Ch. 5 How Ecosystems Work

Ch. 5 Ch. 5 How Ecosystems WorkHow Ecosystems Work

ListList two examples of ecological succession. two examples of ecological succession.

ExplainExplain how a pioneer species contributes how a pioneer species contributes to ecological succession.to ecological succession.

ExplainExplain what happens during old-field what happens during old-field succession.succession.

DescribeDescribe how lichens contribute to primary how lichens contribute to primary succession.succession.

Chapter 5 Objectives

I. Energy Flow in EcosystemsI. Energy Flow in Ecosystems A. Life Depends on the SunA. Life Depends on the Sun PhotosynthesisPhotosynthesis – when plants use sunlight to make – when plants use sunlight to make

sugar moleculessugar molecules performed by plants, algae, and some bacteria performed by plants, algae, and some bacteria

6CO6CO22 + 6H + 6H22O + solar energy = CO + solar energy = C66HH1212OO66 + 6O + 6O22

I. Energy Flow in EcosystemsI. Energy Flow in Ecosystems

Result of photosynthesis is energy rich Result of photosynthesis is energy rich molecules called molecules called CarbohydratesCarbohydrates

When an animal eats a plant, some When an animal eats a plant, some energy is transferred from the plant to the energy is transferred from the plant to the animal, and use this energy to grow, animal, and use this energy to grow, move, and reproduce. move, and reproduce.


Producer – Producer – an organism that makes its own an organism that makes its own food – an food – an AutotrophAutotroph

--organisms that perform photosynthesisorganisms that perform photosynthesis

ConsumerConsumer – organisms that get their energy – organisms that get their energy by eating other organisms – by eating other organisms – heterotrophsheterotrophs

All organisms get their energy from the All organisms get their energy from the sunsun either by using it directly through either by using it directly through photosynthesis like producers, or indirectly by photosynthesis like producers, or indirectly by eating producers or other consumerseating producers or other consumers


In 1977 scientists discovered areas on the In 1977 scientists discovered areas on the bottom of the ocean that were full of life even bottom of the ocean that were full of life even though sunlight did not reachthough sunlight did not reach

-deep ocean communities got their -deep ocean communities got their energy from bacteria who could use hydrogen energy from bacteria who could use hydrogen sulfide from the hot water vents to make their sulfide from the hot water vents to make their own foodown food

-these bacteria served as the food for -these bacteria served as the food for other organisms so a whole ecosystem could other organisms so a whole ecosystem could be supportedbe supported

B. What Eats WhatB. What Eats What Organisms can be classified by the source of their energyOrganisms can be classified by the source of their energy

HerbivoresHerbivores – consumers that eat only producers – plant- – consumers that eat only producers – plant-eaterseaters

CarnivoresCarnivores – consumers that eat other consumers – – consumers that eat other consumers – meat-eatersmeat-eaters

OmnivoresOmnivores – consumers that eat both producers and – consumers that eat both producers and consumers – all-eatersconsumers – all-eaters

DecomposersDecomposers – consumers that get their food by – consumers that get their food by breaking down dead organisms -bacteria and fungibreaking down dead organisms -bacteria and fungi

C. Cellular Respiration: Burning C. Cellular Respiration: Burning the Fuelthe Fuel

Your body gets the energy out of the food Your body gets the energy out of the food by using the oxygen you breathe to break by using the oxygen you breathe to break down the fooddown the food

-you are then able to use the energy -you are then able to use the energy stored in the foodstored in the food

Excess energy is stored as fat or sugar.Excess energy is stored as fat or sugar.

