Music The whole earth was once just sand, gravel, and rock.

Nothing lived on it.

All the life was in the sea.

Music Little by little, over a long, long time, organisms adapted to living on land, taking advantage of the sunlight and the gases in the atmosphere.

This is how nature works!

Theme Music Music Plants are among the first organisms to arrive on land.

They captured the energy from the sun and then later on, other organisms changed, taking advantage of the energy the plants were capturing.

That was the beginning of interactions among living things on land.

A group of interdependent organisms living in the same area and under similar conditions is called a community.

On land, these groups are called terrestrial communities.

Over millions of years since the first terrestrial communities, living organisms have created communities in just about every kind of landscape.

In some places similar climate, geography, geology, and life forms exist over a large area.

These areas are called biomes, and they include tundra, rainforests, grasslands, taigas, temperate deciduous forests, and deserts.

Near the north and south poles, covering a fifth of the earth, is a treeless biome with a permanently frozen layer of soil just beneath the surface.

This biome is the arctic tundra.

A similar biome, found above the tree line on mountains, is called the alpine tundra.

All tundra organisms survive in extreme cold and dry winds.

On the tundra in the summer, the surface thaws for just 6 to 10 weeks.

The long, warm days thaw ice and snow, forming shallow lakes on the top of the permafrost.

The lakes nourish insects that are a perfect food for birds that live on the tundra during the short summer.

Animals that live on the tundra year- round are adapted to very cold temperatures and severe conditions.

The world's largest biome, spanning much of Canada, Asia, and Europe, has snowy winters and brief, warm summers.

It is covered with trees like pines that are called conifers.

This biome is called the taiga.

Trees like black spruce, balsam fir, tamarack, and white cedar are adapted to survive here because their needles use less water than broad leaves.

Broad-leaf taiga trees like birtch and aspen are flexible and bend without breaking under heavy snow.

Farther from the poles, In the eastern U.S.

and Canada, Europe, Japan, and parts of China, are forests where the summers are warm and humid, growing seasons are long, and winters are distinct.

The seasons change gradually here.

This biome is the temperate deciduous forest.

As the climate cools and the growing season ends, many trees in this biome drop their leaves to save water and save their branches from heavy ice and snow.

These trees, called deciduous, are dormant in winter.

Their leaves emerge again in spring.

There are tropical and temperate climates on every continent but Antarctica.

Another kind of biome covers about a quarter of the Earth, where soil is rich but too dry for forests and too wet for deserts.

These vast areas are the grasslands.

Communities in these areas are built upon grasses.

Grasses are suited to these conditions, with roots that reach water deep down, a structure that slows moisture loss, the ability to bend and twist to minimize wind damage, and a way to keep vital parts below the reach of drought, fire, and grazing animals.

Whether the climate is temperate or tropical, wetness and warmth are the conditions that foster the richest living communities.

The biomes with both of these are temperate and tropical rainforests.

The vegetation here is dense.

The trees here can grow very tall, and to support their height, their trunks flare out at the base.

The roots spread out and collect nutrients from water that’s staying near the surface.

Temperate rainforest communities thrive in cool coastal areas that may get up to 100 inches of rain a year.

The largest temperate rainforest stretches for more than a thousand miles from Oregon to Alaska.

Near the equator, where 400 inches of rain may fall in a year, are the wettest, warmest, and most diverse biomes of all: tropical rainforest.

About half are in Latin America, and the rest are scattered in Asia, Africa, and the Pacific Islands.

More than half of the living things in the world live in tropical rainforests.

The moisture and the warm temperatures there promote communities with lots of different kinds of interdependent organisms.

It's amazing that living things could come out of the sea to live on land and become part of so many different kinds of communities.

It seems like there's a community for every kind of landscape.

Some animals and plants can only live in one place and nowhere else, and others can live in many different places.

Let’s go ask Dave at the Nature Center.

why that's so.

Music Hi, Dave.

It looks as if you has a hawk down the flight way.

You're right, Patrice.

We're getting it ready for school programing again.

The red tail hawk can live with a number of different kinds of communities, right?

Right.

They do.

They're the most adaptable and most widespread hawk in North America.

As long as they got a mixture of habitat and woodland, shrubland, grasslands, they seem to do pretty well.

Is it because of what they eat that they can survive in so many different kinds of communities?

You're right.

Not only are they adaptable in where they’ll live, but part of their adaptability is their ability to take advantage of different kinds of foods.

But they're also very tolerant of climatic differences.

So they can survive in the humidest of rainforests but they also can survive in the harshest desert.

Music Deserts are lands of extremes.

Temperatures in deserts can be frigidly cold at night and scorching hot in the day.

Most people think of deserts as hot, sandy, dry places.

Well, all deserts are dry and some are sandy.

But not all deserts are hot.

