2.2 Introducing Ecosystems
Picture a moose in the woods, moving through the spaces
between trees. The moose feeds on shrubs, trees, and aquatic
plants around a small pond. You see a beaver dam that has
formed the pond. The animals, plants, and pond water are all part
of a complex system of living and non-living things.
A Complex System
This complex system, made up of groups of living organisms and
their non-living environment, is called an ecosystem. The
components of an ecosystem are interrelated, which means that
changes in one component can affect other components.
Living and Non-Living
Living organisms in an ecosystem are biotic factors. Biotic
factors include organisms, their waste, their homes, and their
remains. Insects, fungi, beavers, moose droppings, and shrubs
are all biotic factors. The non-living features of an ecosystem are
abiotic factors. Weather, water, and rocks are abiotic factors.
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Everything Is Related
Biotic and abiotic factors affect one another, so any change in
biotic or abiotic factors can change an ecosystem. For example,
when a forest is cut down to make room for houses, the trees
that were once home to insects, birds, and squirrels are no longer
there. The animals will need to find a new place to live.
Populations and Communities
In most ecosystems, there are many different species. Members
of the same species that live in the same ecosystem are a
population. For example, all the snapping turtles in a pond are a
population. All the coho salmon in a stream are a population.
All the populations of different organisms in an area form a
community. In a pond, the populations of turtles, frogs, fishes,
mosquitoes, aquatic plants, algae, and other living things make
up the community.
BEGIN FIGURE CAPTION:
Figure 1 shows how ecosystems are composed of individual
organisms, populations, communities, and the physical
surroundings in which communities of organisms live.
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BEGIN SIDEBAR:
DIG DEEP
Did You Know?
In Hot Water!
Thermophiles are organisms that are adapted to live in extremely
hot environments in thermal vents or hot spots in the ocean floor.
Water shoots up from these vents at high pressure. Water
temperatures in the ocean can be as low as 2 °C, but in some
thermal vents, temperatures reach 400 °C! The vents are
surrounded by ecosystems that include bacteria, clams, mussels,
and tube worms.
END SIDEBAR.
Differences in Ecosystems
Ecosystems can be large or small and can include many or few
organisms. An ecosystem can be as large as an entire forest or as
small as a rotting log. A large forest ecosystem can contain other
smaller ecosystems. A community of bacteria and fungi living in a
rotting log is part of a smaller ecosystem.
Each ecosystem has distinct features. You could describe a pond
ecosystem by its organisms or by its physical characteristics,
such as depth and temperature. Table 2 shows some examples
of large and small ecosystems.
Table 2 Examples of Large and Small Ecosystems
Ecosystem
coniferous forest
coral reef
beaver pond
Characteristic
abiotic features
Characteristic
biotic features
- large forests and
bogs
- long, cold winters
- black bears, red
and warm summers
squirrels, moose,
- moderate rainfall
and biting flies
- a lot of snow
- short growing
season allows fewer
organisms to grow
- aquatic organisms,
including corals,
- warm and shallow
sponges, and many
waters
different fish species
- usually located in
- easily damaged by
tropical regions
changes in water
temperature and
quality
- shallow water that - many aquatic
is warm in summer; species, including
icy cover in winter
insects, fishes, frogs,
- may last only a few turtles, muskrats,
years dams could
break and cause
flooding
rotting log
and beavers
- nearby forest is a
food source for
beavers
- decomposing
- moist environment bacteria and fungi
- very little light may - beetles, ants, and
last only a few years other insects
or decades
- log provides shelter
for small animals
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BEGIN TEXTBOX:
TRY THIS ECOSYSTEM ABCs
SKILLS: Analyzing, Communicating
Everything we use comes from the biotic and abiotic parts of the
environment.
1. List 10 items you have used or handled in the past two days.
2. List the materials that make up each item. For example, a
pencil is made up of wood, graphite, rubber, and metal.
3. Classify each material as abiotic or biotic.
4. Is the item made up of only biotic materials, only abiotic
materials, or both?
A. Compare the items in your diagram. What type of items did
you use the most of: abiotic or biotic? T/I
END TEXTBOX.
2.2 Wrap Up
- Ecosystems are made up of biotic and abiotic factors.
- Biotic factors are the living things, their remains, and features
associated with their activities in an ecosystem.
- Abiotic factors are the non-living physical features of an
ecosystem.
- A population is made up of all the individuals of the same
species in the same ecosystem.
- A community is all the populations in the same ecosystem.
CHECK YOUR LEARNING
1. Classify each of the following as biotic or abiotic: temperature,
wind, sunlight, dead leaves, spiders, sand, milk, hair, ice, plastic.
K/U
2. Does a population include abiotic features, biotic features, or
both? Explain. K/U, T/I
3. Élise thinks that human activities can change only the biotic
features of an ecosystem. Is she correct? Explain your thinking.
T/I, C