C. Cellular Respiration: Burning C. Cellular Respiration: Burning the Fuelthe Fuel

Cellular respirationCellular respiration – process of – process of breaking down food to yield energybreaking down food to yield energy

-occurs inside cells of most -occurs inside cells of most organisms organisms including plant and including plant and animalsanimals

You use the energy to walk, breathe, You use the energy to walk, breathe, think, or play a sport, to make more body think, or play a sport, to make more body tissues, fight disease, grow, stay healthytissues, fight disease, grow, stay healthy

D. Energy TransferD. Energy Transfer

Each time one organism eats another, a Each time one organism eats another, a transfer of energy occurstransfer of energy occurs

According to the second law of According to the second law of thermodynamics – at each energy thermodynamics – at each energy transfer only 10% is available at the next transfer only 10% is available at the next level, the rest is lost as heatlevel, the rest is lost as heat

You can trace the transfer of energy as it You can trace the transfer of energy as it travels through an ecosystem by studying food travels through an ecosystem by studying food chains, food webs, and trophic levelschains, food webs, and trophic levels

Food chainFood chain – a sequence in which energy is – a sequence in which energy is transferred from one organism to the next as transferred from one organism to the next as each organism eats another organismeach organism eats another organism

In an ecosystem, energy flow is usually more In an ecosystem, energy flow is usually more complex because there are so many species complex because there are so many species interactinginteracting

Food webFood web – shows many feeding relationships – shows many feeding relationships that are possible in an ecosystemthat are possible in an ecosystem

Food ChainFood Web

Trophic LevelsTrophic Levels Trophic levelTrophic level – each step in the transfer of – each step in the transfer of

energy through a food chain or webenergy through a food chain or web

-each time energy is transferred from one -each time energy is transferred from one organism to another, some of the energy is lost organism to another, some of the energy is lost as heat and less is available to organisms at as heat and less is available to organisms at the next levelthe next level

90 percent of the energy at each trophic level 90 percent of the energy at each trophic level is used to carry out the functions of livingis used to carry out the functions of living

Trophic LevelsTrophic Levels

10 percent becomes used as part of the 10 percent becomes used as part of the organisms body and stored in its molecules – organisms body and stored in its molecules – this is what is available to the next trophic level this is what is available to the next trophic level when one organism consumes anotherwhen one organism consumes another

Energy pyramid is used to visualize the loss of Energy pyramid is used to visualize the loss of energy from one trophic level to the nextenergy from one trophic level to the next

-each layer represents one trophic level -each layer represents one trophic level


producersproducers form the base because they form the base because they contain the most energycontain the most energy

--herbivoresherbivores make up the next level make up the next level because they contain less energybecause they contain less energy

--carnivorescarnivores that feed on herbivores make that feed on herbivores make up the next levelup the next level

--omnivoresomnivores that feed on carnivores and that feed on carnivores and producers make up the top levelproducers make up the top level


The decreased amount of energy at each trophic The decreased amount of energy at each trophic level affects the organization of an ecosystemlevel affects the organization of an ecosystem

-because so much energy is lost at each level, -because so much energy is lost at each level, there are fewer organisms at the higher trophic there are fewer organisms at the higher trophic levelslevels

-the loss of energy limits the number of trophic -the loss of energy limits the number of trophic levels in an ecosystemlevels in an ecosystem

ObjectivesObjectives

ListList the three stages of the carbon cycle. the three stages of the carbon cycle. DescribeDescribe where fossil fuels are located. where fossil fuels are located. IdentifyIdentify one way that humans are affecting the one way that humans are affecting the

carbon cycle.carbon cycle. ListList the three stages of the nitrogen cycle. the three stages of the nitrogen cycle. DescribeDescribe the role that nitrogen-fixing bacteria the role that nitrogen-fixing bacteria

play in the nitrogen cycle.play in the nitrogen cycle. ExplainExplain how the excess use of fertilizer can how the excess use of fertilizer can

affect the nitrogen and phosphorus cycles.affect the nitrogen and phosphorus cycles.

II. The Cycling of MaterialsII. The Cycling of Materials A. The Carbon CycleA. The Carbon Cycle Carbon is an essential part of all living Carbon is an essential part of all living

thingsthings Carbon cycleCarbon cycle – a process by which – a process by which

carbon is cycled between the carbon is cycled between the atmosphere, land, water, and organismsatmosphere, land, water, and organisms

Carbon is the essential component of Carbon is the essential component of proteins, fats, and carbohydrates, which proteins, fats, and carbohydrates, which make up all organisms.make up all organisms.

