Constructing Carbon Cycle Diagrams
- Ecologists use the terms pool and flux to describe the carbon cycle and recycling of other elements:
- A pool is a reserve of the element, which can be organic or inorganic.
- A flux is the transfer of the element from one pool to another.
Carbon dioxide in the atmosphere is an inorganic pool, while the biomass of producers in an ecosystem is an organic pool.
Key Carbon Fluxes in Ecosystems
- Photosynthesis: Absorption of carbon dioxide from the air or water, converting it into carbon compounds.
- Feeding: Transfer of carbon compounds when organisms consume others.
- Respiration: Release of carbon dioxide to the atmosphere by respiring cells.
Creating a Carbon Cycle Diagram
Carbon cycle diagrams use text boxes to represent pools and arrows to indicate fluxes.
1. Identify Carbon Pools
- Common pools include:
- Atmosphere: Carbon dioxide ($CO_2$).
- Producers: Plants and algae store carbon in organic compounds.
- Consumers: Animals store carbon in their bodies.
- Decomposers: Fungi and bacteria store carbon temporarily.
- Fossil Fuels: Coal, oil, and natural gas act as long-term carbon stores.
In aquatic ecosystems, carbon is also stored as dissolved $CO_2$ and bicarbonate ions ($HCO_3^-$).
2. Identify Carbon Fluxes
- Key fluxes include:
- Photosynthesis: Moves carbon from the atmosphere to producers.
- Feeding: Transfers carbon from producers to consumers.
- Respiration: Releases carbon back to the atmosphere from all organisms.
- Decomposition: Moves carbon from dead organisms to decomposers and the atmosphere.
- Combustion: Releases carbon from fossil fuels or biomass to the atmosphere.
Use arrows to represent fluxes in your diagram. The direction of the arrow shows the flow of carbon.
3. Label Pools and Fluxes
- Clearly label each pool and flux in your diagram.
- Use text boxes for pools and arrows for fluxes.
Label an arrow from the atmosphere to plants as "Photosynthesis" to show how carbon is absorbed.
4. Include Human Impacts
- Highlight human activities like combustion and deforestation that alter the natural carbon cycle.


