Chapter 5: Energy Flow in the Ecosystem

Chapter 5: How Ecosystems WorkEnergy Flow in the EcosystemThe Cycling of MatterHow Ecosystems Changep. 116-135Key termsPhotosynthesisProducerConsumerDecomposerCellular respirationFood chainFood webTrophic level

Carbon cycleNitrogen-fixing bacteriaNitrogen cyclePhosphorus cycleEcological successionPrimary successionSecondary successionPioneer speciesClimax community

5.1 Energy Flow in the Ecosystem Describe how energy is transferred from the sun to producers and then to consumersDescribe one way in which consumers depend on producersList 2 types of consumersExplain how energy transfer in a food web is more complex than a food chainExplain why an energy pyramid is a representation of trophic levels

Life Depends on the SunAll life is dependent on the sun for energy. Plants algae and some bacteria use the suns energy and convert it into sugars/carbohydrates by photosynthesis

From producers to consumersProducer- autotrophs or self-feeders makes only energy by photosynthesis or chemosynthesis

Consumer- other feeders or heterotrophs- eat other organisms to survive

Ecology 2010Consumers- have to eatHeterotrophs- can not make own food, eat other organismsGrouped based on types of food they eat:Herbivores- eat producers (antelope)Carnivores- eat other consumers (lion)Omnivores- eat producers and consumers (grizzly bear)Detritivores- consumers that feed on wastes, dead organisms (vulture)Decomposers- break down organisms (bacteria, fungi)

6Cellular Respiration: Burning the FuelIf oxygen is available, organisms can obtain energy from food by a process called cellular respiration. The summary of cellular respiration is presented below.

In symbols:6 O2 + C6H12O6 6 CO2 + 6 H2O + ATP (Energy)

In words:Oxygen + Glucose Carbon dioxide + Water + Energy

The cell has to release the chemical energy in food molecules (like glucose) gradually, otherwise most of the energy would be lost in the form of heat and light.7Cellular Respiration 2009

Ecology 2010Energy transferAll organisms need energy to carry out essential functions, such as growth, movement, maintenance and repair, and reproduction. In an ecosystem, energy flows from the sun to autotrophs, then to organisms that eat the autotrophs, and then to organisms that feed on other organisms. The amount of energy an ecosystem receives and the amount that is transferred from organism to organism affect the ecosystem's structure.

8Ecology 2010Energy FlowTransfer of energy from one organism to anotherTrophic levels- organisms position in a sequence of energy transfers Food chain- single pathway of feeding relationships between organisms in an ecosystem that results in energy transferFood web- interconnected food chainsWeb cd 37 c, d, e

9Food ChainsA food chain is a series of steps in which organisms transfer energy by eating and being eaten.

Food chains can vary in length. An example from the Everglades is shown.

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Food Webs In most ecosystems, feeding relationships are much more complicated than the relationships described in a single, simple chain because many animals eat more than one kind of food.

Ecologists call this network of feeding interactions a food web. An example of a food web in the Everglades is shown.Ecology 2010Ecology 2010

Ecology 2010Limitations on trophic levelsOnly 10% of the energy available at one trophic levels is transferred to the next trophic level not enough to support more levelsHigher tropic levels contain less energy support fewer organisms

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Pyramids of Biomass and Numbers The total amount of living tissue within a given trophic level is called its biomass.

The amount of biomass a given trophic level can support is determined, in part, by the amount of energy available. Ecology 2010Ecology 2010

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5.2The Cycling of MaterialsDescribe the short term and long term process of the carbon cycle.Identify one way that humans are affecting the carbon cycle.List the three stages of the nitrogen cycleDescribe the role that nitrogen fixing bacteria play in the nitrogen cycleExplain how the excess use of fertilizer can affect the nitrogen and phosphorus cycles. Recycling in the BiosphereUnlike the one-way flow of energy, matter is recycled within and between ecosystems.

Elements pass from one organism to another and among parts of the biosphere through closed loops called biogeochemical cycles, which are powered by the flow of energy.

Ecology 2010Ecology 20104 major cyclesWater cycleCarbon cycleNitrogen cyclePhosphorus cycleWeb cd 37 f, g, h,

10min videohttp://www.youtube.com/watch?v=09_sWPxQymA&feature=related

22Carbon CycleShort term: Plant convert carbon dioxide into carbohydrates during photosynthesisConsumers eat the plants break down carbon during cellular respirationLong Term: carbon converted into carbonates (bones and shells) limestone rock (largest carbon reservoirs) Carbon also converted into fats, oils, other energy storing molecules release into soil or air after the organism dies can form coal or natural gas(fossil fuels)http://www.youtube.com/watch?v=U3SZKJVKRxQ

How Humans Affect the Carbon CycleBurn fossil fuels release carbon into air6 billion metric tons of carbon is released per year about will remain in the air increasing CO2 into the air at steady rate global warming increase the temperature of the Earth

