Transcript Chapter 4 Notes

Chapter 4 Notes
Ecosystems
Ecosystems
• Community – a group of various species
that live in the same place.
• Ecosystem – includes a community of
organisms and their physical environment.
Physical Factors
• = nonliving factors
• Called abiotic factors
• Example: oxygen, sunlight, rocks, sand,
and water.
• Habitat – the place where an organism
lives.
Biodiversity
• The variety of organisms in a given area.
• Physical factors have a big influence on
biodiversity.
-low water sunlight, etc. = less
biodiversity.
Succession
• All ecosystems change.
• As the ecosystem changes, the kinds of
species that the ecosystems supports
changes.
• The replacement of one community by
another at a single place over a period of
time is called succession.
Change in a new environment
• The first organisms to appear in a newly
made habitat are called pioneer species.
• Pioneer species are often small, fastgrowing plants that reproduce quickly.
Equilibrium
• If a major disruption strikes a community,
many of the organisms may be wiped out.
• An ecosystem responds to change in such a
way that the ecosystem is restored to
equilibrium.
• Sometimes the ecosystem will find and
equilibrium in which different species
dominate after a change.
Major Biological Communities
• Terrestrial Biomes
– Tropical
– Temperate
– High-Latitude
**Two key factors that
determine biomes are
temperature and
precipitation.
Definitions
• Climate- the average weather conditions in
an area over a long period of time.
• Biome – a large region characterized by a
specific kind of climate and certain kinds of
plants and animal communities.
Tropical Biomes
• Located at low latitudes near the equator.
• All tropical biomes are warm.
– Tropical rain forests
• Receive large amounts of rain and are warm all year
– Savannas
• Tropical grasslands
• Get less rain than tropical rain forests
• Example: eastern Africa(zebras, giraffes, lions and elephants)
– Tropical deserts
• Get very little rain
• Have fewer plants and animals than other biomes
Temperate Biomes
• Have a wide range of temperatures throughout the
year.
– Temperate grasslands
• Moderate precipitation and cooler temperatures than savannas
• Highly productive for agriculture
– Temperate forests
• Mild climates that receive plenty of rain
• Deciduous forest trees shed their leaves in the fall because of
cold winter. Evergreen forests do not shed their needles.
• Deer, bears, beavers, and raccoons.
– Temperate deserts
• Receive little precipitation
• Have a wide temperature range throughout the year.
High-Latitude Biomes
• Have cold temperatures.
– Taiga
• Coniferous forests in cold, wet climates.
• Winters are cold and long. Most precipitation falls in the
summer.
• Wolves, moose, and bears
– Tundra
• Gets very little rain, so plants are short.
• Water is frozen for most of the year.
• Foxes, lemmings, owls, and caribous.
Aquatic Ecosystems
•
•
•
•
Freshwater ecosystems
Wetlands
Estuaries
Marine ecosystems
Freshwater ecosystems
• Bodies of freshwater
• Lakes, ponds, rivers, streams
• Fish, arthropods, mollusks, and other
invertebrates
Wetlands
• Link between land and fully aquatic
habitats.
• Contain “water-loving” plants
• Supports many species of birds, fishes and
plants.
Estuaries
• Area where fresh water from a river mixes
with water from an ocean.
• Constantly receive fresh nutrients from the
river and the ocean.
Marine ecosystem
• Found in the salty water of oceans
• Kelp forests, seagrass communities, and
coral reefs.
• Open ocean (far from land) has plankton
and large predators (dolphins, whales, and
sharks)
ENERGY FLOW IN
ECOSYSTEMS
Trophic levels
•
•
•
•
Every thing organisms do requires energy.
Energy flows through ecosystems.
Organisms eat other organisms.
The primary source for energy in an
ecosystem is the sun.
Producers
• Photosynthetic organisms that are the basic
food source for an ecosystem.
Consumers
• Organisms that eat other organisms instead
of producing their own food.
Decomposers
• Bacteria and fungi
• Organisms that break down the remains of
animals.
MEMORIZE THIS
• In an ecosystem, energy flows from the sun
to producers to consumers to decomposers.
• Each step is called a trophic level.
Assignment
• Pg. 97, 2-17.
• Pg. 99, 1-9
Loss of Energy
• Energy is stored at each link in a food web.
• Some energy dissipates(releases) as heat
into the environment and is not recycled.
The Ten Percent Rule
• Only about 10 percent of energy
consumed by an organism is kept, the
other 90% is given off as heat energy.
• A 100 kg lion requires 10000 kg of
producer energy to survive.
Energy Pyramid
• A triangular diagram that shows an
ecosystem’s loss of energy, which results as
energy passes through an ecosystem’s food
chain.
• Each layer in an energy pyramid represents
one trophic level.
• The lowest level has the most energy.
The End
• We are not going to go through the cycles.