Group Matyssek Introduction to the Kranzberg site, Hypotheses and Methods, Interactions and Timetable Ecophysiology of Plants Working Team: Markus Löw (PhD Student), Häberle and Matyssek

Kranzberg site

Experimental Design 10 adult beech trees 1x O3 (ambient ) 2x O3 Sun (control) 2x O3 (<150 ppb) Sun branches Shade branches

some facts on Kranzberg Forest beech/spruce mixed stand age: 50-60 y. height: 25 m precipitation: 730 -790 mm mean temp.: 7.0 -7.5 °C ozone conc.: daily mean: 40 ppb max. 100 ppb

Scaling within CASIROZ Tree Stem increment Stem respiration Xylem Sap Flow My work: Branch Growth pattern Gas exchange of twigs Modeling Leaf Chlorophyll fluorescence Photosynthetic performance Stomatal conductance and transpiration Seasonal phenology Root patterns species Cell metabolism antioxidants Gene expression

Main Hypotheses of Group Matyssek whole-tree response patterns to chronic O3 stress relates to the O3 uptake rater than AOT concept Gas exchange  conductivities  validation Uptake (flux) vs. AOT concept Micro-deposition samplers (Fabian) Carbon sink (C gain, Biomass production, Sugars [Rennenberg, Oßwald]) Xylem sap flow (whole-tree C & N cycling (Rennenberg) Isotope ratios 13C/12C, WUE, 18O/16O (Rennenberg), PEPC / RUBISCO (Oßwald) Porometry and continuous gas exchange measurements structural & functional branch assessments: first flush, lammas shoot, phenology  C sink

Main Hypotheses II O3 exposure in shade crowns cannot be neglected with respect to whole-tree sensitivity O3 exposure during dusk and at night is significant. Therefore the risk of O3 injury is as high as under day-conditions (stomata closed and no light dependent supply of antioxidants) Antioxidant status and damage amplifying reactions determine the degree of symptom development Methods: Night time measurements in cooperation with antioxidant-measurements (Tausz)

Main Hypotheses III chronic Ozone impact constrains carbon sink strength in adult trees to an extent which is relevant in relation to expected stimulation under increasing CO2 conditions Assessments: structural & functional branch assessments, stem increment (Dendrometer), respiration, senescence

Main Hypotheses IV Response mechanisms to ozone in adult trees are not consistent with findings in young trees Comparison within CASIROZ between adult and young trees Comparison to published data

Interactions Examples of immediate cooperations: Rennenberg (Isotopes, C & N cycling) Wieser (Gas exchange young trees, branch autarchy?) Oßwald (RUBISCO, PEPC, sugars, starch) Tausz (antioxidants, night assessments) Hanke (leaves: cytokinins, ABA) Ceulemans (modeling) Fabian (climatic data, O3-regimes)

Timetable