Post on 10-Jan-2016
description
NLR_AM (AQRTa) modelAsko NoormetsUniversity of Toledo Toledo, Ohio, USA
ModelNoormets et al., In press, EcosystemsR10 (mol CO2 m-2 s-1) reference respirationEa (kJ mol-1 K-1) activation energyR (8.3134 J mol-1 K-1) universal gas constantTref (K) reference air temperatureTa (K) ambient air temperaturea (mol CO2 mol-1 PAR) apparent quantum yieldf (mol quanta m-2 s-1) PARPmax (mol CO2 m-2 s-1 ) light-saturated assimilation rate
FeaturesMonthly time-windowCo-fitting respiration and assimilation models
Reflect functional changesProvide robust parameter estimates
1. Monthly time windowInformation content diurnal synoptic phenological
Baldocchi et al., 2001, GCBKatul & Parlange, 1995, Water Resour. Res.Stoy et al., 2005, Tree Physiol.; 2006, GCB
Seasonal changesNoormets et al., 2006. Ch. 4 in Ecology of Hierarchical LandscapesDeForest et al., 2006. Int. J. Biomet.
Time window Weekly vs. monthly integrationdomain of functional changediurnal pH, Rubisco, CHOseasonal SLA, xylem conductance, SWC, VPD
Time window Weekly vs. monthly integrationdomain of functional changediurnal pH, Rubisco, CHOseasonal SLA, xylem conductance, VPD, SWCOverlapping vs. non-overlapping windows
2. Co-fitting R & AConstrains parameter estimatesbroader data spread = better constrained model
Compromises nighttime accuracy
Other modelsCofilled: AQRTAlso done: RT+AQ
Temp.R10Window1.Taconst.Month2.Taconst.Week3.Tsconst.Month4.Tsconst.Week5.Taf (SWC)Month6.Taf (SWC)Week7.Tsf (SWC)Month8.Tsf (SWC)Week
Tair vs. Tsoil & confounding factorsTair and Tsoil are out of phaseSR peaks at ~4-7 PM ER higher after dusk than before dawnCHO transport highest after dusk
? Tsoil- vs. CHO-dependence ?
Conclusions - ways to improveNeed:Formal criteria for selecting time window
More sophisticated ER function
Likelihood-based estimates