ECOSYSTEMS
Ecosystem a natural system made up of Freshwater pond ecosystem:
plants, animals and the environment Plants like reeds grow in the water
- There are often complex around the edge of the pond
interrelationships between the living On the banks grow grasses, bushes and
and non-living components of an trees
ecosystem At the edges of the pond, the water is
Biotic living features of an ecosystem e.g. shallow and there will be plants like
plants water lilies
Abiotic non-living environmental factors e.g. At the centre the water is deeper and
climate (temperature and rainfall) there will be fish
Ecosystems can be at different scales: On the surface are ducks and small
- Local small-scale ecosystem (pond, insects such as water boatman
hedgerow or woodland)
- Global-scale ecosystem (tropical
rainforest, deciduous woodland). These
are called biomes.
Key terms:
Producers – convert energy from the environment into sugars
E.g. plants that convert energy from the Sun by photosynthesis
Consumers – get energy from the sugars produced by the producers
E.g. pond snail eats plants
Decomposers – break down plant and animal material and return the nutrients to the soil
E.g. bacteria and fungi
Food chain – shows the direct links between producers and consumers in the form of a simple line
Food web – shows all the connections between producers and consumers in a more complex way
Nutrient cycling – when plants or animals die, decomposers help the recycle the nutrients making
them available once again for the growth of plants or animals
How does change affect an ecosystem? Changes due to human activities
- Global-scale changes, such as climate Agricultural fertilisers can lead to
change eutrophication: nitrates increase
- Local-scale changes, such as changes to growth of algae, which will deplete
a habitat – e.g. when a hedge is oxygen and fish may die
removed Ponds may be drained to use for faming
Natural Changes Woods cut down, destroying habitats
Rapid changes can have serious impacts for birds and affecting the nutrient
Extreme weather e.g. drought can cycle
devastate ponds and lakes – they could Hedgerows removed to increase size of
dry up in places, which changes the fields – habitats destroyed, affecting
edge-of-pond environment the plant/animal balance
Plants will dry out and die, fish, starved Many farmers are trying to keep ecosystems in
of oxygen, might not survive balance by using less fertiliser. Some have
planted hedgerows to protect wildlife.
What if a pond owner added some perch, a predator, to an ecosystem? (example)
This will reduce the With fewer frogs, there
The perch will eat more
amount of food for will be an increase of
of the smaller fish and
creatures further up the creature below frogs in
small animals e.g. frogs
food chain, e.g. herons the food chain, e.g. slugs
, GLOBAL ECOSYSTEMS
Distribution:
- Defined by the dominant type of vegetation that grows in the region
Global ecosystems form broad belts across the world from west to east. Variations in these west-
to-east belts of vegetation are due to factors such as:
Ocean currents
Winds
Distribution of land and sea
Characteristics of global ecosystems:
Tropical rainforest – close to the equator
High temperatures and heavy rainfall associated with equatorial low pressure belt
Cover 6% of the Earth’s land surface
More than half of the world’s species of plants and animals live in this ecosystem
Desert – roughly 30° north and south of the equator
Cover 1/5 of the world’s land surface
Associated with sub-tropical high pressure belts
Sinking air stops clouds forming, resulting in high daytime temperatures, low-night time
temperatures and low rainfall
Polar – roughly 50-60° north of the equator
Deciduous trees shed their leaves in winter to retain moisture
Coniferous trees are cone-bearing evergreen, retaining their leaves to maximise
photosynthesis during the brief summer months
Temperate grassland – roughly 30-40° north and south of the equator
Experience warm, dry summers and cold winter
Grasses can tolerate these conditions and this land is mainly used for grazing animals
Mediterranean – roughly 40-45° north of the equator
Hot, sunny and dry summers, with mild winters
Due to pressure belts migrating slightly north and south during the year
Tropical grassland (savanna) – between 15-30° north and south of the equator
Distinct wet and dry seasons
Dry season can be very hot and wild fires can break out
Violent thunderstorms can occur during the wet season
Tundra – from the Arctic Circle to about 60-70° north
Low-growing plants adapted to retain heat and moisture in the cold, windy and dry
conditions
Fragile ecosystem, easily damaged by humans and threatened by developments such as
oil exploitation and tourism
Ecosystem a natural system made up of Freshwater pond ecosystem:
plants, animals and the environment Plants like reeds grow in the water
- There are often complex around the edge of the pond
interrelationships between the living On the banks grow grasses, bushes and
and non-living components of an trees
ecosystem At the edges of the pond, the water is
Biotic living features of an ecosystem e.g. shallow and there will be plants like
plants water lilies
Abiotic non-living environmental factors e.g. At the centre the water is deeper and
climate (temperature and rainfall) there will be fish
Ecosystems can be at different scales: On the surface are ducks and small
- Local small-scale ecosystem (pond, insects such as water boatman
hedgerow or woodland)
- Global-scale ecosystem (tropical
rainforest, deciduous woodland). These
are called biomes.
