Amazon Rainforest

• Tropical rainforests cover just 6% of the earth's surface but they account for 30-50% of global photosynthesis
• Estimates show that the Amazon basin has lost over 17% of it's primary forest in the last 50 years
• Causes of Amazon rainforest loss

  • Cattle ranching (80%)
  • Mostly in the South and East parts of the basin (brazil) and in the north-western arc (Columbia and Ecuador)
• Forest scrub that replaces trees absorbs 40% less carbon
• When burned for land clearance, between 30-60% of the carbon in tropical rainforests is released into the atmosphere
• The size of the Brazilian Amazon Rainforest has been decreasing at an average rate of 0.03% per year since 2000
• In a typical year the Amazon absorbs 2.2 billion tons of CO2, while emitting 1.9 billion tons through decomposition and organism respiration, making it a major carbon sink
• The ability of the Amazon to absorb carbon is rapidly declining, from 2 billion tons in 1990 to only 1 billion by 2015
• Rainforest clearing accounts for 75% of Brazils co2 emissions
• Name ways that people are using to limit human impact on the Amazon:?

  1. Selective Logging (only felling old trees)
  2. Replanting (new trees planted to replace cut down trees)
  3. Environmental Laws (eg the Brazilian Forest code says landowners have to keep 50-80% if their land as forest)
  4. Protection (central amazon conservation complex set up in brazil 2003)
• The Amazon Rainforest is located in South America, primarily within Brazil, but also extends into Peru, Colombia, and several other countries. It is situated around the Amazon River and its tributaries, covering an area of approximately 5.5 million square kilometers. The rainforest is mostly found in the Amazon Basin, which lies between the Andes Mountains to the west and the Atlantic Ocean to the east.
• The ITCZ is essential to the Amazon's climate as it dictates the seasonal rainfall patterns that sustain the rainforest. The north-south movement of the ITCZ causes a distinct wet and dry season, with the wet season being characterized by heavy rains due to the convergence of trade winds and rising moist air. This consistent supply of moisture is crucial for the biodiversity and ecological processes within the Amazon Rainforest.
• The Amazon rainforest is between 2 Hadley cells at the equator. Due to the Amazon being in this area, the climate is hot and wet because of the low pressure and evapotranspiration. This makes the Amazons climate suitable for rich vegetation biodiversity.
• The amazon basins process are mainly influenced by the vegetation and climate
• The dense canopy in the Amazon rainforests intercepts water. This allows water to be stored in the vegetation temporarily. Over time the water is released back into the soil via stem flow or into the atmosphere via evapotranspiration. When the water returns to the soil (pedosphere) it can be taken up by other plants (biosphere) again via their roots or evaporated into the atmosphere.
• The trees and plants in the Amazon rainforest prevent flooding and soil erosion. Due to the fact the biosphere intercepts and stores water temporarily and plant roots help with the soil's structure.
• The impact of deforestation on the tropical rainforest water cycle includes:?

  1. Reduced Evapotranspiration
  2. Altered precipitation patterns
  3. Increased surface runoff + Soil erosion
  4. Reduced infiltration and groundwater recharge
  5. Changes in river flow
  6. Local and Global Climate Change
• • Positive Feedback in the Amazon Rainforest: Deforestation can create feedback loops that exacerbate its impacts. Reduced rainfall leads to drier conditions, which can make remaining forests more susceptible to fires, further reducing forest cover and perpetuating the cycle.
• younger trees absorb more co2 than mature trees
• How does deforestation caused Increased Runoff and Soil Erosion?

  • Higher Surface Runoff: The absence of trees means less water is absorbed by the soil, leading to increased surface runoff. This can cause flooding and reduce the amount of water that infiltrates the ground to recharge groundwater supplies.
  • Soil Erosion: Tree roots help to stabilize the soil. When trees are removed, the soil becomes more susceptible to erosion by water. This not only depletes the soil of nutrients but also leads to sedimentation in rivers and streams.
• How does deforestation cause Reduced Evapotranspiration?

  • Decreased Transpiration: Trees and plants play a crucial role in transpiration, where water is absorbed from the soil and released into the atmosphere as water vapour. Deforestation reduces the number of trees, leading to a significant decrease in transpiration.
  • Reduced Evaporation: The canopy of the rainforest also contributes to evaporation. When trees are removed, the surface area for evaporation is reduced, diminishing the overall moisture returned to the atmosphere.