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F215-Module 3-Ecosystems and Sustainability

5.3.1 Ecosystems

a. Define the term ecosystems

Ecosystems-All of the living organisms and no-living components in a specific
habitat and their interactions.

b. State that ecosystems are dynamic systems

They are dynamic systems because the population rises and falls due to the
interactions of living organisms…

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o The rate of energy flow passing through each trophic level.
o Gross primary productivity-The rate at which plants convert light energy
into chemical energy.
o Net primary productivity-The energy available to the primary consumer.
It is gross primary productivity-the energy lost when the plant respires.

g. Discuss the efficiency…

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o When the plants die and decay, nutrients accumulate in the sand making
the conditions more favourable.
o Plants like sea sandwort and sea couch grass colonise it. The sea couch
grass has long roots which help to stabilise the sand.
o More nutrients are added so plants like sea…

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Nitrogen fixing
Can occur via lightening or the Haber process.
Mostly happens using nitrogen fixing bacteria e.g. Rhizobium.
They are in root nodules of legumes or free in the soil.
Mutualistic relationship with the plants by providing fixed
nitrogen and getting carbon compounds.
In anaerobic conditions nitrogen reductase reduces nitrogen…

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4. Because of there being less predators, less prey is eaten so they prey's
population increases.

5. Because there is more prey the predator population increases.

d. Explain the terms interspecific and intraspecific competition

Interspecific competition

o Competition between individuals of different species.

o Affects both the population size of…

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o Protecting areas of land as yet unused by humans.

f. Explain how the management of an ecosystem can provide resources in a sustainable
way, with reference to timber production

Small scale production

o Coppicing-Cutting the tree close to the ground and new shoots will grow
from them.


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Natural New drugs to cure of financial value to
environments are a diseases may be humans.
valuable source of found.
potentially Every living thing
beneficial Tourism. has a right to
resources. survive.

Wild insect species Humans have an
are needed for ethical
pollination. responsibility to
looks after species.
Reduction in…

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Introduced species

o E.g. goats which out compete the giant tortoise and they trample the

o They destroy the natural environment.

o They outcompete local species.

o They can carry disease which other species may be vulnerable to.


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