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PACKET #33CHAPTER #13
Ecosystems &The Flow of Energy &
Matter
Introduction
Ecosystem Encompasses all the interactions among organisms
living together in a particular place, and among those organisms and their abiotic environments
Individual communities and their abiotic environments Earth, which encompasses the biosphere (all of
Earth’s communities) and its interaction with Earth’s water, soil, rock and atmosphere, is the largest ecosystem
ENERGY FLOW
Ecosystems
Energy Flow Through Ecosystems
The flow of energy is linear—as energy cannot be reused by organisms Energy begins as solar energy, which is trapped by
photosynthesis in the form of chemical energy Chemical energy is then available to do work
Energy Flow II
Energy flow describes who eats whom in ecosystems A food chain describes
the sequential passage of energy
A food web shows the complexity of interconnected food chains Remember that a food
web is composed of many food chains
Energy Flow III
Food Chain Refresher Primary producers are
autotrophs and comprise the first trophic level
Herbivores, primary consumers, comprise the second trophic level May find omnivores here
Carnivores and/or omnivores, comprise trophics level three and higher all the way to the decomposers
Energy Flow IV
Ecological Pyramid Illustrates the trophic
levels May be a pyramid of
Numbers
Energy Flow V
Ecological Pyramid Illustrates the trophic
levels May be a pyramid of
Biomass
Energy Flow VI
Ecological Pyramid Illustrates the trophic
levels May be a pyramid of
Energy
Cycles of Matter in Ecosystem
Introduction
Biochemical cycles are cycles of matter between the abiotic and biotic components of the environment
Carbon, nitrogen, phosphorus and water cycles are central to life on earth
Carbon, nitrogen and water cycles have atmospheric components and cycle on a global scale
Carbon Cycle
Carbon dioxide is the pivotal molecule in the carbon cycle
Human activities, since the beginning of the Industrial Revolution, have contributed an increasing amount of carbon dioxide to the atmosphere by burning fossil fuels
Nitrogen Cycle
Bacteria are essential to this cycle Nitrogen fixing bacteria
converts nitrogen gas to ammonia
Nitrifying bacteria converts ammonia to nitrate
Denitrifying bacteria converts, anaerobes, convert nitrate to nitrogen gas
Nitrogen is needed for the production of proteins
Nitrogen oxides are also an ingredient in photochemical smog
Phosphorus Cycle
Fertilizers, runoff containing animal wastes, and sewage introduce phosphorus into aquatic ecosystems
Phosphorus loss accelerated by clear cutting Brazil
Water Cycle
Enough said!
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