Biology - Ecologyvhilliard.weebly.com/uploads/4/1/0/1/41019357/ecology_notes.pdf · Unit 1 –...

Biology - Ecology

Topic 1 – Ecology and Roles in EcosystemsTopic 2 – Ecological Relationships and Competition

Unit 1 – Ecology and Roles in Ecosystems

Ecology can be defined as the relationships between organisms and their environments.

This term can be expanded to s te ca be e pa ded toinclude many many organisms and is collectively called an ecosystemecosystem.An ecosystem is the relationship among many living species within a region and howspecies within a region and how they interact with each other and the non-living environment.

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Population can be defined as members of the same species living in the same area. This can be an ecosystem or habitat.

Examples:p• Maple trees within a forest• Salmon in the same river

Community is the total of allCommunity is the total of all populations in an ecosystem or habitat.

Example:Example:• All species of trees and animals

within the forest

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Within any ecosystem there two factors in which all organisms react.

Abiotic factors include:• The physical environment

such as sunlight, temperature, wind, rocks, water, etc.

Biotic factors include:• The living environment suchThe living environment such

as the plants, animals, bacteria, etc.

Homework: Read pg 22 – 23 complete

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pg pQ 1 – 6 on 23


Throughout nature there are many different ecosystems with either ysimilar or completely different species of plants and animals.The boundaries between ecosystems

ll t h b t thare generally not sharp, but rather gradual where there is an intermingling of organisms from each ecosystem These transitions areecosystem. These transitions are called ecotones.Ecotone can be defined as the transition area between two ecosystems, where organisms from each interact.

Example:• A marsh between a pond and a

field

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Ecotones are more stable than ecosystems because:

There tend to be a greater number of species of organisms within these areasThis provides for alternative food sources for predators.

Ecosystems with greaterEcosystems with greater biodiversity tend to be more successful because there are more organisms to interact withmore organisms to interact with one another.

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Biodiversity is the number of different species of organisms in an ecosystem. Ecotones show good biodiversity.With increased biodiversity we t c eased b od e s ty esee:

More speciesMore predator preyMore predator-prey relationshipsMore stable ecosystemsLess possibility of extinction any given speciesAlternative food sources.

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With decreased biodiversity we see:

Fewer speciesPredators may loose their source of foodLeads to a very unstable ecosystemExtinction of one species couldExtinction of one species could lead to the destruction of the entire ecosystem.

Homework:Homework:“Canada’s Endangered Species” pg 14, 15 #1, 2“Extinction in the Modern World” pg 16-19 #1-3“What is the Value of Wolves” pg 20, 21 # 1-3

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Unit 1 – Ecology and Roles in EcosystemsFood Chain – a step – by – step linking of organisms that feed on each other.

Example• Wheat, field mouse, snake, ea , e d ouse, s a e,

hawkProducers are organisms that can make their own food.Most producers are plants and are often called autotrophs.Consumers are living things thatConsumers are living things that depend upon other organisms for their food. Consumers are divided into three main types.

Herbivores – animals that eat only plant food• Moose grasshopper or

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Moose, grasshopper, or rabbit


Carnivores – animals that only eat other animalsanimals

Examples• Frog, snake, fox, lion, etc

Omnivores – animals that eat both plant and animal material.

Examplesp• Raccoons, humans, etc.

Decomposers – Organisms that breakdown once living matter into nutrients for theironce living matter into nutrients for their own use and into material that can be returned to the environmentDecomposers are also called saprobes orDecomposers are also called saprobes or detrivoresDetritus – decaying materialDetrivore organisms that feed on detritus

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Detrivore – organisms that feed on detritus

Unit 1 Ecological Relationships andUnit 1 – Ecological Relationships and Competition

Symbiotic Relationships – two organisms living in close relationship with one another.Also called symbiosis.There are three types of symbiotic relationships:

Mutualism – where both organismsMutualism – where both organisms benefit from the relationship

• Example clown fish and sea anemone

Commensalisms – where one organism benefits from the relationship and the other is unaffected

• Example remora and sharkParasitism – where one organism is benefited and the other is harmed or killed

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killed.• Example human and tapeworm


Exotic Species – are introduced species into an ecosystem and they are not native to the area.

Example: Moose in Newfoundland

Habitat – is a place where an organism lives

Example: pond marsh etcExample: pond, marsh, etcNiche – the role an organism has in its habitat.

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Competition exists between organisms within an ecosystem. Exotic species can alter theExotic species can alter the balance within the ecosystem and have negative effects upon the natural populations within the t e atu a popu at o s t t eregion.Competition can be either:

Interspecific – competitionInterspecific competition between members of different species for the same resourcesIntraspecific – competition p pbetween members of the same species for the same resourcesHomework

Roles in Ecosystems pg 40 – 44 # 1 - 3

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Over long periods of time the makeup of a community or ecosystem will change.This change is called SuccessionSuccess oThere are two types of succession:

P i h tPrimary where one ecosystem is completely transformed into a different type.

