Ecosystems and Biomes

Chapter 2: Section 1

“Energy Flow in Ecosystems”

Objectives

• After completing the lesson, students will be able to:– Describe the energy roles of organisms in an

ecosystem;– Explain food chains and food webs;– Describe how much energy is available at each

level of an energy pyramid.

Energy Roles

• An organism’s energy role is determined by how it obtains energy and how it interacts with the other living things in its ecosystem.

• An organism’s energy role in an ecosystem may be that of a producer, consumer, or decomposer.

Producers

• Energy first enters most ecosystems as sunlight.

• Producer—An organism that can make its own food.

• Producers are the source of all the food in an ecosystem.

• Examples: grass and oak trees.

                        

Consumers

• Consumer—An organism that obtains energy by feeding on other organisms.– Herbivores—Consumers

that eat only plants– Carnivores—Consumers

that eat only animals– Omnivore—Eats both

plants and animals– Scavenger—A carnivore

that feeds on the bodies of dead organisms.

Decomposers

• Decomposers—Organisms that break down wastes and dead organisms and return the raw materials to the environment.

• Two major groups of decomposers are bacteria and fungi

Food Chains and Food Webs

• Food chain—A series of events in which one organism eats another and obtains energy.– 1st—Producer– 2nd—First-Level Consumer– 3rd—Second-Level Consumer

Food Web—Consists of many overlapping food chains in an ecosystem.

Energy Pyramid

• When an organism in an ecosystem eats, it obtains energy. The organism uses some of its energy to move, grow, and reproduce, and carry out other life activities.

• This means that only some of the energy will be available to the next organism in the food web.

Energy Pyramid

• Energy Pyramid—Shows the amount of energy that moves from one feeding level to another in a food web.

• The most energy is available at the producer level. At each level in the pyramid, there is less available energy than at the level below.

• An energy pyramid gets its name from the shape of the diagram—wider at the base and narrower at the top, resembling a pyramid.

• In general, only about 10% of the energy at one level of a food web is transferred to the next, higher, level. The other 90% is used for the organism’s life processes or is lost as heat to the environment.

Energy Pyramid

• Since 90% of the energy is lost at each step, there is not enough energy to support many feeding levels.

• Organisms at higher feeding levels of an energy pyramid do not necessarily require less energy to live than organisms at lower levels. Since so much energy is lost at each level, the amount of energy in the producer level limits the number of consumers the ecosystem can support. As a result, there usually are few organisms at the highest level in a food web.

Ecosystems and Biomes

Chapter 2: Section 2

“Cycles of Matter”

Objectives

• After completing the lesson, students will be able to . . .– Describe the three major processes that make

up the water cycle;– Describe the carbon-oxygen cycle and the

nitrogen cycle

Recycling Matter

• The supply for matter is limited, which means there isn’t much of it.

• If matter could not be recycled, ecosystems would quickly run out of the raw materials necessary for life.

• Energy, on the other hand, is not recycled

Recycling Matter

• Matter cycles through an ecosystem over and over.

• Matter in an ecosystem includes water, oxygen, carbon, nitrogen, and many other substances.

The Water Cycle

• Water is necessary for life as we know it.

• Water cycle—The continuous process by which water moves from Earth’s surface to the atmosphere and back.

• The process of evaporation, condensation, and precipitation make up the water cycle.

Evaporation

• Evaporation—The process by which molecules of liquid water absorb energy and change to the gas state.

• Liquid water evaporates from Earth’s surface and forms water vapor, a gas, in the atmosphere.

• Most water evaporates from oceans and lakes.• Water is also produced through living things;

plants release water vapors from their leaves, people release water through waste and water vapor when they exhale.

Condensation

• Condensation—The process by which a gas changes to a liquid.

• As water vapor rises higher in the atmosphere, it cools down. When it cools to a certain temperature the vapor turns back into tiny drops of liquid water.

Precipitation

• Precipitation—Rain, snow, sleet, or hail.