The Carbon CycleThe Carbon Cycle

The Long & Short Cycles The Long & Short Cycles of Carbonof Carbon a short term cycle is when producers like plants a short term cycle is when producers like plants

convert CO2 in the air into glucose during convert CO2 in the air into glucose during photosynthesisphotosynthesis

-some carbon enters a long-term cycle if carbon -some carbon enters a long-term cycle if carbon is converted into is converted into carbonatescarbonates which make up which make up the hard parts of bones and shellsthe hard parts of bones and shells

As a Long Term CycleAs a Long Term Cycle over millions of years carbonate deposits over millions of years carbonate deposits

produce huge formations of limestone rocksproduce huge formations of limestone rocks-limestone is one of the largest -limestone is one of the largest carbon carbon

sinkssinks or carbon reservoirs on Earth or carbon reservoirs on Earth

-carbon can be released into the soil or air after -carbon can be released into the soil or air after an organism dies and decomposes and form an organism dies and decomposes and form deposits of coal, oil, and natural gas deposits of coal, oil, and natural gas underground called underground called fossil fuelsfossil fuels

Humans affect the carbon Humans affect the carbon cyclecycle

When we burn fossil fuels, we release When we burn fossil fuels, we release carbon into the atmosphere as carbon carbon into the atmosphere as carbon dioxidedioxide

-cars, factories, and power plants -cars, factories, and power plants rely rely on these fossil fuels to operateon these fossil fuels to operate

-about 6 billion metric tons of carbon a -about 6 billion metric tons of carbon a year are released as COyear are released as CO22

B. The Nitrogen CycleB. The Nitrogen Cycle

All organisms need protein which is All organisms need protein which is essential for new cells - nitrogen is essential for new cells - nitrogen is needed for proteins.needed for proteins.

Nitrogen makes up 78% of the gases in the Nitrogen makes up 78% of the gases in the atmosphere, but organisms cannot take in atmosphere, but organisms cannot take in and use atmospheric nitrogenand use atmospheric nitrogen

Nitrogen FixationNitrogen Fixation Nitrogen must be altered, or fixed, before Nitrogen must be altered, or fixed, before

organisms can use itorganisms can use it

The only organisms that can fix nitrogen is The only organisms that can fix nitrogen is bacteria called bacteria called nitrogen-fixing bacterianitrogen-fixing bacteria

-all organisms depend on these bacteria to -all organisms depend on these bacteria to supply nitrogen supply nitrogen

Bacteria are an important part of nitrogen cycleBacteria are an important part of nitrogen cycle

Nitrogen CycleNitrogen Cycle

Nitrogen cycleNitrogen cycle Nitrogen cycleNitrogen cycle– a process in which nitrogen is cycled – a process in which nitrogen is cycled

between the atmosphere, bacteria, and other between the atmosphere, bacteria, and other organismsorganisms

-bacteria take nitrogen from the air and transforms it -bacteria take nitrogen from the air and transforms it into molecules that living things can useinto molecules that living things can use

-the bacteria live within nodules on the roots of plants -the bacteria live within nodules on the roots of plants called legumes – beans, peas, clovercalled legumes – beans, peas, clover

-they use sugars provided by the legumes to produce -they use sugars provided by the legumes to produce nitrogen-containing compounds like nitratesnitrogen-containing compounds like nitrates

-the excess nitrates are released into the soil-the excess nitrates are released into the soil

Animals get nitrogen by eating plants or other Animals get nitrogen by eating plants or other animalsanimals

After nitrogen cycles from the atmosphere into After nitrogen cycles from the atmosphere into living things, it is returned to the atmosphere by living things, it is returned to the atmosphere by bacteriabacteria

-decomposers are essential to the nitrogen cycle -decomposers are essential to the nitrogen cycle because the break down wastes such as urine, because the break down wastes such as urine, dung, leaves, and other decaying plant and animal dung, leaves, and other decaying plant and animal matter and return the nitrogen that these organisms matter and return the nitrogen that these organisms and wastes contain to the soiland wastes contain to the soil

-after decomposers return the nitrogen to the soil, -after decomposers return the nitrogen to the soil, bacteria transform a small amount of the nitrogen bacteria transform a small amount of the nitrogen into nitrogen gas which returns to the atmosphereinto nitrogen gas which returns to the atmosphere

