Tropical Rainforests

Distribution of Tropical Rainforests

Tropical rainforests are found on or near the Equator (roughly between 28 degrees north and south).
The main concentrations of tropical rainforests are:

 The Congo Basin in central and west Africa

 The Amazon in Brazil, Peru, Bolivia and Ecuador
 SE Asia (Malaysia, Thailand, Vietnam, Indonesia and the Philippines)
 Madagascar
 North east Australia
 Southern India and Sri Lanka
 Central America
Remember when you are describing maps, if you can't remember the names of individual
countries, then use compass points and continents. You can also use lines of latitude to help
you describe as well as general locations e.g. inland or coastal.

Deforestation rates vary massively, one reason is the inaccessibility of many of the forests and
the way people classify deforestation. However, it is claimed that now only about 5% of the
earth's surface is covered in tropical rainforests, compared to nearly 15% 50 years ago. Many
people believe that tropical rainforests could disappear this century.

Deforestation: The removal (cutting down) of trees.

Reforestation: The replanting of trees once they have been cut down.

Afforestation: Planting trees in an area that previously did not have trees.
Importance of Tropical
Reasons for Deforestation Problems Caused by Deforestation
Rainforests
 Biodiversity: Although  Cattle Ranching: As the  Flooding: Flash floods become more
rainforests cover only world's population gets common after deforestation because there
about 5/6% of the world's bigger and richer, the is less interception and less root uptake
land mass, it is estimated demand for meat is and transpiration. As such rainwater
that they could contain up increasing. To rear the reaches the ground quick, saturating it and
to 50% of the world's cattle increasing tracts of causing surface run-off and potential
biodiversity. This is the rainforest are being flooding.
potentially up to 15 cleared to make pastures  Landslides: By removing trees and
million species. for grazing. vegetation, you are making the soil less
 Photosynthesis: Tropical  Subsistence Farming: stable. Combine this with saturated ground
rainforests are often Because of the large and the likelihood of floods increases.
referred to as the 'lungs of amounts of poor people  Biodiversity loss: Because all the species
the earth' and convert that still live in tropical that live in the rainforest are not known it
large amounts of the areas, subsistence farming is hard to calculate species loss. However,
greenhouse gas carbon is still widespread. scientists believe that 1 mammal or bird
dioxide back into oxygen. Because rainforest soil extinction can be extrapolated to
It is estimated that the loses its fertility quickly approximately 23,000 extinctions.
Amazon rainforest alone after deforestation, the  Reduced photosynthesis: As more and
produces about 20% of most common form of more trees are removed the rate of
the earth's oxygen. subsistence farming is photosynthesis reduces, releasing more
 Flood control slash and burn. With carbon dioxide into the atmosphere and
(interception, growing populations this contributing to the greenhouse effect.
transpiration): method of farming can  Silting of rivers: With increased flooding
Rainforests are an cause widespread and surface run-off moil soils and silt is
excellent natural measure deforestation. washed into rivers, this can not only
to reducing flooding.  HEP: Many of the world's change local ecosystems (water
 There is leaf cover in great rivers flow through temperature and clarity) but can also
rainforests all year so rainforests e.g. the reduce the depth of rivers making
interception continually Amazon. These great navigation harder.
happens, extending rivers rivers often have the most  Silting of seas and oceans: With the
lag time. All vegetation HEP potential. increased frequency of flooding and
uptakes water and Unfortunately when a dam landslides more silt gets washed into the
transpires it. and reservoir are built it oceans. The increased amount of silts
 Control of soil erosion: causes damage during reduces the transparency of the sea
The root systems of trees construction, but also reducing the light reefs receive and the
and shrubs hold the very floods large areas. temperature of the water. Increased silt
thin soil of rainforest in  Mining: With an ever can also block important shipping lanes.
place. If trees are increasing demand for the  Breaking of nutrient cycle: The top soil
removed then both world's natural resources, of rainforests is very thin an receives the
erosion of topsoil and countries and companies majority of its nutrients from rotting flora