E l d t f i i t• Example – pond transforming into a forest

Secondary where an area has been completely disturbed by

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been completely disturbed by some kind of disaster


Primary succession can occur both on land and in water.An example of how a pond can change into a forest.

Step 1Step 1• The pond is inhabited by a pioneer

community of algae and bacteria

Step 2Step 2• Over time sediment deposits build

up on the bottom of the pond making it shallow. The sediments

i ht f llmight come from small invertebrates and soil washing into the pond from the shore

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Step 3• As the pond becomes p

shallower with more sediment being deposited a marsh forms where water loving plants such as bulrushes and cattails grow

Step 4S ep• At the end of the process a

climax community forms as a terrestrial communityterrestrial community replaces the aquatic one from which we started. Trees and shrubs now have

16a place to grow.


Secondary succession does not bring about as drastic change in the ecosystem as primary succession and y p yis caused by some disaster.

Example fire:• Fire destroys the climax community of

fir and spruce trees.a d sp uce ees• New growth of aspen and other fast

growing trees take hold on the burned over area.

• Fir and spruce trees take over and replace aspen as the new climax community

Climax Community – the final stage of succession in a particular area.

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Unit 2 – Energy in EcosystemsEcosystems

Topic 1 – Sources of EnergyTopic 2 – Pests and Pesticidesp

U it 2Unit 2 – Energy in Ecosystems

Solar EnergyThe sun provides all the energy that is used on the planet. It is what powers

tecosystems.It also provides:

• Light and warmth• Makes evaporation possible to provide

precipitationprecipitation• Provides energy for photosynthesis

Distribution of the total sun’s energy that hits the earth:

30% reflected by clouds or off the30% reflected by clouds or off the earth’s surface44% heats the earth’s surface and atmosphere25% heats and evaporates water25% heats and evaporates water1% generates wind0.023% used by plants for photosynthesis

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The earths ability to absorb energy is indirectly related to the albedo of different objects.the albedo of different objects.Albedo – percent of light energy that an object reflects.The higher the albedo the less e g e t e a bedo t e essenergy the object absorbs because most of it is reflected away.Hi h lb d tHigh albedo – snow, water, sandLow albedo – forests, dark rocksrocks

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In order for organisms to survive they must have a constant supply of food.Energy to make food comes primarilyEnergy to make food comes primarily from the sun. Which is then passed from one organism to another throughout the ecosystem.Organisms within an ecosystem areOrganisms within an ecosystem are divided into two main groups:

Producers (mainly plants) –autotrophs; capable of making their own food by photosynthesis orown food by photosynthesis or chemosynthesisConsumers (mainly animals) –heterotrophs; cannot make their own f d d d d dfood and depend on producers or other heterotrophs for their food.

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To show how energy moves through an ecosystem we represent it as a food chain or webFood chain:

Shows how energy is transferred from one organism to another. Arrows are used to indicate theArrows are used to indicate the direction of energy flowFood chains always start with a producerL i il bl f iLess energy is available for organisms at the top of the chain.

Food Webs:Several interconnected food chainsThey give a more realistic model of how energy is transferred throughout the ecosystem

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Example of a food chain:

Example of a food web:

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Each level of a food chain is called a tropic level and represents a loss of energy for each levelenergy for each levelTropic levels always start with producers.Example:

Tropic level Type Example

1st P d S t1st Producer Spruce tree

2nd Primary consumer

Deer

3rd Secondary wolf3 Secondary consumer

wolf

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As energy flows through an ecosystem the organisms use that for their various needs.that for their various needs.The study of the patterns of energy change is called thermodynamicsThere are two basic laws of thermodynamics:

Energy can be converted from one form to another but energyone form to another but energy cannot be created or destroyed.During energy transformation some of the energy might be gy glost (as heat or light) and is not passed on to the next form

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Pyramid of Energy:This pyramid shows how energy is lost as it is passed from one organism to the nextto the nextGenerally 10% of the energy is carried forward to the next species. This is called the 10% ruleThe energy that is not available for the next organism is used by the first in itsnext organism is used by the first in its day to day activities of survival

4th trophic level 10KJ owls

3rd trophic level 100 KJ shrewsshrews2nd trophic level 1000KJ grasshoppers

1st trophic level 10 000KJ grass

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Unit 2 – Energy inUnit 2 Energy in Ecosystems

Pyramid of numbers:A diagram drawn to representA diagram drawn to represent the physical count of the number of organisms at each trophic level It may or maytrophic level. It may or may not look like a pyramid.

