Why should tropical rainforests matter to us?

• Distribution of the equatorial climate

  • the TRF biome is mainly found in a band between 15 degrees north and south of the equator within the equatorial climate zone.
  • only covers 6% of the Earth's surface.
  • Amazon, largest remaining rainforest on Earth, usually associated with Brazil, covers several other countries.
  • Central America, including Belize, Costa Rica and Panama.
  • Central Africa, including Cameroon, Guinea and Gabon.
  • Indo-Malaysia, including Malaysia and Indonesia.
• Climate characteristics

  • location, low latitudes within 23.5 degrees north and south of the equator, South America, Asia and Africa.
  • annual precipitation, over 2000mm.
  • temperature range, average temperature between 26-28, constant high temperatures, diurnal range of 7 degrees.
  • no seasons, hot and wet all year, high humidity over 75-80%.
  • many soils are latosols, due to leaching and rapid uptake of nutrient by plants, soil is not very fertile, nutrients concentrated in the upper topsoil.
  • contain the highest biodiversity on Earth, 50-80% of all plant and animal species.
• Structure of the tropical rainforest

  • ground layer 0m
  • shrub layer 3-4m
  • under canopy 15m
  • canopy 30m
  • emergent 45-55m
  • all parts are interdependent, a change in one part affects others, deforestation leads to the loss of habitats and reduction in biodiversity, loss of trees impacts the nutrient cycle.

  
• Nutrient cycle

  • TFR have a continual growing season with high rainfall and temperatures all year round.
  • trees and plants lose their leaves, high levels of moisture and temperatures lead to rapid decomposition and recycling of nutrients.
  • plants grow quickly which leads to a rapid uptake of nutrients from the soil.
  • most nutrients is stored in biomass, few stored in soil and litter.
  • result of rapid nutrient cycle is that the soil in not very fertile.

  
• Soil

  • deep soils that rely on the rainforest to maintain fertility.
  • nutrients leached away quickly when the forest is felled and the layer of humus is no longer being replaced.
  • they are very infertile as the layer of topsoil and organic matter is thin, the soil is acidic due to the rapid leaching of nutrients due to heavy rainfall.
  • rapid plant growth means that any nutrients are rapidly taken up by plants and there's a lack of weathered rock due to the depth of the soil.

  
• Water cycle

  • precipitation is intercepted by the rainforest canopy, this protects the soil from erosion.
  • water on the trees and plants evaporate rapidly due to the high temperatures, leading to cloud formation and high levels of precipitation.
• Interdependence in the tropical rainforest

  • Zam trees produce seeds for agouti to eat and to disperse and help germinate but agouti are hunted for meat meaning less seeds are able to grow.
  • important medical plants and plant and animal species become extinct.
  • Indigenous communities are forced to abandon their traditional lifestyle due to the lack of food to hunt and gather.
• Human threats to the rainforest biodiversity

  • agriculture, particularly large scale slash and burn.
  • mining and logging.
  • hydroelectric power.
  • road building and settlements.
  • wildfires, linked to climate change caused by humans.
• Goods

  • tangible products which can be taken from the ecosystem.
  • building materials.
  • existing food crops and wild meat and fish.
  • water.
  • energy.
  • medicines.
• Services

  • services provided by the ecosystems are essential for life to survive.
  • gas exchange and climate regulation, important on a global as well as local level as plants and trees absorb CO2 during photosynthesis and emit oxygen, referred to the lungs of the world, the tropical rainforest is one of the largest global carbon sinks.
  • nutrient recycling and water cycle and soil quality.
  • disease and pest control.
  • leisure and recreation.
  • cultural heritage.
• Value to people

  • Indigenous communities like Awá in Brazil depend on the rainforest for food, materials, fuel and medicines.
  • people obtain food by hunting, gathering and fishing.
  • homes, clothes and tools are made from the natural resources of the forest.
  • land is cultivated in small areas at a time though a process called shifting cultivation.
• Products of the rainforest

  • gold, iron ore and other valuable minerals.
  • sugars, nuts and bananas.
  • rubber and perfumes.
  • many modern medicines come from rainforest plants including 25% of ingredients used in cancer treatment drugs.
  • hydroelectric power is common due to the amount of available water.
• Value to the environment

  • provides 20% of the world's freshwater.
  • over 50% of the world's plants and animals are found in TRF.
  • rainforests are vital in controlling the amount of CO2 in the atmosphere so limiting global warming.
  • tree and plant roots hold soil together and shelter the ground, reducing soil erosion.
• Human impacts on tropical rainforests

  • the main impact is deforestation.
  • wildfires are a natural cause of deforestation but the frequency and severity of them have increased with a link to human caused climate change.

