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Tropical Rainforests
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Tropical rainforests are found in places with a hot (over 30°C) and wet (over 2000 mm) equatorial climate.

Rainforests grow in the tropics, close to the equator and the plants have a twelve month growing season. As a resultant, the rainforest is the most luxuriant vegetation system in the world.

Vegetation

The tropical rainforest is different from all other ecosystems because of its biodiversity. Over 50 species of tree may be found in only 1 hectare of soil in the rainforest.

The forests appear to be evergreen but the trees are deciduous and take it in turns to lose their leaves.

The rainforest is organised into five layers. From the top they are as follows;

  • emergents,
  • canopy,
  • under canopy,
  • shrubs,
  • forest floor

Soil

The profile of the soil in the rainforest is called a Latolsol. Latosols are reddish brown and the red colour comes from the oxides of iron and aluminium in the soil. They are very deep soils. The heavy rain in the rainforest leads to leaching (minerals washed out) and this is why the top layer of soil is often light in colour.

Adaptations

As there is great competition for sunlight and water in the rainforest the trees try to grow very tall. They have a shallow spreading root system to collect as much nutrients as they can. The wide buttress roots at the base of the tall trees help to prevent them falling over.

Many other plants have to devise methods of competing for light. Ferns on the forest floor are able to cope in low-light conditions. Lianas are creeping plants that grow up the tree trunks and use them to get to the sunlight. Parasitic plants such as orchids grow in cracks in the branches high up in the canopy.

Humans use the rainforest in the following ways;

  • Logging - chopping down of trees
  • Ranching - large areas of trees chopped down for cattle farming
  • Mining - valuable minerals such as iron ore, bauxite and even gold
  • Rubber tapping - some trees provide natural rubber from the sap
  • Tourism - increasing number of tourists want to visit the rainforest
  • Farming - farms vary from tiny subsistence farms to huge plantations growing a single crop such as palm oil

Social Issues

  • Indigenous people e.g. Amerindians are left with out homes and many have been killed, either deliberately or by diseases introduced by people coming to the rainforest.
  • Too many tourists and tourist facilities can damage an area

Environmental Issues

  • Chopping down of large areas of woodland can influence global warming
  • Animals habitats are destroyed

Political Issues

  • Lots of groups do not agree about what should be done with the rainforest and this leads to great conflict

Tropical rainforests are found in places with a hot (over 30°C) and wet (over 2000 mm) equatorial climate.

Rainforests grow in the tropics, close to the equator and the plants have a twelve month growing season. As a resultant, the rainforest is the most luxuriant vegetation system in the world.

Vegetation

The tropical rainforest is different from all other ecosystems because of its biodiversity. Over 50 species of tree may be found in only 1 hectare of soil in the rainforest.

The forests appear to be evergreen but the trees are deciduous and take it in turns to lose their leaves.

The rainforest is organised into five layers. From the top they are as follows;

  • emergents,
  • canopy,
  • under canopy,
  • shrubs,
  • forest floor

Soil

The profile of the soil in the rainforest is called a Latolsol. Latosols are reddish brown and the red colour comes from the oxides of iron and aluminium in the soil. They are very deep soils. The heavy rain in the rainforest leads to leaching (minerals washed out) and this is why the top layer of soil is often light in colour.

Adaptations

As there is great competition for sunlight and water in the rainforest the trees try to grow very tall. They have a shallow spreading root system to collect as much nutrients as they can. The wide buttress roots at the base of the tall trees help to prevent them falling over.

Many other plants have to devise methods of competing for light. Ferns on the forest floor are able to cope in low-light conditions. Lianas are creeping plants that grow up the tree trunks and use them to get to the sunlight. Parasitic plants such as orchids grow in cracks in the branches high up in the canopy.

Humans use the rainforest in the following ways;

  • Logging - chopping down of trees
  • Ranching - large areas of trees chopped down for cattle farming
  • Mining - valuable minerals such as iron ore, bauxite and even gold
  • Rubber tapping - some trees provide natural rubber from the sap
  • Tourism - increasing number of tourists want to visit the rainforest
  • Farming - farms vary from tiny subsistence farms to huge plantations growing a single crop such as palm oil

Social Issues

  • Indigenous people e.g. Amerindians are left with out homes and many have been killed, either deliberately or by diseases introduced by people coming to the rainforest.
  • Too many tourists and tourist facilities can damage an area

Environmental Issues

  • Chopping down of large areas of woodland can influence global warming
  • Animals habitats are destroyed

Political Issues

  • Lots of groups do not agree about what should be done with the rainforest and this leads to great conflict

Rainforest destruction - Kalimantan, Indonesia and Costa Rica

This video features Kalimantan on the Indonesian island of Borneo. It is home to some of the oldest tropical rainforest in the world. Over time, large parts of this rainforest have been destroyed to make room for farming. However, this deforestation has led to soil erosion, which means the crops have failed. The forests will take decades to recover. In Costa Rica, the rainforests are being conserved by the creation of National Parks. The local population rely on the forests for much needed tourism.

