ELSS- the Amazon Rainforest

Area it occupies + countries

- more than 6m km²
- 70% is in Brazil, extends into Peru, Ecuador, Venezuela, Colombia, Bolivia and Guyana

Climatic features

- high average annual temps between 25°C and 30°C
- small seasonal variation in temp
- high average annual rainfall, >2000mm, with no dry season

Global distribution of rainforests

- found in a narrow belt either side of the equator
- all between the tropic of cancer and tropic of capricorn (25° N and S of equator)
- vast majority within 10° N and S of equator

Reasons for the Amazon climate

- high average temps are a response to intense insolation throughout the year (high solar radiation)
- convectional rainfall occurs all year
--> occurs when heated air from earths surface rises upwards along with the water vapour and condenses when it reaches a higher altitude
- between 50-60% of precipitation in Amazonia is recycled by evapotranspiration
- water losses from the Amazon Basin result from river flow and export of atmospheric vapour to other regions
--> this is influenced by an inward flux of moisture from the Atlantic Ocean

% of intercepted rain that is evaporated

20%

High temps allow the atmosphere to...

hold more moisture
- means it is misty in the rainforest

The water cycle in the Amazon is a...

feedback loop, a cycle of rainfall
- atmosphere to biosphere and reverse

Water is in one store for...

short periods of time

WC: Geology

- impermeable catchments have minimal water storage capacity, resulting in rapid run-off
- permeable and porous rocks such as limestone and sandstone store rainwater and slow run-off

WC: Relief

- most of the Amazon Basin comprises of extensive lowlands
- in areas of gentle relief water moves across the surface (overland flow) or horizontally through the soil (throughflow) to streams and rivers
- in the west the Andes create steep catchments with rapid run-off
- widespread inundation across extensive floodplains (e.g. the Pantanal) occurs annually, storing water for several months and slowing its movement into rivers

WC: Temperature

- high temps year round generate high rates of evapotranspiration
- convection is strong, leading to high atmospheric humidity, the development of thunderstorm clouds and intense precipitation
- water is cycled continually between the land surface, forest trees and the atmosphere by evaporation, transpiration and precipitation
- high temps drive convectional rainfall
--> could lead to flash floods

WC Deforestation: average km² lost between 1970 and 2013

17,500km²/year

WC Deforestation: amount of primary forest destroyed or degraded since 1970

1/5, though in recent years rates of deforestation have slowed

WC Deforestation: km² of Bolivian rainforest cleared for subsistence farming and cattle ranching between 2000 and 2012

30,000km²

WC Deforestation: impacts of the Bolivian deforestation

massive reduction in water storage and accelerated run-off

WC Deforestation: impact of converting rainforest to grassland

increases run-off by a factor of 27, and half of all rain falling on grassland goes directly into rivers

WC Deforestation: how rainforest trees influence the water cycle + impact of deforestation

- extract moisture from the soil
- intercept rainfall and release it to the atmosphere through transpiration
- stabilise albedo and ground temps
- sustains high atmosphereic humidity which is responsible for cloud formation and heavy continental rainfall
--> deforestation breaks this cycle and can lead to permanent climate change

WC Deforestation: predicted decline in regional rainfall due to deforestation

20% decline as the rainforest dries out and forest trees are gradually replaced by grassland

WC Deforestation: impact of regional WC on further away regions

means that forests hundreds of kilometres downwind of degraded sites are affected too

WC Deforestation + stores of water: Tree storage

fewer trees = less water storage = more surface run-off as trees are not there to intercept the rainfall
--> water reaches rivers faster, increases probability of flash floods

WC Deforestation + stores of water: Soil storage

less trees = fewer roots, and roots hold water in the soil = ;ess water stored in soil
--> less trees = more exposed soil
--> soil receives more sunlight and gets warmer, increases evaporation levels

WC Deforestation + stores of water: Store in permeable rock

increases water stored in permeable rock as less water is stored by trees that could intercept the rain

WC Deforestation + stores of water: Atmospheric store

less trees = decrease in water flow to the atmosphere by evaporation and transpiration as rainfall isn't being intercepted
--> therefore less water in atmospheric store

WC Deforestation + flows of water: Evapotranspiration

decrease in evapotranspiration because less trees = less transpiration and less intercepted rainfall = less evaporation

WC Deforestation + flows of water: Precipitation

less precipitation because a decrease in evapotranspiration = less water in the water cycle and atmosphere, therefore less water condensing into clouds and rainfall

WC Deforestation + flows of water: Run-off

increases level of run-off because there are less trees to intercept the rainfall before it reaches the ground
--> water reaches ground faster

WC Deforestation + flows of water: Run-off speeds

increase because there is less vegetation to intercept/absorb water and the ground has often become very hard/dry due to to not being shaded by the trees anymore
--> hard ground = faster run-off speeds because water cannot infiltrate into the ground/soil

WC Deforestation + flows of water: Risk of flood

increased as less water can be stored and intercepted by vegetation, so water reaches the ground faster and a larger amount of water reaches the river

WC Deforestation + flows of water: Forest albedo and ground temps

increased proportion of sunlight reflected from the surface because there is less vegetation to block the sunlight and also less clouds due to less precipitation
--> higher ground temps as less of the ground is shaded by trees and vegetation

