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Ecology > Chapter 20: Production > Flashcards

Chapter 20: Production Flashcards

1
Q

When was the first use of the term ecosystem and what did it refer to?

A

-Tansley (1935)
-Refers to all the components of an ecological system that influence the flow of energy and elements

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2
Q

Ecosystem Concept

A

integrates ecology with other disciplines such as geochemistry, hydrology, and atmospheric science

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3
Q

Where does the energy in ecosystem originate?

A

autotrophs

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4
Q

Primary Production

A

chemical energy generated by autotrophs during photosynthesis and chemosynthesis

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5
Q

Source of Energy for all organisms

A

primary production

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6
Q

Where are fossil fuels derived from?

A

primary production

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7
Q

Where is energy assimilated from autotrophs stored?

A

carbon compounds in plant tissues

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8
Q

Primary Productivity

A

rate of primary production

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9
Q

Gross Primary Production (GPP)

A

total amount of carbon fixed by autotrophs

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10
Q

What is GPP controlled by?

A

-climate through its influence on photosynthetic rate
-Leaf area index: leaf area per unit of ground area

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11
Q

What is the variation in LAI among biomes?

A

-less than 0.1 in Arctic tundra (less than 10% of the ground surface has leaf cover)
-12 in boreal and tropical forests (12 layers of leaves between the canopy and the ground, on average)

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12
Q

What is the relationship between shading and photosynthesis?

A

-When shading increases, the incremental gain in photosynthesis for each added leaf layer decreases
-Eventually, the respiratory costs associated with adding leaf layers outweigh the photosynthetic benefits

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13
Q

How much fixed carbon do plants use in photosynthesis for cellular respiration?

A

about half

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14
Q

What type of plants have higher respiratory carbon losses?

A

plants with a lot of non-photosynthetic tissue (trees)

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15
Q

What increases with temperature?

A

respiratory rate

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16
Q

What biome has the higher respiratory losses?

A

tropical forests

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17
Q

Net Primary Production (NPP)

A

GPP-Respiration

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18
Q

NPP

A

-the amount of energy captured by autotrophs that results in an increases in biomass (living plant matter)
-the energy left over for plant growth and for consumption by detritivores and herbivores

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19
Q

How do plants respond to environmental conditions?

A

allocating carbon to the growth of different tissues

20
Q

How does allocation of NPP to storage products affect the plant?

A

provides insurance against loss of tissue to herbivores, disturbances such as fire, and weather events such as frost

21
Q

How much NPP may be allocated to defensive secondary compounds?

A

up to 20%

22
Q

What varies during succession and why?

A

-NPP as LAI and species composition all change

23
Q

When is NPP the highest?

A

usually during intermediate stages when plant diversity and nutrient supply tend to be highest

24
Q

What happens to NPP and LAI in old growth forests?

A

-NPP may decline as LAI and photosynthetic rates decrease
-But Old-Growth ecosystems have large pools of stored carbon and nutrients for many animal species
-Decrease in NPP over time is less pronounced in grasslands than in forests

25
Q

What is the ultimate source of energy of all organisms in an ecosystem?

A

NPP

26
Q

What is an indication of ecosystem health?

A

variation in NPP

27
Q

What is associated with the global carbon cycle?

A

NPP

28
Q

Terrestrial Ecosystem

A

NPP is estimated by measuring increase in plant biomass in experimental plots and scaling up to the whole ecosystem

29
Q

Harvest techniques for NPP

A

-measure biomass before and after growing season
-this is a reasonable estimate of aboveground NPP if corrections are made for herbivory and mortality

30
Q

Why is measuring below ground NPP more difficult?

A

-fine roots turn over more quickly than shoots (they die and are replaced quickly)
-roots may exude carbon into the soil and transfer it to mycorrhizal or bacterial symbionts
-Harvests must be more frequent and additional correction factors are needed

31
Q

What’s another way to measure below ground biomass other than harvest techniques?

A

it can be estimated from aboveground measurements and algorithms that relate above and belowground biomass

32
Q

What are Minirhizotrons and why are they helpful?

A

-underground viewing tubes outfitted with video cameras
-allow researchers to directly observe root growth and death
-led to advances in understanding below ground production processes

33
Q

When are harvest techniques impractical?

A

large or biologically diverse ecosystems

34
Q

What can be used as a proxy for GPP and NPP?

A

chlorophyll concentrations

35
Q

How can chlorophyll concentrations be used to estimate GPP and NPP?

A

estimate using remote sensing methods that rely on reflection of solar radiation

36
Q

What wavelength colors do chlorophyll absorb?

A

blue and red and has a characteristic spectral signature

37
Q

What wavelengths do plants reflect?

A

near infrared wavelengths

38
Q

read slides 30-33

A
39
Q

How is NPP measured from GPP and respiration measurements?

A

-change in CO2 concentration is measured in a closed chamber
-sometimes whole stands of plants are enclosed to study CO2 exchange

40
Q

Net Ecosystem Exchange (NEE)

A

-GPP minus total respiration
-more refined estimate of ecosystem carbon storage than NPP

41
Q

Eddy Correlation or Eddy Covariance

A

NEE is estimated by measuring CO2 at various heights in a plant canopy

42
Q

How does a gradient of CO2 develop?

A

Because of photosynthesis and respiration

43
Q

How does the time of day affect the CO2 concentration?

A

-during the day, CO2 decreases in the canopy with photosynthesis
-at night, CO2 is higher in the canopy

44
Q

What is the network that measures the amount of carbon and climate conditions?

A

eddy covariance sites

45
Q

What does most of the photosynthesis in aquatic habitats?

A

phytoplankton

46
Q

Read slides 43-45

A

Ecology (12 decks)

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