Acclimation in beech and spruce after four years of prolonged summer drought and recovery upon re-watering

• Applicant: Professor Dr. Thorsten Grams, since 4/2018
• Subject Area: Forestry
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 393882426

The “Kranzberg Roof Project” (KROOF) has been initiated in 2013 and received funding from DFG through a joint proposal of three partners, i.e. Part A / Prof. Pretzsch (Forest Growth and Yield, TU München), Part B / Prof. Matyssek (Ecophysiology of Plants, TU München) and Part C / Prof. Munch/Dr. Pritsch (Soil Ecology, Helmholtz-Zentrum München). The three partners aim to jointly continue KROOF together with newly associated Part D / Prof. Lang (Soil Science, University Freiburg).The present proposal is a renewal of Part B by Rainer Matyssek and Thorsten Grams (TU München, Germany) and Barbara Beikircher (University of Innsbruck, Austria), forming a D-A-CH project (co-funded by FWF, Austria). It is one out four proposals (Parts A – D) submitted in parallel to DFG. The focus of the present proposal is on ecophysiological aspects of the acclimation of European beech and Norway spruce after four years of prolonged summer drought and subsequent recovery upon re-watering. Experimentally induced intense summer drought in Kranzberg Forest using novel, rain-sensitive rainout-shelters is to be continued until early summer 2018. Subsequently, recovery will be initiated through controlled irrigation of individual plots, allowing for detailed assessments of recovery processes. In parallel, drought recovery is analyzed on five sites along a natural precipitation gradient in response to the extraordinary drought encountered in 2015. Research focus during repeated drought and subsequent recovery is detailed by the following five objectives:Objective 1: Tree hydraulic conductivities and vulnerability to drought-induced embolisms, comparing juvenile and adults treesObjective 2: Water uptake by aboveground organs and hydraulic redistribution studied via sap flow and deuterium labelingObjective 3: Increase of photosynthesis and stomatal limitation upon re-irrigation in response to growth/sink-limitationObjective 4: Concentration of non-structural carbohydrates after four years of summer drought and re-wateringObjective 5: Depths of soil water uptake and recovery from drought analyzed along a natural precipitation gradient and experimentally induced droughtOverall, the project aims at functional interrelations between water and carbon (C) pools and fluxes from tree rhizosphere to stand level of beech/spruce mixtures focusing on two hypotheses:(i) Upon restoring soil water availability, more anisohydric beech is less sensitive than more isohydric spruce in the aftermath of the multi-year summer drought. Sensitivity is assessed through indices of resistance, resilience and recovery time of various ecophysiological processes such as water potential, conductivity and photosynthesis.(ii) Dry site conditions reduce drought sensitivity of both beech and spruce, whereas mixture is expected to reduce drought sensitivity in beech only.

• DFG Programme: Research Grants
• International Connection: Austria
• Partner Organisation: Fonds zur Förderung der wissenschaftlichen Forschung (FWF)
• Cooperation Partner: Dr. Barbara Beikircher
• Ehemaliger Antragsteller: Professor Dr. Rainer Matyssek, until 4/2018