Year 12 / Functioning ecosystems and succession

Matter returns.

Carbon moves among the atmosphere, producers, consumers, decomposers, soils and water. Photosynthesis takes carbon dioxide into organic matter; respiration and decomposition return carbon dioxide. Combustion releases stored carbon rapidly.

Matter is conserved and can cycle through many reservoirs. Energy enters mostly as sunlight and dissipates as heat, so the ecosystem requires a continuing energy input. Changes in one carbon flux can alter reservoir sizes.

INTERACTIVE MODEL

Carbon reservoirs

Uptake 50 · return 60 · biomass carbon loses 10 model unitsPhotosynthetic uptake50%LowHighRespiration and decomposition return60%0%100%

Explore: Change photosynthesis and respiration fluxes to see the carbon reservoir shift.

\text{atmosphere}\xrightarrow{\text{photosynthesis}}\text{biomass}\xrightarrow{\text{respiration}}\text{atmosphere}

WORKED EXAMPLE

Decomposition slows in a cold, waterlogged soil.

Less organic carbon is broken down per unit time.
Carbon can accumulate in the soil reservoir.

Assumed knowledge

Photosynthesis and respiration.

Learning checkpoints & source

YOUR LEARNING CHECKPOINT

Trace carbon through ecosystem reservoirs.
Distinguish nutrient cycling from energy flow.

QCAA Biology · Unit 3 · Functioning ecosystems and succession ↗

READY TO TRY IT?

Matter returns.

Carbon reservoirs

Decomposition slows in a cold, waterlogged soil.

Put the idea to work.