C. The Phosphorus CycleC. The Phosphorus Cycle

Phosphorus is part of many molecules Phosphorus is part of many molecules that make up the cells of living organismsthat make up the cells of living organisms

Essential in forming bones and teethEssential in forming bones and teeth

Plants get phosphorus from soil and Plants get phosphorus from soil and water, and animals get it by eating plants water, and animals get it by eating plants or plant-eatersor plant-eaters

Phosphorus cyclePhosphorus cycle Phosphorus cyclePhosphorus cycle – the movement of – the movement of

phosphorus from the environment to organisms phosphorus from the environment to organisms and then back to the environmentand then back to the environment

-this cycle is slow and does not normally occur -this cycle is slow and does not normally occur in the atmosphere because phosphorus rarely in the atmosphere because phosphorus rarely occurs as a gasoccurs as a gas

-phosphorus enters the cycle when rocks -phosphorus enters the cycle when rocks erode, small amounts of phosphorus dissolve erode, small amounts of phosphorus dissolve as phosphate in soil and wateras phosphate in soil and water

-plants absorb phosphates in the soil through -plants absorb phosphates in the soil through their rootstheir roots

Phosphorus cyclePhosphorus cycle -phosphorus also enters the cycle when added -phosphorus also enters the cycle when added

to soil and water when excess phosphorus is to soil and water when excess phosphorus is excreted in waste excreted in waste

from organisms and when organisms die and from organisms and when organisms die and decomposedecompose

-some phosphorus also washes off the land -some phosphorus also washes off the land and eventually ends up in the oceanand eventually ends up in the ocean

-phosphate salts are not soluble in water and -phosphate salts are not soluble in water and so they sink to the bottom of the ocean and so they sink to the bottom of the ocean and accumulate as sedimentaccumulate as sediment

Phosphorus CyclePhosphorus Cycle

Human effectsHuman effects Humans effect the Nitrogen and Phosphorus Humans effect the Nitrogen and Phosphorus

cyclecycle -people often apply fertilizers to stimulate and -people often apply fertilizers to stimulate and

maximize plant growthmaximize plant growth -fertilizers contain both nitrogen and -fertilizers contain both nitrogen and

phosphorusphosphorus -the more nitrogen and phosphorus available to -the more nitrogen and phosphorus available to

a plant, the faster and bigger the plant tends to a plant, the faster and bigger the plant tends to growgrow

If excessive amounts of fertilizer are used, the If excessive amounts of fertilizer are used, the fertilize can enter terrestrial and aquatic fertilize can enter terrestrial and aquatic ecosystems through runoffecosystems through runoff

Phosphorus cyclePhosphorus cycle -this can cause rapid and over-abundant -this can cause rapid and over-abundant

growth of algae resulting in an growth of algae resulting in an algal bloomalgal bloom – a – a dense, visible patch of algae that occurs near dense, visible patch of algae that occurs near the surface of the waterthe surface of the water

(Eutrophication)(Eutrophication)

-bacteria break down the dead algae and -bacteria break down the dead algae and plants depleting the oxygen from the water plants depleting the oxygen from the water causing fish and other aquatic organisms to diecausing fish and other aquatic organisms to die

Nutrient Cycles can be Nutrient Cycles can be harmfulharmful

When we burn coal, wood, or oil, a large When we burn coal, wood, or oil, a large amount of nitric oxide is release into the amount of nitric oxide is release into the atmosphereatmosphere

-this is a harmful gas and when it -this is a harmful gas and when it combines with oxygen and water vapor to combines with oxygen and water vapor to form nitric acid (NOX)form nitric acid (NOX)

-nitric acid dissolves in rain and snow -nitric acid dissolves in rain and snow contributing to acid precipitationcontributing to acid precipitation

BellringerBellringer

ObjectivesObjectives

ListList two examples of ecological two examples of ecological succession.succession.

ExplainExplain how a pioneer species how a pioneer species contributes to ecological succession.contributes to ecological succession.

ExplainExplain what happens during old-field what happens during old-field succession.succession.

DescribeDescribe how lichens contribute to how lichens contribute to primary succession.primary succession.

