The Amazon Rainforest

where is the amazon rainforest located?

spans across 9 countries and covers 40% of south America

• nearly 60% of the rainforest is in brazil

• the rest is shared among the other 8 countries such as: colombia, ecuador, peru and venezuela

• covers 2.1 million square miles of land

what are the inhabitants of the amazon rainforest?

• 16,000 species of tree

• 30 million people

• 20% of all species on earth

what is the discharge of the rainforest into oceans

20% of freshwater entering the oceans each day.

175,000 cubic meters per second

what is the climate of the amazon rainforest like?

• 2300m annually but can exceed 6000mm in the NW areas

• the average temp in rainy season is 26ºC and 28ºC in the dryer seasons

• humidity stays high all year ranging from 77%-88%

what portion of rainfall on the amazon ends up being discharged into oceans…

only 1/3, it is estimated that…

1. up to 50% in some areas may never reach the ground (75% intercepted but some drips down from leaves or as stemflow) and is evaporated into the atmosphere via transpiration

2. additional evaporation occurs from the ground and river surfaces

3. this contributes to formation of clouds which release the water back into rainforests as rain (50-80% of water remains caught in the ecosystems water cycle)

how may water remain in a closed system in the rainforest?

• a single molecule of water can be re-cycled many times from when it leaves the surface of the atlantic ocean, carries by westerly prevailing winds, to when it is taken back to the ocean.

How does the carbon cycle operate in the amazon rainforest?

wood is almost 50% carbon, and with over 16,000 species of tree it is a huge carbon sink

warm wet climate is perfect for plant growth and promoted photosynthesis absorbing CO2 and emitting large amounts of oxygen ‘lungs of the earth’

decomposition is an active process where decomposers thrive in wet and warm conditions releasing some CO2

some carbon is stored in the soil, and can dissolve into the water and travelling out of the system as an output.

What is the main cause of change in the amazon rainforest?

deforestation.

between 2000 and 2007 brazilian rainforest was deforested at a rate of 19.4km squared per year (area larger than greece destroyed in this time)

brazil is world’s 4th largest climate polluter with 75% of emissions attributed to deforestation and land use change

Why does deforestation occur so much in the amazon rainforest?

generally result of land clearances for…

• agriculture

• mining

• logging

• road building

• energy development

• settlements and population growth

How does deforestation in general impact the water cycle?

• reduced evapotranspiration = leads to less moisture being returned to the atmosphere. this can decrease humidity and result in reduced plant growth

• change in rainfall patterns = disrupts the recycling of water meaning less rain will fall in certain areas

• increased runoff and erosion = without protective canopy of trees rainfall directly hits the ground and causes increased runoff as the ground will quicker reach its field capacity. in some areas of the rainforest erosions rates have been as high as 200 tonnes of soil per hectare per year.

• Flash floods are more likely to happen as there is less interception and absorption by the forest cover.

• interruption of normal water cycling has resulted in more droughts in the forest, increasing the risk of wildfires

• More soil and silt is being washed into rivers, resulting in changes to waterways and transport

How does deforestation in general impact the carbon cycle?

• reduced carbon sequestration = the amazon rainforest is predicted to store 90-140 billion metric tons of carbon, one of the largest carbon sinks on the planet. removal of preet causes this to be released from the store and makes the forest a far less effective sink.

• feedback loops = deforestation can lead to less evapotranspiration altering the climate, changing the ability for plants to grow, altering temperatures and potentially leading to droughts.

• impacts on climate change = release of carbon via deforestation contributes to climate change and greenhouse gas concentrations in the atmosphere become greater. this can alter the climate and impact the ability for habitats to adapt to this change.

• Tropical soils contain a lot of carbon = The top meter holds 66.9 PgC with around 52% of this carbon pool held in the top 0.3 m of the soil, the layer which is most prone to changes upon land use conversion and deforestation.

logging in the brazilian amazon…

• involves cutting down trees for sale as timber or pulp. 

• The timber is used to build homes, furniture, etc. and the pulp is used to make paper and paper products. 

• Logging can be either selective or clear cutting.

• August 2019-July 2020 logging in brazilian amazon cleared 464,000 hectares

mineral extraction in the amazon…

• forests are also cleared to make way for huge mines.

• Brazilian part of the Amazon has mines that extract iron, nickel, tin, copper, lead, zinc and gold.

road building in the amazon…

• essential way for the Brazilian government to allow development of the Amazon rainforest. 

• However, unless paved many of the roads are unusable during the wettest periods of the year. 

• Trans Amazonian Highway has already opened up large parts of the forest and now a new road is going to be paved

• BR163 is a road that runs 1700km from Cuiaba to Santarem. The government planned to tarmac it making it a superhighway. This would make the untouched forest along the route more accessible and under threat from development.

energy development in the amazon…

• Hydro Electric Power, and there are 150 new dams planned for the Amazon alone.   

• The power in the Amazon is often used for mining. 

• Dams displace many people and the reservoirs they create flood large area of land, which would previously have been forest.  They also alter the hydrological cycle and trap huge quantities of sediment behind them.

• The huge Belo Monte dam started operating in April 2016 and will generate over 11,000 Mw of power. 

Settlement and population growth in the amazon…

• Many people are migrating to the forest looking for work associated with the natural wealth of this environment.

• Settlements like Parauapebas, an iron ore mining town, have grown rapidly replacing forest with a swath of shanty towns. The population has grown from 154,000 in 2010 to 220,000 in 2012.

• The Brazilian Amazon’s population grew by a massive 23% between 2000 and 2010, 11% above the national average.

How does degradation of rainforests contribute to climate change?

• Tropical forests are very important carbon sinks, but deforestation and degradation are turning these sinks into carbon SOURCES. 

• deforestation releases the carbon stored within the trees back into the atmosphere.

• Around 30% of anthropogenic carbon emissions come from burning the rainforests alone.

• Forests that experienced disturbances such as logging and fires store 40% less carbon than undisturbed forests.

• This makes climate change alone a major impact of tropical forest destruction with respects to the carbon cycle.

How can a positive feedback loop be created due to deforestation?

increases in climate change are making the SSE amazon rainforest more vulnerable to wildfires causing an increase in atmospheric aerosol, contributing further to climate change

what is atmospheric aerosol?

small particles of solids, like dust, and liquids, like water, suspended in the atmosphere

More aerosol particles can lead to more, but smaller, cloud droplets. This may reduce the rain that falls from that cloud.

What effects is climate change having on the amazon rainforest?

• Many species will either be unable to move or will have nowhere to go as the environment no longer is suitable.

• Higher temperatures will impact temperature-dependent species like fish, causing their distribution to change.

• Reduced rainfall and increased temperatures may potentially lead to an increase in invasive species, which can out-compete native species.

• The impact of reduced rainfall is a change in nutrient input into streams and rivers, which can greatly affect aquatic organisms.

• Flooding associated with sea-level rise will have substantial impacts on lowland areas such as the Amazon River delta. The rate of sea-level rise over the last 100 years has been 1.0-2.5 mm per year, and this rate could rise to 5 mm per year.