4th trophic level3 robins

5th trophic level1 falcon

3rd trophic level100 ladybugs

2nd trophic level100 000 aphids

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1st trophic level 50 oak trees

Unit 2 – Energy inUnit 2 Energy in Ecosystems

Pyramid of biomass:This is a diagram of the dryThis is a diagram of the dry mass of the organisms at each trophic level. It usually does not look like a pyramidnot look like a pyramid.

3rd trophic level 9 g falcon

2nd trophic level 45 g duck

1st trophic level 1000 g grass

28Assignment: pg 34 – 39, # 1-5

Pests and PesticidesPesticides

P t d P ti idPests and Pesticides

Pest:Defined as an organism gthat people consider harmful or inconvenient.

• Eg: insects, weeds, rodentsg , ,Pesticides:

• Chemicals designed to kill pestspests.

• The types of pesticides have changed or evolved over time as we become more aware of how they react with the environment and organisms.

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Paradigm:Universally recognized scientific belief that shapes scientific thinking and research for a given time.

Paradigm Shift:How scientific thinking changes as a result of newly acquiredas a result of newly acquired knowledge.

• The world was flat.• Sun revolved around the earth.• The idea that pesticides are safe

for the environment.

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Evolution of pesticides:Pesticides have changed over the years to make them boththe years to make them both safer to use and safer for the environment.

First generation:They were pure metals:

• Sulfur, arsenic, lead, mercuryThey were harmful to both insects and humansinsects and humans.

Second generation:Chemicals made in the lab

• DDTThey were fat soluble and affected humans who fed on plants treated with it.

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Pests and Pesticides

Third generation:The newest types of pesticides areThe newest types of pesticides are water soluble and do not accumulate in fats of either animals or humananimals or human.Animals excrete them.They are still harmful to other yanimals other than the ones intended for eradication because the pesticide must be used more pfrequently

Bioamplification:The increased concentration of toxinThe increased concentration of toxin as it is consumed on the way up the food chain. Thi i th j bl ith 2nd

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This is the major problem with 2nd

generation pesticides such as DDT.

Cycling ofCycling of Materials in Ecosystems

T f Ch i lTypes of Chemicals

All chemicals can be classified as either:

Organic• Substances that contain

b th b d h dboth carbon and hydrogen• Proteins, sugars and fats

Inorganic• Substances that do not

contain hydrogen and hydrogeny g

• Carbon dioxide, water and ammonia

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Cycling of OrganicCycling of Organic Material

Plants get nutrients

Animalseat plants

Animals eat other animals

Plants get nutrientsfrom decomposed

materialPlants and animals die

Decomposers breakdown deadbodies and feces into inorganic

molecules and return them to themolecules and return them to thesoil

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C b C lCarbon Cycle

Carbon is one of the most important molecules in to living things. It is one of the few molecules that can form long chained and therefore complex compounds Mostand therefore complex compounds. Most living systems require these complex compounds to build structures and provide energy.There is a limited amount of carbon on the planet and in order to make available toplanet and in order to make available to living organisms it must be re-cycled.Two of the major processes involved in recycling carbon is:

Photosynthesis – the process of y pconverting carbon dioxide and water into simple sugars and releasing oxygen as a waste product. Light energy is required for this process.Cellular Respiration – the reverse process Ce u a esp a o e e e se p ocesswhere sugars are broken down into carbon dioxide and water in the presence of oxygen releasing energy

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C b C lCarbon Cycle

Being a cycle the products from photosynthesis are raw materials for respirationmaterials for respirationThe process can be represented in the following diagram:diagram:

Carbon Dioxide + Water + Light Energy Sugar + Oxygen6CO2 + H

2O C

6H

12O

6 + 6O2

Sugar + OxygenC H O + 6O

Carbon Dioxide + Water6CO + H OC

6H

12O

6 + 6O2

6CO2 + H2O

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C b C lCarbon Cycle

The recycling of carbon involves living things in that:

All living things use carbon (with other molecules) to make body tissue and it is also used as a source of energy.Carbon is returned to the atmosphere (as CO2) or to the 2water and soil as body waste or decomposing bodiesSome of this carbon is converted to fossil fuels (coal or oil) and must be burned before it can return to the environment.

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C b C lCarbon Cycle

Human activities increase the amount of carbon that is recycled. This is done in a number of ways:

Mining and burning fossil fuelsg gBurning of forests (for residential or agricultural purposes).p p )Clearing vegetation contributes to less photosynthesis and the reduction of carbon as a usefulreduction of carbon as a useful substance.

