Chapter 3: The Chapter 3: The BiosphereBiosphere

• Objectives– Identify the levels of organization– Describe the methods used to study

ecology– Identify the source of energy for life

processes– Trace the flow of energy through living

systems– Describe how matter cycles among the

living and nonliving parts of an ecosystem.– Explain why nutrients are important in

living systems.

What is Ecology?What is Ecology?

• Ecology is the scientific study of interactions among organisms and between organisms and their environment.

• What does this mean?• How do we study these interactions?

Levels of OrganizationLevels of Organization

OrganismOrganismAn individual living thing

PopulationPopulation

Members of one species that interbreed and live in the same place at the same time.

• Compete for:– Food– Water– Shelter– Mates

PopulationPopulation

CommunityCommunity• Different populations that live

together in a defined area.• Several populations interacting

together.

EcosystemEcosystem• A collection of all of the organisms

that live in a particular place, together with their nonliving, or physical environment.

• Biotic Factors: living organisms within an ecosystem

• Abiotic Factors: nonliving factors that help shape an ecosystem

EcosystemEcosystem

BiomesBiomes

• A group of ecosystems that have the same climate and similar dominant communities.

BiosphereBiosphere

• The highest level of organization that ecologists study is the entire biosphere itself.

• The portion of the Earth that supports life.

ORGANISM

POPULATION

COMMUNITY

ECOSYSTEM

BIOSPHERE

BIOME

Ecological MethodsEcological Methods

• Ecologists use a wide range of tools and techniques to study the living world.

• Apply the scientific method to do ecological research:– Observing– Experimenting– Modeling

Interactions Between Interactions Between OrganismsOrganisms

All organisms depend upon other living All organisms depend upon other living things things and nonliving thingsand nonliving things to meet to meet their needs, such as:their needs, such as:

•FoodFood•ShelterShelter•ReproductionReproduction•ProtectionProtection

Thus, an interdependence exists Thus, an interdependence exists among organisms and the among organisms and the environmentenvironment

Energy FlowEnergy Flow

• All living things need ENERGY to survive.

• Where does this energy ultimately come from?

AutotrophsAutotrophs

• Organisms that capture energy from sunlight or chemicals and use that energy to produce food.

• Ex. Bacteria, plants, and algae

Also called producers

HeterotrophsHeterotrophs

• Rely on other organisms for their energy and food supply• Also called consumers

Types of ConsumersTypes of Consumers

• Herbivores

• Carnivores

• Omnivores

• Detritivores

• Decomposers

Heterotrophs that eat plants (1st order consumers)

• Heterotrophs that eat animalsHeterotrophs that eat animals• They come in many sizes!They come in many sizes!

Eat both plants and animals

Ex: humans, raccoons, bears

Animals that feed on animal remains and dead matter (collectively called detritus)

EX: mites, earthworms, snails, crabs

Break down decaying matter

Ex: bacteria and fungi

Feeding RelationshipsFeeding Relationships

• What happens to the energy in an ecosystem when one organism eats another?– The energy moves along a one-way

path.

• Energy flows through an ecosystem in one direction, from the sun to autotrophs and then to various heterotrophs

Food ChainsFood Chains

• The energy stored by producers can be passed through an ecosystem along a food chain, a series of steps in which organisms transfer energy by eating and being eaten.

A food chain shows how matter A food chain shows how matter and energy cycle through an and energy cycle through an

ecosystemecosystem

Sun Grass Rabbit Snake Hawk

The arrows show the direction that energy is transferred

Natural Food ChainNatural Food Chain

Each organism represents a trophic level, a step in the food chain.

Food WebFood Web

• Shows all of the possible feeding relationships at each trophic level in the community.

Producers

Primary Consumers-herbivores

Secondary consumers

Tertiary consumers

• A diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web.

• 3 types– Energy pyramids– Biomass pyramids– Pyramids of numbers

• Only part of the energy that is stored in one trophic level is passed n to the next level…. why?– Organisms use much of the energy that

they consume for life processes (reproduction, respiration, and movement).

•Only 10% of the energy available within one trophic level is transferred to organisms at the next trophic level.

• The total amount of living tissue within a given trophic level is called biomass.

• A biomass pyramid represents the amount of potential food available for each trophic level in an ecosystem.

• Pyramid based on the numbers of individual organisms at each trophic level.

• The water cycle is the continuous movement of water between Earth and its atmosphere.

• Carbon is an essential component of proteins, fats, and carbohydrates

• The carbon cycle is a process by which carbon is cycled between the atmosphere, land, water, and organisms.

• Four processes– Respiration (adds)– Combustion (adds)– Decomposition (adds)– Photosynthesis (removes)

• The carbon cycle has been operating to keep the amount of carbon dioxide in balance between the atmosphere and Earth.

• HOWEVER, the burning of fossil fuels has added more carbon dioxide than can be removed by plants during photosynthesis.

• Carbon dioxide is considered a greenhouse gas …it traps heat on Earth.

• This contributes to global warming, which has led to an overall increase in the Earth’s average temperature.

*78% of the atmosphere is composed of nitrogen

*Living things cannot use nitrogen in the atmospheric form

*Lightening and some bacteria convert nitrogen to usable forms, then producers

use them to make proteins. Consumers then eat the producers and reuse the nitrogen to

make their own proteins!

*When organisms die, decomposers return nitrogen to the soil and it is either reused or converted into nitrogen gas and returned to

the atmosphere.

Primary Productivity—rate at which an organic matter is created by producers

Process can be limited by a lack of nutrients

How can people help avoid a shortage of nutrients?

A polar bear, its fur stained with algae, stands in its cage at Higashiyama Zoo in Nagoya, central Japan, Saturday, Sept. 6, 2008. Three polar bears at the zoo changed their colors in July after swimming in a pond with an overgrowth of algae, prompting many questions from visitors concerned about whether the animals are sick or carrying mold, a zoo official said. Credit: AP Photo/Kyodo News, Shuzo Shikano