How Do Ecosystems Work

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How Do Ecosystems Work?
A tour of the Andrews Experimental Forest
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Hidden deep in the Oregon woods is a wild,
ancient placethe Andrews Experimental Forest
Here, for the first time, many ecologists come
together to study the wildlife, soil, plants and
insects. Research at Andrews shows how each bit
of fungus, each pine needle, each animal, and
every event, from the growth of a single tree to
a forest fire is critical to the delicate balance
and existence of the forest. They are showing
how all these parts work together like one
complex organism. All parts working together as
one ecosystem. The Hidden Forest by John Luomo
Prepared by Lyn Neeley, summer 2003 with help
from a NSF grant. Thanks to Kari OConnell,
Melora Halaj, Howard Bruner, Mark Harmon, The
Hidden Forest by John Luomo, and the veg crew
Bob and Aaron.
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What is an Ecosystem?
An ecosystem is an area that contains all living
and nonliving parts that are interdependent and
that interact with each other
How big is an ecosystem?
An ecosystem can be as big as a biome or a forest
or as small as a drop of water. Earth is one big
ecosystem.
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In the past, environmental scientists studied
only one organism like this lady beetle larva
that lives on conifers and feeds on aphids. But
they didnt study the other parts of the beetles
ecosystem.
Now in order to understand each organism,
ecologists study the whole ecosystem and how
the beetle interacts with all parts of its
ecosystem.
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Lets take a close look at what ecologists are
learning about one ecosystem at the Andrews
forest
In 1950 ecologists began studying the Andrews to
help answer the question How do ecosystems
work? The Andrews forest is a coniferous rain
forest that covers about 16,000 acres and is 5
miles across.
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North America
South America
The Andrews Forest is an old growth forest. The
Andrews is located in Oregon. It is part of the
temperate evergreen rain forest biome. That biome
covers the west coast of North America from
Alaska through Canada, Washington, Oregon and
northern California.
The pacific north west coast of the United States
Biome An area on earth with similar climate,
and organisms
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In 1950 the Andrews Forest was established as a
Long Term Ecology Research Center (LTER).
The Andrews Forest was one of the first LTER
centers. Today there are about 30 LTER sites in
the Unites States where long term ecology
research is being done.
In the last 25 years ecologists at the Andrews
have learned more about how one single type of
forest works than anywhere else in the world.
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Old Growth Forests Forests that have had at
least 200 years of succession are called old
growth forests. They are very healthy, stable
ecosystems. Characteristics of old growth forests
include

• 1. Huge old trees that can live up to 1,300 years
  old
• 2. Vertical layers of vegetation of many species,
  ages and sizes
• 3. Biodiversity
• 4. Species that can only be found in old growth
• 5. Snags or dead standing logs
• 6. Dead rotting logs lying on the forest floor

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Geography of the Pacific Northwest
Cascade Mountains 5,000 feet to 14,462 feet high
Andrews forest On the west side of the Cascade
Mountain foot hills.
Coastal Mountains 3,000 to 8,000 feet high
Pacific Ocean
Willamette Valley
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Western sides of Oregon mountains get fresh air
that blows off the Pacific Ocean. The air is
full of evaporation from the sea. It travels
over the coastal mountains and over the
Willamette valley. When the moist evaporation
reaches the high altitudes of the Cascade
Mountains it rises, cools, condenses, forms
clouds and rains or snows on the west side of
the mountain range.
Cascade Mountains
Drought A long period of dryness that can cause
damage to plants.
Andrews forest The coniferous rain forest
receives 90 of its precipitation during winter.
The summers are unusually dry, with drought-like
conditions.
Coastal Mountains
Pacific Ocean
Willamette Valley
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What do you know? In what season does most
photosynthesis take place? (summer or
winter?) What do trees need in order to carry
out photosynthesis? Make a hypothesis about
how trees at the Andrews might have adapted to
solve the problem of carrying out photosynthesis
when they get most of their H2O in the winter but
most of the sun in the summer.
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Gigantic coniferous trees in the temperate rain
forest have trunks 2 to 3 times larger than the
same species of tree on the East Coast. Their
trunks store lots of watersimilar to the hump of
a camel in the desert. The trees store water
during the winter and use it in the dry summers
when most of the photosynthesis takes place.
Coniferous trees grow 25 stories high with trunks
so big that three people cant link arms around
them.
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What do you know?
1. What is a coniferous tree?
2. Whats the difference between needles on
coniferous trees and leaves on a
deciduous trees?
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Conifers have waxy coated needles instead of
leaves. Needles store water in the unusually dry
summer.
Conifers have cones which give them their name
coniferous. Cones protect the seeds of the
tree. Evergreens get their name because they have
needles that stay green all year long.
Deciduous trees like alders, maples and birch
grow in the deciduous forest biome. They loose
their leaves in the winter. They also grow in
the part of the coniferous forest that have more
sunlight reaching the forest floor.
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What do you know?

