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PLANT > NPP (12) > Flashcards

NPP (12) Flashcards

1
Q

NPP?

A

= how much growth a plant can make in a time period.

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2
Q

NPP stands for?

A

N Plant Productivity.

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3
Q

Biomass?

A

= amount of plant material that you can measure at 1 point in time.

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4
Q

Productivity?

A

= amount of plant material that you can measure at 2 points in time.

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5
Q

NPP formula?

A

NPP = GPP – Ra.

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6
Q

From the formula, what is NPP?

A

= amount of carbon uptake by a photosynthetic autotroph after subtracting Ra & the GPP.

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7
Q

GPP stands for?

A

Gross Plant Productivity.

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8
Q

Ra?

A

= autotrophic respiration.

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9
Q

GPP?

A

= rate at which photosynthesis occurs.

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10
Q

Therefore, what is NPP?

A

= sum of the increments in the biomass of a plant/vegetation community.

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11
Q

Egs causes of losses to the system? (3)

A

• Senescence.
• Herbivory.
• Decay.

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12
Q

NPP SI units? (2)

A

● g C m(-2) y(-1)
[C is Carbon]

● g DM m(-2) y(-1)
[DM is Dry Matter]

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13
Q

1gDM is equivalent to?

A

0.45 gC.

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14
Q

1 ton is equivalent to?

A

1t = 10⁶ g.

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15
Q

Why is NPP a central measure of ecosystem performance? (3)

A

• It’s the key measure of the “ecosystem economy”.

• GDP of an ecosystem.

• It’s the energy available to drive ecosystem function at all tropic levels.

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16
Q

Yield formula?

A

Yield = NPP × HI.

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17
Q

HI stands for?

A

Harvest Index.

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18
Q

NPP measurement in a grassland steps? (3)

A

● Place many quadrats across the area.

● Clip the grass in the quadrats with a pair of secateurs.

● Sort live matter from dead before drying & weighing.

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19
Q

Protect grass from?

A

Grazing by macro-herbivores & micro-herbivores (locusts).

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20
Q

Why is it necessary to take grass biomass? (2)

A

• To know how many cattle can feed on the grass.
• To know where to burn.

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21
Q

What is the decision matrix used for?

A

To calculate NPP in each interval & then the sum of the intervals is taken over the year.

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22
Q

From Decision Matrix, when is NPP = change in necromass.

A

NPP = change in necromass

• +Necromass & –Biomass.

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23
Q

From Decision Matrix, when is NPP = 0?

A

NPP = 0.

• –Necromass & –Biomass.

24
Q

From Decision Matrix, when is NPP = (change in biomass) + (change in necromass)

A

NPP = (change in biomass) + (change in necromass)

• +Necromass & +Biomass.

25
Q

From Decision Matrix, when is NPP = change in biomass?

A

NPP = change in biomass

• –Necromass & +Biomass.

26
Q

Necromass?

A

= dead plant material.

27
Q

Biomass?

A

= live plant material.

28
Q

NPP of an annual crop? What to take?

A

Take the mass at the end growing season.

29
Q

What is estimated using the HI? (2)

A

• Yield component (eg. Grain).
• Roots.

30
Q

Why is just the mass taken at the end of growing season?

A

It’s because the mass at time zero is effectively zero.

31
Q

Why is self-reporting inaccurate?

A

It’s because it relies on the farmer saying how many bags they harvested & then measuring the size of the field.

32
Q

NPP measurement in woody vegetation features? (3)

A

• Easy to measure in plantations that were planted.

• Even distribution of sizes.

• Difficult to measure in a natural forest or trees in savannas.

33
Q

Why is it difficult to measure NPP in a natural forest or in trees in savannas?

A

There are lots of different species of variable heights.

34
Q

Result of the difficulty of measuring NPP in a natural forest or in trees in savannas?

A

Different techniques are used to measure these 2 different types of woody vegetation.

35
Q

NPP measurement in a forest steps? (5)

A

● Measure mean manual increment (stem circumference & height growth).

● Apply allometric equations to convert to timber volume.

● Add litterfall to get leaf production & belowground production.

● Put out baskets to catch litterfall.

● Collect, sort, dry & weigh monthly.

36
Q

Allometry?

A

= material relationship between one variable that’s easy to measure & one variable that’s difficult to measure.

37
Q

Egs of NPP measurement in woody vegetation? (2)

A

• Pine plantation.
• Eucalyptus plantation.

38
Q

Allometry features? (2)

A

• Type of biological scaling.
• Useful in measuring tree biomass.

39
Q

Eg of allometry? Explain.

A

Human body
= hearts beat more slowly & brains get bigger.

40
Q

Why is allometry useful in measuring tree biomass? (2)

A

● Establishes a relationship between tree circumference & amount of leaves.

● Establishes a relationship between tree circumference & volume of wood.

41
Q

Why is important to establish a relationship between tree circumference & amount of leaves?

A

To know how much foliage is available.

42
Q

Why is it important to establish a relationship between tree circumference & volume of wood?

A

To know how much timber is available.

43
Q

AGNPP stands for?

A

Above Ground NPP.

44
Q

BGNPP stands for?

A

Belowground NPP.

45
Q

What should you do to estimate BGNPP?

A

• Measure soil respiration & subtract AG litterfall.

46
Q

What should we use for BGNPP? (2)

A

• Use root ingrowth cores.
• Use repeated coring & sorting live roots from dead.

47
Q

What to use to measure root growth?

A

Use rhizotrons.

48
Q

Root ingrowth cores?

A

= rhizotrons.

49
Q

Why timber volume and not mass?

A

It’s because that’s how timber is traded & mass varies among tree species.

50
Q

Upscaling?

A

= when you have taken measurements at a small scale & want to scale that up to a whole plant, whole forest or a whole plant community.

51
Q

Eg of Upscaling?

A

Using an IR analyzer to determine Photosynthetic rate of one leaf.

52
Q

Downscaling?

A

= when you are using large scale measurements & want to downscale that measurement to one tree or a small area.

53
Q

Eg of downscaling?

A

Using remote sensing or measurements of how many trees exist in a forest.

54
Q

Discuss difficulties associated with upscaling & downscaling in measuring biomass & productivity?

A
55
Q

Relationship between accuracy needed, difficulty in obtaining data & cost taking measurement in Upscaling & Downscaling?

A

More accuracy needed, More difficulty in obtaining data, More cost taking measurement.

56
Q

Egs of scientists taking measurements? (2)

A

• NPP of phytoplankton communities.
• NPP in space.

PLANT (15 decks)

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