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© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
6.3 How does a tropical
rainforest ecosystem
function?
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
What is an ecosystem? What are the components of an ecosystem?
Ecosystem
Abiotic
components
Biotic
components
Environment
Plants
Animals
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
What are the biotic components in a
tropical rainforest ecosystem?
Microscopic organisms
Animals
Plants
Biotic
components refer
to living things.
Decomposers
Producers
Consumers They may be
classified into
different trophic
(feeding) categories.
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
What are the biotic components in a
tropical rainforest ecosystem?
1 Producers Producers are green plants. They can produce their own food by ______________. photosynthesis
Carbon
dioxide
Sunlight Chlorophyll
Food
Water
Oxygen
at the presence of
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
What are the biotic components in a
tropical rainforest ecosystem?
2 Consumers
Consumers are animals. They cannot
produce their own food.
Primary consumers:
feed directly on
producers
Secondary
consumers: feed on
primary consumers
Tertiary
consumers: feed
on secondary
consumers
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
What are the biotic components in a
tropical rainforest ecosystem?
2 Consumers
We can classify the
consumers by their
diet.
A crocodile eats animals. It is
a _________. carnivore
A rabbit eats plants only.
It is a _________. herbivore
Humans eat both plants
and animals. They are
__________. omnivores
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
What are the biotic components in a
tropical rainforest ecosystem?
2 Consumers
Producers and consumers make up a food chain.
Rainforest tree
(Producer)
Grasshopper
(Primary consumer)
Lizard
(Secondary consumer)
A food chain usually starts with a producer and ends with a secondary consumer or tertiary consumer.
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
What are the biotic components in a
tropical rainforest ecosystem?
2 Consumers
In a tropical rainforest, individual food chains are interlocked at various levels to form a food web.
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
What are the biotic components in a
tropical rainforest ecosystem?
3 Decomposers
Fungi are an example of decomposers
Decomposers such as fungi and bacteria break down dead plant and animal tissues.
They secrete _________ to break down dead organic materials into inorganic matter. Plants can absorb them easily.
enzymes
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
What are the abiotic components in a
tropical rainforest ecosystem? Abiotic components refer to the non-living things.
They are found in:
Atmosphere
Air
Precipitation
Solar radiation
Hydrosphere
Water at the
earth’s
surface
Underground
water
Lithosphere
Soil
Rocks
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
Can you categorize the
following abiotic
components and state
their importance to
plants and animals?
What are the abiotic components in a
tropical rainforest ecosystem?
Abiotic components
Atmosphere
carbon dioxide
weathered rocks
rivers and lakes
oxygen
ground water
organic materials from soil rainfall solar radiation
carbon dioxide
An input of photosynthesis
of plants.
They provide nutrients to
plants.
rainfall
It provides water for the
photosynthesis of plants.
They provide drinking water
and living habitats for
animals.
oxygen An input of the respiration of
living organisms. solar radiation An input of the
photosynthesis of plants.
It provides moisture in the soil
for the plants. They provide nutrients for plants.
Hydrosphere Lithosphere
weathered rocks rivers and lakes
ground water organic materials from soil
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
How are biotic and abiotic components
linked in a tropical rainforest ecosystem?
Biotic and abiotic components are closely linked by:
Energy flow
Nutrient cycling
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
Why is a tropical rainforest a fragile
ecosystem?
As mentioned before, most nutrients in the tropical rainforest are stored in the biomass. That means a high proportion of the energy and nutrient is stored above ground. This biomass is vulnerable to various disturbances, such as fires or deforestation.
(Credit: K. Wothe/Blickwinkel)
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
Why is a tropical rainforest a fragile
ecosystem?
As the rainforests support the wildlife there, destroying the rainforest will cause the rainforest ecosystem to collapse.
(Credit: Joerg Boethling/Still
Pictures)
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
The biomass stores most of
the nutrients in a rainforest.
Removal of trees caused by a
sudden change in climate or
external agents
Loss of stored nutrients
No supply of nutrients to the soil
created through decomposition
Soil depletion No regrowth of
trees
Collapse of the
ecosystem
Animals die
Why is a tropical rainforest a fragile
ecosystem?
