Battle for the biosphere
What to revise
• The distribution of global biomes reflects climate
as well as other localised factors
• The biosphere acts as a life support system,
providing a wide range of goods and services
• The biosphere is being degraded by human
• Management measures, at a variety of scales,
are being used to conserve the biosphere and
make human use of it more sustainable
What is a biome
• A biome is a plant and animal community
covering a large area of the earth’s
surface. An example of this is tropical
• All of these together make up the Earth’s
Distribution of global biomes
Factors affecting biomes
• Climate (temperature, precipitation,
sunshine hours, humidity)
• Local factors – altitude, geology, relief,
drainage, soil type, distance inland
How limiting factors affect the
edges of the rainforest
Climate patterns affect biome
The biosphere life-support system
• Acts as a life-support system for the planet,
helping to regulate the composition of the
atmosphere, maintaining soil health and
regulating the hydrological cycle.
• The biosphere naturally interacts in good ways
with the Earth’s climate, soil and water. It also
supports people. Plants and animals play a vital
role in maintaining human life and aiding
What is the value of the biosphere?
• It is a provider of goods and services
Threats to the biosphere Impacts Examples
Commercial logging destroys forest unless Logging in the rainforests of the Amazon
Deforestation sustainable forestry principles are used. It and Indonesia
affects rates of flooding, soil erosion and
Commercial intensive farming destroys or Wheat farming in the American Prairies has
Conversion to farmland or alters the ecosystem. Urban sprawl destroys removed natural grassland where bison
ecosystems and encourages wildfires. once grazed. Soya beans are grown for
urban use Biofuels. The urban sprawl of Los Angeles.
Overharvesting causes wild animals to be Big game such as tigers (India) and rhino
Overharvesting/overfishing hunted to extinction. Overfishing of some (Africa). The krill population (Antarctica
species such as krill, needed as food for fish and North Sea) is managed by quotas.
farms, destroys food chains.
Mining cuts away whole hillsides. Opencast Removal of forests for mining iron ore in
Mining and energy mining destroys the surface and restoration the Brazilian Amazon. Tin mining in
is only partly successful. Drilling for oil Malaysia. Oil drilling in Alaska – a very
causes surface damage. Oil tankers cause fragile environment.
Water pollution from sewage, fertilizers and Too much silt and nutrients kill fish or
Pollution industry. Toxic fumes emitted into the
atmosphere, destroy species and damage coral. Acid rain kills forests.
Sometimes we introduce new species Pheasants for shooting. Rhododendrons are
Introduction of alien species deliberately. More usually they arrive by alien species which poison the soil so that
accident, e.g. via ships or aircraft. Alien other plants won’t grow there. Mink
species often breed well and take over. escaping from fur farms.
Eco-tourism has little impact. But high- The Galapagos Islands are under threat due
Tourism and recreation density mass tourism in fragile
environments disturbs wildlife. to tourism.
10 facts about the Amazonian rainforest
1. Many tropical plants are used as industrial raw materials. Plant
oils, gums, resins, tannin, rubber and dyes all come from the
2. Hardwood timber is a valuable resource that can be exported to
help feed the growing population of rainforest countries like Brazil.
3. The rainforest tree canopy protects the soil. If it is removed, there
is a risk of soil being washed away by the convection rain that
falls daily in Amazonia.
4. If soil is removed by rain following deforestation, it gets washed
into the River Amazon. Water temperatures rise as a result of this
sediment being added, making survival hard for some fish.
5. The Amazon forest has been described as ‘the world’s lungs’. Its
trees produce much of the world’s oxygen, which humans
breathe, while also soaking up carbon dioxide.
6. The rainforest is a vital store of carbon. If it were to all disappear,
global carbon dioxide levels would rise considerably – causing
runaway climate change and faster temperatures and sea level
7. Soils are protected from the drying effect of direct sunlight by the
shade that trees provide. Soils suffer from the formation of a hard
crust called laterite if the forest canopy is removed.
8. The tropical rainforest is a gene pool that the health of the entire
planet is dependent upon. Millions of plant, insect and animal
species live in Amazonia. They contain genetic material that can
provide vital medical resources for the fight against diseases like
9. The population of South America is expected to double in the next
40 years. South American people want to clear the forest to gain
10. Trees intercept and slow down rainwater as it moves through a
river’s drainage basin. This helps lower flood risk. Cutting down
trees can result in greater flooding.
• Amazonia is being degraded by human actions.
The Grande Carajas development Brought iron mines and aluminium plants to
programme places where virgin forest once stood in Brazil.
Use of wood as fuel led to further clearances.
Hydroelectric dams The building of hydroelectric dams along the
Amazon’s tributaries flooded forest valleys.
New roads The construction of new roads, such as the
Trans-Amazon Highway, leads to forest loss.
Migration of farmers Landless farmers migrate into Amazonia along
the new roads. They then cut down forest for
firewood or clear land to grow crops. As a result,
the pattern of deforestation often follows the
Forest clearance Huge areas of forest have been cleared for
commercial agriculture. Major crops such as
soya beans are grown on old rainforest soils in
Brazil. In neighbouring Costa Rica, around one-
third of all cleared rainforest land is used for
Deforestation in the Amazon
How can the biosphere be
• Sustainable development – development
that meets the needs of the present
without compromising (limiting) the ability
of future generations to meet their own
• Convention on International Trade in
Endangered Species of Wild Fauna and Flora
• This is an international agreement aimed at
conserving the biosphere at a global scale
• Signed in 1973 and adopted by 166 countries
• The Ramsar Convention on Wetlands is
an intergovernmental treaty for the
conservation and wise use of wetlands
• It was signed in 1971 and adopted by 147
• Ramsar sites
• Located in the Brazilian state of Amazonas.
• Mamiraua is protected by the international
Ramsar Convention as a wetland of global
importance. It is run by the Brazilian
Managing at a local level
• National policies can be delivered in a
local area, involving local people.
Examples: Barnack Hills and Holes or