Key terms:
Producers – convert energy from the environment into sugars
E.g. plants that convert energy from the Sun by photosynthesis
Consumers – get energy from the sugars produced by the producers
E.g. pond snail eats plants
Decomposers – break down plant and animal material and return the nutrients to the soil
E.g. bacteria and fungi
Food chain – shows the direct links between producers and consumers in the form of a simple line
Food web – shows all the connections between producers and consumers in a more complex way
Nutrient cycling – when plants or animals die, decomposers help the recycle the nutrients making
them available once again for the growth of plants or animals
How does change affect an ecosystem? Changes due to human activities
- Global-scale changes, such as climate Agricultural fertilisers can lead to
change eutrophication: nitrates increase
- Local-scale changes, such as changes to growth of algae, which will deplete
a habitat – e.g. when a hedge is oxygen and fish may die
removed Ponds may be drained to use for faming
Natural Changes Woods cut down, destroying habitats
Rapid changes can have serious impacts for birds and affecting the nutrient
Extreme weather e.g. drought can cycle
devastate ponds and lakes – they could Hedgerows removed to increase size of
dry up in places, which changes the fields – habitats destroyed, affecting
edge-of-pond environment the plant/animal balance
Plants will dry out and die, fish, starved Many farmers are trying to keep ecosystems in
of oxygen, might not survive balance by using less fertiliser. Some have
planted hedgerows to protect wildlife.
What if a pond owner added some perch, a predator, to an ecosystem? (example)
This will reduce the With fewer frogs, there
The perch will eat more
amount of food for will be an increase of
of the smaller fish and
creatures further up the creature below frogs in
small animals e.g. frogs
food chain, e.g. herons the food chain, e.g. slugs
, GLOBAL ECOSYSTEMS
Distribution:
- Defined by the dominant type of vegetation that grows in the region
Global ecosystems form broad belts across the world from west to east. Variations in these west-
to-east belts of vegetation are due to factors such as:
Ocean currents
Winds
Distribution of land and sea
Characteristics of global ecosystems:
Tropical rainforest – close to the equator
High temperatures and heavy rainfall associated with equatorial low pressure belt
Cover 6% of the Earth’s land surface
More than half of the world’s species of plants and animals live in this ecosystem
Desert – roughly 30° north and south of the equator
Cover 1/5 of the world’s land surface
Associated with sub-tropical high pressure belts
Sinking air stops clouds forming, resulting in high daytime temperatures, low-night time
temperatures and low rainfall
Polar – roughly 50-60° north of the equator
Deciduous trees shed their leaves in winter to retain moisture
Coniferous trees are cone-bearing evergreen, retaining their leaves to maximise
photosynthesis during the brief summer months
Temperate grassland – roughly 30-40° north and south of the equator
Experience warm, dry summers and cold winter
Grasses can tolerate these conditions and this land is mainly used for grazing animals
Mediterranean – roughly 40-45° north of the equator
Hot, sunny and dry summers, with mild winters
Due to pressure belts migrating slightly north and south during the year
Tropical grassland (savanna) – between 15-30° north and south of the equator
Distinct wet and dry seasons
Dry season can be very hot and wild fires can break out
Violent thunderstorms can occur during the wet season
Tundra – from the Arctic Circle to about 60-70° north
Low-growing plants adapted to retain heat and moisture in the cold, windy and dry
conditions
Fragile ecosystem, easily damaged by humans and threatened by developments such as
oil exploitation and tourism