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
Energy flow in a tropical rainforest
ecosystem
Energy flow is the transfer of energy through various living organisms along the food web. There are five trophic levels in a tropical rainforest ecosystem.
Input
of
solar
energy
T1
Producers
T2
Primary
consumers
T3
Secondary
consumers
T4
Tertiary
consumers
T5 Decomposers
The sun is the primary source of energy that maintains the ecosystem. Energy is passed along the food chain or food web.
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
Energy flow in a tropical rainforest
ecosystem
Input
of
solar
energy
T1
Producers
T2
Primary
consumers
T3
Secondary
consumers
T4
Tertiary
consumers
T5 Decomposers
Producers carry out photosynthesis with the input of solar energy.
Net input of
energy at each
tropic level
Energy loss through
transpiration or
respiration
Heat loss
through
respiration
Energy loss
through decay and
decomposition
Some energy is lost during the transpiration, respiration and decomposition.
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
Energy flow in a tropical rainforest
ecosystem
Input
of
solar
energy
T1
Producers
T2
Primary
consumers
T3
Secondary
consumers
T4
Tertiary
consumers
T5 Decomposers
Net input of
energy at each
tropic level
Energy loss through
transpiration or
respiration
Heat loss
through
respiration
Energy loss
through decay and
decomposition
When primary consumers eat the producers as food, energy is transferred to them. Since primary consumers cannot fully digest the producers, the remains of the producers are being processed by decomposers.
Energy not
being used
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
Energy flow in a tropical rainforest
ecosystem
Input
of
solar
energy
T1
Producers
T2
Primary
consumers
T3
Secondary
consumers
T4
Tertiary
consumers
T5 Decomposers
Net input of
energy at each
tropic level
Energy loss through
transpiration or
respiration
Heat loss
through
respiration
Energy loss
through decay and
decomposition
Energy not
being used
The energy flow carries on at different tropic levels.
Energy not
being used
Energy not
being used
The energy flow carries on at different tropic levels. The higher the tropic level (except decomposers), the ( less / more ) the energy remains.
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
Trophic pyramid
A trophic pyramid shows the amount of organic matter of the living organisms in an area.
As the trophic level increases, the amount of organic matter of each tropic level ( decreases / increases ).
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
Nutrient cycle refers to the circulation of nutrients from the environment to organisms and back to the environment.
Environment Organisms
Nutrients are circulated among three stores
Biomass
Litter
Soil
Nutrient cycling in a tropical rainforest
ecosystem
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
Nutrient cycling in a tropical rainforest
ecosystem
A Biomass Biomass refers to the total weight of living organisms, i.e. plants and animals, of an area.
Biomass
Nutrients are stored in plants and animals.
Plants consume nutrients from the soil and sun’s energy to produce their own tissues through photosynthesis.
When animals eat plants, they take up the nutrients and convert plant tissues to their own tissues.
Uptake
by
plants
Soil
Amount of nutrients
transferred
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
Nutrient cycling in a tropical rainforest
ecosystem
B Litter Amount of nutrients
transferred
Biomass Litter
Dead plants tissues, dead animals and animal wastes accumulate on the ground to form a layer of litter.
Littering
The falling rain dissolves minerals, e.g. nitrogen and carbon in the air, and add the nutrients to the litter.
Some of the nutrients may be washed away by run-off.
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
Nutrient cycling in a tropical rainforest
ecosystem
C Soil Amount of nutrients
transferred
Litter Soil
When litter is decomposed, the nutrients are broken down into inorganic form and stored in the soil.
Nutrients decomposed
from litter
Weathering of rocks contributes nutrients to the soil.
Input from weathered rock
Nutrients of soil may lose through leaching.
© Oxford University Press 2009 Quit
Part 6 Disappearing green canopy―Who should pay for the massive deforestation in rainforest regions?
Nutrient cycling in a tropical rainforest
ecosystem
Biomass
Soil
Litter Litter is quickly decomposed
Heavy rain causes strong
leaching
Quick uptake by plants
Most nutrients are stored in
the dense vegetation
Much input from rainfall
In tropical rainforests, the nutrient store of biomass is huge, but the stores in soil and litter are small.
Amount of nutrients
transferred