Download Tundra Biomes - Warren County Schools

snowfall can reach heights well over your head-or even two or
three times your height! Even so, the summers are rainy and
warm enough to melt all the snow.
A limited number of trees have adapted to the cold climate of
boreal forests. Fir, spruce, and hemlock are the most common
species because their thick, waxy needles keep water from evaporating. Since water is frozen for much of the year in these areas,
prevention of water loss is a necessary adaptation for trees in the
boreal forest.
Many of the animals of the boreal forest eat the seeds produced
by the conifers. These animals include red squirrels, insects, and
birds such as finches and chickadees. Some of the larger herbivores' such as porcupines, deer, elk, moose, and beavers, eat tree
bark and new shoots. This variety of herbivores in the boreal forest
supports a variety of large predators, including wolves, bears,
wolverines, and lynxes.
Tundra Biomes
Figure 21 Far from being a barren
terrain, the tundra explodes
with color in summer. Mosses,
wildflowers, and shrubs flourish
despite the short growing season.
Relating Cause and Effect Why are
The driving wind brings tears to the eyes of the members of the
expedition as you arrive at your next stop. It is now fall. The slicing wind gives everyone an immediate feel for this biome, the
tundra. The tundra is an extremely cold, dry, land biome.
Expecting deep snow, many are surprised that the tundra may
receive no more precipitation than a desert. Most of the soil in the
tundra is frozen all year. This frozen soil is called permafrost.
there no tall trees on the tundra?
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During the short summer the top layer of soil
on the tundra thaws, but the underlying soil
remains frozen.
Plants on the tundra include mosses,
grasses, shrubs, and dwarf forms of a few
trees, such as willows. Looking across the
tundra, you observe that the landscape is
already brown and gold. The short growing
season is over. Most of the plant growth takes
place during the long summer days when many
hours of sunshine combine with the warmest temperatures of the year. North of the Arctic Circle the sun does not set
during midsummer.
If you had visited the tundra during the summer, the animals
you might remember most are insects. Swarms of black flies and
mosquitos provide food for many birds. The birds take advantage
of the plentiful food and long days by eating as much as they can.
Then, when winter approaches again, many birds migrate south to
warmer climates.
Mammals of the tundra include caribou, foxes, wolves, and
hares. The animals that remain in the tundra during the winter
grow thick fur coats. What can these animals find to eat on the
tundra in winter? The caribou scrape snow away to find lichens,
which are fungi and algae that grow together on rocks. Wolves
follow the caribou and look for weak members of the herd to
prey upon.
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What is the climate of the tundra?
Mountains and Ice
Some areas ofland on Earth do not fall into one of the major land
biomes. These areas include mountain ranges and land that is covered with thick sheets of ice.
You read in Section 3 that the climate conditions of a mountain change from its base to its summit. As a result, different
species of plants and other organisms inhabit different parts of
the mountain. If you hiked to the top of a tall mountain, you
would pass through a series of biomes. At the base of the mountain' you might find a grassland. As you climbed, you might pass
through a deciduous forest, and then a boreal forest. Finally, as
you neared the top, the trees would disappear. Your surroundings
would resemble the rugged tundra.
Some land on Earth is covered year-round with thick ice
sheets. Most of the island of Greenland and the continent of
Antarctica fall into this category. Some organisms are adapted to
life on the ice, including penguins, polar bears, and seals.
Figure 22 Many waterfowl spend
summers on the tundra. This black
brant is tending her nest.
Interpreting Data
An ecologist
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has collected
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climate data from two
locations. The total yearly
precipitation is 250 cm in
Location A and 14 cm in
Location B. The graph below
shows the average monthly
temperature in the two
locations. Based on this
information, of which biome is
each location a part? Explain.
Average Monthly Temperature
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Chapter 2
E. 69
Figure 23 Ponds and rivers are
two types of freshwater habitats.
A. At the edge of a pond, two
western pond turtles sun
themselves on a log. B. A brown
bear fishes for salmon in the
rushing waters of a river.
Comparing and Contrasting How
are these habitats similar? How are
they different?
Freshwater Biomes
The next stops for the expedition are located in water biomes. Since
almost three quarters of Earth's surface is covered with water, it is
not surprising that many living things make their homes in the
water. Water biomes include both freshwater and saltwater (also
called marine) biomes. All of these are affected by the same abiotic
factors: temperature, sunlight, oxygen, and salt content.
An especially important factor in water biomes is sunlight.
Sunlight is necessary for photosynthesis in the water just as it is
on land. However) because water absorbs sunlight) there is only
enough light for photosynthesis near the surface or in shallow
water. The most common producers in most water biomes are
algae rather than plants.
Ponds and Lakes First stop among the freshwater biomes
is a calm pond. Ponds and lakes are bodies of standing, or still,
fresh water. Lakes are generally larger and deeper than ponds.
Ponds are often shallow enough that sunlight can reach the
bottom even in the center of the pond, allowing plants to grow
there. Plants that grow along the shore have their roots in the
soil, while their leaves stretch to the sunlit water at the surface.
In the center of a lake, algae floating at the surface are the
major producers.
Many animals are adapted for life in the still water. Along the
shore of the pond you observe insects, snails, frogs, and salamanders. Sunfish live in the open water, feeding on insects and
algae from the surface. Scavengers such as catfish live near the
pond bottom. Bacteria and other decomposers also feed on the
remains of other organisms.
70.E
Streams and Rivers When you arrive at a mountain stream,
you immediately notice how different it is from the still waters of
a lake. Where the stream begins, called the headwaters, the cold,
clear water flows rapidly. Animals that live in this part must be
adapted to the strong current. Trout, for instance, have streamlined bodies that allow them to swim despite the pull of the rushing water. Insects and other small animals may have hooks or
suckers to help them cling to rocks. Few plants or algae can grow
in this fast-moving water. Instead, first-level consumers rely on
leaves and seeds that fall into the stream.
As the river flows along, it is joined by other streams. The current slows.The water becomes cloudy with soil.With fewer rapids,
the slower-moving, warmer water contains less oxygen. Different
organisms are adapted to live in this lower part of the river. More
plants take root among the pebbles on the river bottom, providing homes for insects and frogs. As is true in every biome, organisms are adapted to live in this specific habitat.
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What are two abiotic factors that affect organisms
in a river?
Marine Biomes
Next the members of the expedition head down the coast to
explore some marine biomes. The oceans contain many different
habitats. These habitats differ in sunlight amount, water temperature, wave action, and water pressure. Different organisms
are adapted to life in each type of habitat. The first habitat, called
an estuary (ES choo ehr ee), is found where the fresh water of
a river meets the salt water of the ocean.
Estuaries The shallow, sunlit water, plus a large supply
of nutrients carried in by the river, makes an estuary a very
rich habitat for living things. The major producers in estuaries are plants, such as marsh grasses, as well as algae.
Figure 24 Fresh river
water and salty ocean
water meet in an estuary.
Estuaries such as this
Georgia salt marsh
provide a rich habitat
for many organisms,
including a wading
tricolored heron.
Chapter 2
E. 71