Ecology

Energy Flow, Recycling of materials and Change in Ecosystems

Energy Flow in Ecosystems

Organisms require a constant source of energy to survive

Energy Flow contdStructure of ecosystems depend on the source of energy

Ultimate source of energy for all organisms is the sun

LIFE depends on the SUN

The SUN provides light energyPlants, algae, & some bacteria capture this energy and store it as food (photosynthesis)

Examples

Deer grazes on grass energy is transferred from grass to deer

Examples

Wolves feeding on deer energy is transferred from deer to wolf

Deep-Ocean Ecosystems:An Exception to the RuleDeep ocean ecosystems exist in total darkness

No Photosynthesis takes place

Deep-Ocean Ecosystems (continued)

Geothermal vents in the ocean floor. Very salty, hot acid sulfur springs, anaerobic conditions

The bacteria get energy and raw materials from vents called "smokers" on the ocean floor

Deep-Ocean Ecosystems (continued)

Tube worms rely upon the bacteria that coexist with them to make food at the bottom of the ocean.

Energy Transfer

Food Chains

Food WebsTrophic Levels

Food ChainsA sequence in which energy is transferred from one organism to another as each organism eats another

Algae krill cod Leopard Seal Killer Whale

Food WebA network of interconnecting food chains

(a more realistic view)

Trophic Levels

Each step in the transfer of energy through an ecosystem.

Energy transfer: ProducerConsumer

1st Trophic levelProducersEx: Plants, autotrophs energy from sun

Only small fraction is converted to plant body; rest is lost

2nd Trophic LevelConsumersConsumersPlant eaters(herbivores) Primary consumers

Ex: grasshoppers, snails,birds,mammals

3rd Trophic level

ConsumersSecondary Consumers eat Primary consumers

Ex: mice, small birds, frogs, lions & other large carnivores

4th Trophic Level

ConsumersTertiary Consumerseat Secondary consumers

Ex: snake that eats mice

Energy Pyramid

A diagram that shows the amount of energy at each of the trophic levels

Energy PyramidOne lion

One lion

Ten giraffes

100 producers

Energy Pyramid contd

As energy is transferred less is available for the next level

Energy is lost during metabolism

Only 10% is available for the next level

The Cycling of Materials

Water Cycle

Nitrogen CycleAll organisms need nitrogen to make protein

Only the nitrogen fixing bacteria can fix atmospheric nitrogen

All other organisms are dependent on these N2 fixing bacteria

Nitrogen Cycle

How Ecosystems Change

Ecosystems do not always stay the same

Populations are slowly replaced by other/new populations

Succession

A regular pattern of changes in the type of species of a community

SuccessionCauses:New community makes it difficult for the old to survive

Ex: Pine shade pine seedling can’t grow oak, maple grow replace the pine trees

Succession

Climax Community: the community that is eventually formed if the land is left undisturbed

Secondary Succession

Succession that occurs on a surface where an ecosystem had previously existed.

Secondary Succession

Pioneers The first organism to colonize a newly available area and start the process of succession

Secondary Succession

Fire Maintained Communities

Natural fires caused by lightning are a part of secondary succession

1. Jack pine release seeds after exposed to heat

2. Brush and dead wood removed 3. Some animals depend on

vegetation that sprouts after fire

Primary Succession

Succession that occurs on surfaces where no ecosystem existed

Ex: New Islands, glaciers retreats, cracks in rocks

Primary Succession

Primary succession in city streets

Repeated freezing & thawing helps break down rock