Ecosystem Made up of living and non living parts POND WOODLAND SOIL MOOR Abiotic Food availability Predation Temperature Light intensity Moisture Biotic
Quadrat Estimates the abundance of non moving organisms Throw randomly Count the number of squares an organism is found in Errors ? Non random throwing Counting the same organism over two squares Too few quadrats done
LMM Can measure both light intensity and moisture content of a particular area Errors ? Shadow Read wrong scale Stone Too few readings
Pitfall Trap Alcohol (if you The samples Killed) Pitfall Trap
Results Quadrat 1 2 3 4 5 6 7 8 9 10 Light Intensity A B C D E F G H H H Soil moisture 3 2 3 1 4 3 2 3 4 3 grass 6 8 8 10 15 20 23 25 25 25 Daisies 0 0 0 0 5 11 16 19 22 22 Sorrel 20 15 15 10 10 5 0 0 0 0
Sub-topic 2… How it works…. 3
What is an ecosystem?
An ecosystem is all the animals and the plants in a habitat, together with their environment.
An ecosystem provides everything that the animals and plants that live there need.
A rock pool is an ecosystem, and so is a forest or a lake.
Made up of a number of different habitats sharing the same environment. E.g. a desert.
Habitat - a place where living things live. E.g. a pond.
Community - a group of populations living in a habitat.
Population - a group of organisms of the same species.
What is a habitat ?
A habitat is the place where living things live.
It is more than just a home it includes the whole surrounding area.
The habitat provides the animal or plant with food or shelter .
People and their habitats
People can live all over the world.
We can do this because we are able to build homes for different conditions.
Also we can change our clothes to best suit the temperature around us. White clothes reflect the heat Animal skin and fur act as insulators and keep heat in.
Animals and plants
Most plants and animals are specially adapted to survive in a particular habitat.
They have developed special features to suit the demands of their environment.
This is called adaption .
Energy Flow in a Habitat Plants trap energy converting it to biomass. Producers Plant biomass eaten by animals Primary Consumers Larger animals eat animals that eat plants Secondary Consumers All energy initially comes from the sun as light energy
Terminology to Learn
Herbivore - animals that eat only plants.
Carnivore - animals that eat only animals.
Omnivore - animals that eat plants and animals.
Top Carnivore - animals not eaten by anything else.
Decomposer - organisms that live on dead material.
Trophic Levels - each step along a food chain.
What people do
Sometimes, humans cause problems for the plants and animals in an ecosystem.
Oil spills pollute the sea and beaches.
Forests are cut down to make way for roads, and so that land is available for cattle to graze.
What does this food chain show?
The plant is eaten by the slug.
The slug is eaten by the frog.
The frog is eaten by the heron.
Food Web Write out four food chains found in the food web .
How do Organisms Interact?
What happens to the locust population if
the slugs die out?
What happens to the plant population?
Pyramid of Numbers This is another way of showing a food chain.
Why do the numbers drop as
you go up the trophic levels?
Draw the pyramid of numbers
for these food chains.
5000 Dandelions 100 Rabbits 1 Fox 1000 Pea Pods 100 Slugs 10 Frogs 1 Bird
Pyramids of Numbers - examples 5000 Dandelions 100 Rabbits 1000 Pea Pods 100 Slugs 10 Frogs 1 Fox 1 Bird
Pyramid of Numbers 1 Partridge Now draw the pyramids of numbers for these food chains. 1 Pear Tree 3000 Greenfly 1000 Ladybirds 5000 Dandelions 100 Rabbits 1 Fox 500 Fleas
Pyramids of Numbers - examples 2 5000 Dandelions 100 Rabbits 3000 Greenfly 1000 Ladybirds 500 Fleas 1 Tree 1 Partridge 1 Fox
Pyramid of Biomass Biomass is how much dry mass is present in each trophic level. For this reason Biomass Pyramids always look the same .
Each animal in the food chain eats another animal or a plant in order to gain energy.
The energy flow in the ecosystem keeps all of the animals alive.
Pyramid of Energy transfer
Where does the energy come from?
In every ecosystem, Energy is trapped and stored by the plants (primary producers).
Some energy is always lost in the transfer of energy between trophic levels
Ecologists have calculated 10% of energy available in a trophic level is taken up by the level above
Energy flow in a food chain
98% energy lost
90% energy lost
90% energy lost
90% energy lost
Energy flow through Producers
Most of the sunlight that falls on leaves is not absorbed and used
Some is reflected from the leaf’s surface
Some passes straight through the leaf
Only part of the light is useful and can be absorbed by chlorophyll
The overall efficiency of energy transfer during photosynthesis is less than 10%
So only about 8% of sunlight energy reaching the plant is transferred into useful chemical energy.
What is this chemical energy used for?
For respiration and growth
When the plant grows, its biomass will increase. This will provide food energy for herbivores.
It may be transferred between trophic levels from producers to primary consumers.
