The South Hesse Oak Project (SHOP): Species- and site-specific efficiency of the photosynthetic apparatus of Mediterranean and Central European Oaks

Abstract

In three experimental sites in Southern Hesse, differing in management procedures, one- to three-year-old saplings of Quercus robur, Q.pubescens, and Q.ilex were planted to study their performance under Central European climate conditions. Toward the end of the growth period (mid–late September 2011), during a very dry period, we measured JIP transients of photosystem II chlorophyll fluorescence induction curves to evaluate the effects of abiotic site factors on the photosynthetic apparatus by comparing them to data from well-watered saplings measured before the onset of senescence processes. In all three sites, Q. robur saplings in September showed the strongest deviation from the measurements in August, followed by Q. pubescens. Q. ilex, in general, was nearly unaffected by September climate conditions or performed better than plants measured in August. Differences in the behavior between species and sites could be explained by the species’ different drought susceptibility and by differential induction of early leaf senescence (in Q. robur and Q. pubescens). We conclude that measurement of the JIP transient is a feasible method in forestry to compare adverse microclimatic site effects and genetically fixed reactions of the photosynthetic apparatus in the field.

Keywords::

• Drought stress
• JIP test
• Quercus ilex
• Quercus pubescens
• Quercus robur
• senescence

Acknowledgements

This study was financially supported by the research funding programme “LOEWE – Landes-Offensive zur Entwicklung Wissenschaftlich-ökonomischer Exzellenz” of Hesse's Ministry of Higher Education, Research, and the Arts. The experimental site at LA was established together with the Nordwestdeutsche Forstliche Versuchsanstalt (NW-FVA), Göttingen, which is the responsible managing agency of the site. The authors are thankful to M. Forrest and J. Steinkamp (BiK-F, Frankfurt) for help in the establishment of the sap-flow meters, to H. Schepp (Hessen-Forst, Lampertheim) and H. Rumpf (NW-FVA Göttingen), R. Ebert (City of Rüsselsheim) and to H. Scheel and R. Divisch (City of Frankfurt) for the possibilities to establish the field plots and for their help in managing the experimental sites.