Lecture 18: Ecosystems: Water cycle, carbon cycle, & nitrogen cycle

Question 1

Major physical and biological processes couple water movement to ____________________ and _______________ in ecosystems.

Answer 1

• energy transformation
• element cycling

Question 2

Water movement is therefore a ______________________________________ and for understanding energy flow in an ecosystem

Answer 2

valuable proxy for element cycling

Question 3

Direct human impacts on the water cycle

Answer 3

• Land conversion impacts water runoff pathways and rates
• Altered water runoff pathways and rates

Question 4

Direct human impacts on the water cycle - land conversion

Answer 4

• Developed areas (city-building and especially concrete).
• Agricultural land conversion.
• Dams
• Irrigation.

Question 5

Direct human impacts on the water cycle - Altered water runoff pathways and rates

Answer 5

• substantial impact on soil erosion — direct impact and indirect impact on crops
• can further impact vegetation cover,
  droughts, and fire

Question 6

The movement of major organic elements serves as a _____________________________

Answer 6

good proxy to energy flow

Question 7

Carbon is ____________________________ and transferred in ___________________________________, so carbon transfer is directly coupled with energy flow.

Answer 7

• generated from photosynthesis
• trophic interactions and decomposition

Question 8

Net ecosystem production

Answer 8

a measure of the balance of carbon gain and loss in an ecosystem

Question 9

Positive net ecosystem production

Answer 9

serves as a carbon sink

Question 10

carbon sink

Answer 10

Removes carbon, as the main “greenhouse gas”, from the atmosphere

Question 11

what happens when carbon sources outweigh carbon sinks

Answer 11

• results in an increase in greenhouse gases and temperatures
• as we are seeing from human activity

Question 12

what are the 6 major transformations that drive the carbon cycle

Answer 12

1. photosynthesis
2. respiration
3. sedimentation and burial
4. exchange
5. extraction
6. combustion

Question 13

6 major transformations drive the carbon cycle - photosynthesis

Answer 13

Biological removal from the environment

Question 14

6 major transformations drive the carbon cycle - respiration

Answer 14

Biological return to the environment

Question 15

6 major transformations drive the carbon cycle - sedimentation and burial

Answer 15

carbon storage

Question 16

6 major transformations drive the carbon cycle - exchange

Answer 16

Balanced gain/loss between ocean and atmosphere

Question 17

6 major transformations drive the carbon cycle - extraction

Answer 17

Removal of carbon storage by human activity

Question 18

6 major transformations drive the carbon cycle - combustion

Answer 18

• Burning of stored carbon sources
• rapid return of carbon to the environment
• and especially the atmospheric “compartment” of the carbon cycle

Question 19

define residence time

Answer 19

Time spent in any stage of the cycle by the average carbon molecule

Question 20

The global carbon cycle – Photosynthesis & respiration

Answer 20

• Biological exchange between the environment and organisms
• Biological material is a major “sink” for carbon

Question 21

What have humans done to the carbon sink of biological material?

Answer 21

• Humans have reduced the amount of biological material
• Results in more carbon in the air becuase it isn’t going to the sink

Question 22

The global carbon cycle – ocean-atmosphere exchange

Answer 22

• Physical exchange of carbon dioxide between the atmosphere and all water bodies
• Carbon dioxide uptake by the oceans and the process of sedimentation has offset the atmospheric increases from human activity.

Question 23

Carbon dioxide __________________ in water at the interface between air and water, and is also lost back to the atmosphere.

Answer 23

readily dissolves

Question 24

Oceans contain about ______ the carbon dioxide found in the atmosphere – _____________

Answer 24

• 50 times
• major carbon sink

Question 25

The global carbon cycle – Sedimentation & burial

Answer 25

• Process occurs only in aquatic systems
• The excessive “consumption” of carbonate ions due to ocean acidification is also impacting shell formation in marine animals

Question 26

What happens to ocean water when carbon dioxide absorption levels increase

Answer 26

It becomes more acidic - coral reef bleaching

Question 27

explain the sedimentation process

Answer 27

• When carbon dioxide dissolves in water it forms carbonic acid.
• Carbonic acid dissociates into hydrogen ions (source of elevated pH!), bicarbonate ions, and carbonate ions.
• Carbonate ions combine with calcium to form calcium carbonate.
• Calcium carbonate has low solubility and precipitates out of the water to form sediment — a long-term carbon store

Question 28

The average ________________ of carbon in the atmosphere is only 5 years — contrasting 31 years for autotroph material.

Answer 28

residence time

Question 29

The ________________ and ______________________________ makes atmospheric carbon dioxide levels sensitive to increased inputs from sources outside the normal cycle — ______________________

Answer 29

• short residence time
• relatively low level of atmospheric carbon
• like a river bursting its banks

Question 30

changes in carbon dioxide, even the steady decline to present day levels, were coupled with ___________________________________

Answer 30

massive shifts on global land cover and weather patterns

Question 31

Emerging consequences of elevated carbon dioxide in plants

Answer 31

• Elevated growth for some plants
• Reduced plant quality, even if abundance is greater
• Reduced growth or die-off
• Overall, shifts in community structure, including subsequent changes in competitive dynamics

Question 32

Emerging consequences of elevated carbon dioxide - elevated growth for some plants

Answer 32

results in important changes in relative abundance of certain species

Question 33

Emerging consequences of elevated carbon dioxide - reduced growth or die-off

Answer 33

it is due to complex interactions with related temperature increases, and nutrient and temperature availability

Question 34

define the greenhouse effect

Answer 34

• Carbon dioxide absorbs infrared thermal radiation from the earth and re-radiates it
• More carbon dioxide = more re-radiation.
• A steady, recorded rise in annual temperature is tightly correlated with steady rise atmospheric carbon dioxide

Question 35

food production can suffer large ______ with increasingly _________________ patterns

Answer 35

• loses
• unpredictable weather

Question 36

__________ of relatively small change in global climate patterns can have severe impact on established _______________________.

Answer 36

• Speed
• expectations of human activity and especially food production

Question 37

Why do we care about a 1ºC increase in temperature?

Answer 37

Small change in mean annual temperatures may hide increasingly erratic temperature patterns

Question 38

why isn’t the term global warming accurate

Answer 38

it hides the far more significant issue of global climate change

Question 39

what is more accurate than the term global warming

Answer 39

global climate crisis is more accurate and all-encompassing

Question 40

While we wait for global governmental efforts, individual changes do make a difference, and ________________________

Answer 40

collective individual efforts change markets