Litter Decomposition and Nutrient Cycling

Question 1

Litter decomposition

Answer 1

Produced from dead plant matter and animal matter

Question 2

What happens during the decomposition of litter?

Answer 2

Transformed into soil organic matter

Question 3

What does the process of litter decomposition determine?

Answer 3

The rates of nutrient recycling

Question 4

How do decomposers help in nutrient cycling?

Answer 4

• 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

Question 5

Litter decomposition stages

Answer 5

1. Start
2. Fragmentation
   Leaching
3. Microbial mineralization
   Further fragmentation
4. Stable phase
   Lignin degradation

Question 6

Fragmentation

Answer 6

The process of breaking down the raw complex materials (Done by detritivores)

Question 7

Detritivores

Answer 7

Consume dead organic matter

Question 8

Leaching

Answer 8

The process of releasing nutrients in the water and seeping into the soil

Question 9

Microbial mineralization

Answer 9

Microorganisms release gases; Nitrogen, Sulphur, Phosphorus due to decomposition and other inorganic compounds are readily assimilated by plants.

Question 10

Lignin degradation

Answer 10

Most abundant organic material on Earth; it decomposes slowly

(Only fungi and bacteria can decompose lignin)

Question 11

When does litter decomposition decompose at a slower rate?

Answer 11

When tissues are physically tough, with high lignin and low Nitrogen content

Question 12

When does litter decomposition decompose at a faster rate?

Answer 12

1. Easily decomposable C compounds (sugars, starch)
2. Warmer wet climates

Question 13

What is the link between decomposition and nutrient cycling?

Answer 13

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)

Question 14

What are the Terrestrial Nitrogen Cycle primary inputs?

Answer 14

1. Biological Nitrogen fixation
2. Human Nitrogen fixation

Question 15

What is the Terrestrial Nitrogen Cycle internal cycling?

Answer 15

1. Nitrogen mineralization
2. Nitrification
3. Ion exchange
4. Uptake

Question 16

What are the Terrestrial Nitrogen Cycle primary losses?

Answer 16

1. Leaching
2. Gaseous efflux (ammonia, denitrification)

Question 17

What are the Terrestrial Phosphorous cycle primary inputs?

Answer 17

1. Weathering of parent material

Question 18

What is the Terrestrial Phosphorous cycle internal cycling?

Answer 18

1. P mineralization
2. Ion exchange (sorption)
3. Uptake

Question 19

What are the Terrestrial Phosphorous cycle primary losses?

Answer 19

1. Leaching / erosion

Question 20

Biological nitrogen fixation

Answer 20

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)

Question 21

What is considered to be important in nutrient cycling?

Answer 21

1. Sorption
2. Immobilization

Question 22

Sorption

Answer 22

The retention of Phosphorous on soil particles, makes Phosphorous unavailable to plants for uptake

Question 23

Immobilization

Answer 23

The process in which nitrate and ammonium are taken up by soil organisms and therefore become unavailable to crops.

Question 24

How do humans impact nutrient cycling?

Answer 24

Fertilizer use, fossil fuel combustion, and cultivation of legume crops that exceed the total amount of biological Nitrogen fixation

Question 25

How does fertilizer impact nutrient cycling?

Answer 25

Fertilizer increases crop yields which leads to nutrient imbalance and pollution in waterways

Question 26

What happens when there are chronic nutrient inputs?

Answer 26

May stimulate Net Primary Production Causes: Oligotrophic water bodies becomes eutrophic

Question 27

Oligotrophic water body

Answer 27

Few in nutrients - clear water

Question 28

Eutrophic water body

Answer 28

Abundant in nutrients - cloudy water

Question 29

What does eutrophication lead to?

Answer 29

Dead zones

Question 30

Are dead zones reversible in eutrophic bodies of water?

Answer 30

Yes - if nutrient inputs are reduced

Question 31

How does deforestation affect nutrient cycling? Occurs from?

Answer 31

Causes a large amount of nutrients to be lost in ecosystems Occurs from: leaching, erosion, gaseous emission