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Paper 1B Tropical rainforests - Coggle Diagram
Paper 1B
Tropical rainforests
What are the four layers of the rainforest?
Undercanopy
The undercanopy receives
about 5%
of the sunlgiht falling on to the forest
It is hot, damp and shaded from the wind.
Lianas (vines) climb through the trees here to reach the sunlight
Canopy
The canopy trees grow to around
20-40m in height
.
They compete for the sunlight overhead
Strong light levels mean that there is an abundance of life here for example monkeys, snakes, pythons
Shrub layer
The ground layer receives very little light.
Hot, wet conditions drive rapid decomposition of fallen leaves
Plants, fungi or micro-organisms that tolerate low light levels and get nutrients from breaking down dead matter are found here
The shrub layer consists of tree saplings and shade-tolerant ferns.
Emergent layer
Emergent trees can grow to more than
50m in height
.
They seek to outcompete surrounding trees to reach the sunlight
Desforestation
Deforestation is the action of clearing a wide area of trees
What are the main causes of deforestation
Substinence and commercial farming
Substinence farming is often dominated by slash and burn techniques
In 2004 it was estimated that in Brazil alone 500,000 substinence farmers each cleared an average of one hectare of forest
Commercial farming is a very significant driver of deforestation
It is estimated that cattle farming accounts for around 80% of tropical rainforest destruction in Brazil
Soybean production is also a key driver of deforestation in the Amazon.
Logging
Logging by definiton leads directly to deforestation
Over 90% of Brazils timber production comes from the Amazon.
Between 60-80% of all loggig in the amazon is thought to be illegal, meaning it is very difficult to monitor
Road building
The trans-amazonian highway is 4000km in length
Deforestation was required to build it, and by building it large areas of the rainforest have been opened up for exploitation by other means
This may include logging, farming and mineral extraction.
mineral extraction
Energy development
More than 70% of the Peruvian Amazon
This includes indigenous territories and conservation areas has been sacrificed for oil and gas.
Dam buildings also creates widespread deforestation.
settlement
population growth