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 contd Structure 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 energy Plants, 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 Rule Deep 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 Webs Trophic Levels

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

Algae  krill  cod  Leopard Seal  Killer Whale

Food Web A network of interconnecting food chains (a more realistic view)

Trophic Levels Each step in the transfer of energy through an ecosystem. Energy transfer: Producer  Consumer

1 st Trophic level Producers Ex: Plants, autotrophs  energy from sun Only small fraction is converted to plant body; rest is lost

2 nd Trophic Level Consumers Consumers  Plant eaters(herbivores)  Primary consumers Ex: grasshoppers, snails,birds,mammals

3 rd Trophic level Consumers Secondary Consumers  eat Primary consumers Ex: mice, small birds, frogs, lions & other large carnivores

4 th Trophic Level Consumers Tertiary Consumers  eat Secondary consumers Ex: snake that eats mice

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

Energy Pyramid 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 Cycle All organisms need nitrogen to make protein Only the nitrogen fixing bacteria can fix atmospheric nitrogen All other organisms are dependent on these N 2 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

Succession Causes: 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