CASIROZ Fall Meeting Antwerp 2003 What I did last summer Markus Löw (PhD student) Ecophysiology of Plants, Freising, Germany Working Team: Löw, Häberle, Matyssek TU Munich

In this presentation: Assessments e.g. Flush, Senescence and Symptoms Climatic issues gas exchange measurements: Photosynthesis, Conductance Chlorophyll fluorescence Quantum Yield of PS II, Imaging PAM Any Changes for next year? Timetable for next year

Assessments: e.g. senescence 20 branches enclosed in nets from end of September until November per tree one shade and one sun branch 14 assessments Senescence: end of growing season:

Climatic issues extremely dry summer in 2003! this summer was worse than 1947 or 1976 Available water for roots (mm) Data from „Waldzustandsbericht Bayern 2003“

Measured under ambient light conditions during CASIROZ sampling days 11am – 1pm always at the same leaf Porometry, conductance LiCor 6400 Portable Photosynthesis System

Porometry, photosynthesis Steady state measurement August saturating light 360 ppm CO 2 Temperature ~ 25°C, rH ~ 45% 1x O 3 n= 38 2x O 3 n= 58 Lammas shoots n=22 Photosynthesis reduced by at least 50% compared to previous years!

Porometry & Fluorescence Steady state measurement August saturating light 360 ppm CO 2 Temperature ~ 25°C, rH ~ 45% New LiCor Leaf Chamber Fluorometer: simultaneous gas exchange and chlorophyll fluorescence new developed test: Lammas shoot leaves are less tolerant to high light than other sun leaves But quantum yield is still high in all leaves: no drought effects visible in terms of PS II Lammas shoot leaves have best capacity of PS II (quantum yield) compared to other sun leaves

Imaging PAM New technique: shows Chlorophyll Fluorescence values as a 2D false color picture: Non invasive diagnostic method on PS II observe changes over time (months) e.g. calculate affected area Zangerl, A. R., Hamilton, J. G., et. al. (2002 ) Impact of folivory on photosynthesis is greater than the sum of its holes. Proceedings of the National Academy of Sciences of the United States of America 99, “… on average, indirectly affected area was six times that of the area directly affected by tissue removal.” “... indirectly affected area remained photosynthetically active, but at a reduced rate, its contribution to photosynthesis reduction […] was three times that of the directly affected area.”

Imaging PAM Compare visible symptoms with fluorescence findings: In contrast to findings on folivory: surrounding area is not affected

Does ozone injury develop like this? ?

Differences young / old trees Young trees: many small destinct stipples Old Trees: few large stipples, diffuse area Holes

Changes & Improvements 2004 combine Imaging PAM and Porometer in the field to get a picture of actual ozone uptake in the leaf measure dark adapted leaves to determine quantum yield: LiCor „Leaf Chamber Fluorometer Dark adapting clips“ are needed but no major changes in the time schedule for next year: measure more leaves to improve observation of forming necroses

Timetable