Upscaling Ozone Flux in Forests from Leaf to Landscape

Udine

2008

S. 35-41

Bandaufführung

10254S

147745

Although stomatal conductance for ozone (O3) correlates with leaf to air water vapor difference (VPDLa) at the leaf level, uncertainty in up-scaling to the whole free level can be overcome by means of sap flow measurements at the tree trunk. Further up-scaling to the stand level is possible by relating whole tree O3 flux to silvicultural and/or tree-allometric data. In such a way, canopy conductance and O3 uptake can be related to ground surface area. When normalized, canopy conductance is demonstrated to follow a functional relationship to VPDLa across several forest ecosystems thus ailowing a generalitizion of model approaches. Further up-scaling to the landscape level, however, needs further investigations due to differences in the response of canopy conductance to environmental drivers in forest stands and grassland ecosystems, respectively.Key-words: Ozone uptake, trees, forest, stand, grassland, up-scaling.