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C b C lCarbon Cycle

Reservoirs for carbon:There are two main reservoirs for carbon they are:

• Inorganic• Atmospheric – CO2 gas• Oceans – dissolved CO2, Calcium

carbonate in shells CaCO3

• Earth’s Crust – carbon in sediment in the ocean is heated and compressed to form rock

• Organic:• Found in the bodies of animals• Bogs peat and coal• Bogs – peat, and coal

(compressed peat)

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NitNitrogen

Th l t it iThe element nitrogen is important to living things in a number of ways:

Required by cells to makeRequired by cells to make proteinsRequired to make DNA, the genetic blueprint of living

iorganismsNitrogen gas (atmospheric nitrogen, N2)

Makes up 79% of theMakes up 79% of the atmosphereNitrogen gas is very stable and is unavailable for organisms to useIt must be converted to a nitrate (NO3

-) compound before organisms can make use of it.

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organisms can make use of it.

Nit C lNitrogen Cycle

Nitrogen moves in a cycle in ecosystems from living things – to the environment – to living things.g gNitrogen must be “fixed” (converted to a nitrate compound) before it can be used by organisms.There are two parts to the nitrogenThere are two parts to the nitrogen cycle:

Nitrogen fixation – the process of converting atmospheric nitrogen (N2) into nitrate ion (NO )into nitrate ion (NO3

-)This is accomplished by:

• Lightning – nitrogen + oxygen = nitrates

• Nitrogen fixing bacteria – these bacteria live in plant roots

Denitrification – conversion of nitrates back into nitrogen gas

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Nit C lNitrogen Cycle

Nitrogenfixing bylightning

nitrogen gasin atmosphere g g

denitrifing bacteriarelease nitrogen animals eat

plants

ammonificationof dead organisms

nitrogen fixingby monerans

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plants

nitrogen fixingbacterianitritenitrate

ammoniumplants usenitrites and nitrates

soil

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F tiliFertilizers

Fertilizers are chemicals used to restore nutrients to the soil once plants use them.Nutrients such as nitrogen and gphosphorous need to be replaced once crops have been harvested.Disadvantages of using fertilizers:

Make the soil acidicMake the soil acidicFertile runoff causes too much algae to grow in lakes. This can:

• Require too much oxygen to decompose dead algaedecompose dead algae

• Block sunlight from entering lakes preventing photosynthesis

Decomposing plants cause too many bacteria in lakes which convertbacteria in lakes which convert nitrates to nitrites. Excess nitrates are dangerous to both animals and humans.

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Sustainability and Biomesand Biomes

S t i bl S tSustainable Systems

A sustainable ecosystem is one that:Survives and functions over timeMeets the needs of the organismsMeets the needs of the organisms now and well into the future

Biome:A biome is a collection of ecosystems th t i il l t d tthat are similar or related to one another.Canada has 4 biomes:

• Tundra• Boreal forests• Temperate deciduous forests• grasslands

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T dTundra

Characteristics of the Tundra:The northern most biome in CanadaIt has low precipitation between 10It has low precipitation between 10-12 cm per yearRelatively few organisms given the large area of the biomeLow temperature, which leads to a short growing systemMain vegetation consists of grasses and shrubsand shrubsActive layer – this is the top most layer that thaws each year providing nutrients to plantsP f t thi l f il (b lPermafrost – this layer of soil (below active layer) never thaws

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B l F tBoreal Forest

Characteristics of the boreal forest:

This biome is just south of the tundraMain type of vegetation isMain type of vegetation is conifersHas a harsh climate with rapid temperature changesrapid temperature changesIt has a longer growing season than the tundraAcidic soil which limits the types of plants that grow

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TemperateTemperate Deciduous Forest

Characteristics of the temperate deciduous forest:p

Dominated by oak and maple treesHas mainly moderate temperatures with less snow fall than the Borealsnow fall than the Boreal forest biomeContains a wide variety of

l t d i lplants and animals

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G l dGrassland

Characteristics of the grassland biome:g

Dominated by grasses (prairies)Has little rainfall per year (25 – 75 cm)WindyWindyFertile soil ideal for growing wheat, etc

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Harvesting theHarvesting the Forests

The forests provide a valuable resource that if managed properly could provide employment for many people.y p pForest harvesting can be done in two ways:

Cl ttiClear cutting:• Removal of all trees in an

areaSelective cutting:

• Only certain trees are harvested

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Impact on ClearImpact on Clear Cutting

After an area has been clear cut if reforestation occurs it is generally with one speciesgenerally with one species (monoculture)Clear cutting increases soil erosion because root systemserosion because root systems are destroyed and there is nothing left to hold back the soilErosion leads to increasedErosion leads to increased nutrients (such as nitrates) washing into rivers and ponds. This leads to:This leads to:

More algae growthMore fish die

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Impact of SelectiveImpact of Selective Cutting

This is a better way of harvesting the forests gbecause only the largest trees are removedThis provides room for smaller trees to matureThere is less runoff andThere is less runoff and therefore less damage to the environment in generalg

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