landslides are more likely are looking at increasingly and fauna. Be removing trees you also
 Source of nutrients to isolated locations, places remove animals and therefore the source
humus layer in soil: The like rainforests and of the soils nutrients. With increased
topsoil in rainforests is Antarctica. The rainforests erosion the top soil (humus) layer is
very thin and relies on the are believed to have many quickly washed away.
nutrients provided by resources including metals  Sandification/desertification: Because
rotting plants and animals. and fossil fuels beneath rainforest soil loses its fertility very
Because of the rainforests their soils. Gold mining quickly after deforestation it quickly
climate, there is a can be particular damaging becomes hard to grow any vegetation on
constant supply of leaf as mercury is used in its it, leading to sandification and possibly
litter. extraction and often runs desertification.
 Medical remedies: off into rivers.  Loss of indigenous homes: By clearing
Rainforests have been the  Road building: Building rainforests you are obviously destroying
source of many of today's new roads like Trans the homes of indigenous groups. But also
drugs, including the basic Amazon highway from moving close to indigenous groups can
ingredients for the Brazil to Bolivia not only spread disease and alter local culture and
hormone contraceptive causes deforestation itself, traditions.
pill, quinine (a anti- but its also opens up new  Reduced rainfall: Deforestation can lead
malaria drug) and curare areas to urbanisation, to reduction in local rainfall because less
(a paralysing drug). mining and farming water is intercepted and transpired from
 Cash crops and causing further vegetation into the atmosphere reducing
agricultural products: deforestation. the formation of clouds and rainfall.
Yam, coffee, rubber,  Urban growth: With the
mango, banana, world population
sugarcane, cocoa and increasing as well as rates
avocado were all first of urbanisation increasing
discovered in rainforests. many cities like Manaus in
 Ecotourism: With people Brazil are growing rapidly
becoming ever more causing deforestation.
environmentally  Population growth: As
conscious and looking for populations grow,
increasing adventures, particularly in countries
ecotourism to rainforests like Brazil, Peru, India and
is increasing. This not Vietnam that contain
only helps protect rainforests the demand for
rainforests, but creates land increases, both to
income for locals. grow food and to live).
Ecotourism is an  Plantations: Primary
important income to products are often seen as
countries like Costa Rica an income source for
and Belize. LEDCs, many of who
 Home to indigenous have large areas of
groups: Although the rainforest. At the same
number of indigenous time with fossil fuels
groups and people have running out, alternative
declined rapidly since fuels sources are been
 searched for including
biofuels e.g. Palm oil. This
has lead to widespread
deforestation in countries
like Malaysia and
Indonesia to plant cops
like palm oil.
 Timber (hardwoods):
Hardwoods like mahogany
and teak that take
hundreds of years to grow
colonisation in South are still in high demand to
America, it is estimated make things like furniture.
that there are still over The extraction of these
200,000 people that trees can kills trees around
consider the Amazon their them. Also many countries
home. like China are also
demanding large amounts
of normal timber that are
not always taken from
sustainable sources.
 Hunting: Hunting takes
two forms, one form is for
bushmeat to feed families
and enough the sale of
animals either alive e.g.
parrots or dead for their
skins e.g jaguars.

Tropical Rainforest Climate Because tropical rainforests are close to the equator, they have very
similar climates all year around. Their temperature is constant at between 25 and 30 degrees Celsius. They
also receive rainfall all year around, although the monthly amounts may vary slightly. Tropical rainforests
normally experience convectional rainfall. This is because they are close to the equator where temperatures
are hot. The hot temperatures warm up the land, causing evaporation and transpiration and then convection.
Not only is the weather similar between months, it is also very similar between days. Days will start of
warm and then the temperature and humidity will build up. By the afternoon the air is saturated and tropical
rainforest normally experience intense rainstorms. Because tropical rainforests are near to the equator the
hot air rises causing low pressure.

Tropical Rainforest Vegetation and Adaptation

Emergents: Emergents are tall trees that grow above the canopy layer in order to reach sunlight. Emergents
can grow in excess of 50 metres.

