Chapter 10 Ecosystems p. 317 - 329

What is an ecosystem? A community of living organisms interacting with one another and with non-living parts of the environment they live in Individual population community ecosystem Examples: forest, lake, island, mountain

Trophic relationships Feeding connections among living organisms in an ecosystem Can be represented by a food chain (p.319) 3 trophic levels: Producers Consumers Decomposers

Producers Plants Autotrophic (self feeding) Convert carbon dioxide to glucose with help of solar energy Beginning of food chain, they introduce energy to an ecosystem

Consumers Heterotrophic (feed on other living organisms) 4 types: Primary or 1st order (herbivores), feed on producers (plants) 2nd, 3rd, 4th order consumers, eat consumers of preceding order (usually carnivores, can also be omnivores)

Decomposers Organisms that feed on waste and remains of other living organisms (dead leaves, wood, animal remains, excrement, etc.) Examples are worms, fungi, bacteria, some insects

Trophic networks More than one food chain is possible in an ecosystem This means there are many trophic relationships A trophic network illustrates all of them

Material flow and chemical recycling Matter an energy are constantly exchanged between organisms Matter is recycled when decomposers break down organic matter into inorganic matter This allows an endless cycle of exchange in an ecosystem

Flow of inorganic matter Flow of organic matter Decomposers Detritus Consumers Producers Environment Flow of inorganic matter Flow of organic matter

Energy Flow From one trophic level to another energy is lost (waste, movement, growth, reproduction, heat) Only 10% of energy is available at next level Energy IS NOT recyled, we need a constant supply from the sun (p.325)

Primary productivity in ecosystems The amount of new biomass generated by producers (energy available from plants) limits the # of organisms that can live in an ecosystem Influenced by: Sunlight Water Nutrients Temperature

Disturbances Events that damage an ecosystem Can lead to elimination of organisms or can alter the availability of resources 2 types: Natural, such as storms, flooding, forest fires, volcanic eruptions, drought, etc. Human, such as litter, logging, oil spills, etc.

Ecological succession Series of changes that occur in ecosystems after a disturbance. Continue until a balance is restored