CHAPTER 2 – PRINCIPLES OF ECOLOGY Section 2-2: Nutrition and Energy Flow (p.46-57)

How Organisms Obtain Energy  An important characteristic of a species niche is how it obtains ENERGY  Ecologist trace the flow of energy through communities to discover nutritional relationships between organisms

How Organisms Obtain Energy  The ultimate source of energy for life is the SUN  Plants use the sun’s energy to manufacture food in a process called Photosynthesis

Autotrophs  An organism that uses light energy or energy stored in chemical compounds to make energy-rich compounds Also called a producer Also called a producer Examples: Examples: GrassGrass TreesTrees AlgaeAlgae

Heterotrophs  An organism that cannot make its own food and feeds on other organisms  Can feed on autotrophs or other heterotrophs

Herbivore  A heterotroph that only feeds on plants  Examples:

Carnivores  A heterotroph that only eats other heterotrophs  Examples:

Scavengers  Do not kill for food  Eat already dead animals  Examples:  Role benefits ecosystems – recycles nutrients

Omnivores  Organisms that eat both plants and animals  Examples:

Decomposers  Break down the complex compounds of dead and decaying plants and animals Nutrient recycling Nutrient recycling  Examples:

Flow of Matter and Energy in Ecosystems  As you eat food, such as an apple, you consume Matter  Matter flows through the levels of an ecosystem from producers to consumers

Food Chain  A simple model that scientists use to show how matter and energy move through an ecosystem  Example:  A portion of energy is given off as HEAT

Trophic Levels  A feeding step in a food chain  First Order Eats autotrophs Eats autotrophs Herbivore Herbivore Example Example  Second Order Eats first order organisms Eats first order organisms Carnivore Carnivore Example Example

Food Web  A model that represents all the possible feeding relationships at each trophic level in an ecosystem  More realistic because… Most organisms depend upon more than one other species for food Most organisms depend upon more than one other species for food  Let’s look at an example of a food web…

Ecological Pyramids  Can show how energy flows through an ecosystem  Base represents: Autotrophs (1 st trophic level) Autotrophs (1 st trophic level)  Higher levels represents: Heterotrophs (2 nd, 3 rd, trophic levels) Heterotrophs (2 nd, 3 rd, trophic levels)

3 Types of Pyramids

 Shows how much energy is transferred from producers to consumers  Energy decreases 10% at each level Energy

Numbers  Shows population size decreases at each higher trophic level  Not always true Thousands of insects can eat off one tree Thousands of insects can eat off one tree

Biomass  Represents the total weight of living matter at each trophic level

Cycles in Nature  Matter is constantly recycled.  It is never LOST!

The Water Cycle  Life on Earth depends upon WATER  How the cycle works: Evaporation Evaporation Liquid to gas (called water vapor)Liquid to gas (called water vapor) Condensation Condensation Water vapor condenses on dust in air + forms cloudsWater vapor condenses on dust in air + forms clouds Precipitation Precipitation Water falls to ground in form of rain, ice, or snowWater falls to ground in form of rain, ice, or snow Transpiration Transpiration Loss of water by plants – puts water vapor into airLoss of water by plants – puts water vapor into air

What is looks like…

The Carbon Cycle  Carbon is an important part of all living things Makes up all molecules of life – Makes up all molecules of life – carbohydrates, proteins, fats, nucleic acidscarbohydrates, proteins, fats, nucleic acids  Parts of Carbon Cycle: Photosynthesis Photosynthesis Autotrophs use CO 2 from air to make energy-rich compoundsAutotrophs use CO 2 from air to make energy-rich compounds Respiration Respiration Both autotrophs + heterotrophs use CO 2 in processes and release CO 2 back into the evironmentBoth autotrophs + heterotrophs use CO 2 in processes and release CO 2 back into the evironment Other ways: Other ways: Death + decayDeath + decay Burning of fossil fuelsBurning of fossil fuels FiresFires

What it looks like…

The Nitrogen Cycle  Atmospheric Nitrogen Nitrogen makes up 78% of atmosphere Nitrogen makes up 78% of atmosphere  Nitrogen-fixing bacteria Bacteria found on roots of plants fix nitrogen into different compounds in the soil Bacteria found on roots of plants fix nitrogen into different compounds in the soil  Animal consumption Eat plants or other animals Eat plants or other animals Waste materials enter ground Waste materials enter ground Decomposers – put Nitrogen back into atmosphere Decomposers – put Nitrogen back into atmosphere

What it looks like…

The Phosphorus Cycle  Short term Plants get P from soil Plants get P from soil Animals eat plants – get P Animals eat plants – get P When animals die, P gets returned to soil When animals die, P gets returned to soil  Long term P enters water P enters water P gets absorbed into rocks P gets absorbed into rocks Millions of years later, rocks erode, releases P back into cycle Millions of years later, rocks erode, releases P back into cycle

What it looks like…