Download Plants are - Yarra Hills Secondary College

...THE BIOSPHERE...
Sub-topic 1
Investigating an Ecosystem
Ecosystem
POND
WOODLAND
SOIL
Made up of living and non living parts
Biotic
Food availability
Predation
MOOR
Abiotic
Temperature
Light intensity
Moisture
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
Pitfall
Trap
Alcohol (if you
The samples
Killed)
More
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
15
20
23
25
25
25
grass
6
8
8
10
Daisies
0
0
0
0
5
Sorrel
20
15
15
10
10
11
5
16
0
19
22
22
0
0
0
Tullgren
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.
Ecosystems
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

Population - a group of organisms of the same
habitat.
species.
Habitats
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
All energy initially comes from the sun as light energy
Plants trap energy Plant biomass
converting it to eaten by animals
biomass.
Primary
Producers
Consumers
Larger animals eat
animals that eat plants
Secondary
Consumers
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.
Trophic levels
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.
5000 Dandelions
1000 Pea Pods
100 Rabbits
100 Slugs
10 Frogs
1 Fox
1 Bird
•Why do the numbers drop as
you go up the trophic levels?
•Draw the pyramid of numbers
for these food chains.
Pyramids of Numbers examples
1 Bird
1 Fox
10 Frogs
100 Rabbits
100 Slugs
5000 Dandelions
1000 Pea Pods
Pyramid of Numbers
5000 Dandelions
1 Pear
Tree
100 Rabbits
3000
Greenfly
1 Fox
500 Fleas
1000
Ladybirds
1
Partridge
Now draw the pyramids
of numbers for these
food chains.
Pyramids of Numbers examples 2
500 Fleas
1 Fox
100 Rabbits
5000 Dandelions
1 Partridge
1000 Ladybirds
3000 Greenfly
1 Tree
Pyramid of Biomass
Biomass is how much dry mass is present in
each trophic level. For this reason Biomass
Pyramids always look the same.
Energy flow
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?
The Sun
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
Sun
Producer
98% energy lost
90% energy lost
Primary consumer
90% energy lost
Secondary consumer
90% energy
lost
Tertiary consumer
Energy flow through
Producers
Most of the sunlight that
falls on leaves is not
absorbed and used
What happens?
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
Respiration
primary
consumers
Producer
decomposers
energy input
SUN
Only 10% of the stored energy in the deer is
transferred to the lion
What
happens to
the other
90%?
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?
kJ/m²/yr
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:
–movement
–life processes
–HEAT
–Excretory products
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
producers
Most food chains start
with
what is eaten by what
Plants are
predators
Animals are
prey
Animals that hunt and
eat others are called
consumers
Animals that are caught and eaten are
a green plant
called
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.
A population is a group of
organisms of the same species
living in the same place at the
same time
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
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



Random
Clumped
Regular
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
Generation
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
# of bacteria
1
2
4
8
16
32
64
128
256
512
1024
2048
4096
8192
16,384
32,768
65,536
131,072
262,144
524,288
1,048,576
time
0
15min
30min
45min
1hr
75min
90min
105min
2hrs
3hrs
4hrs
5hrs
But can a population continue to grow at this rate? NO
Limiting factors will control population growth
•Food shortages
•Lack of space
•Accumulation of own waste products
•Lack of other resources like oxygen, living space etc.
Population Growth
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)
For example...
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
Population Mortality
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)
Density-Dependent




Predation
Increased
competition for
scarce resources
Sickness
Others?...
Density-Independent

Weather





Ice Age
Global Warming
Flood
El Nino
Etc.
Range of tolerance of environmental conditions is an
important factor:
temperature, light, salinity, nutrients, water etc
COMPETITION…
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
Lightning
Nitrogen in the air
Eating
waste
Formatio
Decomposing
n of
oxides of
nitrogen NH3 and its
N2
fixing
bacteria
compounds
Nitrifying
Fertilisers
bacteria
Nitrates in the soil
Nitrates absorbed by
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..
DOMESTIC
AGRICULTURAL
INDUSTRIAL
LOOK AT THE FOLLOWING EXAMPLES OF EACH…
DOMESTIC POLLUTION
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
Agricultural pollution..
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
Industrial pollution…
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
FOSSIL FUELS…
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.
…On pollution
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
Nuclear power…
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..
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 microorganisms 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
Indicator 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…
Fresh-water species…
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
Invertebrates are more easily caught and therefore more commonly
Used as indicator species
These and some others are shown on the following slide…
The oxygen decline and rise downstream from a point
source is called the oxygen sag.
Lichens…
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 windblown sand covers other healthy vegetation.
Manipulating ecosystems..
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…