the parks have been working together with the Native American people to help integrate them even more closely Learn from them, integrate them in all our restoration projects, in the park, operations as much as we can, so that tribal hands and tribal voices are also being heard just as much as the park's voices.

{BARRY} What we're doing here, we are reclaiming this land, trying to undo the injustice that happened here, ripping up all the concrete that was laid down, taking the creek out of the channel and putting it back into the valley with natural meanders so that everything that depends on a healthy stream can thrive.

It's a big part of what we do as Yurok people.

We believe in restoring balance to the ecosystem.

We see it as an investment in our future.

[STOMPING] {GABE} The elk like to- like to yank them out For whatever reason.

[LAUGHS] {ARI} They really treat this area like a little buffet.

So down that way, some of our plants they just like, snap right in half and are munched on.

{RICHARD} Planting silal all through the floodplains to bring back the native ecosystem we got going.

And to make a public landmark for people to come hang out, and enjoy what we're building, enjoy what was here originally {MIKAYLA} I think all restoration is important for all the land and I think this is going to be healthy healing for everybody.

{BARRY} People who come from all over the world can come in and see what we've done here, and we're really proud of that.

{STEVE} The area was once this terrible, smoky place, and now it's going to be a place of healing, a place of connection.

But we're also healing the relationship with the local community and the local indigenous people.

We're creating a more sustainable economy that's connecting people back to the north Coast.

[ACOUSTIC GUITAR MUSIC] {STEVE} Well, what I've been most impressed with, with the Yurok tribe is their skill and their passion for this work.

{BARRY} I think we've always had a good relationship with the Park Service, but it's gotten better over the past ten years.

The National Park Service really supports the work that Yurok tribe does.

{WEYK-SEYR} I mean, that'd be cool if there was a whole bunch more salmon up here.

Plus, it's cool the stewardship, you know, it's like we're taking care of it.

Especially considering, like, what all this was, you know, the old mill and all those things.

So it's it's pretty crazy.

It feels good.

You know?

It feels good.

I think.

[MUSIC CONTINUES] {DAVID} The Klamath River reaches the Pacific here.

There's a small delta of sediments brought down the river.

But this is where the salmon enter the river.

And, 100 years ago, could proceed 257 miles upstream to spawn.

When settlers came in and built dams, diverted the waters, pumped dry the marshes and the wetlands, those Chinook salmon no longer had an opportunity to make it upstream, and the thousands of indigenous people who depended upon them no longer had that resource.

Now, dams are being removed and the Chinook are very slowly returning.

{BARRY} We're standing in the in the watershed of Prairie Creek, which flows into Redwood Creek.

So anadromous fish, meaning fish that live in the river part of their life and live in the ocean part of their life.

Those type of fish use Prairie Creek in particular to spawn in.

These fish have evolved with a certain type of stream, and that's a stream that meanders, has pools.

When the Prairie Creek was pushed over and channelized, it took away all of the natural features.

It became a canal, basically.

And so what we see is this loss of habitat.

And if there's no habitat for fish to spawn in, then they don't spawn.

We're restoring the natural features of this stream.

So meanders, that provides areas for fish to rest, areas for fish to feed.

And then we're putting wood in the stream.

Slows the stream down creates all this habitat.

We're seeing fish already use those areas, which is really exciting and - but not surprising.

There's a kind of a big network of tagging that goes on so we can kind of track them around.

We've actually seen fish that have been tagged in the Klamath River leave the Klamath River, going to the Pacific Ocean, come up Redwood Creek, come up Prairie Creek and use these off channel ponds.

And these this new habitat to rear.

{VOLUNTEER} Bull mat grass Yeah, it's invasive in the, the clogs up the waterways.

This is a good example of one right here.

How is this lays flat like that If you get too many of them in there, they'll just make a big mat and then the water can't pass.

And whenever done that it has this very robust like almost corn stock.

Look through it.

{BARRY} We're learning things, and we're, we're starting to see a little bit of success.

[UPLIFTING SLOW MUSIC] {DAVID} You have to actually see them in person to appreciate how extraordinary these plants are.

