Stomatal Conductance Modeling Exercise:
Below is a dataset containing meteorological observations and tower-derived GPP estimates collected at MMSF during the course of a severe drought occurring in 2012.
The data can be downloaded here
DOY Hour VPD (kPa) SWP (Mpa) VWC (m3/m3) Par (umol/m2/s) CO2 (ppm) GPP (umol/m2/s)
161.00 13.00 1.78 -0.31 24.16 1581.51 378.88 31.17
162.00 13.00 0.81 -0.40 22.18 1039.02 393.49 26.87
163.00 13.00 2.19 -0.35 23.29 1981.02 391.32 14.06
164.00 13.00 1.65 -0.37 22.79 1959.24 390.29 28.01
165.00 13.00 2.28 -0.40 22.08 1975.11 386.57 21.81
166.00 13.00 2.61 -0.43 21.51 1964.63 388.04 17.56
167.00 13.00 2.32 -0.46 21.06 1921.93 384.74 20.38
168.00 13.00 1.34 -0.49 20.65 1620.87 392.81 20.75
169.00 13.00 2.08 -0.53 20.05 1912.18 385.83 22.01
170.00 13.00 2.28 -0.57 19.51 1942.83 389.73 19.74
171.00 13.00 2.51 -0.63 18.85 1817.14 390.25 19.51
172.00 13.00 2.51 -0.67 18.37 1718.25 388.63 20.61
173.00 13.00 2.37 -0.71 17.99 2004.02 390.08 17.98
174.00 13.00 2.53 -0.76 17.61 1597.01 384.12 26.28
175.00 13.00 2.72 -0.80 17.27 1151.81 382.42 22.52
176.00 13.00 2.40 -0.86 16.83 1974.86 389.35 17.76
177.00 13.00 2.02 -0.90 16.54 1992.69 389.01 12.18
178.00 13.00 2.58 -0.96 16.12 1976.11 386.41 16.60
179.00 13.00 3.77 -1.03 15.74 1945.17 386.67 7.43
180.00 13.00 3.20 -1.08 15.48 1858.93 386.64 16.02
181.00 13.00 3.29 -1.12 15.26 1815.67 389.95 12.42
182.00 13.00 2.84 -1.15 15.00 1679.99 394.88 19.59
183.00 13.00 2.91 -1.21 14.83 1743.00 393.03 19.10
184.00 13.00 2.42 -1.24 14.66 1782.24 395.40 20.37
185.00 13.00 3.41 -1.29 14.47 1846.70 399.83 12.69
186.00 13.00 4.39 -1.34 14.26 1653.94 397.45 11.65
187.00 13.00 4.14 -1.38 14.09 1599.68 392.84 8.08
188.00 13.00 4.19 -1.41 13.99 726.34 392.89 7.05
189.00 13.00 2.08 -1.41 14.00 183.91 402.59 NaN
190.00 13.00 2.65 -1.45 13.84 1751.20 383.80 17.21
191.00 13.00 3.23 -1.51 13.64 1964.57 385.53 13.61
192.00 13.00 3.03 -1.54 13.54 2000.73 384.07 16.73
193.00 13.00 3.13 -1.59 13.37 1614.61 384.63 11.51
194.00 13.00 1.91 -1.60 13.35 1801.13 396.36 23.55
195.00 13.00 0.89 -1.58 13.40 1973.77 404.49 21.15
196.00 13.00 1.96 -1.62 13.29 1807.26 398.74 14.46
197.00 13.00 2.14 -1.65 13.19 832.07 400.72 9.93
198.00 13.00 2.52 -1.70 13.05 1703.59 398.55 12.63
199.00 13.00 2.94 -1.70 13.04 1531.01 397.72 11.89
For the purposes of this exercise, the data are limited to midday (i.e. hour 1300) values. Use the data to generate estimates of stomatal conductance using the Leuning model, and plant hydraulic model, and the Medlyn optimality model. As a reminder, here are the model forms, and some suggested parameter values.
Use the data to generate estimates of stomatal conductance using the Leuning model, and plant hydraulic model, and the Medlyn optimality model. As a reminder, here are the model forms, and some suggested parameter values:
Leuning
Let:
= 1.1 kPa
= .001 mol/m2/s
= 6.5 dimensionless
= 50 ppm
Hydraulic Model
Let:
= 0.3 mol/m2/s
= 0.3 (appropriate for a 30-m-tall tree)
Assume:
constant = -1.8 MPa (isohydric species)
Optimality Model
Let:
= .001 mol/m2/s
= 2