AQA Geography Paper 1 : The Living World
3.1.2.1 Ecosystems
(Case study booklet - Example) Epping Forest, in Essex, is a deciduous woodland
with high biodiversity. Producers, consumers and decomposers are all
interdependent.
Nutrients in the fallen leaves are converted into humus in the soil to be absorbed
for plant growth. This will include fruits and berries ready to support primary
consumers.
The biomass store is large because of the great height of the trees and dense
undergrowth beneath them. The soil store is large as there is plenty of humus.
There are high flow rates between litter, soil and biomass, reflective of the fast
cycle of new growth each year.
Ecosystems are very sensitive to change. The biotic and abiotic components can
be altered by natural factors or human management. Changes could result in the
collapse of a food chain.
All organisms in an ecosystem depend upon each other. Within a community,
species depend on each other for food, shelter, successful pollination and
successful seed dispersal.
Only about 10% of the biomass is transferred from each trophic level to the next.
The remaining 90% is used by the trophic level to complete life processes.
Biomass can be lost between stages because not all the matter eaten by an
organism is digested. Some of it is excreted as waste such as solid faeces,
carbon dioxide and water in respiration and water and urea in urine.
Declining biodiversity was fixed with the reintroduction of the grey wolf to the
Yellowstone ecosystem. This led to the increased population of grizzly bears,
coyotes and mice, and a fall in the population of Elk from 20,000 to 10,000 in 8
years. The reduced grazing meant vegetation could recover and there was more
tree cover. Riverbanks became more stable, beavers created ponds and
recolonised Yellowstone. The kills made by wolves led to more food for
scavengers.
,3.1.2.2 Tropical rainforests
Tropical rainforests are very wet with over 2000mm of rainfall per year. They are
very warm with an average daily temperature of 28 °C. The atmosphere is hot
and humid, and the climate is consistent all year round. There are no seasons.
Most of the soil is not very fertile but there is a thin layer of fertile soil at the
surface where the dead leaves decompose. Due to heavy rainfall the nutrients
are quickly washed out of the soil.
The warm and wet climate provides perfect conditions for plant growth. The wide
range of plant species supports many different animals, birds and insects.
A tropical rainforest consists of the ground level/shrub layer, under canopy,
canopy and emergent.
Plant and animal adaptations
Lianas are woody vines that have roots in the ground but climb up the trees to
reach the sunlight. Their leaves and flowers grow in the canopy.
Tree trunks are tall and thin to allow trees to reach the sunlight. The bark on
the trees is smooth to allow water to flow down to the roots easily.
Plants have drip tips, which are leaves with pointy tips. These allow water to run
off quickly without damaging or breaking them.
Trees have buttress roots, which are large roots with ridges to create a large
surface area that helps to support the larger trees. This provides stability.
Epiphytes are plants that live on the branches of trees high up in the canopy.
They get their nutrients from the air and water, not the soil.
, The sloth uses camouflage (they have hair full of green algae to help them
camouflage amongst the leaves) and moves very slowly to make it difficult for
predators to spot. They also have sharp claws which makes them expert climbers
so they can access food in the canopy and escape predators.
The spider monkey has long, strong limbs to help it to climb through the
rainforest trees.
The flying frog has fully webbed hands and feet, and a flap of loose skin that
stretches between its limbs, which allows it to glide from plant to plant.
The toucan has a long, large bill to allow it to reach and cut fruit from branches
that are too weak to support its weight. Their big bills (beaks) help the toucan to
regulate its temperature in the hot rainforest climate. They can transfer heat via
blood vessels to the surface of their beaks from which it is lost. They also have
perfect claws to help them to perfectly balance on the branches. They are
coloured similarly to the vegetation to help them camouflage.
Biodiversity
Activities that create air and water pollution are reducing biodiversity in many
ecosystems.
Deforestation
(Case study booklet – Case Study) Causes of deforestation in the Amazon
rainforest, Brazil:
Subsistence farming using slash and burn techniques involves the use
of fire to clear the land. The burning creates valuable nutrients that helps
plants grow.
Commercial farming for cattle accounts for 80% of tropical rainforest
destruction in Brazil. The land can not be used for long.
Commercial farming for crops is resulting in the forest being cleared.
The amount of rainforest cleared for the cultivation of soybean doubled
between 1990 and 2010.
Logging accounts for 3% of all deforestation in Brazil. There is often
selective logging as timber companies are interested in mahogany and
teak, which are used to make furniture.
Road building is needed to bring in equipment and transport products to
markets. The Trans-Amazonian highway began construction in 1972
and is 4000km long. It has opened up remote areas of the Amazon.
There is mineral extraction especially for gold. In 1999, 10,000
hectares of land were being used for gold mining. Today it is over 50,000
hectares.
Energy development, which uses the unlimited supply of water and
ideal river conditions, has encouraged dams to be produced to generate
hydroelectric power. This floods large areas of rainforest.
Settlement and population growth has led to more areas of the
rainforest being used for construction materials or building plots.
