tropical rainforests ecology. what is a rainforest? in ecological terms- “ multi-storied closed,...
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Tropical Rainforests
Ecology
What is a rainforest?
• In ecological terms- “ multi-storied closed, broad-leafed vegetation with a continuous tree canopy of variable height and with characteristic diversity of species and life forms”.
• Home to over 50% of all species on Earth
Location
Forest Climate• Global heat and water pumps• Rainforests are dark, - they absorb
heat. • Above a rainforest the air is cooler so
it is more likely to rain. • Inside rainforest, below canopy,
humidity stays high. • The forests stay wet and evaporate
vast quantities of water through their foliage and into the air above, forming clouds.
• Some falls again as rain in the tropics but often clouds are carried great distances to fall as rain in the mid latitudes
http://www.bbc.co.uk/weather/world/south_america/
Climate ComparedManaos(Brazil) London (England)
The Forest Structure
• Notes:
Adaptations
Fertile & Fragile
• Soil in r/forests very thin - trees have shallow roots
• Depends on rapid recycling of nutrients
• Removal of trees devastates this nutrient cycle
Rainforest Nutrient Cycle
Abundant trees
Numerous fallen leaves
Rapid decay to form humus
Nutrients added to soil
Rich soil
Rich tree growth
Rainforest Nutrient Cycle
Trees removed
No leaves falling
No decaying leaves to form
humus
Remaining Nutrients
leached from soil
Soil deteriorates
V.difficult for new trees to
recover
Deforestation - the destruction of rainforests
Forest Fires and Deforestation in Mato Grosso, Brazil
The Amazon River Basin
• Clear-cutting– Starting point for other activities - logging, mining,
agriculture, roads, settlements
– mongobay
Causes of Deforestation
• Agriculture• Clearing forest for
cattle ranching, plantations (palm oil) or crops - eg. soybeans
Causes of Deforestation
• Logging• Removal of trees for
valuable hardwoods • (e.g. mahogany, teak)• Often illegal or
uncontrolled
Causes of Deforestation
• Mineral Extraction(Mining)
• Mining trucks, equipment, open pits and roads at the Rio Huaypetue gold mine in southeastern Peru Location: Southeastern Peru; from Cuzco to Boca Manu
• mongobay
Rates of Deforestation in South America
% loss per year
http://www.mongabay.com/deforestation_rate_tables.htm
Rates of Deforestation Worldwide
Hectares per year
http://news.mongabay.com/2005/1115-forests.html
What else is causing loss of rainforest?
• Look up the following websites and see what you can find.
• http://www.rainforestinfo.org.au/background/causes.htm
• http://www.greenpeace.org/international/ • http://www.sfu.ca/~ftcheng/educ260/
resources.html• http://www.bbc.co.uk/nature/animals/features/
321feature4.shtml
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