lecture 3

Question 1

what did early paradigms assume?

Answer 1

ssumed natural ecosystems in equilibrium -early perspective

Question 2

why are models made? ex?

Answer 2

○ Weather-the idea of it, up to the invention of the telegraph was completely local, no way of conveying info in real time to others further away
* How we think about climate and weather changes based on our perspectives, new technology allowed us to think differently about climate
* Ecosystems are similar- if you spend time in one area, that’s your perspective, there are many other perspectives
Our everyday experience is stable, but many factors transcend lifetimes

Question 3

what would a natural system in equilibrium look like?

Answer 3

○ Closed systems - internal recycling
○ Deterministic dynamics;; stable endpoints
○ Absence of disturbance and human influence (considered rare)
○ Equilibrium- the idea that theres some stable state that’s reached
○ Easier to study than something that fluctuates

Question 4

are most systems in equilibrium? ex?

Answer 4

ost places are not in equilibrium
§ The system today is still experiencing the effects of events from 12 years ago-opal

Question 5

how was the non equilibrium view an advancement?

Answer 5

past events, internal and external forces shape ecosystems
○ Maybe unbalanced inputs and outputs
○ No single stable equilibrium
Human activities and disturbance important

Question 6

what are steady state equilibriums?

Answer 6

• Another conceptual advance; differs from equilibrium view
  
  • Compromise between full non equilibrium model and equilibrium model
  • vs Open system- an average over time driven by random factors

Question 7

describe the steady state system dynamics

Answer 7

• Open systems, but inputs=outputs
  ○ No trend over time (e.g. h2o in = h2o out)
  ○ Can be temporal and spatial variation (e.g. plant growth varies in summer vs winter and between wet and dry years)
  No long term directional tre

Question 8

jenny 1941 concept? how was it an advancement?

Answer 8

Ecosystem structure and function governed by independent state factors and interactive controls
* 5 main state factors: set the bounds for the characteristics of an ecosystem
* Conceptual advance - emphasized controls over processes rather than descriptions of pattern
* Independent - not influenced themselves by ecosystem characteristics

Question 9

what are the 5 state factors jenny

Answer 9

climate
topography
time
parent material (rock that gives rise to soil)
potential biota

Question 10

which state factor most strongly influences?

Answer 10

climate

Question 11

describe climate as a state factor

Answer 11

• The state factor that most strongly determines ecosystem structure and processes (on broad scales)
  
  • e.g. global climate explains distribution of biomes

Question 12

describe parent material as a state factor

Answer 12

Within a biome, parent material (rock that gives rise to soil) strongly influences the types of soils that develop and explain regional variation in ecosystem processes

Question 13

describe topography as a state factor. what do slope angle, aspect, and elevation impact?

Answer 13

• Influences microclimate and soil development at a local scale
  
  • Slope angle: influences drainage, erosion
  • Aspect: influences temperature and precipitation
  • Elevation and slope
    ○ Steep slope= theres a steep change in microclimate
    ○ Aspect: temp and precipitation based on exposure from elevation and slope
    Changed elevation changes climate massively

Question 14

what does potential biota influence as a state factor? where is it especially dominant?

Answer 14

• Governs types and diversity of organisms that will occupy a site
  Especially dominant factor on island ecosystems: usually less diverse bc of differences in potential biota (new species reach islands less often)

Question 15

describe time as a state factor

Answer 15

• Influences the development of soil and evolution of organisms over long time scales
  Important component of succession, development, and change in communities and ecosystems over time

Question 16

look at plant community succession

Answer 16

ok

Question 17

Critiques of Jenny’s 5 independent state factors? (3)

Answer 17

• Parent material - weather depends on community of moss and lichen that secretes acids while they grow
  
  • Ecosystem processes both respond to and control the factors that directly govern their activity
    Interactive controls; factors that operate at the ecosystem scale and both control and respond to ecosystem characteristics

Question 18

how can jenny’s model be expanded

Answer 18

include microenvironment (rate of ecosystem proccesses), resources, disturbance, and biotic community

Question 19

ex of why jenny’s model could be improved (3)

Answer 19

○ Soil fertility (resource) may control the dominant plant community that develops, but responds to weathering rates
○ Disturbance regime controls nutrient cycling, but responds to ecosystem type (availability of fuel)
Microenvironment controls decomposition rate, but responds to topography

Question 20

what do state factors and interactive controls determine?

Answer 20

together, these state factors and interactive controls largely determine characteristics and processes

Question 21

look at human activities diagram

Answer 21

ok

Question 22

is an ecosystem linear?

Answer 22

• Within that, feedback in ecosystem from species interactions
  Complexity of the model and non linearity
  feedpacks are amplifying (positive) and stabilizing (negative) when the recip effects differ in sign

Question 23

how are climate and weather different?

Answer 23

• Difference in temporal scale
  weather refers to short-term changes in the atmosphere, climate describes what the weather is like over a long period of time in a specific area.

Question 24

marco vs micro climate?

Answer 24

• Macroclimate: prevailing climate for a region
  microclimate : small scale variation in climate caused by a distinctive substrate, location, topography, aspect, etc

Question 25

why is climate important?

Answer 25

• State factor that most strongly governs global distribution of terrestrial biomes
  Single best predictor of ecosystem structure and function because of its impact on net primary productivity

Question 26

what is climate ultimately driven by?

Answer 26

Climate is ultimately driven by incoming and outgoing solar radiation (earth’s energy budget)

Question 27

what is radiation measured on?

Answer 27

Electromagnetic spectrum

Question 28

where does solar radiation fall?

Answer 28

200-4000nm

Question 29

what determines wavelenth emitted? sun emissions? earth?

Answer 29

• Temp of a cosmic body determines wavelength of radiation emitted
  
  • Sun 6k degrees cel emits high energy shortwave radiation
  • Earth = 15 degrees C - kow energy longwave radiation emitted

Question 30

how do pp use the wavelengths?

Answer 30

• Certain wavelengths are used by the vast majority of primary producers
  
  • Theres a range that excites the molecules in photosynthesis
  • Green is the part of the spectrum not used by plants, making them green

Question 31

what are the major chemical constituents of the atmosphere?

Answer 31

N2 78%
O2 20.9%
Ar 0.93%
CO2 0.04%

Question 32

what are aerosols? how can they happen?

Answer 32

• Aerosols - small particles suspended in atmopshere
  ○ Natural (volcanic eruptions, dust, sea salt) or anthropogenic (pollution)
  ○ Nuclei for water condensation (clouds)
  ○ High albedo (reflect incoming SW radiation - cooling effect)

Question 33

what impact do clouds have? (3)

Answer 33

• Clouds (H2O) -complex effects on earth’s radiation budget
  ○ High albedo (cooling)
  ○ Absorb LW radiation (warming; greenhouse gas)