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2 PhD positions (salary BAT IIa/2) are available at the University of Freiburg, Germany
in the project: Water relations of European beech and interacting vegetation
in beech dominated forests


The project is funded by the German Reasearch Council (DFG) and is part of the
Germany-wide Research Group: "Competitive Mechanisms of Water and
Nitrogen Partitioning in Beech-Dominated Deciduous Forests"

Stable isotopes
1) One position is mainly on the assessment of oxygen, hydrogen and carbon
stable isotopes and the application of models to characterise the
evaporative 18O and 2H enrichment of leaf water/organic matter in
trees and herbaceous vegetation.

Modelling
2) One position is mainly on the modelling of water-relations in beech trees and
competing vegetation applying tree-scale hydrodynamic models. The work
of this PhD student will be supervised by Dr. E. Priesack GSF in
Munich, Germany; and part of the work will also be done there.


Project description:
Three highly interconnected though independent approaches [a) xylem
flow measurements, b) stable isotope analysis/modelling, c) a
hydrodynamic model system PLATHO/Expert-N] are applied for assessing
water relations of trees and co-occurring vegetation on different
time-scales on a whole plant level. Water flow/movement within the
plant and partitioning between species will be modelled and
additionally analysed using sap flow sensors, leaf level gas exchange
and by tracing  delta18O and  deltaD in potential water sources and in xylem
water.  Delata 18O,  deltaD and  delta13C in organic pools with different turn
over-times will be assessed to characterise responses of stomatal
conductance (gs) and transpiration (T) to environmental conditions. In
addition, isotopic signatures will be used to predict gs and T
applying process-oriented models. Based on the model system Expert-N
and the functional-structural plant growth model PLATHO a tree
hydrodynamic model for beech will be developed. The model will be
applied to simulate soil-plant-air system water relations including
mycorrhiza effects on water uptake from soil and will be inserted as
tree water flow sub-model to the ecosystem-scale model. Both, the
isotopic approach and the hydrodynamic model will be calibrated and
validated with measurements at the three field sites. Cross-validation
between the two independent approaches will be carried out at
additional sites.

Qualification: Master (Diplom) in Biology, Environmental
Sciences, Chemistry, Physics or equivalent science degree

For further information contact Arthur Gessler (contact details below)

Please send your applications (preferentially as electronic version)
with a CV and the names of two referees to:


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Arthur Geßler

Institute of Forest Botany and Tree Physiology
University of Freiburg
Georges-Köhler Allee 53/54
79085 Freiburg
Germany
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Phone:   ++49 (0)7612038310
Mobile:  ++49 1751505030
Fax:     ++49 (0)7612038302
Email:   [log in to unmask]
Url:     www.arthur-gessler.de
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