Unit 5: Carbon Cycle Flashcards
(22 cards)
What is a biome?
A biome is an ecological community whose global distribution corresponds with climatic regions of the Earth.
What is a tropical rainforest biome?
A tropical rainforest is a dense forest ecosystem found near the Equator with high rainfall (over 2,000 mm/year) and consistently high temperatures (25–30°C). It has high biodiversity and multi-layered vegetation.
Where are tropical rainforests distributed globally?
They are found between 0–15° latitude, mostly around the Equator.
Major regions include:
• Amazon Basin (South America)
• Congo Basin (Africa)
• SE Asia (Indonesia, Malaysia)
What are the key characteristics of tropical rainforests?
• Evergreen trees with waxy leaves
• Four layers: emergent, canopy, understory, forest floor
• High net primary productivity (fast carbon cycling)
• Rapid decomposition and nutrient recycling
• Thin soils (leached but nutrient-rich due to fast cycling)
Give an example of a tropical rainforest and its importance to the carbon cycle.
The Amazon Rainforest stores over 100 billion metric tons of carbon in vegetation and soils. It acts as a carbon sink, absorbing CO₂ via photosynthesis and storing it in biomass.
What is a temperate grassland biome?
A temperate grassland is a biome with moderate rainfall (250–750 mm/year) and seasonal temperature variation, dominated by grasses and few trees. It supports agriculture and grazing.
Where are temperate grasslands found globally?
They are found in mid-latitudes (30–55°),
Examples:
• North America (Prairies)
• Eurasia (Steppes)
• Argentina (Pampas)
What are the key characteristics of temperate grasslands?
• Deep, fertile soils rich in organic matter
• Dominated by grasses due to limited rainfall
• Large seasonal temperature swings (hot summers, cold winters)
• Used for cereal farming and grazing
How do temperate grasslands affect the carbon cycle?
They store carbon in deep soils (especially in roots and humus).
While less productive than rainforests, they are important long-term carbon stores.
However, ploughing and overgrazing can release carbon.
Where is Carbon stored in an Ecosystem?
• Green plants:
- Nearly 20 per cent of carbon in Earth’s biosphere is stored in
plants, including root systems below the soil surface
• Animals:
- These play a small role in carbon storage because the biomass of
animals is much less than plant biomass
• Litter:
This is fresh and un-decomposed plant debris on the surface of the
soil; it includes leaves, other dead organisms and excrement.
• Soil:
- Humus is a black substance that remains in the soil after most of
the organic litter has decomposed; it gets dispersed throughout
the soil by earthworms
Climate of a TRF?
The climate of tropical rainforests can be summarised as hot and wet.
What is Gross Primary Productivity (GPP)?
The amount of energy produced by photosynthesis in a unit area during one year.
What is NPP?
The amount of new biomass produced each year need to be measured; this is measured by Net Primary Productivity (NPP), which is GPP minus the energy lost in respiration.
Key features of the Emergent layer in a TRF?
Tallest trees (up to 60m); exposed to strong sunlight and wind; adapted with small, waxy leaves.
Key features of the Canopy layer in a TRF?
Dense layer forming a roof; receives most sunlight; blocks light from below; rich in biodiversity.
Key features of the Lower tree/Under canopy layer in a TRF?
Shadier, less dense; young trees and shade-tolerant species; grow slowly due to limited light.
Key features of the Ground / Shrub layer (understorey) layer in a TRF?
Very little light; dark and humid; plants have large leaves to capture light; home to insects and decomposers.
Climate of a temperate grassland?
Can be summarised as hot wetter summers and cold drier winters.
How does Light influence plant growth & carbon storage in Temperate Grasslands?
The sun’s rats are concentrated during summer at these latitudes but are much weaker when daylight hours are reduced
How does Temperature influence plant growth & carbon storage in Temperate Grasslands?
Temperature variations will change plant growth rates
How does Precipitation influence plant growth & carbon storage in Temperate Grasslands?
Low average rainfalls
Higher in summer, more plant growth
Lower in winter, less.
Summarise the Dust Bowl Case Study
The Dust Bowl of 1930’s Mid-West USA
The famous ‘Dust Bowl’ drought of the mid-west plains, affected areas that were once
temperate grassland. The event had major impacts on agricultural soils and contributed to
the ‘great depression’.
The drought period 1934 to 1939:
• Affected 100 million acres (400,000 km2) centred on the Texas and Oklahoma and affected adjacent of New Mexico, Colorado, and Kansas.
• Was made worse by poor farming practices that removed the natural drought tolerant grasses and exposed the soil
• Caused millions of tons of topsoil to eroded by strong winds
• Led to 2.5million people abandoning their farms
