Litter Decomposition and Nutrient Cycling Flashcards
Litter decomposition
Produced from dead plant matter and animal matter
What happens during the decomposition of litter?
Transformed into soil organic matter
What does the process of litter decomposition determine?
The rates of nutrient recycling
How do decomposers help in nutrient cycling?
- Decomposers help nutrients get added back to the soil or water, so the producers can use them to grow and reproduce
- Most decomposers are microscopic organisms, including protozoa and bacteria
Litter decomposition stages
- Start
- Fragmentation
Leaching - Microbial mineralization
Further fragmentation - Stable phase
Lignin degradation
Fragmentation
The process of breaking down the raw complex materials (Done by detritivores)
Detritivores
Consume dead organic matter
Leaching
The process of releasing nutrients in the water and seeping into the soil
Microbial mineralization
Microorganisms release gases; Nitrogen, Sulphur, Phosphorus due to decomposition and other inorganic compounds are readily assimilated by plants.
Lignin degradation
Most abundant organic material on Earth; it decomposes slowly
(Only fungi and bacteria can decompose lignin)
When does litter decomposition decompose at a slower rate?
When tissues are physically tough, with high lignin and low Nitrogen content
When does litter decomposition decompose at a faster rate?
- Easily decomposable C compounds (sugars, starch)
- Warmer wet climates
What is the link between decomposition and nutrient cycling?
Soil microorganisms either mineralize (release) or immobilize (take up) nutrients from decomposing organic matter based on their nutrient requirements and the litter quality (C : nutrient ratio)
What are the Terrestrial Nitrogen Cycle primary inputs?
- Biological Nitrogen fixation
- Human Nitrogen fixation
What is the Terrestrial Nitrogen Cycle internal cycling?
- Nitrogen mineralization
- Nitrification
- Ion exchange
- Uptake
What are the Terrestrial Nitrogen Cycle primary losses?
- Leaching
- Gaseous efflux (ammonia, denitrification)
What are the Terrestrial Phosphorous cycle primary inputs?
- Weathering of parent material
What is the Terrestrial Phosphorous cycle internal cycling?
- P mineralization
- Ion exchange (sorption)
- Uptake
What are the Terrestrial Phosphorous cycle primary losses?
- Leaching / erosion
Biological nitrogen fixation
A process in which nitrogen gas (N2) from the atmosphere is incorporated into the tissue of certain plants
(Inputs of weathering is more common than biological fixation)
What is considered to be important in nutrient cycling?
- Sorption
- Immobilization
Sorption
The retention of Phosphorous on soil particles, makes Phosphorous unavailable to plants for uptake
Immobilization
The process in which nitrate and ammonium are taken up by soil organisms and therefore become unavailable to crops.
How do humans impact nutrient cycling?
Fertilizer use, fossil fuel combustion, and cultivation of legume crops that exceed the total amount of biological Nitrogen fixation
How does fertilizer impact nutrient cycling?
Fertilizer increases crop yields which leads to nutrient imbalance and pollution in waterways
What happens when there are chronic nutrient inputs?
May stimulate Net Primary Production
Causes: Oligotrophic water bodies becomes eutrophic
Oligotrophic water body
Few in nutrients - clear water
Eutrophic water body
Abundant in nutrients - cloudy water
What does eutrophication lead to?
Dead zones
Are dead zones reversible in eutrophic bodies of water?
Yes - if nutrient inputs are reduced
How does deforestation affect nutrient cycling? Occurs from?
Causes a large amount of nutrients to be lost in ecosystems
Occurs from: leaching, erosion, gaseous emission
