(forest critters chittering) - [Mark] Stepping into the forest awakens the senses.

From the creatures stirring below ground, up to the leaves of the tallest branches rustling in the wind, there is movement happening at each level of the forest.

This is By Nature's Design Inside the Forest.

Floor to Foliage.

- Forests are dominated by trees and have a continuous canopy cover.

So that gives us, you know, a subset of the plants, the trees, the canopy trees that are receiving full sunlight, and then a lot of things going on in the understory that are happening in the shade.

So we get this really stratified ecosystem with forest floor, a mid-story, and then a canopy that's intercepting a majority of the light.

A high proportion of the land surface is covered by forest, about 30% of the terrestrial area of the earth is covered by forested lands.

And because that's such a big area, we get really different sorts of forests.

So that goes from tropical rain forests down near the equator, all the way up to boreal forests in the north.

And here we sit sort of in the middle temperature region, temperature climate for forests.

And so we have what we call deciduous forests.

So those are forests that have pretty strong seasonal signature.

So we go from leaves on in the growing season, that's late spring, summer, early fall, to open canopy in the winter.

So we have full sunlight hitting the forest floor part of the year, and then we have closed canopy part of the year.

Deciduous forests are sort of distributed around the globe in areas that have this similar climate.

So we have them in North America, we have them in large parts of Europe, and we have them in Northeastern Asia.

So those are spaces where we have sort of similar climate regions and we get these sorts of forests.

(gentle music) - So forests are important for a lot of reasons.

One thing is a forest is really a home.

So a forest is a home to a lot of different creatures.

And so really simple one that almost everybody knows, squirrel.

If we didn't have trees and forests, we would not have squirrels.

And then it starts to get a little bit more complicated even with a squirrel because it's not just the trees that provide the home for a squirrel, it's the type of trees.

So we need certain types of trees that are also going to provide certain things to, in this case, like a squirrel.

So we need oak trees that are going to produce acorns or hickories, trees that are going to produce hickory nuts that squirrels live on.

So there's some creatures that are kind of broad, like squirrels that everybody knows and sees in the park that need forests to live.

But then there's also a lot of really spectacular creatures in the forest that most of us will never see.

So for instance, there's a whole range of migratory songbirds that fly thousands of miles from sometimes South America, Central America to Ohio to nest.

And again, most of us won't see these day-to-day walking down the streets, you're not going to see most of these birds, but if you do, they're spectacular.

They're the brightest oranges and the brightest reds and the brightest yellows that you can imagine.

And again, without forests, we would not have those species here in Northeastern Ohio.

So there's a lot of different creatures that really depend on forests for a place to live.

(gentle music) Another reason that forests are important is they're really good at cleaning and filtering water, and they're also really good at managing storm water.

When it rains, forests will, first of all, the canopy, the higher level of the trees and the forest, they'll actually catch a lot of rain.

The rain just stops.

It hits the leaves, for instance, and stays there.

Hits the branches, runs down, stays there.

So already it's reducing the amount of rain that's hitting the ground.

And then at least when we have a healthy forest, the ground under the trees is actually like a sponge.

All the leaves that have fallen over decades and hundreds of years in some cases create this very spongy layer that also just soak up water like a sponge.

So they're good for catching water before we even have to worry about it flooding something.

(gentle music) - [Mark] There are many benefits that forests provide and it all starts beneath your feet on the forest floor.

This is where organisms thrive by breaking down fallen leaves and trees providing nutrients to the surrounding plants.

- Traditional forest floor is where anything that falls from above settles and becomes soil eventually.

So that's leaves, animal droppings, rainwater.

If you're near a body of water or a stream, it might be rocks or sediment that are blown around in the wind or in rain events.

And those all contribute to the vast array of organisms that inhabit a typical forest floor.

In an urban forest, a lot of those inputs are stripped away because we've gotten rid of most of the trees, so they're not dropping leaves.

And when they do, we collect them and take them somewhere else.

We've planted turf grass and all kinds of things that don't contribute to the forest floor in the same way that might naturally be expected.

We cover a lot of the floor with impervious surfaces that make it so that water doesn't travel across the floor in the way that it maybe should.

You can expect to see, even in the city, animals, chipmunks, squirrels, voles, raccoons, groundhogs.

There's all kinds of animals that still hang out on the forest floor.

Lots of insects will still lay their eggs and procreate in that area.