Some food energy may be transferred to decomposers.
When leaves are shed, fruit and seeds are dispersed and when the plant itself dies.
Decomposers eat the dead plant tissues to get energy.
Energy flow through a green plant
Released in primary
What happens to the other 90%?
Only 10% of the stored energy in the deer is transferred to the lion
Write down what happens to the missing 90% of the energy in a deer ( Kudu) that is not transferred to the lion.
What are the units?
Unit of energy/ area/time
(kilo Joules per metre squared per year.)
Important to remember that pyramids of energy transfer are NEVER inverted.
The reasons for the inefficiency of this energy transfer are:-
Some plant material passes out of the body of the herbivore as faeces without being digested.
A lot of energy is used in respiration.
Some energy passes to decomposers in dead remains.
Carnivores are able to achieve 20% efficiency. Why?
20% of the herbivores biomass ends up as the carnivores biomass.
This is possible because proteins are more efficiently digested than are carbohydrates.
Energy Flow in a food chain
Some people eat kudu.
What is the food chain?
Grass Kudu human
Of the 1000 000kJ of Energy which falls on one square metre of grass in a year only 100kJ available for humans.
Where does all the energy go?
Plants convert a small % of light energy into glucose (biomass)’
The energy works its way through the food chain,
but trophic level 2 only takes 10% of total energy of trophic level 1
The 90% of energy lost is used in staying alive:
This explains why pyramids of biomass get smaller as they go up and why food chains are rarely more than 4 links long .
Match the words and phrases. A food chain shows Most food chains start with Plants are Animals are Animals that hunt and eat others are called Animals that are caught and eaten are called producers consumers predators prey a green plant what is eaten by what
A population is a group of organisms of the same species living in the same place at the same time
Millions of different populations all evolving according to their own self interest in a particular environment.
But each population is a part of the environment of its neighbors, so any evolutionary change has a ripple effect .
Properties of populations
Birth rate; count number of live births in a given period.
Death rate; count number of deaths in a given time period.
Growth rate; balance between birth/death rate. For population to grow, birth rate must exceed death rate.
Age structure, Density,and dispersion are also factors
A population is a group of organisms of the same species living in the same place at the same time
Population Density and Dispersion
Population density is simply the number of individuals measured per unit of area or volume
Additionally, the population can clump in different ways
Population Growth The growth rate of a population is the increase in the number of individuals over time. Exponential growth is when the number of individuals grows at a constant rate. Growing bacteria in a lab is a good example
But can a population continue to grow at this rate? NO
Limiting factors will control population growth
Lack of space
Accumulation of own waste products
Lack of other resources like oxygen, living space etc.
Since each organism of a population is governed by the selfish gene, populations tend to grow.
If unlimited resources are present, growth will be exponential
It will proceed very quickly for rapidly reproducing organisms and more slowly for slowly reproducing ones
The curve, however, will always be a “J” curve or an exponential growth curve
Population Growth 2
Resources are never unlimited, though.
As population rises, resources decline.
If the growth is too rapid, resources are rapidly depleted and a population crash can occur
This pattern occurs often with many populations (including humans)
Gypsy moth caterpillar
Population Growth 3
More often what happens is that the resources slowly decrease, the growth rate slowly decreases, and they meet.
This point that they oscillate around is the carrying capacity of the environment for that particular organism
So when would you “harvest” these individuals? (1,2,3,4,or 5)
S - shaped curve
Organisms differ on strategies of reproduction and differ on types of predation
Those organisms that put much care into their few young tend to have good survivorship of young
Those organisms that spread their young all over tend to have poor survivorship of their young
A graphic representation of the rates of survival at different ages is called a survivorship curve
Growth Rate Limiting Factors (affecting birth or mortality rates)
Increased competition for scarce resources
Range of tolerance of environmental conditions is an important factor: temperature, light, salinity, nutrients, water etc
Competition is the STRUGGLE FOR RESOURCES WHICH ARE IN SHORT SUPPLY
PLANTS compete for Light,Nutrients and Water
ANIMALS compete for Food, Territorities,Shelter, and Water
EACH SPECIES AFFECTS THE DISTRIBUTION OF OTHERS..
Where do decomposers come in?
When living things die their bodies are broken down by decomposers so releasing the elements they contain.
These minerals can be used by plants to grow so the cycle repeats over again
An example of Fungi You know
The Nitrogen Cycle Nitrogen in the air Denitrifying bacteria Eating Nitrates in the soil N 2 fixing bacteria waste NH 3 and its compounds Nitrates absorbed by roots N 2 fixing bacteria Decomposing Fertilisers Nitrifying bacteria Lightning Formation of oxides of nitrogen
Sub-Topic 3… Control and management
Sources of pollution.
Pollution affects the entire environment around us. AIR, LAND, SEA, and FRESH WATER…
The main sources of pollution are..
LOOK AT THE FOLLOWING EXAMPLES OF EACH…
Car exhaust fumes contain harmful gases and lead which pollute the air.
