BIOE 20C Lecture Notes - Lecture 18: Herbivore, Decomposer, Photosynthesis
12 Sep 2016
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Lecture 18 12/3/2015 9:01:00 PM
Ecosystems
• All species within an area plus
• Abiotic components
• =groups of communities + chemical and physical environment
• Characterized by flow of energy and matter
4 Basic Components
• Abiotic environment
• Producers
• Consumers
• Decomposers
Energy vs. Matter
• Matter cycles in ecosystems
• Energy flows through ecosystems
Autotrophs
• Self-feeders
• Able to produce their own food
• Fix carbon (inorganic to organic)
• Most (not all) photosynthesize
• Most energy goes to respiration
• Less becomes biomass
Consumers
• Eat other organisms while they are still alive
• Include herbivores, predators, and parasites
Decomposers
• Consume non-living organic material
• Play key role in recycling matter
Food Chains vs. Food Webs
• Food chain=1 possible path of energy flow in an ecosystem
• Food web=all possible paths of energy flow in an ecosystem
• Strata of a food chain=trophic levels
find more resources at oneclass.com
find more resources at oneclass.com
Grazing vs. Decomposing Food Webs
• Grazing food web:
o Energy flow: primary producer>herbivore>carnivore
o Herbivore=primary consumer
o Carnivore=secondary, tertiary, quaternary consumer
• Decomposing food web
o Energy flow: dead organisms/waste>primary consumers
(=detritivores)>secondary etc. consumers
Food Web Characteristics
• Energy availability
• Energy transfer
Energy Availability
• Production efficiency
o % of assimilated material that becomes new biomass
o (Net productivity/biomass assimilated) x 100
o Varies greatly between taxa
• Measure of how much energy ingested becomes biomass
Energy Transfer
• Trophic transfer (ecological) efficiency
o Overall transfer from one trophic level to the next
o Typically around 10%
• Measure of how efficient energy transfer is between trophic levels
Eltonian Pyramids
• Depict flow of matter/energy through food chains
• Graphic representation of trophic transfer efficiency
• Pyramids can be constructed by
o Abundance
o Biomass
o Energy production per unit area (most accurate)
Ecosystem Productivity
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
12/3/2015 9:01:00 pm: all species within an area plus, abiotic components, =groups of communities + chemical and physical environment, characterized by flow of energy and matter. 4 basic components: abiotic environment, producers, consumers, decomposers. Energy vs. matter: matter cycles in ecosystems, energy flows through ecosystems. Autotrophs: self-feeders, able to produce their own food, fix carbon (inorganic to organic, most (not all) photosynthesize, most energy goes to respiration, less becomes biomass. Consumers: eat other organisms while they are still alive, include herbivores, predators, and parasites. Decomposers: consume non-living organic material, play key role in recycling matter. Food chains vs. food webs: food chain=1 possible path of energy flow in an ecosystem, food web=all possible paths of energy flow in an ecosystem, strata of a food chain=trophic levels. Grazing vs. decomposing food webs: grazing food web, energy flow: primary producer>herbivore>carnivore, herbivore=primary consumer, carnivore=secondary, tertiary, quaternary consumer, decomposing food web, energy flow: dead organisms/waste>primary consumers (=detritivores)>secondary etc. consumers.