So it still functions to a degree like it should, but definitely much less effectively.

(gentle music) - The forest floor is really characterized, especially in older, healthier forest by a thick organic layer.

And that's really something that a lot of the species are depending on.

The forest floor is really responsible for a lot of the nutrient turnover.

And so everything else in the forest is really reliant on that layer to make nutrients available.

The roots are anchored into the forest floor.

They're uptaking nutrients.

Those nutrients are made available by the plethora of organisms that are existing right there in the forest floor.

And then they're using that to grow biomass above ground.

That biomass is going to exist and sort of interact in the matrix of plants and animals and other organisms above ground until those things synapse or die and then they go back into the forest floor and those nutrients cycle back through.

(gentle music) In the forest floor, I think one of the most striking bits of it is the spring ephemerals that we see just seasonally.

So spring ephemerals get their name because their life history strategy is ephemeral.

So they are individually long lived, but most of the year we don't see them.

So they're having a life strategy that's ephemeral in that they're trying to seek out light on the forest floor, which is usually deeply shaded.

So their life history strategy is that they pop up as soon as it gets warm enough, they try to do all their photosynthesis energy grabbing for the year before or as soon as that canopy leaves out.

So they're in a little bit of a race for time.

So they're coming up really quickly, they're photosynthesizing, and then they're synapsing above ground and just storing all that energy below ground for the rest of the year once they're sort of in deep shade because it's not sort of worth the energy investment to maintain those structures above ground when there's very little light in the understory most of the year.

Species like that contribute a lot of biodiversity to our forest.

They're really critical for some invertebrates, some bee species that will come out really early in the spring, some of the first food that those species have.

So really critical players on the landscape.

(gentle music) - These are Virginia bluebells.

Virginia bluebells are a plant that grows only really in riparian areas, forests that are found along the river or along streams or things like that.

And they're this beautiful blue color that also, they also kind of have these shades of purple intermixed with them.

They are pollinator magnets.

And so there are things buzzing all around me, little tiny flies, little small-tongued bees.

There's bumblebees in here.

It's finally gotten warm enough that they're out and flying, but just a phenomenal spring wildflower, a wildflower that is threatened by invasive species as well as things like invasive earthworms and climate change.

So we love Virginia bluebells and it's just a great day to capture them.

(gentle music) - This time of year, if you walk through a forest, you'll see a whole bunch of different species that are only here for a short window of time.

Here today we have violets, a couple species.

We have some that are purple as well as yellow.

We also have some species above ground, not blooming right now, but squirrel corn is existing above ground right now.

People like to eat ramps or wild leeks and here is a specimen right here, though occasionally these will carpet the whole of the forest floor for certain parts of the year.

Cut leaf tooth wart, also another species that blooms a little bit earlier, so probably last week was blooming.

And then some wild phlox that we're getting right now in the understory.

So here is a bigger patch of phlox sort of existing in this matrix with the squirrel corn, trout lily, which would have been blooming maybe two weeks ago, as well as a few other species that are not necessarily ephemeral, but like this gallium, this bed straw that will be here probably throughout the summer.

(gentle music) - [Mark] The forest floor cannot function properly without a healthy understory to protect it.

This level sits between the floor and the canopy of the forest.

(gentle music) The understory provides habitat to a variety of species through shrubs and herbaceous plants.

- So the understory layer in a forest usually consists mostly of shrubs.

Sometimes small trees will be mixed into there.

And again, usually generally maybe everything that's 20 feet or shorter usually can be considered mostly the understory.

It can be a little taller, a little shorter, but that's the understory.

And again, that's the kind of the mid-level of the forest.

We do get a lot of, again, birds nesting in those areas, get a lot of insects in those areas.

There's a lot of some specific butterflies that need that kind of understory, shrubby layer to survive.

And yeah, it really makes a big hit when it's not there.

(gentle music) So in the understory in Northeast Ohio, unfortunately, a lot of it is dominated by non-native invasive shrubs and vines.

So some of our most common understory plants in this area are multi-floor rows, bush honeysuckles, different privets.

All these have mostly escaped from landscaped areas and now they're dominating the understory in the forest floor.

If the understory is like pretty whacked, then that's a pretty good indication that there's probably too many deer in that area.

If the deer at a decent population level that supports like forest health, then you'll see all kinds of small trees popping up and shrubs and a lot of wildflowers.

If you don't see all that in the understory, then there are probably too many deer.