There's nothing like them anywhere else in the world.

It's hard to guess how long ago this giant fell.

But the redwood does not deteriorate very quickly.

It takes hundreds of years.

The age often is determined by the number of rings And the tree ring people have done a lot of research You can't just count the rings to determine the age because weather cause the rings to do odd stuff.

And here we can actually see the tree rings and imagine that this is just one year's growth.

And there are hundreds and hundreds and hundreds and hundreds of tree rings here.

When the trees fall, you can get perhaps a clear idea just how enormous they are.

And this one is, a couple Yetmans tall.

Who knows how long It looks like it goes on forever.

Still going.

You still got a long way to go.

[GENTLE MUSIC PLAYING] Still going I think I've covered a football field.

Ok, I'm still going And now I begin to see where the end might have been.

Oh, and gradually becomes part of the living ecosystem.

Sometimes you'll see what it looks like.

Two redwoods growing together.

And it's hard to know whether it's a single trunk that has split, or two of them that have united into one tree.

Where this tree fell I can look way up inside this fallen tree and see that it's a place where animals can get out of the rain if they want, or even make their dens.

And these roots, they go on in all directions, and they intertwine with other trees.

So they develop this relationship that they they depend on each other for stability.

And maybe even they communicate with each other.

The understory in the redwood forest is fairly simple.

The amount of shade that they provide means that, a lot of plants don't have enough sunlight to grow.

But the ferns and these oxalis They do quite well here.

But there are not many plants that can compete with the lack of sunlight caused by the redwoods.

And of course, that means that there is more moisture available for the redwoods just not being intercepted.

One of the reasons that redwood survives so well is this bark.

It's very thick.

And it has fire resistance.

Now, the trees will burn.

At certain times a year, if they're struck by lightning.

But it takes a lot.

And this bark helps insulate them from fire [GENTLE MUSIC] There are not a lot of trees in the world that you can walk through like this.

But this one also has been struck by lightning.

Maybe back in 720 A.D.. And it is still functioning quite well because the actual- the vascular tissue, the tissue that - that, brings the water and the nutrients up and moves it down, is between this burnt part and the outer bark, and they can continue to function as a tree for perhaps 100 years afterwards.

It's astonishing.

This is a founder's tree 346 feet tall.

And there are others that are even taller and many others in this Humboldt Redwoods State Park.

[RELAXING MUSIC BEGINS] {DAVID} We are hoping to find the trailhead so that we can hike into the grove of the Titans.

[ACOUSTIC GUITAR MUSIC BEGINS] It was only discovered in the last decade or so that there are some immense trees up in this area.

One of the more sobering aspects of the Redwood forest is how very quiet it is [AMBIENT NATURE SOUNDS] [SOFT ACOUSTIC GUITAR] [RAIN FALLING] [FOREST BIRDS] In this grove are the four largest redwoods that have been identified.

But coming here makes you realize how much we owe to the people who have saved these forests And how sad it is that we have lost 95% of them.

[SOFT MUSIC] The tree rings that redwoods give us provide challenges for scientists.

But as they uncover more and more secrets of the redwoods, those trees are revealing a great deal about how we human beings have changed the climate to our detriment.

[MUSIC ENDS] {DAVID} Join us time In the Americas with me, David Yetman {DAVID} East of the Cascade Range of the western U.S.

is a vast, largely empty interior.

It's an arid land of skinny ranges that stretch north to south with intervening valleys.

Much of it is known as the Great Basin Ideal for a long road trip through a land of mountains and valleys rich in ores and mines, often abandoned and roaming herds of wild horses.

[HORSE NEIGHS] {DAVID} The Carson House in Eureka, California is perhaps the best example of Queen Anne-style Victorian construction in the United States.

It's a very famous house.

It was built by a man named William Carson who came here in the mid-19th century and found some gold, but ultimately introduced redwood as a lumber for building.

{ANNOUNCER} Funding for In the Americas with David Yetman was provided by Robert and Carol Dorsey.

[MUSIC] The Guilford Fund.

Arch and Laura Brown.

And Hugh and Joyce Bell.