Domestic rubbish pollutes the land. Poisons can seep into the soil from landfill sites. Litter on our streets !!
Raw sewage (e.g. Faeces) can pollute the sea and fresh water
Excess fertiliser and pesticides can pollute the water supply. Animal waste can do this as well…
This kills the flora and fauna in fresh water and..
Leads to the rapid growth of bacteria which reduces the oxygen content of the water
Inorganic waste such as Mercury and lead pollute the land, sea, and rivers.
Organic waste such as paper fibres and food pollute the land, sea, and rivers.
Oil tankers washing out tanks
pollute the sea and great lakes
Burning Coal, Oil, and Gas produces poisonous gases (such as Sulphur dioxide and Nitrogen Oxide).
These pollute the atmosphere.
They may even be converted into ACID RAIN
This can only be prevented by scrubbing the fumes before they are released to get rid of the Sulphur dioxide. This involves the use of LIMESTONE slurry.
Lime can also be added to the water and land polluted by acid rain. The lime neutralises the acid.
Pollutants may REDUCE the biodiversity in an ecosystem
Eg fossil fuels produce Sulphur Dioxide when burned
This can cause ACID RAIN
This can lower the pH in Lochs killing some INVERTEBRATES And FISH
Used to generate electricity as an alternative to fossil fuels.
The waste produced is very dangerous.
It remains radioactive for many hundreds of years.
Accidents can occur which will release radioactivity into the environment. This can travel for many hundreds of miles (Chernobyl !!).
This causes diseases such as cancers, and genetic mutations in future generations.
The waste must be sealed in lead containers
and dumped on the ocean bed in remote areas
or buried deep underground
Organic waste is the unwanted products of living things .
Raw (untreated) sewage, dead leaves, and stale food are examples.
It is a perfect food for micro-organisms that bring about decay (decomposers).
Bacteria and Fungi are the main micro-organisms which do this job.
In this country, Raw sewage is broken down into harmless Substances by these micro-organisms. This is an example Of a Biological treatment
Pollution and Biodiversity…
If untreated sewage or fertiliser enters a river or lake it provides food for BACTERIA.
Their population numbers increase
They use up all the oxygen in the water
Species which cannot tolerate low Oxygen levels die out
THIS RESULTS IN A DECREASE IN THE VARIETY OF SPECIES
Some species of living organisms can only survive under specific environmental conditions.
These are sometimes useful in identifying certain conditions present in the environment, such as oxygen levels, or poisonous gases.
These species are known as indicator species.
Freshwater and land-based indicator species are important in Monitoring pollution levels in the environment…
Some species can tolerate high levels of pollution and very low oxygen levels e.g.. Sludge worms and Rat-tailed Maggots.
Others are less tolerant of pollution but can survive with little oxygen, e.g. Bloodworms and Water lice.
Others need plenty of Oxygen and little or no pollution, e.g. Mayfly and Stonefly Nymphs, and most Fish
These and some others are shown on the following slide… Invertebrates are more easily caught and therefore more commonly Used as indicator species
Oxygen Sag The oxygen decline and rise downstream from a point source is called the oxygen sag.
Lichens are organisms that are sensitive to industrial pollution.
Different species have differing levels of tolerance to Sulphur Dioxide.
They can be used to assess the levels of pollution in an area.
They are also sensitive to Acid Rain…
Look at some examples of Lichens on the following slide…
Management of natural resources…
Our continued existence on Earth depends upon how well we manage the planet’s natural resources.
These include the air, water, plants and animals, and the soil on the land.
The land is one of the most important natural resources.
The land has to managed well or problems will result…
When the management goes wrong…
Over-use of fertiliser and pesticides (soil structure breaks down)
Using large quantities of grain to feed animals (Peoples' diet has too much animal protein)
Cash-crops (e.g. Coffee) grown rather than food crops
Grazing and Biodiversity…
Grassland is made up of a variety of plants
Some species grow quickly and dominate
Some species don’t grow as quickly and struggle to compete and survive
GRAZING is the eating of plants by herbivores.
Cattle are the main source of wealth in poor developing countries.
UNSELECTIVE GRAZERS EAT ALL TYPES OF PLANT
Intensity of Grazing…
LOW levels of unselective grazing allows the grasses to grow and out compete other less vigorous species.This REDUCES the variety of species
MEDIUM levels keep the grasses in check allowing less vigorous species to survive.This INCREASES the variety of species
HIGH levels result in OVERGRAZING.This DECREASES the variety of species and the soil cannot retain water.
This leads to an increase in desert area as wind-blown sand covers other healthy vegetation.
Farmers can change components of an ecosystem.
This can allow more of a desired species of plant to grow.
The farmer cultivates the land, adds fertilisers, controls soil pH, content of nutrients, and water.
The land is protected by
fences to keep out consumers.
An altered and artificial ecosystem is produced for the benefit of Man…