• As more water condenses, the drops of water in the clouds grow larger and heavier, eventually falling back down to Earth.

The Carbon and Oxygen Cycles

• Carbon is the building block for the matter that makes up the bodies of living things.

• Producers take in carbon dioxide from the atmosphere during photosynthesis.

• In this process, the producers use carbon from the carbon dioxide to produce other carbon-containing molecules.

• At the same time, oxygen is also cycling through the ecosystem.

The Nitrogen Cycle

• Nitrogen gas is called “free” nitrogen, meaning it is not combined with other kinds of atoms.

• Most organisms can use nitrogen only once it has been “fixed,” or combined with other elements to form nitrogen-containing compounds.

The Nitrogen Cycle

• Nitrogen Fixation:– Nitrogen fixation—The process of changing

free nitrogen gas into a usable form of nitrogen.– Nodules—Bumps on the roots of certain plants

that house nitrogen-fixing bacteria.– These plants, known as legumes, include

clover, beans, peas, alfalfa, and peanuts.

The Nitrogen Cycle

• Return of Nitrogen to the Environment:– Once the nitrogen has been fixed into chemical

compounds, it can be used by organisms to build proteins and other complex substances.

– Decomposers break down complex compounds in dead organisms and returns simple nitrogen compounds back into the soil.

– Eventually, bacteria breaks down the nitrogen compounds completely and release free nitrogen back into the air. Then the cycle starts again.

Ecosystems and Biomes

Chapter 2: Section 3

“Biogeography”

Objectives

• After completing the lesson, students will be able to . . .– Describe some different means that disperse

organisms;– Identify the factors that limit the distribution of

a species

Biogeography

• Biogeography—The study of where organisms live.

• Bio– “life”

• Geo– “Earth”

• Graph– “Description”

Continental Drift

• Continental Drift—The very slow motion of the continents.

• All of today’s continents were once together in a large landmass known as Pangaea. Slowly, the continents started to drift apart to where they are presently located.

• The movement of the continents has had a great impact on the distribution of species.

Means of Dispersal

• Dispersal—The movement of organisms from one place to another.

• Dispersal can be caused by wind, water, or living things, including humans.

Wind and Water

• Wind provides a means of dispersal fro seeds, the spores of fungi, tiny spiders, and many other small, light organisms.

• Water transports objects that float in which organisms, such as insects, get a “free ride” to another location.

Other Living Things

• Example: – A goldfinch may eat seeds in one area and

deposit them elsewhere in its waste. – A duck may carry algae or fish eggs on its feet

from pond to pond. – Dogs and cats can carry sticky plant burs that

attach to their fur.– Humans intentionally/unintentionally transports

organisms from one region to another.

Other Living Things

• Native Species—Species that have naturally evolved in an area.

• Exotic Species—Species that has been carried into a new location by people

Limits to Dispersal

• Three factors that limit dispersal of a species are physical barriers, competition, and climate

Limits to Dispersal

• Physical Barriers– Water

– Mountains

– Deserts

• Competition– When an organism enters a

new area, they have to compete for resources. Organisms have to have a unique niche in order to survive.

• Climate—The typical weather in an area over a long period of time.

• The different types of climate can limit the number of organisms that can inhabit an area.

Ecosystems and Biomes

Chapter 2: Section 4

“Earth’s Biomes”

Objectives

• After completing the lesson, students will be able to . . .– List and describe Earth’s major land biomes;– List and describe Earth’s major freshwater and

ocean biomes

Biomes

• Biome—A group of ecosystems with similar climates and organisms.

• It is mostly the climate conditions—temperature and rainfall—in an area that determine its biome.

Rain Forest Biomes

• Climate of Rain Forests = warm and humid

• Tropical Rain Forests– Found close to the equator– Receive lots of rain– Sunlight is fairly constant– The abundant plant life provides many habitats for

animals– Contain more species of plant an animals than all the

other land biomes combined.

Rain Forest Biomes

• Canopy—A leafy roof formed by tall trees.

• Understory—A layer of shorter plants that grow in the shade of a forest canopy.