  
• Logging

  • felling trees for timber.
  • indigenous people have done this on a small scale for thousands of years.
  • now with the building of roads into rainforests it is done on an industrial scale and the timber is often exported to the USA or Europe for furniture and construction.
  • tropical hardwood trees like teak are very popular.
• Mineral extraction

  • takes place in rainforests especially for gold, copper and diamonds.
  • the forest and soil are removed from large areas for open cast mining.
  • chemicals used in the mining process pollute the rivers.
  • oil and gas are also found deep below the ground and drilling for them can lead to air and water pollution.
  • building roads for pipelines leads to further destruction of rainforests.
• Agriculture

  • involves clearing trees in order to use the land.
  • poor farmers clear small areas of forest to feed their families.
  • when the soil loses fertility they move on to clear a new patch of forest rather like shifting cultivators.
  • in the Amazon most farming is carried out by big companies that clear vast areas of land to grow soya beans or graze cattle, as Brazil is the world's largest producer of beef and soya.
• Tourism

  • an alternative way to use the rainforest without chopping its trees down.
  • some countries have created protected areas of forest where deforestation is banned.
  • indigenous people can be involved in protecting the forest and continue to lead their traditional way of life.
  • foreign tourists like to visit rainforests and this can help the local economy.
• Environmental impacts of deforestation

  • deforested areas are planted with monoculture which reduced biodiversity.
  • interception and infiltration decrease which reduces evapotranspiration and as a result precipitation decreases, also overland flow increases which leads to soil erosion and sedimentation of rivers.
  • sediment builds up on riverbeds, reducing their capacity and increasing flood risks.
  • lack of interception increases the leaching of nutrients.
  • les trees increase the amount of CO2 in the atmosphere adding to the enhanced greenhouse effect.
  • soils become less fertile and drier.

  
• Social impacts of deforestation

  • indigenous communities have less land to sustain their traditional way of life meaning land does not get the opportunity to recover and less food is available.
  • this means there is a loss of culture and tradition.
  • improved quality of life for some people due to increased income and jobs.
  • increased risk of landslides which can destroy homes and block roads.
  • loss of potential medicines.
  • increased risk of flooding settlements.
• Economic impacts of deforestation

  • more jobs available in mining, forestry, agriculture and HEP.
  • increased income for the country through the export of goods from the forest like minerals, timber and crops.
  • almost 1/4 of Brazil's GDP comes from activities in the deforested areas of the Amazon.
• Rate of deforestation

  • the global rate of deforestation peaked in 1980 when 151 million hectares of forest was felled.
  • the rate has slowed to a 47 million hectare net loss, the number of trees felled minus the number planted.
  • this is due to the increasing recognition of the value of rainforests as natural capital.
• Costa Rica case study

  • located in Central America and is home to 6% of the worlds biodiversity and attracts 2 million tourists a year.
  • tropical rainforests, cloud forests and dry forests.
  • mangroves, beaches, coral reefs and volcanoes.
• Sustainable management of tropical rainforest

  • deforestation in Costa Rica peaked in 1985 and since then the rate of deforestation has declined to almost 0.
• Sustainable management strategies 1

  • agroforestry, trees and crops grown together, some crops benefit from the shelter of the tree canopy, trees prevent soil erosion an crops benefit from the nutrients in leaf litter.
  • selective logging, trees are felled only at a certain height, young trees are allowed to mature to ensure the canopy height is maintained.
• Sustainable management strategies 2

  • afforestation, trees are planted to replace the original primary forest lost, however this secondary forest lacks the biodiversity of the first as it takes a long time for species to re-establish.
  • monitoring, satellite technology and photos are used to ensure that no illegal activities are taking place and that landowners follow guidelines for sustainability.
• Ecotourism

  • sustainable development that aims to create local employment while conserving the natural environment.
  • it doesn't damage the natural environment and is on a relatively small scale.
  • it consults with the local community about planned developments.
  • it ensures that infrastructure improvements benefit local people as well as tourists.
• Samasati Nature Retreat

  • no heavy machinery was used in the construction.
  • employs only local people.
  • colours of buildings blend with the landscape, and buildings fit between trees so none were destroyed and are on stilts to reduce humidity and allow natural drainage.
  • drinking water comes from natural springs.
  • timber came from an afforestation project in Costa Rica.
  • natural light and ventilation minimise energy use.
  • only biodegradable soap detergents and shampoo are allowed.
  • rainwater collected in roots and used for toilets and showers.
• Ecotourism activities in Samasati Nature Reserve

  • bird watching.
  • canopy exploration.
  • horseback riding.
  • sea and river kayaking.
  • walking and hiking.
  • white-water rafting.
  • yoga and meditation.