Lesson 14.5- The carbon cycle in the tropical rainforest Flashcards
How is carbon stored in the amazon?
- It absorbs 2.4 billion tonnes/yr of carbon in biomass
- 17% of the global land vegetation carbon stock.
- The Amazon forms part of a rainforest carbon sink of 1-3 GT of carbon/yr.
- 40% of carbon in tropical rainforests is found below ground in root systems and organic matter in soil
How is carbon transferred in the amazon
- Transfers of carbon between the atmosphere, biosphere and soil are rapid.
- Warm and humid conditions so fast decomposition of dead organic matter. Rates of carbon fixation through photosynthesis are high.
Inputs of carbon in the amazon
- Photosynthesis: The Amazon absorbs around 2 billion tonnes of carbon dioxide annually, acting as a major carbon sink.
- Decomposition: Dead plants and animals release carbon, contributing to the 123 billion metric tonnes of carbon stored in biomass and soil.
- Human Activities: Deforestation and burning have turned parts of the Amazon, like the southeast, into carbon emitters.
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Outputs of carbon in the amazon
- Decomposition transferring carbon from the biosphere into the pedosphere (soil) which is then transported in run off into rivers and the ocean
- Respiration transferring carbon from the biosphere back into the atmosphere
- Deforestation transferring carbon from the biosphere to the atmosphere.
What are the physical factors affecting the stores of carbon in the amazon?
- Temperature
- Vegetation
- Organic matter in soil
- Mineral composition in rocks
Physical factors affecting the stores of carbon in the amazon- Temperature
- High temperatures (as well as high rainfall and intense sunlight) mean high rates of photosynthesis.
- Also, high temperatures promote rapid decomposition as microbes can break down cellulose quickly.
- Decomposition releases nutrients to the soil for immediate take-up by tree root systems. This all leads to a large biomass store.
Physical factors affecting the stores of carbon in the amazon- Vegetation
- Warm and wet climate creates dense vegetation. This means large fluxes of photosynthesis, absorbing carbon dioxide. This makes the atmospheric carbon store small and the biomass store large.
Physical factors affecting the stores of carbon in the amazon- Organic matter in soil
- Tropical soils are strongly leached by heavy precipitation. Layer of topsoil holds huge amounts of carbon due to rapidly decomposing leaf litter and also the extensive root systems.
- Decomposition and respiration creates a large flow of carbon transfer to the atmosphere.
Physical factors impacting the stores of carbon in the amazon- Mineral composition in rocks
- Carbonates are found close to the Andes Mountains, but most of the Amazon basin is granites.
- Chemical weathering plays an important role in soil formation- carbonate rocks are weathered quickly, releasing carbon into soil. However, granites do not contain much carbon so there aren’t large fluxes into the soil.
What are the human factors causing change in the carbon cycyle in the Amazon?
- Deforestation
- Converting lands into croplands and pasture
Human factors causing change in the carbon cycyle- Deforestation
- Deforestation decreases the carbon above ground biomass store. Removal of roots leads to reduction of below ground biomass. Photosynthesis and respiration reduced.
- Also reduces inputs of organic material to soil. Soil depleted of carbon and exposed to strong sunlight supports fewer saprobionts, reducing the flow of carbon from the soil to the atmosphere.
Human factors causing change in the carbon cycle- Converting lands into croplands and pasture
- Converting land to croplands and pasture contain only a small amount of carbon compared to forest trees.
- Biomass of grasslands is 16.2 tonnes/ha and soya cultivation is just 2.7 tonnes/ha.
How is the carbon cycyle impacted by humans- The natural carbon cycle
1) Trees suited to humid and warm conditions, which promotes photosynthesis.
2) They absorb large amounts of carbon dioxide from the atmosphere acting as an important carbon sink.
3) Decomposition and respiration releases CO₂ back to the atmosphere and soil, where carbon is stored.
How is the carbon cycle impacted by humans- Human/deforestation rainforest carbon cycle
1) Lack of trees so photosynthesis is reduced.
2) Fires to clear land leads to CO₂ being released into the atmosphere. Forests become a carbon source instead of a carbon sink.
