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Ecology > Nutrient and energy cycling > Flashcards

Nutrient and energy cycling Flashcards

1
Q

Ecosystem’s dynamics involve 2 main processes

A
  • energy flow
  • chemical cycling
  • irregardless of ecosystem size
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2
Q

Laws of physices

A
  1. energy cannot be created or destroyed –>solar radiation is conserved and lost from organisms as heat
  2. every exchange of energy increases entropy of universe –> not completely efficient –> always some energy lost as heat
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3
Q

Law of conservation of mass

A
  • matter can’t be created or destroyed
  • chemicals are recycled
  • ecosystem is an open system, absorbing energy and mass, and releasing heat and waste
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4
Q

What if nutrient’s outputs from ecosystem exceed its input?

A

that nutrient will limit production

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5
Q

2 types of biogeochemical cycles

A
  1. Perfect: fast, continuous cycling of nutrients. Involves vast, abiotic, atmospheric reservoir
  2. Imperfect: “lose” nutrients for a time because they are tied up in sediment or at the bottom of the ocean
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6
Q

Carbon Cycle

A
  • not perfect or imperfect
  • mostly photosynthesis and respiration
  • needs to be dissolved in water
  • sometimes tied up in unusable form
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7
Q

Nitrogen Cycle

A

-perfect cycle with big atmospheric pool
-only nitrogen fixers can use atmospheric nitrogen directly –> they turn it into ammonia for other organisms
-70% of atmosphere
-terrestrial cycling = 10x fixation
biggest pool of actively cycled N2 is in ocean
-pocket gophers bring N-poor soil to surface
-firetree in hawaii
-aquatic invertebrates recycle 15-70% of N into ammonia for plants

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8
Q

Phosphorus Cycle

A
  • imperfect –> no atmospheric pool
  • mostly in mineral deposits and MARINE SEDIMENTS
  • slowly made available by weathering of rocks
  • Release is episodic –> associated with spring snowmelt
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9
Q

Nutrient Spiraling

A
  • in streams
  • go downstream –> cycling doesn’t happen much in one place
  • spiraling length is distance required for nutrient to complete cycle
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10
Q

Water cycle

A
  • perfect cycle
  • 70% oceans, 2% icecaps, 1% freshwater
  • distribution is nonstatic –> relies on heat, evaporation, clouds, precipitation, consumption
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11
Q

transpiration

A

moves water into, through, and out of plants

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12
Q

evaporation

A

-surface water converts to gaseous phase

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13
Q

turnover time

A
  • time required for entire body of water to be cycled
  • oceans = 3100 yrs
  • rivers 12-20 days
  • atmosphere 9 days
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14
Q

nutrient pool

A

amount of nutrient in portion of ecosystem

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15
Q

nutrient sink

A

absorbed is greater than released

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16
Q

nutrient flux

A

movement of nutrient between pools

17
Q

nutrient source

A

released is greater than absorbed

18
Q

Photosynthesis equation

A

6H2O + 6CO2 + energy = C6H12O6 + 6O2

19
Q

Chemosynthetic auxotrophs

A

bacteria on the sea floor near volcanic activity

-necessary parts of community

20
Q

Net Primary Production

A

fixation of energy by auxotrophs in ecosystem over time (measured in biomass)

21
Q

Where are the most productive places?

A
  • tropical rainforests
  • estuaries
  • coral reefs
  • marine ecosystems aren’t super productive, but contribute a lot because of large area
22
Q

Gross Primary Production

A

conversion of energy (usually from light) to chemical energy of organic molecules per unit time

NPP = GPP - R (usually about 1/2 of GPP)

23
Q

3 things that affect TERRESTRIAL NPP

A

moisture and temperature

  • increases evapotraspiration
  • increases PP
  • soil fertility (N and P)
  • especially N in dry alpine meadow
24
Q

2 things that affect AQUATIC NPP

A

light and nutrients (more so than light)

  • depth of light penetration
  • N and P are often limiting nutrients

-P is positively associated with phytoplankton biomass

25
Q

Eutrophication

A
  • presence of excessive nutrients
  • happens when too much phosphorus is added
  • after fertilization stopped, phytoplankton went back to normal
26
Q

secondary production

A

production of biomass by heterotrophic animals over time

27
Q

detritivores / decomposers

A
  • heterotrophs that get nutrients from dead shit
  • usually prokaryotes and fungi
  • affect all trophic levels
  • rate of decomp is affected by temp, moisture, and chemical composition
28
Q

Leave decomposition

A
  • slower when more lignin

- faster when more nitrogen (like in streams)

29
Q

Temperature and decomposition

A

high temp = high rate of decomp

30
Q

Tropical rainforests and decomposition

A
  • fast decomp – low soil nutrients

- most nutrients are tied up in trees

31
Q

Anaerobic environments –> good or bad for decomp

A

bad

32
Q

Litter

A
  • high in tropical rainforests
  • low in desert
  • highest in high latitude boreal forests bc of slow decomp
  • w/o decomp, chemicals couldn’t be recycled and GPP would go way down
33
Q

Extreme pH and decomp

A
  • bad

- Bogs accumulate peat bc acid

34
Q

ultimate decomposers

A
  • bacteria and fungi

- final degradation to CO2 and H2O

35
Q

reducer-decomposers

A

all detritivores besides ultimate decomposers
plant material: microarthropods, nematodes, earthworms, milipedes, slugs

animal material: carion flies, beetles, crows, vultures

Ecology (13 decks)

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