CS.1 - Amazon Rainforest

What size area does the Amazon rainforest occupy?

Over 60 million km²

What percent of the rainforest is in Brazil, and what other countries?

70% in Brazil, but also extends into parts of neighbouring Peru, Ecuador etc.

Introduce the Amazon:

The Amazon rainforest in South America occupies more than 6 million km², with 70% being in Brazil and the rest in neighbouring countries such as Peru and Ecuador, and is dominated by tall, evergreen hardwood trees.

What is the average annual temp?

25 - 30°C

What is the average annual rainfall?

Over 2000mm per year, with no dry season

What percentage of precipitation is recycled by evapotranspiration?

50-60% of precipitation is recycled by evapotranspiration

What percentage of rainfall is intercepted by forest trees?

around 10% is intercepted by forest trees

What type of rainfall is it?

High-intensity, convectional rainfall

How many GT/year of water is precipitated

13.8GT of water each year precipitated

How many GT per year of water is evaporated?

7.2GT evaporated per year

How many GT of water per year flow in from the Atlantic Ocean

8-10GT flow in per year from the Atlantic Ocean

How many GT of water per year lost to the atmosphere of other regions?

3.5GT lost to the atmosphere of other regions

How many GT water per year are lost as river flow to the Atlantic Ocean

5.5GT water lost as river flow

Why are there high rates of evapotranspiration?

• High temperatures

• Abundant moisture

• Dense vegetation

What is the NPP of the Amazon rainforest?

Averaging 2500 grams/m²/year

What is Net Primary Productivity

The amount of carbon retained in an ecosystem

The difference between the amount of carbon produced through photosynthesis and the amount of energy used for respiration

What is the average biomass of the AZ?

400-700 tonnes/ha

How much carbon stored in the above-ground biomass of a tree?

180 tonnes

How much carbon stored in the below-ground biomass (just biomass) of a tree

64 tonnes

How much carbon stored below-ground in soil and biomass?

226

What is the total annual carbon absorption by photosynthesis of a tree?

30.4 tonnes per year

What is the total annual carbon emission by respiration

24.5 tonnes/year

Draw the tree diagram

Name the physical factors that affect the flows and stores in the water cycle

• Temperature

• Rock permeability

• Porosity

• Relief

What is rock permeability

Rock permeability is their ability to allow fluids to flow into/through it

What is the impact of rock permeability on the water cycle of the AZ?

• Much of the amazonian basin is ancient shield such as igneous and metamorphic

  • Comprising impermeable rocks

• Minimal water storage capacity → rapid runoff

What is rock porosity

A measure of the void spaces (e.g. pores) within a rock or sediment that allow the rock to hold fluid

What is the impact of rock porosity on the water cycle in the AZ?

• A very small amount of the rocks are porous limestone and sandstone. These can store rainwater and slow runoff

• A bit of the rock in the Amazon basin is carboniferous limestone

  • Allows infiltration, percolation, water can be stored

  • More throughflow and groundwater flow, which are slower methods of water transfer

What is the impact of relief on the amazon basin?

• Much of the Amazon basin is a lowland environment

• In this gentle relief, water can infiltrate more easily, allowing horizontal movement through the soil (throughflow) and only slow overland flow

• Some areas are so flat and extensive (floodplain areas of the major rivers) that they are classed as wetlands

  • e.g. the Pantanal - the largest wetland ecosystem in the world

  • These areas store water for months on end

• The AZ extends into the foothills of the Andes mountains to the West, and here the relief is much steeper

  • Runoff via overland flow is very rapid

What is the impact of temperature on the AZ water cycle?

• High temps → frequent and intense convectional rainfall

• High rates of evapotranspiration then recycle water

• Water constantly being moved between the surface, soil, trees and atmosphere by uptake, evaporation, transpiration and precipitation

Name the 4 physical factors that impact the carbon cycle in the AZ?

• Temperature

• Vegetation

• Organic matter in soil

• Mineral composition of rocks

How does temperature impact the carbon cycle in the AZ?

• High temps → high rainfall → high biomass totals

  • Allows the biome to become a vast carbon store

• Higher temperatures also leads to faster decomposition

How does vegetation impact the carbon cycle in the AZ?

• Acts as both a store and sink

• Carbon transferred via processes like photosynthesis, connecting the rainforest carbon store to the atmospheric carbon store

How does organic matter in soil impact the carbon cycle in the AZ?

• The rainforest soils are home to some of the most efficient decomposers (bacteria, fungi) in the world

• High temps + high humidity → rapid decomposition

• Consequently, nutrients are released to the soil very quickly, for immediate uptake by tree root systems

• This carbon cycle releases CO2 back into the atmosphere

How does mineral composition of rocks impact the carbon cycle in the AZ?