Deforestation

Main Causes

  • Farming – Forest is cleared to set up subsistence farms or larger cattle ranches. ‘Slash and burn’ technique is often used to clear the forest.
  • Mineral Extraction – Minerals such as gold and iron ore are mined and sold. Trees are cut down to expose the ground, and to clear access routes.
  • Commercial logging – trees are felled for pure profit.
  • Population pressure – Trees are cleared to make new settlements as population increases and demand for space increases.
  • Road building – More settlements and industry lead to more roads being built, so trees are cleared to build them.

Environmental Impacts of deforestation

  • Fewer trees mean fewer habitats and food sources for animals and birds, reducing biodiversity as organisms must move or die out.
  • With no trees to hold the soil together, heavy rain will wash it away, taking away with it the nutrients
  • This soil is often washed into the river, where it can kill aquatic life and make the water undrinkable
  • Without a tree canopy to intercept rainfall and tree roots to absorb it, more water reaches the soil, increasing the risk of flooding, and reducing soil fertility. This makes it less likely that plant life can re-grow in the area
  • Without trees there is no leaf fall, and no nutrient supply to the soil – so it is less fertile
  • Trees cannot photosynthesis, replacing carbon dioxide with oxygen. In addition, burning vegetation to clear the forest produces more carbon dioxide and other pollutants. GLOBAL WARMING
  • Without trees, water is not removed from the soil and evaporated into the atmosphere – reducing cloud formation and therefore rainfall; so overall climate is indirectly impacted.

Social impacts of deforestation

  • Quality of life for some local people improves as more jobs become available.
  • Livelihoods of some people are destroyed, as deforestation can cause the loss of animal and plant life – which some people depend on to make a living.
  • Some native tribes have been forced to move when trees have been cleared
  • There are often conflicts between native people, landowners, mining companies and logging companies over land use

Economic impact of deforestation

  • A lot of money is made from selling timber & products; mining and commercial farming
  • These industries also create many jobs in the area

 

Sustainable Management

Selective Logging

  • Only some trees are felled, most are left standing
  • This is less damaging to the environment than outright felling, as the overall structure of the forest is maintained; i.e. the canopy is still in place, so the forest can regenerate and be used in the future
  • In addition, instead of using trucks to clear trees, other methods such as horse and helicopter felling are used to clear trees

Replanting

  • New trees are planted to replace the ones which have been cut down
  • This means trees are conserved for the future
  • The same type of tree that has been cut down is normally replanted, so that species variety is maintained for the future
  • Environmental laws protect many countries’ forests, ensuring logging companies replant trees they have felled

Reducing Demand for Hardwood

  • Hardwood is the term given to wood from certain tree species, including mahogany and teak. The wood tends to be dense and hard, and it is used to make furniture, among other things
  • There is a high demand from richer companies for hardwood
  • This has led to some tropical hardwood trees becoming rarer as people chop them down and sell them
  • Some richer countries are trying to reduce demand, so that fewer of these species are cut down, and they are available for future generations to use
  • Such strategies include heavily taxing imported hardwood or banning its sale
  • Some countries with tropical rainforests ban logging of hardwood species

Education

  • Some local people do not know what the environmental impacts of deforestation are. Often locals are just trying to make money in the short-term, to overcome their own poverty
  • Educating these people about the impacts of deforestation, and how to reduce them, will decrease their effect on the environment
  • Education also focuses on alternative ways to make money without damaging the environment
  • This all means the rainforest is conserved for the future
  • Educating the international community about the impacts of deforestation will reduce demand for hardwood products, and may also put pressure on governments. It may also stimulate eco-tourism in tropical rainforests

Reducing Debt

  • Many tropical rainforests are in less economically developed countries – such as Nigeria, Belize & Burma
  • A large number of these countries are in debt to richer countries and organisations such as the world bank; they have allowed damaging activities such as logging, farming and mining to take place, in an attempt to reduce debt
  • Reducing or cancelling debt would mean countries no longer need to do this, however there is no guarantee the money would be spent on conservation. Many of these countries are also rife with corruption.
  • Conservation, or debt-for-nature, swaps guarantee money is spent on conservation, as the richer country pays off the debt in exchange for an investment in conservation

Protection

  • Environmental laws can be put in place to protect rainforests, for example banning the logging of certain tree species, banning illegal logging, and banning the use or sale of wood from non-sustainably managed forests
  • Many countries have set up national parks and nature reserves within rainforests, in which damaging activities such as logging are restricted or banned. However, lack of funds or resources can make it difficult to police these restrictions. In addition, corruption can mean that illegal logging takes place while officials ‘turn a blind eye’

Ecotourism

  • Ecotourism is tourism which does not harm the environment, and benefits local people
  • Ecotourism provides a source of income for local people – they can act as guides, provide accommodation and transport, etc.
  • This means logging and farming are relied on less to generate income; and so fewer trees are cut down, preserving them for the future
  • Ecotourism is generally small-scale, with only small numbers of tourists in an area at a time. This helps to minimise the environmental impact of the tourism
  • Ecotourism causes little harm to the environment; e.g. by ensuring waste and litter are disposed of properly, water and land contamination is prevented
  • Ecotourism helps the sustainable development of an area because quality of life is improved without preventing future generations from using the same resources
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