Carbon Cycle Pack D Flashcards
(21 cards)
What are the carbon stores in each biome?
TRF - 550 billion tonnes
Temperate forests = 310 billion tonnes
Temperate grasslands = 285 billion tonnes
Tundra = 160 billion tonnes
What are examples of TRFs?
- Amazon
- Congo
- Bornea (Indo-Malaysian)
What are examples of grasslands?
- Prairies (N America)
- Steppe (Russia)
- Veldt (South Africa)
- Pampas (Argentina)
What are the characteristics of TRFs?
- Found between 23° north and south of the equator
- Large number of animals
- Dense vegetation with many layers (evergreen trees)
- High plant growth and levels of biomass
How do light, precipitation and temp affect stores and flows in the TRF?
- Sun’s ray are concentrated as sun is directly ahead
- Little seasonal variation so high numbers of sunlight hours
- Average annual temperatures are between 25-30°C
- High temperatures mean more carbon is stored in vegetation
- Convectional rain on most days
- High precipitation with 2000mm a year
- Rainfall and temperature and not limiting factors
What are the stores in the TRF?
- Total carbon stored in biomass and soil is 550billion tonnes
- Above ground store is 180 tons per hectare
- Below ground store is 100 tons per hectare
- Large store in animals
- Atmospheric carbon sequestration is high all year with more sequestered than released
- High NPP of 2500g/m2/year
What is the humus layer?
- Dark layer of fertile soil
- Supports all biomass
- Beneath is infertile soil with limited nutrients
What are the flows in the TRF?
- Rapid cycling between atmosphere an biosphere
- High temperatures mean CO2 is fixed at a faster rate
- Decomposition is rapid so carbon quickly returns to the soil
- Heavy rainfall leaches the soil of carbon removing it into rivers then the sea
What is the positive feedback cycle for decomposition and soil nutrients in the TRF?
- Trees shed all year
- High temperatures mean leaves decompose quickly
- Organic carbon and nutrients enter the humus layer
- Shallow roots take up nutrients/organic carbon quickly
- Trees grow rapidly
How much carbon is stored in the Amazon?
- 100 billion tonnes
- 2.4 billion tonnes of CO2 taken in per year
- 1.7 billion tonnes released per year
- Carbon sink
How are trees a large carbon store in the Amazon?
- Large evergreen trees
- One tree stores 180 tonnes/ha above ground and 40 tonnes/ha below ground
- 60% of all C is above ground in branches, stems and leaves
How does the geology and relief in the Amazon affect the carbon cycle?
- Mostly igneous/metamorphic (e.g. crystalline shields)
- These have very few carbonates, so not a key store of C, and are hard to weather
- Limestone outcrops in the West near the Andes contain carbonates so are a carbon store on a regional scale
What are the characteristics of grasslands?
- Found 40° to 60° N and S of equator
- Dominated by grassland vegetation with very few trees (rainfall too low to support large plants)
- Limited species due to one type of plant dominating
- Soils are thick and nutrient rich (often converted for arable farming)
How do light, precipitation and temp affect stores and flows in the grasslands?
- Summer temperatures up to 40°C and down to -40°C in winter
- No growth in winter so less carbon stored in vegetation
- Have 500mm or less rain each year
- In 5 months of the year, rainfall is <50mm
- Rainy seasons are late spring and early summer
- Sunlight varies seasonally
- Temperature and rainfall are limiting factor (arid vs cold)
What are the stores in the grasslands?
- Total store of carbon in biomass and soil is 185 billion tons
- Above ground store is 2 to 10 tons per ha
- Below ground store is 100 to 200 tons per ha due to dense network of roots
- Store in animals is low
- Atmospheric carbon sequestration varies with seasonal plant growth
What are the flows in the grasslands?
- Decomposition happens quickly in summer due to the high temperatures and in autumn due to humidity
- Affected by wildfires and release carbon as they get so warm and dry
- Low rainfall means less leaching, so carbon remains in the soil
How would a grassland in a higher altitude area be impact?
- More precipitation (orographic)
- Colder temperatures
What are the characteristics of the tundra?
- Cold temperatures
- Limited liquid water
- Short summer growing season of 3 months
- Few nutrients from crystalline, igneous rock
- Plant growth varies seasonally
What are the stores in the tundra?
- Low NPP of 200g/m2/yr
- Biomass carbon store is 4-29 tonnes per ha
- Permafrost is a carbon sink of 1600 gigatons and contains dead organic matter
What are the flows in the tundra?
- In growing season, carbon transferred from plants into soil as leaf litter is created and decomposed
- Microorganisms more active in summer, releasing CO2
- Waterlogged conditions rom seasonal pools starve decomposers of O2 so no respiration or decomposition
- Slow decomposition in permafrost but may become a source as frozen organisms thaw and decay, releasing CO2 and CH4
What are the feedback cycles in the tundra?
Positive:
- Increased temperature
- Permafrost melts
- Methane released
Negative:
- Increased temperature
- Ice melts (more liquid water and space)
- Plants grow better
- Decreased CO2