Canopy: The canopy layer contains about 50% of the rainforests wildlife. The canopy layer is extremely
thick and sits at between 25 and 35 metres.

Shrub Layer: The shrub layer is near the forest floor and is also extremely dense. Because the canopy is so
thick the shrub layer has to adapt to survive in less light.

Lianas: These are woody vines that climb up other trees to try and get into the canopy and capture sunlight.

Strangler Figs: Strangler figs grow around the outside of other trees taking their light and nutrients and
slowly killing the host tree. However, when the host tree collapses so does the strangler fig.

Butress Roots: Very long roots that are designed to support tall trees and to suck up the maximum amount
of nutrients in fairly nutrient poor soil.

Fan Palms: Huge wide leaved plants that aim to capture as much sunlight and rainfall as possible.

Humus Layer: Rainforest soils are fairly infertile and dependent on the humus layer (decaying biological
matter). If the source of humus is removed through deforestation then soils degrade very quickly.

Evergreen: Most vegetation in rainforests does shed its leaves once a year. However, because the climate of
rainforests is similar all year, they shed their leaves at different times providing a constant source of
biological matter and keeping the rainforest green.

Drip tip leaves: A lot of vegetation have leaves designed for rainfall to travel over them and drip to the
ground. This is because the vegetation does not wanted to be damaged by large quantities of water.
Tropical Rainforest Animals

Tropical rainforests have a huge amount of biodiversity within them - some estimates suggest that up to 50%
of the earth's biodiversity live there (flora and fauna). The are many big famous mammals like tigers in SE
Asia, jaguars in Central and South America and leopards in Africa. However, there are also much smaller
mammals like sloths and primates like lemurs that live in rainforests. All mammals and primates have
adapted in different ways to survive in the rainforest e.g. camouflage. As well as mammals and primates
there are many other animals like birds, amphibians, reptiles and insects. Many rainforest animals are under
threats. Threats include:

 Habitat loss (deforestation)

 Climate change (reduction in rainfall or increases in temperature)
 Pollution (especially reptiles and amphibians)
 Hunting (food food, skins and parts for Chinese medicine)
 Cross breeding with domestic animals

 Diseases (bird flu)

Sustainable forestry: Forestry that does not cause permanent damage to any ecosystem and that can be
maintained indefinitely (not damaging for future generations).
Protecting Tropical Rainforests

There are a number of ways to try and protect tropical rainforests, some of the most common are:

 Creation of National Parks: More National Parks can be created to stop deforestation and loss of
biodiversity. National Parks are areas of land protected by government law.
 Rainforest Sales: Poor countries who make money from deforestation have muted the idea of
selling their rainforests. One country which is hoping to do this is Guyana. This may include carbon
offsetting where polluters can buy parts of the rainforest to offset some of the pollution that they are
creating.
 Consumer Labelling (FSC): Consumer labelling can ensure that people only buy wood based
products that have been taken from a sustainable source. The Forest Stewardship Council lends its
label to products produced sustainably.
 Sustainable forestry: Increase sustainable forestry, this would mean no destruction of rainforests
because they take a long time to grow but instead the use of fast growing trees. Where deforestation
is necessary in rainforests, possibly by indigenous groups, this should be selective cutting rather than
clearfelling.
 Ecotourism: The promotion of ecotourism gives tropical rainforests and biodiversity an economic
value. If the value of tourism is greater than the value of selling trees and wild animals then locals
will have the incentive to protect them.
 Bans on Rainforest Products: There should be trading bans on endangered products from
rainforests e.g. animal skins and hardwoods.
 Education: Improved global education on the importance of biodiversity and tropical rainforests.
 Global Initiatives: Global treaties like Kyoto which aim to reduce climate change should include
greater protection for tropical rainforests which can actually reduce climate change.
 Recycling (and reducing and reusing): If we reduce our consumption of wood based products as
well as reusing them and recycling them then less trees need to be cut down to make them.