Biome - A plant and animal community covering a large area of the Earth's surface.
There are 9 major biomes, they are:
Tropical rainforests - located in a band either side of the equator where the sun is concentrated but there is also heavy rainfall,
Deserts - found close to the Tropic lines where the sub is concentrated but the air is dry,
Deciduous - grow in higher latitudes like the UK where the sun's rays aren't so concentrated and cooler winter temperatures encourage trees to loose their leaves,
Coniferous - found 60 degrees north where temperatures are so cold that the trees have evolved pine needles to reduce moisture loss,
Tundra - found at the Arctic Circle where the sun's rays have little strength and temperatures remain mostly below freezing,
Polar and mountain ice
The influence of climate on the distribution and t
As you move further from the equator and the latitude increases, temperature decreases. Average temperature is the main factor affecting plant growth, plants grow the most in Tropical rainforests because the sun's concentration is at it's greatest. This is because at the equator, the sun's rays hit the earth at right angles, concentrating the rays and making it hot. At the poles, the rays are spread out over a greater area and are much less concentrated. A lack of heat and light limits the vegetation growth so plants become stunted and low growing.
Precipitation occurs in low pressure belts where air massed meet and air rises. At the equator, the air is always rising = low pressure - clouds and rain - rainforests. at 30 degrees north and south of the equator the air is always sinking - high pressure - no clouds and no rain - desert.
Altitude - temperature decreases by 1 degree ever 100m higher, so as the height increases, it gets increasingly cold and wet.
The sea - keeps places near the coast cooler in summer and warmer in winter as it changes temperature more slowly than the land - continentality.
Prevailing winds - if the most common winds come from across land, the climate is dry. If they come from across the sea - wet, across the poles - cold, from the equator - warm.
UK forests are rarely found in limestone areas as it creates dry soil conditions.
Services the Biosphere provides to humans
The biosphree is a life-support system which provides many vital services to us such as:
Regulating the composition of the atmosphere - forests remove carbon dioxide from the atmosphere reducing global warming. Forests give out oxygen - purifying the atmosphere.
Maintaining the health of the soil - forests provide leaf litter which forms humus, this make the soil more fertile for growing crops.
Regulating water within the hydrological cycle - forests protect watersheds from soil erosion and intercept precipitation - preventing flash flooding. They also trap silt therefore keeping the water pure.
Protect against natural hazards such as storms and floods.
Pollination for food web/chains.
Goods the Biosphere provides to humans
- fish and meat
- sustainable harvesting of fruits, nuts and berries
- natural vegetation can be replaced with crops like wheat and rice
2) Raw materials
- wood pulp
- Mangrove trees
- Vitamin C in oranges
- St John's Wort is a plant used to help treat depression
- Periwinkle Plant used to treat Hodgkin's disease
In Britain, deciduous forest wood helped make and fuel the factories that drove the industrial revolution.
Tropical rainforests are vital for poor countries in South America where wood is used in many ways to help build local incomes.
Coniferous forests in North America provide much of the world's softwood which is used to make paper.
Threats to the Biosphere
Habitats are being increasingly damaged and destroyed by humans, this leads to an increased number of species on the 'Red List' of endangered animals.
Immediate causes for threat include logging, overfishing and pollution. There are also root causes such as increasing population, economic development - more money means consuming more resources such as food and fuel.
Other threats include:
Pollution of air and water
Introducing alien species
Tourism and recreation
Changing land use
The Tropical Rainforests - Amazonia
The Tropical Rainforests of Amazonia are located in Brazil. There are indigenous people who have lived there for many generations and have had almost everything provided for them by the forest:
Wood for building and cooking
Herbs for medicine
Food - nuts, fruit, meat and fish
Crops - shifting cultivation (sustainable process)
However, the rainforest is currently being exploited for:
Logging for timber/paper (100,000 square km cut down each year)
Farming - soya
Mining for oil
Government building HEP dams
Roads e.g Trans-Amazon highway
Future population pressures mean more land is needed each year for farming and housing.
Due to these exploitations, the soil is eroded and washed away causing floods, a loss of habitats for wildlife and rivers have become dirty and polluted.
The affect of climate change on Biomes
It is possible that we are heading towards another mass extinction of species. We are threatening the ability of the biosphere to provide goods and services due to:
Using more food, oil, water and minerals
Human induced change such as global warming
Climate change affects Biomes in many ways such as:
Breaking up habitats,
Change in habitats due to increasing temperature, changing rainfall and rising sea levels,
Extreme weather becoming more common,
Oceans becoming more acidic due to fresh water being added - killing coral reefs,
Increased pests and diseases,
Species face extinction - krill numbers falling,
Emperor penguins decreased 50%
Saving the Biosphere - Global Scale
It is important for humans to work together to save the biosphere. Biodiversity is important and everyday we are facing the extinction of more species.
Deciding what to focus on saving is difficult, should we save the hotspots (greatly concentrated areas of mass biodiversity) or a representation of all the biomes? Should we work to restore devastated areas? Should we conserve high profile animals or keystone species?
World Summits allow countries to work together to help making saving the biosphere possible, through organisations such as:
RAMSAR which works to conserve Wetlands,
CITES which aims to stop ivory trade and crocodile skin trade,
Rainforest conservation - debt-for-nature swap agreements (USA and Guatemala),
World Heritage Sites - over 800 important sites have been awarded recognition due to their biosphere e.g. Galapagos Islands,
National Parks cover 13% of the land surface protecting areas of outstanding natural beauty.
Saving the biosphere - national and local scale
National actions include:
National parks in England and Wales to protect areas such as the Peak District,
Community Forests - new areas of trees near cities,
Paying farmers to replace hedgerows
Local actions include:
Biodiversity action plans such as Havering Wildlife Trust
Sustainable Management - Meeting the needs of the present without compromising the needs of future generations through:
- Educating Locals
- Protected Areas
- Only cutting large trees
The Caledonian Forest - Scotland,
This forest is all that remains from the original that existed at the end of the last ice-age. The EU has provided funding for the restoration of the forest for the benefit of future generations. There are plans to:
- Bring back lost animal habitats and populations
- Restore biodiversity to its natural level by adopting a countryside management strategy known as Environmental Stewardship (protecting the world for future generations) which includes reintroducing wild boar which had been hunted to extinction and an aim to introduce wolves and brown bears to the forest in the future.
Klum - Cameroon Republic
Aim to make the forest sustainable through:
- an area of selective logging
- counteract deforestation with tree nurseries (afforestation)
- protected areas
- crops grown beneath the trees instead of cutting them down.