Decomposition

Question 1

What is decomposition?

Answer 1

the breakdown of dead organic material (proteins) to release inorganic matter (nitrates and CO2)

Question 2

What is the rate of decomposition affected by?

Answer 2

temperature, moisture, and exact nature of the dead organic material

Question 3

What is litter quality?

Answer 3

the predominant dead organic material in terrestrial ecosystems, plant material

Question 4

How is the rate of decomposition commonly measured?

Answer 4

litterbags are weighed and placed into environment and weighed again after some incubation time

Question 5

When is rate of decomposition faster?

Answer 5

may be faster during initial phase of decomposition as more easily broken down organic materials are quickly utilized

Question 6

What was the LIDET decomposition experiment measuring?

Answer 6

at 28 locations, 4 plant species (sugar maple leaves, bluestem grass roots, chestnut oak leaves, and red pine needles)

Question 7

What were results of LIDET decomposition experiement?

Answer 7

• temp and precip increase decomposition of maple leaves but variation site to site
• temp slightly better predictor of maple leaf decomp
• bluestem root decomp better explained by variation in precip

Question 8

What may better explain decomposition rates in contrast to temperature and precipitation?

Answer 8

• actual evapotranspiration
• potential evapotranspiration
• composite climatic decomposition indices

Question 9

What is actual evapotranspiration?

Answer 9

the actual rate at which water vapor is returned to the atmosphere from the ground and by plants

Question 10

What is potential evapotranspiration?

Answer 10

the maximum achievable evapotranspiration for a given crop

Question 11

What best explains the patterns in the LIDET experiment?

Answer 11

a CDI based on plant water stress and monthly temperature variation

Question 12

Does leaf material decompose faster in water or dry land?

Answer 12

water, especially in streams where mechanical breakdown is accelerated

Question 13

What do shaded aquatic ecosystems depend on?

Answer 13

allochthonous (introduced from diff environment) input of organic material from terrestrial ecosystem

Question 14

What does variation in decomposition affect?

Answer 14

productivity, biological diversity, and ecological structure

Question 15

What makes up the decomposition “triangle”?

Answer 15

litter quality, decomposing organisms, and climate

Question 16

What is decomposition chemically similar to and why?

Answer 16

respiration (breakdown of organic matter)

Question 17

What does decomposition depend upon in terms of reactions?

Answer 17

series of redox (reduction/oxidation) reactions; electron transport

Question 18

Under anaerobic conditions what occurs?

Answer 18

less mass is lost and more CH4 is produced (rather than CO2)

Question 19

What is step-wise anaerobic decomposition?

Answer 19

large complex organic molecules are hydrolyzed to simple organic molecules which are fermented into organic acids which undergo methanogenesis to produce methane

Question 20

What are anoxic decomposers?

Answer 20

use oxygen in nitrates, nitrites, and sulfates to break down organic molecules to release CO2

Question 21

What is controlled anaerobic decomposition used for?

Answer 21

to preserve meats, grains, fruits, milk, etc

Question 22

Why is the decay curve higher for deciduous (Tulip Poplar) than evergreen (Rhododendron)?

Answer 22

lower C:N ratios equal higher decomposition rates (relatively higher N)

Question 23

How do lignin and tannins and other phenolics affect decomposition rate?

Answer 23

negatively affect

Question 24

How is initial N content related to decomp rate?

Answer 24

positively correlated

Question 25

What happens if hemlocks are replaced by rhododendron which have a higher C:N ratio?

Answer 25

• decomposition and nutrient cycling will slow
• may also open up forest canopy resulting in dryer soil (even slower decomp)

Question 26

What is detritus?

Answer 26

dead organic material that is part of the food web

Question 27

What amount of NPP goes to detritus production?

Answer 27

over 1/2 in terrestrial ecosystems

Question 28

What is used to assist investigators in identifying the date of death?

Answer 28

body farms

Question 29

In the human body, what increases as decay?

Answer 29

ammonia in the vitreous humor of eye increases linearly (up to 100 hours after death)