Any such analysis should consider the possible bias of fluctuations in O3. Bunce's recent paper on impacts of fluctuating CO2 on assimilation provides a useful reminder that both free-air and chamber studies can result in spikes of very high gas concentration. One would expect that a spike of O3 would be especially deleterious because, as Ken notes, O3 damages the plant tissues.
It's the old question of drinking a glass of wine vs. drinking a glass of water followed by a shot of absolute alcohol.

There is a need for someone to critically review past studies on O3, taking a hard look at effects of brief spikes in O3.
- Jeff

-----Original Message-----
From: DSSAT - Crop Models and Applications [mailto:[log in to unmask]] On Behalf Of Boote,Kenneth J
Sent: Friday, February 01, 2013 8:36 AM
To: [log in to unmask]
Subject: Re: Accounting for the effects of ozone damage in crop models

Maurits,

Right now, none of the DSSAT models consider ozone damage effects.  Very few crop models do consider that.  I believe there are some data sets out there (North Carolina USDA as well as the SOYFACE-Illnois) from which damage functions could be created/calibraed, to impact RUE in RUE-based models and leaf rate in leaf-style models.  The effect is not just on assimilation, but also on transpiration reduction and that coupling may not be there.  More than that, ozone is not just an instantaneous thing, but really should "damage" the photosynthesis mechanism, going forward.  Martin Kropff back 15-plus years ago, worked on a nice approach for leaf-level models, but maybe that was SO3?

We are all lacking time, resources, and people to do this.  That is what it will take.  Are you volunteering?

Ken Boote

________________________________________
From: DSSAT - Crop Models and Applications [[log in to unmask]] on behalf of Berg, van den Maurits [[log in to unmask]]
Sent: Friday, February 01, 2013 5:12 AM
To: [log in to unmask]
Subject: Accounting for the effects of ozone damage in crop models

Dear colleagues,

Regarding the subject, I was wondering if you have any suggestions, experiences, papers.
Eventually, we want to be able to account for this in global-level scenario analyses.

Many thanks,
Maurits van den Berg





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