WC Deforestation + flows of water: Cloud formation

decreased because of the lower levels of evapotranspiration
--> less water in the atmosphere = lower levels of water vapour that could condense into clouds

CC Human impacts: How quickly fossil fuels release carbon stores

very slowly

CC Human impacts: Burning anything releases...

more carbon into the atmosphere, esp fossil fuels

CC Human impacts: Impact of increased CO2 in the atmosphere

increases global warming

CC Human impacts: Fewer plants from deforestation means...

less CO2 removed from the atmosphere- most severe factor

CC Human impacts: % of carbon in the biomass of trees of unaffected rainforests

in rainforests unaffected from human activity, the biomass of trees represents 60% of all carbon in the ecosystem

CC Human impacts: impact of deforestation

exhausts the carbon biomass store

CC Human impacts: deforestation and hydrographs

deforestation will reduce the lag time, raise the peak and reduce the base flow

CC Causes of deforestation: Agriculture- impact of commercial cattle farming

- leading cause of deforestation in the the Brazilian Amazon
- leads to the destruction of the nutrient cycle, meaning the land can only sustain herds for a short period of time because the quality of pasture declines quickly

CC Causes of deforestation: Other agriculture

subsistence farming

CC Causes of deforestation: Building of...

roads

CC Causes of deforestation: Development of...

energy- hydroelectric power stations, dams and reservoirs

CC Causes of deforestation: Settlement and...

population growth

CC Causes of deforestation: Mining of...

gold, iron, bauxite and oil
- 1999, 10,000 hectares of land used for mining
- increased to 50,000 hectares by 2016

CC: tonnes of stored carbon

major global reservoir of stored carbon- 2.4bn tonnes/year

CC: amount of carbon stored by trees

large forest trees store 180 tonnes of carbon above ground and 40 tonnes in their roots

CC: The Amazon is...

very humid- ideal for plant growth

CC: Why the rainforest? How does it compare to another forest?

- exchanges of carbon between the atmosphere, biosphere and soil are rapid
- photosynthesis is high
- leaf litter and other dead organic matter accumulates temporarily at the soil surface and within rainforest soils due to the warm, humid conditions
- the decomposition of organic litter releases nutrients to the soil, for immediate take-up by tree root systems and emits CO2

CC: Issues with the rainforest and carbon stores

- soils are acidic and contain only limited carbon and nutrients stores
- poor soils support a biome with the highest NPP and biomass of all ecosystems, emphasises the speed with which organic matter is broken down, mineralised and recycled
- the geology of the Amazon Basin is dominated by ancient igneous and metamorphic rocks and carbonates are largely absent form the mineral composition of these rocks
--> however in western parts of the basin close to the Andes, limestone rocks are present
--> these are significant regional carbon stores in the context of the slow carbon cycle

Positive effects on the WC and CC: International and...

national concern- due to deforestation and global climate change

Positive effects on the WC and CC: Brazil is committed to restoring...

120,000km² of rainforest by 2030

Positive effects on the WC and CC: Indigenous people have lived...

sustainably for thousands of years, maintaining the water balance, carbon cycle and the forests biodiversity- as hunter gatherers and shifting cultivators

Positive effects on the WC and CC: Modern strategies include...

- protection through legislation
- projects to reforest areas destroyed by cattle ranching etc
- improving agricultural techniques

% of logging that is illegal

90%

Positive effects on the WC and CC: The Parica Project in Rondonia (western Amazon)

a sustainable forestry scheme which aims to develop a 1000km² commercial timber plantation on govt-owned, deforested land

Positive effects on the WC and CC: The Parica Project- number of trees and years to grow

the plan is for 20m fast-growing, tropical hardwood seedlings, planted on 4000 smallholdings, to mature over a period of 25 yrs

Positive effects on the WC and CC: The Parica Project- financial assistance is given...

to smallholders for land preparation, planting and the maintenance of plots

Positive effects on the WC and CC: The Parica Project- the project is a...

monoculture

Positive effects on the WC and CC: The Parica Project- how it impacts the forest

means that trees elsewhere in the forest won't be cut down- carbon can flow from the atmosphere into the biosphere
- more storage in biosphere = less impact on climate change

What is a monoculture?

a form of agriculture that is based on growing only one type of crop on a specific area

Pros and cons of monoculture

Pros:
- re-establishes water and carbon cycles
- reduces run-off and the loss of plant nutrients and carbon from the soil
- sequesters carbon in the trees and soil
- reduces CO2 emissions from deforestation
Cons:
- will not replicate the biodiversity of the primary rainforest

Organisations that manage the Amazon

- Forestry Stewardship Council
- CITES
- UN Forum on Forests, est 2000
- Central Amazon Conservation Complex (CACC)
- Greenpeace and WWF
- 68 national parks in Brazil

Strategies for managing the Amazon

- debt reduction: countries are relieved of some of the debt in return for protecting rainforests
- ecotourism
--> tourists often learn how to help the Amazon, get involved in projects and conservation efforts
--> can help to rebuild water and carbon cycles if a reserve/protected area is created for the resort

Protecting the Amazon: What has happened so far?

2010- Debt for nature swap, USA converted US$13.5m of debt from Brazil into a fund to support the protection of the rainforest