General model for nutrient cycles in a forest:
- Inputs: rain, dust, biological fixation, rock weathering.
- Outputs: stream water, gas emissions (fire and nitrification), loss to ground water
- Transfer of nutrients between plants and the soil (leaching from leaves, decomposition of litter, root turn over, death, animals excretion)
- Internal redistribution of mobile nutrients such as Nitrogen and Phosphorus (retranslocation)
Nutrient cycles in a forest:
- Nitrogen and Phosphorus cycle:
- Nutrient starts in the soil is up taken by trees (this is assisted by the mycorrhizal endosymbiosis in the roots of trees)
- It returns to the soil by litter fall, leaching and decomposition. The decomposition of organic matter is assisted by microbes called detritivores, which returns the nutrients to the soil.
- This cycle keeps repeating.
Microbes are important in:
- Assisting plants in nutrient poor soils (such as Australia soils) to uptake nutrients
- Breaking down organic matter to make nutrients available to the soil again
- Breaking down atmospheric nitrogen can only be done by algae such as cyanobacteria