Tropical Rainforests
Tropical Rainforests of the world
A
C
B
Rainforests are found 5° north and south of the Equator
Amazon Zaire basin Indonesia
3 main areas of Rainforest Amazon Basin – A on the map.
It is South America covering most of Brazil, the 5th largest country in the world. It gets its name from the river Amazon which flows through it.
Zaire – B on the map. It is in central Africa getting its name from the river running the through it.
Indonesian – C on the map. It gets its name from a group of islands called Indonesia which lie between Asia and Australia.
Climate
Main featuresVery hot – 27°C daily average
Very wet – over 2000mm rain annually
No seasons – same weather conditions all year
Reasons WhySun directly overhead at noon
giving intense light and heat
Moist air rises quickly in noon heat. Rising air cools, water vapour condenses each afternoon into heavy convectional rain.
At the Equator every day has equal hours of daylight and darkness. No ‘summers’ or ‘winters’.
Layers of the Tropical Rainforest
Shrub layer
Lianas
Epiphytes
Life in each layer
Emergent Layer: This is the top layer of the rain forest. The tall trees break out above the canopy layer to the sunlight. Many of the birds live in this area. The birds eat fruit and fly in the open areas of the emergent layer. They look for nesting places and are away from predators.
Canopy: The canopy is full of life. It receives more sunlight than the layers below. There are plants that grow in this area. Their roots don't reach the ground. These are called air plants. The roots get their moisture from the humid conditions. The canopy is home to may birds and monkeys.
Understory and Forest floor
Understory: This layer get little light. Many animals like frogs, bats, apes, owls, and more live in this area. Some are nocturnal. There are anteaters and leafcutter ants. Many animals go from the understory to the canopy and back. These two layers are brimming with life.
Forest floor: This is where many insects live. Many seeds fall to the forest floor. Here you will then also find the animals that eat seeds and bugs. It is very dark here due to the dense canopy.
Adapting to rainforest life Vegetation in the rainforest has evolved characteristics which
help it survive in this unique environment. The illustration shows four rainforest plants: a fan palm, a strangler fig, a liana and a tree with buttress roots.
Each of these plants is adapted to rainforest conditions in a different way.
Fan palms have large, fan-shaped leaves that are good for catching sunshine and water. The leaves are segmented, which allows excess water to drain away.
Rainforests have a shallow layer of fertile soil, so trees only need shallow roots to reach the nutrients. However shallow roots aren't great for supporting huge rainforest trees, so many tropical trees have developed huge buttress roots. These stretch from the ground to two meters or more up the trunk, which help anchor the tree to the ground.
Lianas are woody vines that start at ground level, and use trees to climb up the canopy where they will spread from tree to tree to get as much light as possible.
Strangler figs start at the top and work down. The seed is dropped in a nook at the top of a tree where it starts to grow, using the debris collected there. Gradually the fig sends aerial roots down the trunk of the host, until they reach the ground and take root. As it matures, the fig will gradually surround the host, the aerial roots will criss-cross the trunk and start to strangle. Meanwhile the figs branches will grow taller, dominating the sunlight, while invasive roots rob the host of nutrients. Eventually the host will die and decompose leaving the hollow, but sturdy trunk of the strangler fig.
Animal Life in the Rainforest
Write a letter
Write an account of a recent visit to the Rainforest. Send this letter to your friend or family.
Say what you saw, what you did.Mention the sights, sounds, animals and
the weather.
Rainforest under threat
An area the size of a football pitch is removed from the Rainforests every second
At this rate there will soon be no Rainforest left
Causes of Deforestation
Roads
Firewood
Growing towns
Mining
Cattleranching
Farming
Logging
Forest fires
Consequences of deforestation
Plants and animals – habitats, food, no where to live
Soil – washed away by lots of rain. No good for crops
World climate – no oxygen for people, less water in the atmosphere so more deserts
Slash and Burn FarmingNative American tribes cut down small areas of Rainforest to farm. The trees they cut down are burnt and the ash is spread over the fields. They do this to add nutrients to the soil and make it fertile (able to grow more crops).They farm for only 2/3 years as the rain washes the nutrients out of the soil. The farmers then move to another area and repeat this process. The original cleared area is then able to regrow its trees as the surrounding trees are able to retake it and make new forest.
Soil Conservation
This is working to preserve the environment so soil is not lost due to the actions of man.
Problems of human intervention Roads divide up parts of the rainforest and can
cut off connections between different biotic and abiotic systems. For example, a road can stop monkeys such as the Golden Lion Tamarin from travelling to gather food and, in turn, distribute seeds to re-sow plants in the forest.
Land clearance for farming, transportation and mining can lead to deforestation. Hardwood trees take many years to grow, so can be difficult to replace.
Farming is estimated to be responsible for 25 percent of the Amazon forest being cleared.
Fertile soils that make farming possible are quickly washed away when the forest is cleared for farming, mining or transportation.
Loss of animal habitat occurs when trees are cut down and animals that live in them have to find somewhere else to live. Hence, deforestation can result in endangering animals and plant life, or even causing them to become extinct.
Profits from large-scale farming and selling resources often go back to MEDCs or large companies and don't benefit rainforest communities.
Why are rainforests important?
Rainforests are extremely importantin the ecology of the Earth.
85% of the planets plants and animals live in the Rainforest. Remove the trees and most will die out.
The plants of the rainforest generatemuch of the Earth's oxygen.
These plants are also very important to people in other ways.
Many are used in new drugsthat fight disease and illness
We need the trees for paper, wood, furniture etc