(gentle music) - The understory layer is pretty much anything in between the forest floor and the canopy of a tree, depending on the tree that could be six feet to 20, 30, 40 feet.

So it's all that kind of interstitial space between what's on the floor and kind of the lower levels of the tree canopy.

The understory is going to be kind of that nursery.

If you think of like it's preschool and elementary school for trees, and just like humans, you kind of want to have scaffolding and protection for your young organisms so that they can grow up to be robust, healthy, mature adults, hopefully.

And so when there's not a good understory layer, then in time that impacts the quality of the canopy.

And young trees need kind of protection from harsher conditions that mature trees can handle.

So too much sunlight, too much wind, that kind of stuff.

The mature trees in a forest generally protect younger trees that are in that understory layer.

And then you also have shrubs and other shorter, smaller growing vegetation that is going to inhabit that space.

(gentle music) - [Mark] Protecting both the understory and the forest floor is a canopy layer.

This is the tallest and densest part of the forest where most trees develop leaves and grow among each other.

As the canopy braves in clement weather, its thick leaf cover slows rain and wind, sheltering the floor and understory from disturbances.

(gentle music) - So the canopy layer is usually the top layer of the forest, the highest layer when you're standing underneath the trees and looking up, what you're looking at is the canopy layer.

That is layer that is mostly dominated by the leaves of the highest branches of the trees.

And again, in our area here in Northeast Ohio, that layer is usually 80 feet, maybe 100 feet above ground.

Other areas of the country can be much, much higher, hundreds of feet in the air.

But around here, if we have a good, healthy forest with a canopy of 100 feet, that's pretty good.

(gentle music) So in a healthy forest, one expects to see in the canopy layer is a lot of leaves.

When the wind's blowing, you'll see a lot of leaves blowing.

You'll hear a lot of rustling, which is one of the coolest aspects of a forest on a windy day.

The canopy layer is also where a lot of larger birds nest.

So for instance, great blue herons, they nest in the higher levels of trees.

A lot of other smaller birds might nest in the lower areas.

A lot of the bigger birds in general maybe nest higher.

Owls you may see up in, again, the higher layers, you may see them lower also obviously, but yeah, a lot of those bigger birds will be up at the top where the branches are stronger.

- The canopy trees are relying on all the basic things that plants need, right?

So they need light, they need water, they need nutrients, they need some space.

So they have the advantage in the forest in that they are the first interceptors of light.

So they have light in abundance and then they are anchoring into the forest floor and from that they are pulling up moisture, water, they're uptaking soil nutrients, they need space.

And in that way, forests are highly shaped by competition.

So it's a system where we have lots of individuals, lots of species, and they're sort of duking it out for space and space equals light within the forest for water resources, for nutrient resources.

(gentle music) The canopy and the forest floor have a tightly-linked, cyclical relationship in that the forest floor is providing the nutrients that are being taken up by the tree.

A lot of that is going into the protection of leaves seasonally.

And then on the other end of that season, they are synapsing, dropping those leaves and that's feeding those nutrients back into the forest floor.

And so a lot of what we would find in terms of nutrients, carbon, structure in the forest floor is directly shaped by the canopy trees.

(gentle music) - So the canopy layer is interesting and it actually needs kind of a broad range of things to function properly from the subground, below ground, root to the very top, tip tops of the trees.

And one interesting in like again, a healthy forest that hasn't been too disturbed is there are a lot of types of fungus that actually live below the forest floor in the ground.

And they have this interesting relationship with a lot of the native trees where they're providing nutrients and input to the trees and the trees are kind of returning that favor in some ways.

So there's this cool relationship between the tallest trees in the forest and things that you will never see, little microscopic organisms in the soil.

So they need that and then they need all the way up to the upper layers where they need to be able to get the same.

All plants need water, all plants need sunlight, all plants need food or nutrients.

And without those three things, then the forest will not survive.

(gentle music) - In a regular forest, removing the trees that are shading the forest floor, contributing leaves and other decaying materials impacts how the forest floor functions, and that happens naturally.

Trees fall in regular forests and open up space and then new trees fill that space.

But in cities, the biggest threat is kind of a combination of us extracting natural parts of that process, so leaf collection and then us adding things that shouldn't necessarily be there, whether it's turf grass or asphalt or concrete.

(gentle music) - [Mark] Altering how a forest functions is just one way this ecosystem suffers.

