Ecology: food webs, interactions, Ch. 5.1 SEV1.b: Relate energy changes to food chains, food webs, and to trophic levels in a generalized ecosystem, recognizing that entropy is a primary factor in the loss of usable energy during movement up the trophic levels. SEV1.e: Distinguish between abiotic and biotic factors in an ecosystem and describe how matter and energy move between these.

Key terms  Producer  Consumer  Decomposer  Food chain  Food web  Trophic levels

Energy flow-Food Chains  Plays a critical role in the maintenance of a healthy ecosystem  Energy originates from the SUN!!  Flows upwards through the food chain, starting with plants (autotrophs)  The energy from one organism is transferred to the organism that consumes it

Trophic levels  This is an organism’s place in the food chain  Primary producers – first trophic level –Plants generate energy through photosynthesis  Primary consumers – second trophic level –Cannot create their own energy, choose to eat plants –Herbivores –Ex – Insects, grazing animals like rabbits, deer

Trophic levels  Secondary consumers – Third trophic level –Carnivores – eat herbivores and other carnivores –Ex: woodpeckers, skunks  eat insects; raccoons, foxes, snakes, etc.  Tertiary consumers – Fourth trophic levels –Large carnivores, such as lions, bears –Largest dietary variety, can eat from all trophic levels

Trophic levels  Decomposers – organisms that break down the organic compounds in other organisms  Very top of the food chain (“eat” everything) –Example – Fungi, bacteria –See table page 127.

Sun Water Producer (Grass) Primary Consumer (Grasshopper) Secondary Consumer (Snake) Tertiary Consumer (Hawk) Decomposer (Fungi) Trophic Levels

Food Web  Nutrients and energy are cycled through an ecosystem by various organisms  This occurs via interconnected food webs –Sun provides energy to producers –Producers provide energy to primary consumers –Primary consumers provide energy to secondary consumers –Secondary consumers provide energy to tertiary consumers

Foxes Small Birds Fungi and Bacteria Grasshoppers Hawks Rabbits Grasses and Plants

Interactions standard  SEV3.e: Describe interactions between individuals (i.e. mutualism, commensalism, parasitism, predation, and competition).

Symbiosis  Two dissimilar organisms live together and one or both are affected by the relationship  Three types –Mutatualism – Both benefit  Lichens (moss and algae) –Commensalism – One benefits, other unaffected  Pilot fish and shark –Parasitism – One benefits, other is harmed  Fleas on dogs

Types of symbiosis Parasitism Commensalism Mutualism

Predator/Prey Interactions  Predation is one type of interspecific competition  Predator eats the prey –Keep numbers stabilized within the ecosystem as they balance each other out –If the number of predators goes up, number of prey goes down; if prey goes down, number of predators goes down, in a continuous cycle

Competition interactions  Competition within a community Two types –InTRAspecific – One population competing –InTERspecific – Multiple populations competing

Succession Ch. 5.3 SEV3.b: Explain succession in terms of changes in communities through time to include changes in biomass, diversity, and complexity. SEV3.c: Explain how succession may be altered by traumatic events.

Key terms  Ecological succession  Primary succession  Secondary succession  Pioneer species  Climax community

Succession  How ecosystems change over hundreds- thousands of years.  The orderly, gradual, and natural changes and species replacements that takes place in an ecosystem after a disturbance  Lichens  moss, small plants  grass, insects  small animals, shrubs  birds  trees, large animals

Primary Succession  The development of an area where no ecosystem has existed before.  A disturbance was so great no living matter survived  Ex. Bare rocks, sand dune, a new island by volcano, glaciers, etc.

Secondary succession  The development of a community in an area that follows disruption of an existing community  Disturbance occurred but did not remove all living matter  Ex. Forest fire, hurricane, human activities such as logging, clear cutting, farming, or mining

Pioneer species  The first organisms to colonize any newly available area and begin the process of succession.  Small, fast-growing, and fast-reproducing  Ex. Lichens, mosses

Steps of succession  Volcano erupts, lava covers all living things. Lava cools and hardens.  Insects and spiders move onto cooled lava, organic material in air settles in cracks.  Seeds from pioneering plants grow, soil accumulates.  New plants grow, animals arrive, complex ecosystem forms, thousands of years pass.

Climax community -A stable, mature community at the end of succession -Balanced