Ph. Wipfler and G.Deckmyn Kranzberg Forest Experiment : upscaling to the forest. From the empirical approach to the mechanistic simulation of ozone effects using the ANAFORE forest model.

Upscaling to the forest level Problem: Clear ozone effects at the leaf, biochemical and physiological level High variability and limited number of sample trees obscure the possible growth effect

1. Empirical approach, Ph. Wipfler Solution 1 = Empirical approach, using the annual diameter increment –Solution 1a: Extending the sample –Solution 1b: Compensating the initial differences in growth setting the growth of former period as reference including diameter as covariate

Empirical approach, Ph. Wipfler Two ways to select trees Treatment / control –Well sampled (environmental / phyiological data) –Small sample (n=5) Gradient more cases (35) Gradient  more statistical possibilities

Results 1: control site / test site Empirical approach, Ph. Wipfler Average annual diameter growth (100 = average diameter increment of control) The average diameter growth of a former period as reference (100 = average diameter increment )

Results 2: Gradient Correlation analysis Empirical approach, Ph. Wipfler dfcoeffsign Correlation analysis: Coefficient and significance of the the parameter related to ozone exposure Wipfler et. al. (2006) in press

Results 2: gradient Regression analysis Empirical approach, Ph. Wipfler Significance and parameters of the model id = a + b*d + c*SUM 00 with id = diameter increment at breast height (cm), d = diameter breast height at the beginning of the period (cm), and SUM 00 = ozone exposition (ppb). parameterFStd. errorSign. a b (diameter) c (ozone)1,1e Wipfler et. al. (2006) in press

dfcoeffsign. Norway spruce Correlation analysis: Coefficient and significance of the the parameter related to ozone exposure parameterFStd. errorSign. a b (diameter) c (ozone)-9,41e Empirical approach, Ph. Wipfler Results with Norway spruce (Picea abies [L.] KARST.) Regression analysis: id = a + b*d + c*SUM 00 Wipfler et. al. (2006) in press

2. Modelling approach, G. Deckmyn Why mechanistic modelling? –Improve on understanding s.a. Explain specific results –Synthesize knowledge –Explore research hypothesis –Predict effects at stand and landscape level

2. Modelling approach, G. Deckmyn The ANAFORE (analysing forest ecosystems) model: stand scale Deciduous and coniferous C, H 2 O and N fluxes at halfhourly or daily time steps Based on known models (Farquhar, Penman-Monteith, Dewar) Allocation according to refined pipe theory leading to wood quality (pipes, density etc.) representation Individual trees or categories of trees (dominant- suppressed)

2. Modelling approach, G. Deckmyn

Ozone modelling: simulate the immediate effects, the cummulative effects are a result include different pathways for ozone: at least 1 for drought affected, 1 insensitive to drought defense = cost, damage = unable to pay the defense cost Shade leaves have less cost, but also less C (photosynthesis) to pay the cost

Modelling approach, G. Deckmyn Stem biomass of some trees

2. Modelling approach, G. Deckmyn Some preliminary results from the unvalidated model

2. Modelling approach, G. Deckmyn Ozone: simulated data

2. Modelling approach, G. Deckmyn Conclusions - We can improve our understanding of the kranzberg results –We can investigate the flux concept after validation of the Dewar stomatal model –We can differentiate between immediate and cummulative effects –We can differentiate between sun and shade leaves –We can investigate the interaction with drought, T, CO 2, soil,... –We can investigate the total C balance at the stand level –We can upscale –...We have a lot more work to do....

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