III. How Ecosystems ChangeIII. How Ecosystems Change

A. Ecological SuccessionA. Ecological Succession Ecological successionEcological succession – a gradual – a gradual

process of change and replacement of process of change and replacement of the types of species in a communitythe types of species in a community

Primary succession Primary succession – a type of – a type of succession that occurs on a surface succession that occurs on a surface where no ecosystem existed beforewhere no ecosystem existed before

-rocks, cliffs, sand dunes-rocks, cliffs, sand dunes

Secondary successionSecondary succession Secondary successionSecondary succession – the more common – the more common

type of succession where succession occurs type of succession where succession occurs on a surface where an ecosystem has on a surface where an ecosystem has previously existedpreviously existed

-areas that have been disturbed by -areas that have been disturbed by humans, animals or natural processes humans, animals or natural processes

such such as storms, floods, fires, earthquakes, as storms, floods, fires, earthquakes, volcanoesvolcanoes

Example – Mount St. Helens eruption wiped Example – Mount St. Helens eruption wiped out everythingout everything

Mount St. Helens Mount St. Helens SuccessionSuccession

the first species to regrow were the first species to regrow were pioneer pioneer speciesspecies – the first organisms to colonize any – the first organisms to colonize any newly available area and begins the process of newly available area and begins the process of ecological successionecological succession

-pioneer species makes the area habitable for -pioneer species makes the area habitable for other speciesother species

-tend to be smaller species like mosses and -tend to be smaller species like mosses and grassesgrasses

-they are replaced by larger and larger -they are replaced by larger and larger organisms organisms

climax communityclimax community --climax communityclimax community – a final and stable – a final and stable

communitycommunity Natural fires caused by lightening are a Natural fires caused by lightening are a

necessary part of secondary successionnecessary part of secondary succession

-some trees release seeds only when exposed -some trees release seeds only when exposed to the heat of a fireto the heat of a fire

-minor fires remove the brush and deadwood -minor fires remove the brush and deadwood that would otherwise contribute to major fires that would otherwise contribute to major fires burning out of controlburning out of control

-some animal species feed on vegetation that -some animal species feed on vegetation that only sprouts after firesonly sprouts after fires

Ecological SuccessionEcological Succession

Old-field successionOld-field succession Example of secondary succession is old-field Example of secondary succession is old-field

successionsuccession Old-field successionOld-field succession – occurs when farmland – occurs when farmland

is abandoned when a farmer stops cultivating a is abandoned when a farmer stops cultivating a fieldfield

-grasses and weeds quickly build up-grasses and weeds quickly build up -over time taller plants move into the area-over time taller plants move into the area -taller plants gradually replace smaller ones-taller plants gradually replace smaller ones -finally the slower growing trees like oaks, -finally the slower growing trees like oaks,

hickory, beech, and maple take overhickory, beech, and maple take over

Primary successionPrimary succession Primary succession is much slower than Primary succession is much slower than

secondary succession because it begins where secondary succession because it begins where there is no soilthere is no soil

-it can take several hundred to several -it can take several hundred to several thousand years to produce fertile soilthousand years to produce fertile soil

-lichens are usually the first pioneer species -lichens are usually the first pioneer species because they can live with no soilbecause they can live with no soil

Lichens are composed of a fungus and an Lichens are composed of a fungus and an algaealgae

How it happensHow it happens as the lichen grows it breaks down the rock and as the lichen grows it breaks down the rock and

soil slowly accumulates as dust particles in the soil slowly accumulates as dust particles in the air are trapped in cracks in the rockair are trapped in cracks in the rock

-dead remains of lichens and bacteria -dead remains of lichens and bacteria accumulate in the cracksaccumulate in the cracks

-mosses may grow larger and break the rock -mosses may grow larger and break the rock even more, then they die and decay and add even more, then they die and decay and add material and nutrients to the growing soilmaterial and nutrients to the growing soil

-fertile soil is formed from broken rock, decayed -fertile soil is formed from broken rock, decayed organisms, water, and airorganisms, water, and air

Get A calculator from the Get A calculator from the Box Box

Quick LabQuick Lab

Documents

Ch. 5 How Ecosystems Work