Ecology

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Objectives

1. To study new vocabulary associated with ecology i.e. ecology, biosphere, ecosystem, habitat, population, community

2. To outline the types of ecosystem available e.g. desert, rainforest, marine, grassland

3. To study one ecosystem in detail

4. To examine environmental factors that affect organisms

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ObjectivesName the sun as the primary source of energy.

Name feeding as the pathway of energy flow.

Present a grazing food chain.

Present a food web.

Construct a pyramid of numbers.

Investigate how the Carbon cycle and the Nitrogen cycle operate

Examine the human impact on an ecosystem

Study how pollution occurs

Define conservation and examine one conservation practice

Study waste management in agriculture, fisheries and forestry

Investigate how waste production can be controlled.

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Some Ecology Definitions

Ecology is the study of interactions between living things and their environment.

Biosphere is the part of the planet containing living things.

Ecosystem a group of organisms that interact with their environment together.

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Habitat the place an animal or plant lives.

Population members of the same species living in an area.

Community all the different populations (species) in an area.

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Environmental FactorsBiotic factors living factors.Examples Food, competition,etc.

Abiotic factors non-living factors.Examples Altitude, Aspect

Climatic factors weather over a long time.Examples Temperature, rainfall

Edaphic Factors Factors to do with soil.Examples pH, water content

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What is an ecosystem?

A community of living organisms interacting with one another and their non-living environment within a particular area, e.g. woodland, etc.

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Energy Flow

Ecosystems are unable to function unless there is a constant input of energy from an external source.

Where does this energy come from?

The Sun

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Energy Flow

This is the pathway of energy transfer from one organism to the next in an ecosystem due to feeding, e.g. along a food chain

Feeding allows energy to flow from one organism to another in an ecosystem.

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Energy Flow

Plants catch the energy and change it into sugars.The plants are then eaten by consumers.These consumers get around 10% of the energy from the plant.If these consumers are eaten they pass on about 10% of their energy.Food chains can only be a certain length as the energy eventually runs out.

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Energy flow in the ecosystem

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Food Chain

Is a flow diagram that begins with a plant and shows how food/energy is passed through a series of organisms in a community.

Each organism feeds on the one before it.

A food chain ends when there is not enough energy to support another organism.

An example of a food chain: grass rabbit fox.

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Learning check

What is meant by primary source?

Main source

What is the primary source of energy?

The sun

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Grazing food chain

A grazing food chain is one where the initial plant is living e.g.

Grass grasshoppers frogs hawks

Honeysuckle aphids ladybirds thrushes

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A Detritus food chain

A detritus food chain is one where the chain begins with dead organic matter and animal waste (detritus) e.g.

Fallen leaves earthworms blackbirds hawks

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Detritus Food Chain

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Food Web

A food web shows all the feeding connections in the habitat/ecosystem.

Constructed by showing the links between all the interconnecting food chains in the habitat.

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Food Web

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a) Name a producer?b) Name a primary consumer?c) Name a secondary consumer?

Food Web

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Learning check

Draw a woodland food web constructed using at least two food chains.

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A woodland food web

Construct a two food chains (4 ‘links’) from the above food web

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Another food web

What is the longest food chain you can construct from this food web?

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Learning check

What is meant by a Grazing food chain?

• is a food chain where the initial plant is living

Give an example1. Grass grasshoppers frogs hawks

2. Honeysuckle aphids ladybirds thrushes

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Producers

Producers are organisms capable of making their own food by photosynthesis, e.g. green plants.

Primary producers are the first members of a food chain

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Consumers

Consumers are organisms that feed on other organisms. They cannot make their own food. There are three types:

• Primary consumers – feed on producers

• Secondary consumers – feed on primary consumers

• Tertiary consumers – feed on secondary consumers

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Woodland food chain

Honeysuckle aphids ladybirds thrushes

Primary consumer

Secondary consumer

Tertiary consumer

Producer

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Learning check

Construct a simple food web

Two food chains e.g.

Plant caterpillar thrush fox

Plant earthworm blackbird fox

Combine them to form a food web

dandlionCaterpillar

Earthworm

Thrush

Blackbird Fox

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Trophic Level

Trophic Level refers to the position of an organism in a food chain.

