- Estimated to be storing 80-120 billion tonnes of carbon.
- The above ground biomass in the Amazon is increasing by 0.3-0.5% per year which is because increasing atmospheric carbon levels encourage more plant growth, an example of a negative feedback loop.
- Since the 1990s, the net uptake of carbon by vegetation has halved as there is too much carbon to now absorb.
- This has been overtaken by fossil fuel emissions in Latin America, this means the release of carbon dioxide is greater than the removal of it from the atmosphere.
- Greater amounts of carbon dioxide increase the growth rate of trees, so they live faster and die younger. This has resulted in a surge of tree deaths throughout the Amazon.
Water in the Amazon
- The average discharge into the Atlantic from the Amazon is around 175,000m3 per second. This accounts for about 15% of the total freshwater entering oceans every day.
- Approximate annual rainfall throughout the entire Amazon is 2300mm, but up to half of this will never reach the ground
- Of all the rain which goes back into the atmosphere by evapotranspiration, around 43% falls again as rain, and only 30% reaches the sea, this is a constant closed-loop system.
Drivers of Change to the Cycles in the Amazon
- Between 2000 and 2007, the Amazon was deforested at a rate of 19,268km2 per year, this meant that during this time span, an area of forestry larger than Greece was removed.
- Brazil is the 4th largest climate polluter and 75% of its greenhouse gas emissions are due to deforestation.
- Slash-and-burn techniques are often used to remove forest which results in many negative impacts including reduced humidity in top layer of soil with the facilitation of the sudden evaporation of water which was previously held in the forest canopy.
- This increased albedo, reflectiveness and temperature which reduced porosity of soil leading to faster rainfall drainage, erosion and silting of rivers and lakes.
- When there is evaporation from deforested areas, it forms cumulous clouds that do not hold or produce rain.
- When transpiration occurs from vegetation, it releases water, also with salts and organic fibres which act as condensation nuclei in the sky which help in cloud and rain formation with a loss of vegetation.
- Therefore, transpiration means there are less condensation nuclei so inhibits cloud formation and reduces rainfall.
- There are vast differences between forest and the pasture land which replaces it:
- Forests absorb 11% more solar radiation.
- The average temperature in the forest is 24.1⁰, and in pasture land it is 33⁰ – means higher soil temperatures in pasture land.
- Moisture content in the upper 1m of pasture soil is 15% less than the soil in nearby forests.
Deep forest roots pump more soil moisture to the surface which produces 20-30% more air humidity and therefore 5-20% more precipitation than pastures.