• For conifers what is the
• adaptive advantage of not loosing their
  needles?

• For deciduous trees, what is the adaptive
  advantage of loosing their leaves during the
  winter?

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Ecologists are scientists that study ecosystems
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Ecologists study how ecosystems work There are
six ecological concepts that are being studied
at the Andrews

• Biodiversity
• Food Webs
• Nutrient Recycling Abiotic Factors
• Succession
• Energy Pyramids
• Habitat destruction

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Ecologists Study Biodiversity
Biodiversity is the variety of different species
in an ecosystem. A healthy, stable ecosystem
has a lot of biodiversity.
Spotted Owl
A frog enjoys a soft pad of moss in the sunlight.
Deer
Chipmunk
Dragon Flies
Ferns
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There are many species of plants that cover the
floor of an old growth forest
Colts Foot
Wild Mint
Miniature Dogwood
Oxalis
One ecologist at the Andrews forest research
center said we still haven't even begun to find
all the plants and animals that live in this one
tiny area. John Luomo, The Hidden Forest
Sedum grows in rocky areas
Columbine
Oxallis, a ground cover plant
Wild Strawberries
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Centipedes, salamanders, spiders, and slugs.
Salamanders live in or around rotted moss
covered logs that protect them from predators
like owls, foxes and coyotes.
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Ecologists study Food Chains and Food Webs
Food Chain the direct transfer of energy from
one organism to the next
Food Web the complex interaction of any food
chains in a community
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Ecologists study abiotic factors
Ecologists at Andrews study how all the biotic
and abiotic parts of an ecosystem interact over a
long period of time. They study how nutrients
like nitrogen, sulfur and carbon are recycled.
Almost all the nutrients that enter an old growth
forest remain in the ecosystem and are recycled.
However, when the forests are cut down,
nutrients begin draining out of the forests.
Nitrogen flows out through streams. Carbon stored
in the trees goes back into the air.
Biotic Living organisms
Abiotic Non living parts of the environment
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Ecologists at the Andrews study
Succession is community wide evolution The slow
replacement of one ecological community by
another. It takes at least 200 years of
succession before a stable, diverse old growth
forest is established.
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Ecologists study energy pyramids
10 Kcal
Energy Pyramids show the flow of energy
through an ecosystem
100 Kcal
1000 Kcal
10,000 Kcal
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Habitat Destruction Ecologists at the Andrews
study the difference between the original old
growth forests, those that have been clear cut
and those that have been replanted. In the last
100 years 95 of the original forests in the
pacific northwest have been cut down.
Habitat An area or environment where
an organism lives or where an ecological Community
occurs.
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Trees are used to make lumber and wood products.
Most forests have been clear cut in the last 100
years--since the industrial revolution. As the
human population grows, cities, farms and cattle
ranches are taking the place of forests and other
ecosystems.
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Why is it important to study how Ecosystems
Work?
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Like the coniferous forests in the Pacific
Northwest, ecosystems all over the world are
being endangered because of human interaction
with the environment. By studying how
ecosystems work we are better able understand the
the importance of healthy ecosystems and the
effects of habitat destruction.