The Nitrogen CycleAll organisms need nitrogen to build proteins78% of the gases in the atmosphereMust be altered in a usable formNitrogen fixing bacteria- bacteria that can fix nitrogen- take gas and transform it to a usable form (nitrate), key part in the nitrogen cycleLegumes- beans, peas, clover that bacteria can live in nodulesGets released into the soil plants absorb it and then consumers eat themDecomposers break down decaying and dying things putting the nitrogen back into the cycle

http://www.youtube.com/watch?v=1XC7xT0mIbY

The Phosphorus CycleMakes up cells of living organisms (bones and teeth)Plants get it from soil and water consumers get it from eating plants or other organismsPhosphorus goes from environment to organisms rarely occurs as a gasNo soluble in water sink to bottomFertilizers- contain nitrogen and phosphorus, great for plants and alga (algal bloom) can disrupt or deplete oxygen in aquatic ecosystemsAcid Rain- burning fuel nitric oxide is released acid rainVideo- http://www.youtube.com/watch?v=3iwL24oVpH4Song- http://www.youtube.com/watch?v=JvZ_r-ZB8PUAcid rain- http://www.youtube.com/watch?v=MqHw1hMEkAQ&feature=related

5.3 How Ecosystems ChangeList two examples of ecological successionExplain how a pioneer species contributes to ecological successionExplain what happens during old-field successionDescribe how lichens contribute to primary successionTHINK ABOUT IT In 1883, the volcanic island of Krakatau in the Indian Ocean was blown to pieces by an eruption. The tiny island that remained was completely barren.

Within two years, grasses were growing. Fourteen years later, there were 49 plant species, along with lizards, birds, bats, and insects. By 1929, a forest containing 300 plant species had grown. Today, the island is blanketed by mature rain forest.

How did the island ecosystem recover so quickly?Ecology 2010Ecology 2010Succession- changesEcological succession- gradual regrowth of a community of specieshttp://www.youtube.com/watch?v=V49IovRSJDshttp://www.youtube.com/watch?v=k03vxRYsJ4Y&feature=related

Primary- development of a community in an areas that has not supported life previously, sand dune, rock Web cd 37 bhttp://www.youtube.com/watch?v=vNHnwHaSolA&feature=fvwrel

Secondary- replace of species that follows the disruption (soil is present)Pioneer species- small, grow quick, reproduce quick, invade disturbed habitatsClimax community- stable end pthttp://www.youtube.com/watch?v=_Y9EQbKH_hA&feature=relatedSong: http://www.youtube.com/watch?v=rzE6BNNLew0&feature=related

32Primary Succession Volcanic explosions can create new land or sterilize existing areas.

Retreating glaciers can have the same effect, leaving only exposed bare rock behind them.

Succession that begins in an area with no remnants of an older community is called primary succession.

Ecology 2010Primary Succession For example, in Glacier Bay, Alaska, a retreating glacier exposed barren rock.

Over the course of more than 100 years, a series of changes has led to the hemlock and spruce forest currently found in the area.

Changes in this community will continue for centuries.

Ecology 2010Primary Succession The first species to colonize barren areas are called pioneer species.

One ecological pioneer that grows on bare rock is lichena mutualistic symbiosis between a fungus and an alga.

Ecology 2010Secondary Succession Sometimes, existing communities are not completely destroyed by disturbances. In these situations, secondary succession occurs.

Secondary succession proceeds faster than primary succession, in part because soil survives the disturbance. As a result, new and surviving vegetation can regrow rapidly. Secondary succession often follows a wildfire, hurricane, or other natural disturbance.

We think of these events as disasters, but many species are adapted to them. Although forest fires kill some trees, for example, other trees are spared, and fire can stimulate their seeds to germinate.

Secondary succession can also follow human activities like logging and farming.

Ecology 2010Why Succession Occurs Every organism changes the environment it lives in.

One model of succession suggests that as one species alters its environment, other species find it easier to compete for resources and survive.

For example, as lichens add organic matter and form soil, mosses and other plants can colonize and grow.

As organic matter continues to accumulate, other species move in and change the environment further.

Over time, more and more species can find suitable niches and survive.Ecology 2010Climax CommunitiesEcologists used to think that succession in a given area always proceeds through the same stages to produce a specific and stable climax community.

Recent studies, however, have shown that succession doesnt always follow the same path, and that climax communities are not always uniform and stable.

Ecosystems may or may not recover from extensive human-caused disturbances.

Clearing and farming of tropical rain forests, for example, can change the microclimate and soil enough to prevent regrowth of the original community.

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Mount St. Helens: Back From The DeadPart 1:http://www.youtube.com/watch?v=iqG4Vi-eu5U&feature=relatedPart 2:http://www.youtube.com/watch?v=SeXpFhvLeIc&feature=relmfuPart 3:http://www.youtube.com/watch?v=dq-rHDEoFYw&feature=relmfuPart 4:http://www.youtube.com/watch?v=8Ld8vZvSOvo&feature=relmfuPart 5:http://www.youtube.com/watch?v=XaqEMSUlM58&feature=relmfuPart 6:http://www.youtube.com/watch?v=5X1JFkfcLDo&feature=relmfu

More linkshttp://www.pbs.orghttp://www.wiley.com/college/strahler/0471480533/animations/ch23_animations/animation1.htmlhttp://www.life.uiuc.edu/http://www.fire-ecology.org/http://www.wildfirezone.org/http://www.youtube.com/watch?v=_Y9EQbKH_hA&feature=relatedhttp://www.geowords.org/ensci/imagesbook/04_03_succession.swfhttp://www.nodvin.net/snhu/SCI219/demos/Chapter_4/Chapter_04/Present/animations/50_2_2_1.htmlhttp://www.life.illinois.edu/bio100/lectures/f03lects/03f03-succession.html#successionhttp://bcs.whfreeman.com/thelifewire/content/chp55/55020.html