How many trees are there in the Amazon?
300 billion trees
How much of all the carbon in the planets biomass is stored in the Amazon?
What is the inter-tropical convergence zone?
Where two hadley cells meet at the equator, here the air pressure is low and evapotranspiration happens in huge amounts causing lots of rain. This in turn leads to the rich vegetation and biodiversity of the tropical rainforest
Explain the Amazon in terms of the water cycle.
High humidity levels and unstable weather results in heavy rainfall most days. 75% of this total rainfall is intercepted by the trees and then to the ground through stem flow. However this is being reduced due to heavy deforestation.
25% of all the rain evaporates
Of the remaining 75%, half is used by plants and eventually returned to the atmosphere through evapotranspiration.
The other 50% is infiltrated through the soil or flows overland into nearby channels.
How does anthropomorphic change influence evapotranspiration?
- As evapotranspiration is reduced the atmosphere becomes less humid.
- Transpiration will rapidly decrease.
- With fewer trees, most rainfall will go straight to the floor encouraging surface flow as soils become dry and baked as it becomes more exposed to the sun.
- Reduced evapotranspiration from cleared areas mean the air is less moist, resulting in a reduction in cloud cover.
- The removal of trees through slash and burn facilitates sudden evaporation of water that was previously retained in the forest canopy.
How does anthropomorphic change influence precipitation?
- Particles resulting from burning of trees increases the density of airborne aerosols around which water vapour condenses. As a result, smaller droplets occur in the clouds which are too small to precipitate, resulting in less local rainfall.
- Forests emit salts and organic fibres along with water when they transpire. These act as condensation nuclei and assist in cloud and rain production. Their loss inhibits the formation of cloud and therefore rainfall.
- Any moisture that does evaporate from deforested areas forms shallow cumulous clouds which do not produce rain
How does anthropomorphic change influence flooding?
- Increased surface run off will result in a high risk of flooding.
- The removal of trees through slash and burn reduces porosity of the soil, causing faster rainfall drainage, erosion and silting of rivers and lakes
- Spracken et al. 2012 found that further deforestation in the Amazon could result into a 20% decline in regional rainfall as air blowing from the rainforest contains less moisture.
Explain the Amazon in terms of the carbon cycle.
- The warm and wet tropical climate is ideal for plant growth. This promotes the process of photosynthesis.
- This absorbs huge quantities of carbon dioxide from the atmosphere.
- In return, the rainforests emit oxygen.
- ‘Lungs of the earth’ – a term used to describe the impact of tropical rainforests.
- Wood is about 50% carbon, so rainforests themselves are a huge store as well as a sink in mitigating the effects of global warming
- Respiration by plants, trees and the many animals return co2 back to the atmosphere
- Decomposition is an active process. Bacteria and fungi thrive in the warm, wet conditions. This then releases co2 back into the atmosphere
- Some carbon may also be stored within the soil or dissolved and then removed by streams as an output from the rainforest system
Explain how humans impact the carbon cycle of the Amazon.
- Amazon has shrunk by 0.3% since 2000.
- In a typical year the Amazon absorbs 2.2b tonnes of co2, whilst emitting 1.9b tonnes through decomposition and respiration of organisms. However its capacity to absorb carbon is declining. In the 1990s, the Amazon was absorbing 2 billion tonnes, by 2015 this had decreased to just 1 billion tonnes.
- Photosynthesis ceases until new plant growth begins. This is by the far the most significant impact of deforestation on the carbon cycle
- Rain washes ash into the ground. This increases the carbon content in the soil. In heavy rainfall, carbon in runoff may increase too.
Explain the Tarapoto Process
Began in 1995
Forest policy makers from 8 member countries identified 12 criteria to help manage the forest sustainably at management, national and global level
National level priorities included:
* Investment in research, education and technology transfer
* Existence of policies and a legal framework for land-use planning through ecological and economic zoning
* Management level included
* Proportion of environmental protection areas as against permanent production areas
Explain the Amazon Co-Operation Treaty Organisation
Aimed at promoting sustainable development
8 member countries
Reverse the loss of forest cover worldwide through sustainable forest management, including protection, restoration, afforestation and reforestation, and increase efforts to prevent forest degradationMonitor and prevent illegal logging
Protected areas at the regional levels through conservation corridors going though more than one country