Chapter 3: The Biosphere

•

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?

• 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 Organization

An individual living thing

Organism

Population

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

Population

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

• •

Community

Different

populations

in a defined area.

that live together Several populations interacting together.

Ecosystem

• A collection of all of the live in a particular place, together with their

nonliving organisms

that , or physical environment.

•

Ecosystem

Biotic

Factors: living organisms within an ecosystem •

Abiotic

Factors: nonliving factors that help shape an ecosystem

Biomes

•

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

Biosphere

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

biosphere

itself.

• The portion of the Earth that supports life.

BIOSPHERE BIOME ECOSYSTEM COMMUNITY POPULATION ORGANISM

Ecological Methods

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

Apply the

scientific method

ecological research: – Observing – Experimenting – Modeling to do

Interactions Between Organisms

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

•

Food

• • •

Shelter Reproduction Protection Thus, an interdependence exists among organisms and the environment

Energy Flow

• All living things need ENERGY to survive.

• Where does this energy ultimately come from?

Autotrophs

• Organisms that energy to

capture

sunlight or chemicals and use that

produce

food.

energy from • Ex. Bacteria, plants, and algae Also called

producers

Heterotrophs

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

consumers

Types of Consumers

• • • • • Herbivores Carnivores Omnivores Detritivores Decomposers

Heterotrophs that eat plants (1 st order consumers)

• •

Heterotrophs that eat animals 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 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 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 and energy move through an ecosystem

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

Natural Food Chain Sun Grass Rabbit Snake Hawk The arrows show the direction that energy is transferred

Food Web

•

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

Tertiary consumers Secondary consumers Primary Consumers herbivores Producers

• • 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 on to the 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

the Earth’s average temperature.

, which has led to an overall increase in

*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

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