!!!!Class13 - Productivity and Sensitivity Analysis-USED

8/11/2019 !!!!Class13 - Productivity and Sensitivity Analysis-USED

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07/03/201

Global Warming:

Productivity & Sensitivity Analysis

Definitions Standing croptotal amount of producer biomass/carbon

in an ecosystem at a given point in time

Production:: creation of new organic matter

Gross Primary Production (GPP): total amount of

energy fixed (or CO2 taken up) by all autotrophs in an ecosystem

Net Primary Production (NPP): energy remainingafter autotrophs have met their own energetic needs

NPP = GPPRPP


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STELLA Productivity Model

What are the Standing Crop, GPP & NPP of the simulated

algae population compared to real populations?

Use In-Class 12 Product iv i tyInClass.stmx

pH = 7 and Temp = 27.5

DT = .2 Runge-Kutta2 T = 3000

For GPP and NPP we want to determine the average pgs of

Carbon produced by the model algae population per liter/day

After dynamics settle down, we use 240 hrs (10 days) as the

time frame for sampling productivity& divide final sum by 10

Comparison with Real Populations

Lake exclosure expts.No herbivores: 100-600 ug C/L

1. Standing Crop Model=(68,954,773+62,768,346)/2 pg/L= 065e9pg/L= 65 ug/L 65 ug C/L

2. GPP Model= (2.965e9 pg C/L/day)/10 = .296e9pg C/L/d 296 ug C/L/day

Lake exclosure exptsNo herbivores:

3. NPP Model = (1.491e9 pg C/L/day)/10 = .149e9pg C/L/d 149ug C/L/day

Lake exclosure exptsNo herbivores: 105 ug C/L/day

120 ug C/L/day


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NPP & Standing Crop in Nature?

Standing crop biomass

NPP

1. The concentration of CO2 in the atmosphere has gone from 280

ppm in pre-industrial times to 397 ppm at present. In terms of

partial pressure, thats an increase from .000280 to .000397.

Given these values, what is the expected increase in the

concentration of CO2 and pH of non-buffered water at 25o ?


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Calculating Changes in CO2 and pH

2. Given KA1and knowing the concentration of CO2 we can calculate pH bysolving for [H+]2 from the following equilibrium constant:

1. Current % CO2 in atmosphere = .0397

PpCO2 = .000397 atm

KCO2 = 29.41 Latm/mol

[CO2] = .000397 atm/29.41 atm/mol = .00001349 mol /L

[H+]2 =1.349x10-5mol/L*4.45x10-7= 6e-12

[H+] = SQRT(6e-12) = 2.45x10-6

pH = -LOG10(2.45x10-6) = 5.61

3. Pre-industrial % CO2 in atmosphere = .0280

PpCO2 = .000280 atm[CO2] = .000280 atm/29.41 atm/mol = .00000952 mol /L

[H+]2 =9.52x10-6mol/L*4.45x10-7= 4.236e-12

[H+] = SQRT5.7136e-12) = 2.058x10-6

pH = -LOG10(2.058x10-6) = 5.69

Playing in the Silicon SandboxWhat model parameters could we change to determine their

influence on the system? Write down as many as you can.

Temp Temp Response curve

pH pHResponse curve

Day length Attenuat ion constant

IrradianceatSURFACE Cell C needed to divi de

Photosynthesis curve saturation ,slope etc. Respiration rate

Depthmeters Prespconstant

Attenuatio n PintoL iter (renewal rate of P)

VmaxP

Pmax

Kcarbon

KPhosph

RespirationRate

Pwater

Chalf

Ku

Vmax

Prespconstant

Death rate per Indiv


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Sensitivity Analysis - STELLA

Sensitivity analyses allow us to analyze how model state

variables respond to changes in the model parameters.

This allows us to identify those parameters that have the

most important impact on system dynamics.


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Sensitivity Analysis - STELLA

1. What other variables should we try?:

!!!!Class13 - Productivity and Sensitivity Analysis-USED

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