2.a. CASE STUDY: amazon rainforest Flashcards
what and where is the amazon rainforest?
The amazon rainforest is a 6 million km2 area of rainforet in South America
70% is in Brazil but it also extends into parts of Peru, Ecuador, Venezuala and Columbia.
worlds largest tract of rainforest.
what is the climate like in the Amazon?
- high av temps of 25-30 degrees c
- small seasonal variations in temps
- high av rainfall of more than 2000mm with no dry season
- significant loud cover ensure temps do not reach those of the sub-tropical desert conditions
rates of flow in the water cycle in the amazon rainforest
- Precipitation:
The Amazon Basin experiences high annual rainfall, averaging around 2000 mm. - evapotranspiration
50-60% of precipitaion in the amazon is recycycled via evapotranspiration - rivers + clouds
water losses from the amazon basin are a result of the river flow and cloud migration taking vapour elswhere [flying rivers] - run-off
rapid run off as a result of intensive rainfall + well drained soils.
distinct stores in the water cycle amazon
- soil/ground water
deep tropical soils and abundant rainfall lead to high water content in soils and aquifers - vegetation
trees ansorb water and store from the water and releave it through transpiration.
how much carbon does the amazon store and release each year on a whole
The Amazon rainforest is a major carbon sink, absorbing about 2.2 billion tons of CO2 annually and releasing about 1.9 billion tons through decomposition and respiration
distinct stores in the carbon cycle amazon
- large forest trees typically store 180 tonnes C/ha
and a further 40 C/ha in their roots - soil carbon stores average between 90-200 tonnes/ha
how does temperature affect the carbon cycle in the amazon?
warm, humid conditions ensure speedy decomposition of organic matter and the quick release of CO2. meanwhile rates of carbon fixation through photo synthesis are high.
how does vegetation affect the carbon cycle in the amazon?
major carbon sink by absorbing and storing carbon dioxide.
Through photosynthesis, trees and plants convert atmospheric carbon dioxide into biomass, effectively locking up carbon in their trunks, branches, and roots.
how does organic matter in soil affect the carbon cycle in the amazon?
both storing and releasing carbon.
major carbon sink, holding a significant amount of carbon that would otherwise be in the atmosphere.
decomposition of organic matter releases carbon back into the atmosphere through soil respiration,
how does mineral compostion of rocks affect the carbon cycle in the amazon?
influences silicate rock weathering, which plays a crucial role in the slow carbon cycle.
Specifically, the weathering of silicate rocks releases bicarbonate ions which can then be deposited as calcium carbonate in the ocean,
effectively removing carbon dioxide from the atmosphere.
how does temperature affect the water cycle in the amazon?
increased Evaporation:
Higher temperatures accelerate evaporation,
Moisture in the Atmosphere:
Warm air can hold more water vapor than cooler air. amazon = warm = humid
Cloud Formation and Precipitation:
As warm, moist air rises and cools, it reaches its dew point, causing water vapor to condense to form clouds. The Amazon’s high humidity and consistent heating contribute to frequent and intense rainfall.
Transpiration:
Plants, particularly the massive trees of the Amazon They absorb water through their roots and release it as water vapor through tiny pores on their leaves. This process, along with evaporation, contributes significantly to the moisture content of the atmosphere
how does the permiability and porosity of rocks affect the water cycle in the amazon?
In the Amazon basin, areas with limestone and sandstone bedrock [permiable] may have less surface water and more groundwater storage.
Sedimentary rocks can accumulate large volumes of water, influencing vertical crustal displacement.
Geology:
The Amazon basin is characterized by both crystalline (impermeable) and sedimentary (permeable and porous) rocks.
how does releif affect the water cycle in the amazon?
Relief:
The lowlands of the Amazon basin influence runoff patterns, with gentle slopes contributing to overland flow and through-flow into streams and rivers.
what is the madeira drainage basin?
It’s a major tributary of the Amazon River and is one of the largest sub-basins within the Amazon basin, covering about 23% of its area. The basin has a drainage area of approximately 1,420,000 square kilometers.
what natural factors have affected the flows and stores in the water cycle in the madeira drainage basin?
climate, soil type, vegetation cover, relief, and rock type
how have natural factors affected the flows and stores in the water cycle in the madeira drainage basin?
Climate:
Changes in climate, like ice ages or interglacial periods, can alter water availability, while extreme events like droughts reduce water within the system
Warm, tropical climates like those in the Amazon basin support high rates of evaporation and evapotranspiration, which influence precipitation patterns and water storage.
Soil Type:
Impermeable soils can hinder infiltration, leading to increased surface runoff and saturation.
Permeable soils allow for infiltration and percolation, potentially recharging groundwater supplies.
