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Flashcards in Nutrient and energy cycling Deck (35)
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1

Ecosystem's dynamics involve 2 main processes

-energy flow
-chemical cycling
-irregardless of ecosystem size

2

Laws of physices

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

3

Law of conservation of mass

-matter can't be created or destroyed
-chemicals are recycled
-ecosystem is an open system, absorbing energy and mass, and releasing heat and waste

4

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

that nutrient will limit production

5

2 types of biogeochemical cycles

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

6

Carbon Cycle

-not perfect or imperfect
-mostly photosynthesis and respiration
-needs to be dissolved in water
-sometimes tied up in unusable form

7

Nitrogen Cycle

-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

8

Phosphorus Cycle

-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

9

Nutrient Spiraling

-in streams
-go downstream --> cycling doesn't happen much in one place
-spiraling length is distance required for nutrient to complete cycle

10

Water cycle

-perfect cycle
-70% oceans, 2% icecaps, 1% freshwater
-distribution is nonstatic --> relies on heat, evaporation, clouds, precipitation, consumption

11

transpiration

moves water into, through, and out of plants

12

evaporation

-surface water converts to gaseous phase

13

turnover time

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

14

nutrient pool

amount of nutrient in portion of ecosystem

15

nutrient sink

absorbed is greater than released

16

nutrient flux

movement of nutrient between pools

17

nutrient source

released is greater than absorbed

18

Photosynthesis equation

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

19

Chemosynthetic auxotrophs

bacteria on the sea floor near volcanic activity
-necessary parts of community

20

Net Primary Production

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

21

Where are the most productive places?

-tropical rainforests
-estuaries
-coral reefs
-marine ecosystems aren't super productive, but contribute a lot because of large area

22

Gross Primary Production

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

3 things that affect TERRESTRIAL NPP

moisture and temperature
-increases evapotraspiration
-increases PP

-soil fertility (N and P)
-especially N in dry alpine meadow

24

2 things that affect AQUATIC NPP

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

Eutrophication

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

26

secondary production

production of biomass by heterotrophic animals over time

27

detritivores / decomposers

-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

Leave decomposition

-slower when more lignin
-faster when more nitrogen (like in streams)

29

Temperature and decomposition

high temp = high rate of decomp

30

Tropical rainforests and decomposition

-fast decomp -- low soil nutrients
-most nutrients are tied up in trees