Canopies and Understories

Rain Forest Biomes

• Climate of Rain Forests = warm and humid

• Temperate Rain Forests– Too far north and too cool to be a tropical rain

forest– The term temperate means moderate

temperature

Desert Biome

• Desert—An area that receives less than 25 centimeters of rain per year.

• The organisms that live in the desert are adapted to the lack of rain and to the extreme temperatures.

• Many desert animals are most active at night when the temperatures are cooler.

Grassland Biome

• Grassland—An area that receives between 25-75 centimeters of rain each year, and is typically populated by grasses and other non-woody plants.

• Savannas—Grasslands that are located closer to the equator than prairies.

• Grasslands are home to many of the largest animals on Earth.

Deciduous Forest Biomes

• Deciduous trees—Trees that shed their leaves and grow new ones each year.– Example: Oaks and Maple

trees– Receive enough rain to

support the growth of trees and other plants

– The growing season usually lasts five to six months.

– The variety of plants in the forest creates many different habitats

Deciduous Forest Biomes

• If you were to return to this biome during the winter, you would not see much of the wildlife that you are able to observe during the warm temperatures.

• Hibernation—A low-energy state similar to sleep.– During hibernation an animal relies on fat it has

stored in its body.

Boreal Forest Biomes

• Coniferous trees—Trees that produce their seeds in cones and have leaves shaped like needles.

• Sometimes referred by its Russian name “Taiga”

• Winters are very cold

Boreal Forest Biomes

• Yearly snowfall can reach heights well over your head

• A limited number of trees have adapted to the cold climate

• Prevention of water loss is a necessary adaptation for trees

• Many of the animals found here eat the seeds produced by the conifers

Tundra Biome

• Tundra—An extremely cold, dry, land biome.

• Permafrost—The frozen soil found in the Tundra

Tundra Biome

• Plants on the tundra include mosses, grasses, shrubs, and dwarf forms of a few trees, such as willows.

• Most of the plant growth takes place during the long summer days when many hours of sunshine combine with the warmest temperature.

Mountains and Ice

• 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

Freshwater Biomes

• 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

• Because water absorbs sunlight, there is only enough light for photosynthesis near the surface or in shallow water.

Ponds and Lakes

• 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

Streams and Rivers

• Animals that live in this part must be adapted to the strong current

• Few plants and algae can grow in this fast-moving water

• Different organisms are adapted to live in this lower part of the river.

Estuaries

• Estuary—An area found where the fresh water of a river meets the salt water of the ocean.

• 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

• Major producers: plants and algae

Intertidal Zone

• Intertidal Zone—The part of the shore between the highest high-tide line and the lowest low-tide line.

• Organisms here must be able to withstand the pounding action of waves, sudden changes in temperature, and being both covered with water and then exposed to the air.

Neritic Zone

• Neritic Zone—The region of shallow ocean water over the continental shelf.

• Many large schools of fish feed on the algae, and the formation of coral reefs may occur in the Neritic Zone.

Ecosystems and Biomes

Chapter 2: Section 5

“Succession”

Objectives

• After completing the lesson, students will be able to . . .– Describe the differences between primary and

secondary succession

Succession

• Succession—The series of predictable changes that occur in a community over time.

• Examples: Fires, floods, volcanoes, hurricanes, and other natural disasters.

Primary Succession

• Primary succession—A series of changes that occur in an area where no ecosystem previously existed.

• Such an area might be a new island formed by the eruption of an undersea volcano, or an area of rock uncovered by a melting sheet of ice.

• Pioneer Species—The first species to populate an area.

Secondary Succession

• Secondary Succession—A series of changes that occur after a disturbance in an existing ecosystem.

• Natural disturbances that have this effect include fires, hurricanes, and tornadoes.

• Human activities, such as farming, logging, or mining, may also disturb an ecosystem.

• Unlike primary succession, secondary succession occurs in a place where an ecosystem has previously existed.

• Secondary succession occurs somewhat more rapidly than primary succession.