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HOW DO THE CARBON AND WATER CYCLES OPERATE IN CONTRASTING PLACES, Net…
HOW DO THE CARBON AND WATER CYCLES OPERATE IN CONTRASTING PLACES
Amazon rainforest
Carbon cycle
Tree growth
Leaves shed/organisms die
Decaying vegetation is decomposed
Shallow roots take up nutrients
Water cycle
Geology
Impermeable catchments have low capacity for water storage- rapid runoff
Relief
Gentle relief allows overland flow and through flow to rivers
Temperature
High temperature allows high rates of evaporation and strong convection
Atmosphere-high humidity
Precipitation- 2000mm per year
10% intercepted by vegetation
Evaporation- high temperature and dense vegetation-
Stored in soil
Runoff
6 million2 rainforest spanning across 7 countries with 70% of it in Brazil. Consistent temperature of around 30 with rainfall gradually increasing throughout the year (highest in march with 325mm)
Humid environments allow decomposition to occur much faster, carbon is consistently released. Lots of flows of water
Changes to the carbon cycle
Deforestation exhausts carbon biomass stores
Reduces inputs of organic material to the soil so the soil is depleted of carbon and exposed to strong sunlight
There are less decomposers so reduced flops of carbon to the atmosphere
Deforestation. Destroys the main nutrient stores and removes nutrients from the ecosystem
Roots no longer take up nutrients and are washed away by rain
Soils are left unprotected so are eroded by run off
Impacts
Less carbon absorption by photosynthesis
Less carbon stored above and below the ground
Less emissions by respiration but more emissions thrihgh erosion fire and deomposition
Changes to the water cycle
Deforestation
Why is it happening
Exploitation of minerals under the soil, building materials, food and medicine, land space
19-73-2013 17,500km2 deforested every year
How is it impacting the water cycle
Less vegetation reduces interception
Vegetation absorbs more solar energy, albedo increases so temperature rises
Breach of water storage capacity in soil, more surface runoff
Increased flood risk , lag time and peak flow increase and less uptake of water form soil
Management strategies
Amazon Regional Protected areas
Covers and area 20x the size of Belgium
By 2015, 44% of the Brazilian amazon was protected
Sequesters carbon in trees and soils and reduces c02 emissions, re-establishes cycles by reducing run off and loss of nutrients
Difficult to legally implement due to the size
Reforestation projects
Parcia project in the western amazon aims to develop 1000km2 of timber plantation - 20 million fast growing hardwood that will mature over 25 years
Financial assistance can be given and timber can be transported in the river
Monoculture- biodiversity isn’t replicated
Local projects
Surui people are protected from illegal logging by planting seeds in deforested areas
Provides income
Encourages logging elsewhere
Deforestation and degradation scheme
Provides payment to tribes for abandoning logging
Carbon credits can be purchased by companies and counties to expand their carbon quotas, but encourages emissions
Agriculture
Rotational cropping
Planting crops sequentially on the same plot of land to improve soil health and optimise nutrients
Reduces reliance on one set of nutrients however monocroping can deplete the soil
Arable farming
Growing crops like wheat and barely rather than keeping livestock
Improves productivity
Shifting cultivation
Rainforest grows
Tribes clear small areas
Trees are cut and undergrowth burnt
Houses built on cleared land using the wood
Crops grown and harvested on small plots
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Arctic tundra
Carbon cycle
Permafrost acts as a carbon sink
Low temperatures so slow decomposition
Flux of carbon when the active layer thaws
Short burst of plant growth- small biomass
Input of carbon into the soil
Microorganisms are active and respire c02
Snow insulted microorganisms allowing decomposition
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Water cycle
Small stores of water in the atmosphere
Low precipitation as snow
Settles as snow as soil is impermeable due to permafrost
Lack of vegetation limits transpiration
Low humidity limits evaporation
Snow and ice melt in the summer
Small wetlands and lakes store water as permafrost can drain melted snow
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8 million km2 spanning accross Canada Alaska and Siberia average temperature is below -15degrees c low annual precipitation and low biodiversity underline with thick permafrost
Temperature
Below freeing most of the year , water is stored in the permafrost but shallow active layer thaws in the summer
Rock permeability
Crystalline rocks have low permeability
Relief
Low relief and large glacial deposits prevent drainage
Temperature
Limited plant growth due to lack of liquid water and low temperature , slow decomposition and and small carbon store in biomass
Permeability
Porosity and mineral composition make rocks impermeable to carbon
Changes to the water cycle
Oil and gas
Why is it happening
Oil and gas reserves where discovered in Prudhole bay, Alaska in 1968 with quarries and pipelines being invested in in the 70s and 80s
By 90s is accounted for 1/4 of the USA’s domestic oil production
Impacts
Melting of the permafrost increases runoff and river discharge
Increased flood risk and increased evaporation in the summer
Drainage disrupted
Changes to the carbon cycle
Oil spillages input c02
Destruction of vegetation reduces photosynthesis and c02 uptake
Management strategies
Insulated ice and gravel pads
Roads can be constructed on these to protect the permafrost from melting
Building and pipelines elevated on piles
Allows cold air to circulate beneath prevents permafrost melting
Drilling laterally
Oil ands gas can be accessed several km from drilling site using directional drilling over a wide area from a single site, fewer sites are then needed
Less impact on vegetation and permafrost
Technology
Computers can find where oil i stored by measuring seismic activity rather than using exploration wells
Exploration is targeted, less land damaged
Refrigerated supports
Stabilise the temperature of the permafrost to prevent melting
Net primary productivity
The rate at which plant accumulate energy in thr form of organic matter
2500g/m2 per year in the amazon
Large trees stroke around 180 tonnes of carbon per hectare above ground and 40 tonnes below ground
The whole rainforest absorbs 2.4 billion tonnes per year and releases 1.7 billion tonnes
Albedo
Proportion of sunlight reflected from a surface
Diffusion of heat from machinery directly into the tundra has caused melting of the permafrost.
Dust deposition also darkens snow increasing sun absorption as well as the removal of vegetation that insulates the permafrost
Both c02 and ch4 are released estimated 40 million tonnes of c02 emission per year