3.1.2.1 Ecosystems
(Case study booklet - Example) Epping Forest, in Essex, is a deciduous woodland
with high biodiversity. Producers, consumers and decomposers are all
interdependent.
Nutrients in the fallen leaves are converted into humus in the soil to be absorbed
for plant growth. This will include fruits and berries ready to support primary
consumers.
The biomass store is large because of the great height of the trees and dense
undergrowth beneath them. The soil store is large as there is plenty of humus.
There are high flow rates between litter, soil and biomass, reflective of the fast
cycle of new growth each year.
Ecosystems are very sensitive to change. The biotic and abiotic components can
be altered by natural factors or human management. Changes could result in the
collapse of a food chain.
All organisms in an ecosystem depend upon each other. Within a community,
species depend on each other for food, shelter, successful pollination and
successful seed dispersal.
Only about 10% of the biomass is transferred from each trophic level to the next.
The remaining 90% is used by the trophic level to complete life processes.
Biomass can be lost between stages because not all the matter eaten by an
organism is digested. Some of it is excreted as waste such as solid faeces,
carbon dioxide and water in respiration and water and urea in urine.
Declining biodiversity was fixed with the reintroduction of the grey wolf to the
Yellowstone ecosystem. This led to the increased population of grizzly bears,
coyotes and mice, and a fall in the population of Elk from 20,000 to 10,000 in 8
years. The reduced grazing meant vegetation could recover and there was more
tree cover. Riverbanks became more stable, beavers created ponds and
recolonised Yellowstone. The kills made by wolves led to more food for
scavengers.
,3.1.2.2 Tropical rainforests
Tropical rainforests are very wet with over 2000mm of rainfall per year. They are
very warm with an average daily temperature of 28 °C. The atmosphere is hot
and humid, and the climate is consistent all year round. There are no seasons.
Most of the soil is not very fertile but there is a thin layer of fertile soil at the
surface where the dead leaves decompose. Due to heavy rainfall the nutrients
are quickly washed out of the soil.
The warm and wet climate provides perfect conditions for plant growth. The wide
range of plant species supports many different animals, birds and insects.
A tropical rainforest consists of the ground level/shrub layer, under canopy,
canopy and emergent.
Plant and animal adaptations
Lianas are woody vines that have roots in the ground but climb up the trees to
reach the sunlight. Their leaves and flowers grow in the canopy.
Tree trunks are tall and thin to allow trees to reach the sunlight. The bark on
the trees is smooth to allow water to flow down to the roots easily.
Plants have drip tips, which are leaves with pointy tips. These allow water to run
off quickly without damaging or breaking them.
Trees have buttress roots, which are large roots with ridges to create a large
surface area that helps to support the larger trees. This provides stability.
Epiphytes are plants that live on the branches of trees high up in the canopy.
They get their nutrients from the air and water, not the soil.
, The sloth uses camouflage (they have hair full of green algae to help them
camouflage amongst the leaves) and moves very slowly to make it difficult for
predators to spot. They also have sharp claws which makes them expert climbers
so they can access food in the canopy and escape predators.
The spider monkey has long, strong limbs to help it to climb through the
rainforest trees.
The flying frog has fully webbed hands and feet, and a flap of loose skin that
stretches between its limbs, which allows it to glide from plant to plant.
The toucan has a long, large bill to allow it to reach and cut fruit from branches
that are too weak to support its weight. Their big bills (beaks) help the toucan to
regulate its temperature in the hot rainforest climate. They can transfer heat via
blood vessels to the surface of their beaks from which it is lost. They also have
perfect claws to help them to perfectly balance on the branches. They are
coloured similarly to the vegetation to help them camouflage.
Biodiversity
Activities that create air and water pollution are reducing biodiversity in many
ecosystems.
Deforestation
(Case study booklet – Case Study) Causes of deforestation in the Amazon
rainforest, Brazil:
Subsistence farming using slash and burn techniques involves the use
of fire to clear the land. The burning creates valuable nutrients that helps
plants grow.
Commercial farming for cattle accounts for 80% of tropical rainforest
destruction in Brazil. The land can not be used for long.
Commercial farming for crops is resulting in the forest being cleared.
The amount of rainforest cleared for the cultivation of soybean doubled
between 1990 and 2010.
Logging accounts for 3% of all deforestation in Brazil. There is often
selective logging as timber companies are interested in mahogany and
teak, which are used to make furniture.
Road building is needed to bring in equipment and transport products to
markets. The Trans-Amazonian highway began construction in 1972
and is 4000km long. It has opened up remote areas of the Amazon.
There is mineral extraction especially for gold. In 1999, 10,000
hectares of land were being used for gold mining. Today it is over 50,000
hectares.
Energy development, which uses the unlimited supply of water and
ideal river conditions, has encouraged dams to be produced to generate
hydroelectric power. This floods large areas of rainforest.
Settlement and population growth has led to more areas of the
rainforest being used for construction materials or building plots.
