PACKET #33 CHAPTER #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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