With contributing factors like deforestation, climate change, and the spread of invasive species, the longevity of forests is at risk.

Without forests, the ability to naturally store carbon is lost.

Animals lose their habitats and our water cycle is disrupted.

(gentle music) - Forests in this region and forests around the world have a whole slew of threats these days.

Those include land use conversion, so forests that exist as forests today, but are likely to be converted to other land uses, be that agriculture, housing developments, other sort of ways that we might use the land.

So that's a threat in contributing to loss of forest.

Climate change is reshaping our forests.

So forests might stay as forest, but the composition might change as the climate conditions in which those forests exist change.

We have non-native species and then a subset of that are these emerging forest pests and diseases.

And those are particularly problematic because we could have an emerging pest come in and take out the vast majority of individuals of a given species.

And so we see these big changes in how our forests are composed, what species exist within the forest when we see those diseases come online and take up residence within our forest.

- Invasive species can overtake some of the native species that might grow slower or invasive species could steal nutrients from species that should be there, which kind of is a compounding effect.

You get more invasive species when you have some and then it's just a escalating issue.

(gentle music) So Tree of Heaven, Atlantis is the Latin name, is a species native to China.

It was introduced in the mid 19th century and it was a great urban tree because it grew really fast and gave lots of good shade and it didn't have any insect issues because the native insects didn't like to eat it.

But now we've learned 100, 200 years later almost that they spread really easily and out compete a lot of our native species.

(gentle music) - So here at Cuyahoga Valley National Park, we have a huge giant volunteer program to help us manage invasive plants in particular.

Every week we have multiple events where we are out managing, cutting, removing invasive plants.

And really over the last few years, we've really tried to target some of our more healthier patches of forest to try and promote that understory that is still waiting in some cases to pop back when we remove those plants.

We have done a lot of reforestation over the years and we have some areas again where the forest has come back great on its own, but some areas where it's just struggled.

And so some of those areas where it struggles, we've stepped in to try to promote native reforestation.

And we've had the fortunate, you know, the fortune to have literally thousands and thousands of volunteers help us with reforestation projects.

So we've been able to introduce a lot of people in local communities and even from other areas who visit us to regenerate forest here.

And I think that's pretty cool.

Like it's not only helping us locally with the local ecology and promoting, you know, the habitats and the creatures that should be here, but it's also involving like the bigger community and the opportunity to do something really good for the landscape.

(gentle music) - In this part of Ohio, in this part of the country in general, we've been seeing over the past few decades an increase in forested land, and that's as, you know, agriculture has been centralized and we get a lot of smaller family farms that are being released from agriculture and reverting into forests.

And so we are seeing an increase in forested land and we're also seeing an increase in land that's ripe to be forest.

And that's a really powerful position for citizens of Ohio, Pennsylvania, the Northeast in general to be in because forests are the number one natural climate solution.

So when we think about turning back the tide of climate change, forests are the number one terrestrial tool we have to do that naturally.

(gentle music) In general, we're seeing forests face unprecedented levels of challenges, but also unprecedented levels of land now available to be forested.

- In the city of Cleveland, I think things are looking much better.

Cleveland Tree Coalition is 10 years old now and they're doing a lot of good work.

The Reforest Our City program at Western Reserve Land Conservancy is 10 years old now and doing good work.

And I think people are just generally understanding that trees are beneficial to the urban human experience in ways that they might not have even 10 years ago.

But trees also take a long time to grow, like people.

So, you know, all the trees that are going in the ground now aren't going to be mature for 30, 40, 50 years.

So it's an exercise in delayed gratification, which humans are notoriously bad at.

It's just a constant battle of advocacy and kind of tree roots movements.

(gentle music) - Trees are really valuable in a lot of ways from an ecological perspective, but then also to a very common, like if you're sitting at a table right now watching this, thank the forest.

Forests are being, you know, affected by a lot of things right now.

Forests cannot move, you know, as things change, as it rains more, or as it heats up, or as it floods more, the trees can't move.

They're just stuck.

They need people to speak for them, and so I just hope that the forests have a chance to survive.

- [Mark] A stable forest is critically important to all forms of life.

It begins on the ground with the forest floor.

Healthy soil for its roots is necessary so that trees can grow tall into the canopy and provide leaf coverage for the understory layer.

While there has been some forest loss in this region, it is important to recognize the work underway to protect and regenerate these essential ecosystems.

Each level of the forest is intertwined by nature's design.