Plants are at the 1st trophic level (T1) and

Herbivores occupy the 2nd trophic level (T2).

Carnivores that eat herbivores are at the 3rd trophic level (T3).

The 4th trophic level (T4) is often occupied by the top carnivore.

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Trophic levels

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Pyramid of Numbers

Inverted Pyramid of Numbers

This is where the number of organisms actually increases.

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Learning checkExplain the following terms:• Producer • organism capable of making its own food by photosynthesis

• Consumer • organism that feeds on other organisms – cannot make their own food

• Primary Consumer • organism that feeds on producers

• Secondary Consumer • organism that feeds on primary consumers

• Tertiary Consumer • organism that feeds on secondary consumers

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Learning check

What is meant by trophic level?This refers to the position of an organism in a

food chain.

T1 = 1st trophic level = Plants

T2 = 2nd trophic level = Herbivores

T3 = 3rd trophic level = Carnivores

T4 = 4th trophic level = (T4) Top Carnivore.

Ecological Niche

Ecological niche   is the role an organism plays in the community.

Two organisms with the same niche must compete 

with each other.

e.g. magpies eat from gutters. Swallows eat in flight and thrushes eat at ground level.

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Nutrient RecyclingCarbon is recycled in nature. This is the Carbon Cycle.

Plants take in carbon dioxide and make wood. When they die

they release the carbon dioxide.

Animals are made of carbon.

We get carbon from eating plants and other animals.

Micro organisms, like fungi and bacteria return carbon dioxide

to the air by decomposing dead plants and animals.

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Carbon Cycle

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Three groups of organisms have roles in the carbon cycle

1.Plants remove carbon dioxide from environment through photosynthesis and return it by respiration

2.Animals obtain carbon by eating plants and return it to the air as carbon dioxide in respiration

3.Micro-organisms return carbon to the air as a result of breakdown of animals and plants

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Nitrogen Cycle

Nitrogen is the most abundant gas in air. It takes up 79% of the atmosphere.

The Nitrogen is taken out of the air by Nitrogen fixing bacteria.

The bacteria live on the roots of plants.

They get food from the plants and they give 

the plants  Nitrates. Without these bacteria 

no plants would grow.

This relationship is called symbiotic as 

both organisms benefit.

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Definitions

Nitrogen Fixation is the conversion of nitrogen gas into ammonia (NH3), ammonium (NH4+) or nitrate (NO3-)

Nitrification is the conversion of ammonia and ammonium (NH4+) compounds to nitrite and then to nitrate.

Denitrification is the conversion of nitrates to nitrogen gas.

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Nitrogen Fixing Bacteria

Nitrogen fixing bacteria can be found free in the soil or maybe associated with the roots of certain plants e.g. Legumes. Legumes include clover, soya bean and peas.

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Global WarmingSince the 1970's Scientists have realised that the world's carbon dioxide %

has been increasing.

CO2  is produced mostly from burning fossil fuels. In the atmosphere carbon dioxide traps heat and warms up the planet. That's why it is called global warming. 

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Effects of Global Warming:

1.Warming oceans store the heat and ocean currents change.

2. When the currents heat and change they also 

Change the wind and rain patterns.

This causes floods and droughts, stronger 

hurricanes and storms in different places.

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PollutionPollution is any harmful addition to the environment.

Pollutants are substances that cause pollution.

Types of pollution

1. Domestic pollution   from houses

2. Agricultural pollution   sprays, slurry on fields 

and in rivers

3. Industrial pollution   smoke 

and fumes, acid rain 

Etc

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Ozone Ozone depletion is an example of  air pollution.

Ozone (O3) is a gas that absorbs harmful 

ultraviolet (UV) light.

A hole was first noticed in 1984 over 

Antarctica.

There is also a hole at the Arctic, Australia and sometimes over Europe.

Ozone loss is caused by, CFCs (ChloroFluroCarbons) in aerosols, 

freon gas in fridges and others

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A decrease in Ozone causes skin cancers, damage to crops, damage to animals and plankton reduction  which affects birds, fish, whales and oxygen levels.

Control of Ozone loss CFCs are now banned and 

fridges are recycled carefully and not just dumped.

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ConservationConservation is the wise management of our 

existing natural resources.  

