Block 7 (Carbon Stores In Different Biomes) Flashcards
How much carbon is stored in the terrestrial biosphere?
3000 Gigatonnes
How does the amount of carbon in the biosphere compare to other spheres?
- More than in atmosphere + hydrosphere
- Less than in lithosphere (largest store: 10 mill Gigatonnes in mantle)
Is storage of carbon spread evenly throughout the terrestrial biomes?
No
What are the 3 largest stores of carbon in the terrestrial biosphere?
- Boreal/coniferous forest (26%)
- Tropical rainforest (20%)
- Temperate grassland (10%)
What 2 biomes do we study?
- Tropical rainforest
- Temperate grasslands
Within biomes, where can carbon be stored?
- Biomass (living plants or animals) above or below ground
- Dead organic matter (litter) above ground
- Soil
Define biome
A major community of plants + animals adapted to the characteristics of the environment, including the climate
Define Net Primary Productivity (NPP) in the carbon cycle
Dry weight of biomass added to the biome
Per unit area, per year
What is the average NPP (kg/m2) in a tropical rainforest biome per year?
2,200 kg/m2
What is the average NPP (kg/m2) in a temperate grassland biome per year?
600 kg/m2
Is the NPP generally higher in tropical rainforests or temperate grasslands?
Tropical rainforests
What is the total amount of carbon stored in the world’s tropical rainforest biomes’ soil + biomass?
Approx 500 billion tonnes
Where are tropical rainforest biomes located?
- On Equator + 10N-10S latitudes from it
- Elevations below 1000m
What are the 3 main tropical rainforest formations?
- Amazonian
- African
- Indo-Malaysian
What are the 3 factors that influence carbon storage in biomes?
1) Light
2) Temperature
3) Precipitation
How does light affect carbon storage in tropical rainforests?
- Sun’s rays concentrated all yr (little seasonal variation)
Effect: Year round plant growth + carbon sequestration, creating large biomass store
How does temperature affect carbon storage in tropical rainforests?
- High temps (25C-30C) all yr (little seasonal variation)
Effect: Fast decomposition, returning carbon to atmosphere + soil store from litter so that it can be uptaken into biomass quickly
How does precipitation affect carbon storage in tropical rainforests?
- High average annual rainfall (over 2000mm) from daily convectional rain (little seasonal variation)
Effect: Fast plant growth (biomass store). May leach soil store of carbon.
Summarise the conditions in tropical rainforests
High levels of: light, temperature, precipitation
Provide optimum conditions for plant growth + biomass storage
Give some evidence of high carbon store in biomass (plants) of tropical rainforests
- 2/3 of world’s plant species found in tropical rainforests
- Large trees can store 180 tonnes carbon per ha above ground
Give some evidence of high carbon store in biomass (animals) of tropical rainforests
- 1/10 of world’s animal species found in Amazon TRF alone
- The large amount of plants provide large range of habitats
Summarise the relative carbon stores (biomass, litter, soil) in tropical rainforests
- Biomass = largest carbon store (conditions promote growth)
- Soil = small store (reuptake of decomposed carbon is fast + runoff and leaching happens)
- Litter = smallest store (decomposition fast)
Summarise the relative carbon stores (biomass, litter, soil) in temperate grasslands
- Soil = biggest store (lower rainfall reduces runoff + leaching)
- Biomass = smaller store (seasonal variations in growth + sequestration)
- Litter = smaller store (decomposition + reuptake happens more slowly than in TRFs)
Where are temperate grassland biomes located?
- Temperate regions: 30-50N of Equator
- Some small pockets in South
- Often on periphery of mid-latitude deserts
What are the 4 main temperate grassland formations?
- North American Prairies
- Eurasian Steppes
- S.African Veld
- S.American Pampas
What is the total amount of carbon stored in the world’s temperate grassland biomes’ biomass + soil stores ?
185 billion tonnes
Is more carbon stored in tropical rainforests or temperate grasslands?
Tropical rainforests
How does light affect carbon storage in temperate grasslands?
- Sun’s rays concentrated in summer + weaker in Winter (high seasonal variations)
Effect: pronounced variations in plant growth + biomass storage
How does temperature affect carbon storage in temperate grasslands?
- High seasonal variation in temps (-30C -> 40C)
Effect: Pronounced variation in decomposition rates
How does precipitation affect carbon storage in temperate grasslands?
- Low average annual rainfall (500mm or less) spread fairly evenly across the yr, with snow in winter
Effect: limited plant growth (growth of biomass store) + limited soil store leaching
Summarise conditions in temperate grasslands
Seasonal variations in: light, temp
Generally low precipitation
Causes seasonal variations in carbon storage, with less constant and rapid plant growth than is seen in TRFs
Give some evidence of low carbon store in biomass (animals) of temperate grasslands
- No more than 2-3 species of large grazing mammal (e.g. bison)
- One common animal is earthworms (1m2 may contain 500 - help with decomposition)
- Less habitats so less animals
Give some evidence of low carbon store in biomass (plants) of temperate grasslands
- Only 2-10 tonnes carbon per plant (double in roots)
What are the 2 most common grasses in temperate grasslands?
- Turf grasses (with rhizomes - underground stems from which new plants grow)
- Bunch grasses (without rhizomes - new plants grow from seeds)
The key carbon store in temperate grasslands (soil) can hold how much carbon per hectare?
100-200 tonnes per hectare