3) Lack of life until new plants grow.
4) Low rates of decomposition occurs in this environment.
How do the water and carbon cycles interact?
1) Water evaporates of trees in the rainforest.
2) Condensation occurs clouds form and we get convectional rainfall.
3) Some of this rain, rains on deforested land we get soil erosion and surface run off.
4) This causes soil (containing carbon) to flow into rivers.
5) This decreases the carbon content of the soil and increases the carbon content of the rivers.
6) The water leaves the rainforest water/carbon cycle as an output in a river as there is not as much interception and there is more surface run off.
7) This means there is less evaporation as there is less water in the rainforest.
8) This means there will be less precipitation
9) This can cause droughts and desertification and more trees will die and habitats will be lost (carbon released from the biosphere into the atmosphere)
10) This desertification causes even less evapotranspiration and even less rainfall.
Impacts of climate change on the Amazon.
- Effect on nutrients
- Varying temperature conditions
- Flooding-Mangroves
Impacts of climate change on the Amazon- Effect on nutrients
- The impact of reduced rainfall is a change in nutrient input into streams and rivers, which can greatly affect aquatic organisms.
-Managed by: Reduce deforestation to stop changing the water cycle
Impacts of climate change on the Amazon- Varying temperature conditions
- A more variable climate and more extreme events will also likely mean that Amazon fish populations will more often experience hot temperatures and potentially lethal environmental conditions.
-Managed by: International agreements to limit atmospheric carbon levels
Impacts of climate change on the Amazon- Flooding-Mangroves
- 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.
- Sea-level rise, increased temperature, changes in rainfall and runoff will likely cause changes in species habitats such as mangrove ecosystems
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-Managed by- Sea defences can be created in coastal areas and rivers can be engineered however this will be very expensive.
-Managed by- Mangroves can be replaced with more salt resistant varieties.
How can we manage the rainforest?
- Legislation of large expanses of primary rainforest
- Afforestation projects
- Improving farming techniques
How can we manage the rainforest- Legislation of large expanses of primary rainforest
-ARPA is funded by the Brazilian government, WWF and the World Bank.
-Protects the primary rainforest from commercial development
- 1998 - the Brazilian government established many forest conservation areas.
- 2015- 44% of the Brazilian Amazon comprised of national parks, wildlife reserves and indigenous reserves with no deforestation allowed.
- 2003 – aim was to increase ARPA to 10% of Brazil’s Amazon rainforest by 2013. This has been reached and beaten.
- 2023 - ARPA now protects 44% of the Amazon, including 15% of this in Brazil.
- Future - Aim to improve satellite monitoring of TRF with real time data, so central authorities can quickly notify police and environmental officials about illegal deforestation
How can we manage the amazon rainforest- Legislation of large expanses of primary rainforest
-Evaluation
-Between 1998-2014 6% of the protected areas were deforested and 40% of this was for hydro electric power development
-President Bolsonaro wants to allow more exploitation for economic development - 2,622 applications have been submitted for mining in
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+Protected areas reduced deforestation by 21% between 2008 and 2020
+ARPA has been credited with a 37% decrease in deforestation in the Amazon between 2004-2009.
How can we manage the amazon rainforest- Afforestation projects
- The Surui Carbonation Project and REDD
- Surui people working in cooperation with Google Earth to request satellite photos if they spot illegal logging or mining and report it to the authorities.
- Surui plant native fast-growing tree seedlings which enable them use timber to construct their wooden huts.
- The Surui now receive an income for protecting the rainforest. The payment has been mainly funded by the carbon credit scheme.
- Natura, a cosmetics TNC, purchased 120,000 tonnes of carbon credits in 2013. The money is used to fund the Surui Forest Carbon Project.
How can we manage the Amazon Rainforest- Afforestation projects
-evaluation
-Not applicable for all indigenous people who live in the wild
-Was suspended in 2018 after the discovery of large gold deposits in the territory sparked a surge in deforestation
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+First project lead by indigenous people which got buy in from the local community
+Between 2009-2014 did the equivalent of removing 64,000 cars from the road and generated 299,895 carbon offsets.