Vegetation Cover:
High vegetation coverage increases interception and evapotranspiration, which can reduce surface runoff.
Ecosystem changes, like plant succession, can alter interception rates and impact the water cycle.
Relief:
Steeper slopes promote faster surface runoff and shorter water storage times.
what human factors have affected the flows and stores in the water cycle in the madeira drainage basin?
Human activities in the Madeira River Basin have significantly altered water flows and stores through deforestation, land-use changes, and urbanization, leading to increased runoff, soil erosion, and altered river regimes. Hydroelectric dams further disrupt natural flows, impacting downstream areas.
- deforestation
- urbanisation
- landuse changes
- farming
how have human factors affected the flows and stores in the water cycle in the madeira drainage basin?
- Deforestation:
- Reduced interception:
- Increased runoff [less interception meaning more water flows directly into rivers rather than being absorbed into the ground]
- Decreased infiltration [increased runoff and decreased groundwater recharge.]
- Reduced evapotranspiration [Deforestation lowers evapotranspiration, potentially reducing overall moisture in the atmosphere.] - Land Use Changes:
Urbanization:
Impermeable surfaces in urban areas increase runoff and reduce infiltration, leading to flash flooding and decreased groundwater recharge.
Agriculture:
Intensive farming practices, like plowing, can compact soil, reducing its ability to absorb water and increasing surface runoff.
Ranching and Logging:
These activities can disrupt the natural vegetation cover, leading to similar effects as deforestation, including increased runoff and erosion.
- Dams and Reservoirs:
Disruption of natural flow:
Dams change the natural flow of rivers, creating artificial water stores that can alter downstream water levels and ecosystems.
Water storage:
Reservoirs can store large amounts of water, potentially affecting downstream water availability and altering river flow patterns. - Water Abstraction:
Groundwater over-abstraction:
Excessive pumping of groundwater can lower the water table, potentially drying up rivers and reducing the availability of water for other uses.
Surface water abstraction:
Over-extraction of water from rivers and lakes can reduce river flow and impact downstream users and ecosystems.
what human factors have affected the carbon flows, nutrient stores and soil in the amazon?
Human activities like deforestation, agriculture, and infrastructure development significantly impact the Amazon’s carbon flows, nutrient stores, and soil.
how have human factors affected the carbon flows in the amazon?
Deforestation:
Destroys the major carbon sink, releasing vast amounts of stored carbon (from trees and soil) back into the atmosphere as CO2, contributing to climate change.
Forest Degradation:
Even non-total deforestation, such as selective logging or grazing, reduces carbon storage capacity and can make the forest a carbon source.
how have human factors affected the nutrient stores in the amazon?
Litter Layer Removal:
Deforestation eliminates the protective litter layer that returns nutrients to the soil, leading to nutrient depletion.
Nutrient Leaching:
The absence of a protective vegetation cover exposes the soil to heavy rainfall, resulting in rapid nutrient leaching and loss.
Soil Degradation:
Deforestation and grazing can lead to soil compaction, reducing its ability to retain water and nutrients, further impacting vegetation.
how have human factors affected the soil in the amazon?
Erosion:
Removing the forest canopy exposes soil to erosion by wind and rain, leading to soil loss and reduced fertility.
Reduced Organic Matter:
Deforestation halts the input of organic matter from decaying vegetation, leading to a decline in soil fertility.
Soil Compaction:
Overgrazing and heavy machinery used in agriculture can compact soil, further limiting nutrient availability and water infiltration.
what management strategies have been used to moderate the impacts of the oil and gas industry in the amazon?
- Brazil is commited to restoring 120,000 km2 of rainforest by 2030
- protection through legislation of large expanses of primary forest so far untouched.
- projects of reforestation in degraded areas destroyed by farming, cattle ranching, logging etc
- improving ag techniques to make permanent cultivation possible
have these management strategies been successful? how?
- since 1998 brazillian gov has established many forest conservation areas which now cover an area 20x the size of belgium
- 44% of the rainforest is comprised of national parks and wildlife reserves where farming is banned
- several reforestation programmes sponsored by local authorities and NGOs are underway but so far progress has been slow [eg. parica project in rondonia in the western amazon; aims to develop 1000km2 of commercial timber plantation on gov owned deforested land][however this cannot replicate the biodiversity of the primary rainforest but it is sustainable; it sequesters carbon, reduces co2 emmisions, re-establishes water and carbon cycles& reduces run off]
the Surui people of rodonia in 2009 were the first indiginous group in the amazon to join the UNs reducing emmisions from deforestation and degridation scheme which provides payment to tribesfor protecting the rainforest and abandoning logging. they provide pollution permits to the surui people to then be bought by TNCs
