Earth Life Support System Case Studies Flashcards
Amazon Rainforest
Occupies an area of more than 6 million km^2.
70% in Brazil. High annual rainfall- convectional rainfall.
High average temperatures due to a high angle of incidence of the sun, leading a high amount of radiation.
Temperatures are not extreme due clouds reflecting some of the radiation back into the atmosphere.
Water Cycle - Amazon Rainforest (1)
Convectional rainfall- the ground is heat intensely, causing hot air to rise, cool and condense at its dew point to form cumulonimbus clouds and therefore rainfall.
Less rainfall in August, due the earths axial tilt, so the sun is not directly ahead of Manaus, so there is less insolation and therefore less convectional rainfall.
50-60% of precipitation is recycled by evapotranspiration.
Water Cycle - Amazon Rainforest (2)
Atmosphere- high temperatures allowing large stores of water vapour in the atmosphere. High Humidity.
Evapotranspiration- High rates, due to high temperatures, abundant moisture and vegetation- sustains rainfall.
Precipitation - High average annual rainfall >2000mm. Evenly distributed throughout the year.
Soil and Groundwater- Abundant rainfall and deep soils lead to significant water storage.
Vegetation- Absorbs and stores water from the soil, releasing through transpiration.
Run-Off - High amounts of surface run-off due to high amounts of rainfall.
Carbon Cycle - Amazon Rainforest
Forest trees dominate the biomass of Amazon and they store the most carbon- 100 billion tonnes. Absorbing 2.4 million tonnes a year and releasing 1.7 million tonnes.
Photosynthesis and respiration transfer carbon from the atmosphere to the biomass and vice versa. High temperatures and high rainfall increase Net Primary Productivity, so increasing this flow.
Rapid decomposition of leaf litter, returning carbon into the atmosphere.
Geology- ancient igneous and metamorphic rocks store carbon eg slow carbon cycle.
Human impacts on Water cycle - Amazon
Deforestation leads to less evapotranspiration, so less flows to the atmosphere. Less water this stored in trees as many trees are cut down.
Deforestation also leads to less precipitation as the trees cycle water via transpiration, however with less trees theres going to be less recycling so therefore less rainfall.
Less interception via the trees, so more water on the ground leading to greater evaporation of the water on the ground, along with more surface run-off.
Human Impacts on Carbon Cycle - Amazon
Deforestation leads to less Carbon being stored in the biomass of trees and more carbon being stored in the atmosphere, causing the greenhouse effect.
Rainforests are replaced by grasslands, so less photosynthesis and respiration occurs.
Carbon is leached away from the soil via precipitation when the leaf litter goes into the soil. So soil has very little carbon stored in the soil.
High initial decomposition flow, then very low amounts of decomposition occurs as leaf litter is taken away.
Strategies to Manage Rainforests
The Brazilian government has established forest conservation areas. By 2015 44% of the Brazilian Amazon rainforest will be protected.
Parica project- a sustainable forestry scheme aims to develop 1000km^2 of deforested land. This project is a monoculture and can’t replicate the biodiversity, but still sequesters carbon.
Surui tribe part of the UN’s Reducing Emissions from Deforestation and Degradation scheme (REDD). The scheme pays the tribe for protecting the rainforest and abandoning logging. The Surui people also own Carbon Credits which they can sell.
Improved agricultural techniques- soil fertility can be maintained by rotating cropping and combining arable and livestock operations. Increasing productivity and slow rates of deforestation.
Arctic Tundra
Average monthly temperatures below freezing due to low angle of incidence of the sun, as a result the ground is permanently frozen, with only the top half thawing in summer. Permafrost underlies much of the tundra.
Few plants and animals have adapted to the environment leading to a low biodiversity.
Water Cycle in Artic Tundra
- Low annual precipation (50-350mm) most as snow.
- Small stores of water in atmosphere due to low temperatures and low humidity.
- Limited evapotranspiration due to low temperatures, sparseness of vegetation and sun’s energy used to melt the snow.
- Little groundwater and soil moisture stores as permafrost is a barrier to infilitration.
- In summer when the snow melts there are high amounts surface water and an increase in river flow temporarily.
Carbon Cycle in Artic Tundra
- The permafrost is a vast carbon sink, it contains 1600GT of carbon. The accumulation of carbon due to the slow decompostion of dead plant material.
- There is a small influx of carbon in the summer, when the active layer thaws. Plants grow rapidly, with the long daylight hours, increasing flows of photosynthesis.
- During the short growing season, plants input carbon rich litter into the soil, and the flow of decomposition increases.
- Due to global warming some parts of the permafrost have started melting releasing large amounts of carbon into the atmosphere.
Human impacts on the Carbon Cycle in Artic Tundra
There has been Oil and Gas exploration on Alaska’s North slope. Construction and operation of oil and gas operations has diffused heat to the environment. Dust Deposition leading to increase of sunlight absorbed.
Removal of vegetation cover which insulates the permafrost.
Permafrost melting releases carbon and methane into the atmosphere releasing 7- 40 million tonnes of carbon a year. As well as gas flaring and oil spillages inputting carbon into the atmosphere.
Also the degradation of tundra land has led to a reduction in photosynthesis.
Human impacts on the Water Cycle in Artic Tundra
Melting of the permafrost and snow has led to increase run-off and river discharge leading to flooding. This has increased surface water, leading to evaporation and more water stored in the atmosphere. Strip mining has led to the formation of artificial lakes which disrupt drainage and expose the permafrost to melting. Water has been abstracted from creeks leading reduced water run-off.
Management Strategies - Artic Tundra
Insulated ice and gravel pads- stops permafrost from melting.
Elevated buildings and pipelines prevents heat being transferred to the permafrost.
Drilling laterally and use of computers allows gas and oil to be accessed, without the need for several drilling points, which reduces damage to permafrost.