• Generally, the rocks of this ancient shield are igneous and metamorphic

  • No significant impact on the carbon cycle (few carbonate rocks)

• However, the western Amazon is the exception

  • outcrops of limestone store carbon, contributing to the slow carbon cycle

Introduce the Madeira drainage basin

The Madeira drainage basin is the largest tributary basin of the Amazon river, covering approximately 1.42 million km² across Brazil, Bolivia, and Peru.

The Madeira drainage basin contributes _ of the Amazon’s water volume

Contributes 15% of the Amazon’s water volume

What 3 land use changes impact the carbon and water cycle in the AZ?

• Forestry - The art and science of managing forests so as to yield, on a continuous basis, a maximum in quality and quantity of forest products

• Farming - The practice of cultivating plants and animals for human use

• Urbanisation - Converting land from a rural use (farmland and woodland) to urban use (housing/roads)

What are the impacts of forestry on the water cycle?

• More trees → more interception → slow down water cycle through forest area → reduce flood risk

  • Longer lag times, lower peak flow and total discharge in plantation areas

• Evaporation increases: leaves store water → evaporates directly back to atmosphere

• Run off and stream discharge reduced

• Higher transpiration (where plants absorb water through roots and release it as water vapour through tiny pores called stomata on their leaves)

What are the impacts of forestry on the carbon cycle?

• Changing land use to forest increases carbon stores

• Forest trees extract CO2 from the atmosphere and sequester it for hundreds of years

• But they are only an active carbon sink for the first 100 years

  • So plantations usually have a rotation of 80-100 years

What are the impacts of farming on the carbon cycle?

• Irrigation diverts water from rivers and groundwater supplies to land

  • So some water used by plants then transpirated instead of going back to sea

• Ploughing increases soil moisture loss and can lead to increased run-off and heavy erosion

• Use of heavy machinery can compact the soil → increased runoff

• Animals eat vegetation and remove it

What are the impacts of farming on the carbon cycle?

• Clearance of forest for farming reduces above and below ground carbon stores (biomass)

• less photosynthesis

• Ploughing reduces soil carbon storage and exposes soil organic matter to oxidation

• Harvesting = only small amounts of organic matter returned to the soil

• Rice paddies emit ~60 million metric tons of methane per year

• Livestock release methane

• Increased CO2 from farm machinery emissions

What are the impacts of urbanisation on the water cycle?

• Increased surface runoff after deforestation

• Approximate 50% decrease in evapotranspiration

• Fall in water table as less interception, rain hits the ground faster, less time to infiltrate, surface runoff faster

How much does surface runoff increase after deforestation?

From 1% to 20-30%

Urban areas are responsible for _ of global energy-related CO2 emissions

Over 70% of global energy-related CO2 emissions

What is afforestation?

Planting trees in deforested areas / areas that have never been forested.

This aims to increase carbon sequestration and reduce flood risk

What are the benefits of afforestation?

• Trees are excellent carbon stores

• Applicable at a variety of scales - any scale you like

• Usually has indirect benefits too - e.g. biodiversity and jobs

• Woeks in poorer countries

What are the disadvantages of afforestation?

• Time consuming

• Labour intensive

• Time lag

• Effectiveness of trees as carbon stores decreases over 100 years

What is the REDD scheme?

• In 2009, the Suruí people in the Brazilian Amazon joined the UN’s REDD scheme

• The UN pay the Suruí to protect the rainforest and stop logging with carbon credits

• in 2013 the cosmetics TNC Natura purchased 120,000 tonnes of carbon credits from the Suruí

Name 3 types of improving agricultural practices / reducing unsustainable practices

• Land/crop management

• Livestock management

• Manure management

What are some methods of land/crop management

• Growing crops without ploughing first

  • Conserves soil’s organic content and reduces risk of erosion

• Growing crops interspersed with trees (polyculture)

  • Tree roots bind the soil, improve moisture content and reduce erosion

  • Problem: you need space, and then can’t use machinery

• Terracing slopes to increase infiltration and reduce runoff

  • From slope → stairs, so water enters the flat bit of the stairs better

• Not using heavy machinery on wet soil as this compacts it further → increases surface runoff

• Growing different strains of rice (GMO) that grow in drier conditions

  • However people that eat rice all day will have a very specific, likely non-GMO, taste preference

What is a method of livestock management?

• Improving the quality of animal feed

  • Increases digestibility

  • → Ruminant animals like cows produce less methane

What is a method of manure management

• Manure can be stored in anaerobic containers so that methane can be captured as a source of renewable energy instead of being emitted to the atmosphere