A gradual development of a community over time is Ecological Succession A gradual development of a community over time is called succession. Succession takes place in all communities.

Sometimes, a small community starts to grow in an area where other organism had not previously lived. There is no soil in this area. Usually, there is just bare rock. Over a very long time, a series of organisms live and die on the rock. The rock is slowly transformed into soil. This process is called primary succession. The first organisms to live in an area are called pioneer species.

PIONEER SPECIES: First species to populate an area.

Primary succession is less common than secondary succession and usually involves volcanic activity or an area of rock uncovered by melting ice. Volcanic Island! Receding Glacier!

Secondary succession is more common and occurs more rapidly than primary succession. It is a series of changes that occur in an area where the ecosystem has been disturbed, but where soil and organisms still exist. Examples include: natural disasters like fires, hurricanes and tornadoes and human activities like farming, logging or mining.

Review Graph on Page 39.

Chapter 2 – Ecosystems and Biomes Section 2-1 Energy Flow in Ecosystems

Each and every organism in an ecosystem fills a role of producer, consumer or decomposer.

Producers (plants, algae and some bacteria) use the sun’s energy to turn water and carbon dioxide to food molecules through a process called photosynthesis.

Consumers are organisms that obtain energy by feeding on other organisms. Herbivores eat only plants! Carnivores eat only animals! Omnivores eat both plants and animals!

Decomposers break down nature’s wastes (detritus) Decomposers break down nature’s wastes (detritus). Mushrooms (Fungus) and bacteria are decomposers.

Food Chains and Food Webs Food Chains and Food Webs! The movement of energy through an ecosystem can be shown in diagrams called food chains and food webs. Food Chain Food Web

A Food Chain is a series of events in which one organism eats another and obtains energy. Food chains always start with a producer.

The first level consumer feeds on the producer and the second level consumer feeds on the first level consumer.

A food web shows many overlapping food chains in an ecosystem with producers at the bottom and 1st, 2nd and 3rd level consumers above.

Energy Pyramids show the amount of energy that moves from one feeding level to another in a food web.

The most energy is available at the producer level of the pyramid The most energy is available at the producer level of the pyramid. 90% of the energy at each level is lost, used for the life processes of the organism at that level.