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Abstract
In highly polluted sites, stomatal behavior is sluggish with respect to light, vapor pressure deficit, and internal CO
2 concentration (Ci) and poorly described by existing models. Statistical models were developed to estimate stomatal conductance (gs) of 40-year-old ponderosa pine at three sites differing in pollutant exposure for the purpose of calculating O
3 uptake. Gs was estimated using julian day, hour of day, pre-dawn xylem potential and photosynthetic photon flux density (PPFD). The median difference between estimated and observed field gs did not exceed 10 mmol H
2O m
–2 s
–1, and estimated gs within 95% confidence intervals. O
3 uptake was calculated from hourly estimated gs, hourly O
3 concentration, and a constant to correct for the difference in diffusivity between water vapor and O
3. The simulation model TREGRO was also used to calculate the cumulative O
3 uptake at all three sites. O
3 uptake estimated by the statistical model was higher than that simulated by TREGRO because gas exchange rates were proportionally higher. O
3 exposure and uptake were significantly correlated (
r2>0.92), because O
3 exposure and gs were highly correlated in both statistical and simulation models. © 2002 Elsevier Science Ltd. All rights reserved.
Citation
Grulke, N.E.; Preisler, H.K.; Fan, C.C.; Retzlaff, W.A. 2002. A statistical approach to estimate O
3 uptake of ponderosa pine in a mediterranean climate. Environmental Pollution. 119: 163-175.