Parts of Antartica and Greenland have deserts, but they're cold.

Very cold air can't hold much water vapor.

And without water vapor, it can't rain or snow.

There are some deserts in Antarctica where it hasn't rained in millions of years.

These are the driest places on Earth.

And because it's so dry, very few species can survive in hot deserts, temperatures can reach 120 degrees during the day, but when the sun sets, the temperature can drop quickly.

That's because dry desert air is usually cloudless, so it can't hold heat at night.

With nothing to hold it in, the day’s heat rises out into space.

You'd think there wouldn't be much living here, like in the cold deserts, but hot deserts are home to lots of organisms.

In fact, next to the rainforest and coral reefs, hot deserts are the greatest variety of animal and plant species.

Plants and animals in hot deserts have many adaptations that help them survive in extreme conditions.

Plants in the desert are usually spread out, scattered.

They have to compete for water.

If they were too close together, there wouldn't be enough water to go around.

Desert plants must make the most of the water around them with adaptations that help them to collect and store water.

During the day, plants’ stomata, or pores, close, which helps keep the water from evaporating.

Some desert plants are annuals.

They growing quickly.

Sometimes their whole life cycle is in just a few days.

Seeds of these plants may stay on the ground for years, waiting for a rainstorm before they can bloom.

During the day, desert heat can be deadly to many animals.

Animals like the kit fox and kangaroo rat find shelter under rocks or plants, and burrow underground during the day and come out at night to hunt for food.

Reptiles rely on the heat of the sun to warm their bodies.

The best time for them to hunt is during the day when they're warm.

But sometimes the heat is even too much for them.

They'll move to a shady spot or underground burrow to cool off.

Birds have some advantages over other types of animals that live in the desert because they fly.

They can cover greater distances in their search for food and water, and they're also better adapted to heat than other animals.

Their feathers serve as insulation and protect them from the heat of the sun.

Although most animals found in the desert are small, there are some large mammals that have developed adaptations that help them to survive in the desert.

Life in deserts can be a challenge, but many plants and animals have adapted to survive and thrive in these lands of extremes.

The desert is one terrestrial community with extreme conditions that organisms have been able to successfully adapt to.

Laura and Marshall are going hiking with David Publicover of the Appalachian Mountain Club.

They are going to compare the diversity of plant life along the trail.

And.

Music What we've done is we've laid out a square one meter on a side, and we want to get an estimate of all the vegetation in here.

So we want to write down quadrat number one.

That's what these little square plots are called, they're called quadrats.

And the first thing we want to do is just list all the different species we find in here.

I have, like, ferns.

Yeah.

We have, this is called a wood fern.

So we have wood fern.

So just write these down as we come along.

Well, why are we doing this?

Why are we making a box to figure out - This is just a standard, a standard technique for measuring low vegetation.

If you wanted to figure out how much fern was out here just by walking around, it would be pretty hard to guess.

But this allows you to put in a lot of plots pretty quickly.

You can find out how much fern is around, not only in terms of how many of these little squares does it show up in, which would show you that it's well-distributed across the area, but how much of the ground that covers, which shows you how abundant it is, and you can figure out which are really the dominant plants.

And that's going to change as you go from one area to another.

Music So this is a little bit different than what we had in the last, the last place.

There are different plants here.

There are a lot of beeches around here.

Yeah.

Yeah.

But a lot of the stuff we saw in the last place, the Canada mayflower or the star flower, aren't here.

I've noticed that there are, in this area, there isn't any ferns like the other one where there were lots and lots of ferns.

Yeah, not a lot of ferns.

So this place is a lot different than the last one.

Music Well, anybody can do this.

Look around.

Observe.

Pretty, pretty much.

You don't always have to take all the quantitative measurements.

Anybody, wherever they live, can learn a lot just by going out, observing and looking for the patterns out in the woods, woods or plains or wherever you are.

What kind of plants grow in what place, what grows in wet areas, what grows in dry areas, what sorts of things grow together.

The more you understand it, the more you enjoy it.

Kind of like anything else, like playing guitar or roller skating, the better you get, the more fun it is.

Music What have we learned today?

A group of plants and animals that depend on each other and live in the same area under similar conditions is called a community.

On land, these groups are called terrestrial communities.

Biomes are large areas of land with similar climates and plant life.

Major biomes include the tundra, grasslands, tiagas, temperate deciduous forests, and deserts.

Now you know how nature!

works.

Theme Music Major funding for Nature Works was provided by American Honda Foundation.

Additional funding was provided by Alice Freeman Muchnic Alice J. Reen Charitable Trust, Cogswell Benevolent Trust, the Finisterre Fund, Greater Piscataqua Community Foundation, Morgridge Family Trust, the Natural Areas Wildlife Fund, Rawson L. Wood.

(animal sounds)