The Amazon Rainforest Case Study Flashcards
How much of South America does the Amazon Rainforest cover?
The Amazon is the world’s largest tropical rainforest and covers 40% of the South African landmass.
How does the water cycle affect the Amazon Rainforest?
The water cycle causes the Amazon to be very wet - there is a lot of evaporation over the Atlantic Ocean, and the wet air is blown towards the Amazon. This contributes to the Amazon’s very high rainfall.
Warm temperatures mean that evaporation is high in the rainforest itself, which increase the amount of precipitation.
The rainforest has a dense canopy - this means that interception is high. As a result, less water flows into rivers than might otherwise be expected, and does so more slowly.
The water cycle affects the Amazon environment - it is population by species that are adapted to high humidity and frequent rainfall.
How does the carbon cycle affect the Amazon Rainforest?
The Amazon rainforest stores lots of carbon in its vegetation and soil, so its a carbon sink. The increasing concentration of CO2 in the atmosphere has led to increased productivity in the Amazon rainforest because the vegetation is able to access more CO2 for photosynthesis - the amount of biomass has been increasing.
As a result, the amount of CO2 sequestered by the Amazon rainforest has increased, making it an even more important carbon store.
However, it has been suggested that although trees are growing more quickly, they’re also dying younger. As a result, we may not be able to rely on the Amazon rainforest to continue to be such an effective carbon sink in the future.
Describe the effects that deforestation has on the water cycle?
In deforested areas there is no tree canopy to intercept rainfall, so more rainfall, so more water reaches the ground surface. There is too much water to soak into the soil. Instead the water moves to rivers as surface runoff, which increase the risk of flooding.
Deforestation reduces the rate of evapotranspiration this means less water vapour reaches the atmosphere, few clouds form and rainfall is reduced. This increase the risk of drought.
Describe the effects that deforestation has on the carbon cycle?
Without roots to hold the soil together, heavy rain washes away the nutrient rich top layer soil, transferring carbon stored in the soil to the hydrosphere.
Deforestation means that there is less leaf litter, so humus isn’t formed. The soil cannot support much new growth, which limits the amount of carbon that is absorbed.
Trees remove CO2 from the atmosphere and store it, so fewer trees means more atmospheric CO2, which enhances the greenhouse effect and global warming.
Describe the effects of climate change on the Amazon Rainforest?
Climate change can severely impact tropical rainforests. In some areas temperature is increasing and rainfall is decreasing, which leads to drought. The Amazon had severe droughts in 2005 and 2010.
Plants and animals living in tropical rainforests are adapted to moist conditions, so many species die in dry weather. Frequent or long periods of drought could lead to extinction of some species. Drought can also lead to forest fires, which can destroy large areas of forest, releasing lots of CO2 into the atmosphere.
Scientists predict that a 4 degree temperature rise could kill 85% of the Amazon rainforest. This would result in lots of carbon being released into the atmosphere as the dead material decomposed, and less carbon dioxide being taken in from the air by trees for photosynthesis.
Describe the process of selective logging?
Only some trees are felled and most are left standing. This is less damaging to the forest than felling all the trees in an area. If only a few trees are taken from each area the forest structure is kept - the canopy is still there and the soil isn’t exposed. This means the forest is able to regenerate, so the impact on the carbon and water cycle is small.
Describe the process of replanting?
New trees are planted to replace the ones that are cut down. For example, Peru planes to restore 3.2 million hectares of forest by 2020. Its important that the same types of tree are planted that were cut down, so that the variety of trees is kept for the future and the local carbon and water cycles return to their initial state.
Describe environmental laws put in place to protect rainforests?
Laws that ban the use of wood from forests that are nor managed sustainably.
Laws that ban excessive logging.
Laws that control land use, the Brazilian Forest Code says that landowners have to keep 50-80% of their land as forest.
How are some countries protecting their rainforests?
Many countries have set up national parks and nature reserves to protect rainforests. For example, the Central Amazon Conservation Complex in Brazil was set up in 2003 and protects biodiversity in an area of 49000km while allowing local people to use the forest in a sustainable way.
Within national parks and nature reserves, damaging activities such as logging can be monitored and prevented.