We use natural resources everyday and in some cases we exploit these natural resources.

e.g. over fishing from the sea and growing plant species where they would not normally grow.

The responsibility lies with individuals and big organisations to exercise control to prevent damage to habitats e.g. rainforests.

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ExtinctionThe present rate of extinction is higher than at any

time in the earths history. We have a duty to future generations to pass on the natural environment we have inherited.

Endangered species in Ireland:

Mammals

Badger, All Bat species, All Deer species

Hare species, Hedgehog, Otter

Pine Marten, Red Squirrel, Dolphin species

Porpoise species, Seal species, Whale species

Pygmy Shrew,Stoat

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AmphibiansNatterjack ToadCommon FrogCommon NewtReptilesCommon LizardLeatherback turtleInvertebratesFreshwater crayfishFreshwater pearl musselKerry slug

Benefits of Conservation

1. Prevents organisms from becoming extinct.

2. Maintains the balance of nature

3. Maintains a wide range of living things.

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Examples of conservation• National parks

• Hedgerow and bogland conservation

• Listing of threatened species e.g. lizard, frog and stoat in Ireland

• Zoos and wildlife parks – by breeding endangered species

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You are required to study the effects and control of any one pollutant for Leaving Cert. from either fisheries, agriculture or forestry.

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Conservation Practice from Fisheries

a)Pollution of rivers, lakes and sea that kill fish – once depleted fish stocks take a long time to replace

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b) Over fishing has reduced (and in some cases wiped out) fish stocks at sea. For this reason fish quotas (weight of each species of fish) have been imposed in many countries to try and ensure that enough fish are left in the sea to replenish stocks.

c) Use of small mesh nets can result in too many young fish being caught which will reduce fish stocks.

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Examples of conservation in fishing:

1.Size of mesh in nets is very important so only larger older fish are caught

2.Removal of pollution is very important so fish stocks are maintained.

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Waste Management

Modern living produces large amounts of waste e.g. household rubbish.

Important to manage this waste to prevent pollution and conserve environment.

Lets look at waste management in:

a)Agriculture

b)Fisheries

c)Forestry

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a. Agriculture

Slurry (liquidified waste from farm animals) often pollutes lakes and rivers. Slurry contains high levels of minerals e.g. phosphorus and nitrogen. These minerals cause increased growth of algae in rivers and lakes causing algal blooms.

When algae die they are decomposed by bacteria and the bacteria use

up the oxygen in the water causing

fish to die.

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Addition of nutrients to fresh water is called eutrophication.

We can reduced the amount of slurry getting into fresh water by:

1.Storing slurry in leak proof pits

2.Spreading slurry on dry land in summer rather than on rainy days.

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2. Fisheries

When fish are processed waste materials e.g. heads, tails, blood etc. are neutralised by adding formic acid and then pulped, dried and recycled as fertilisers or pig feed.

3. Forestry

Waste materials include sawdust, small branches etc. Small branches can be spread on the forest floor to help machinery move more easily. These branches decay and add nutrient back into the soil.

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Problems associated with waste disposal

1.Toxic chemicals released from wastes can contaminate water.

2.Waste disposed of in landfill sites can be unsightly and attract rats.

Role of micro-organisms in waste management and pollution control

1. Landfill sites: Bacteria and fungi breakdown the organic waste.

2. Sewage: a) Primary sewage treatment involves physically screening waste and allowing it to settle. This removes large objects and solids.

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b) Secondary treatment:Occurs when waste is broken down by bacteria and fungi. The waste is aerated to allow breakdown to occur. Secondary Treatment breaks down most of the organic matter.

c) Tertiary treatment: Sometimes used to remove minerals e.g. phosphate and nitrates.

Control of Waste Production

“Reduce Reuse Recycle”

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Reduce – Reduce your waste production by reducing your consumption of products you don’t really need.

Reuse – Some things can be reused e.g. glass bottles can be re-used up to 40 times.

Recycle – Many items can be recycled e.g. paper and plastic.

Up to 40% of household waste is organic material that can be broken down by bacteria and earthworms to form compost. This compost can be added to soil to help plants grow.

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2012 Paper > Section A > Question 4

Solutions

2012 Paper > Section C > Question 11