Project description B1
Scientific advisors
Project
Comparison of the carbon yield of the crowns of five tree species in a mixed deciduous forest depending on environmental factors
In project B1 the photosynthesis of five tree species (Fraxinus excelsior, Fagus sylvatica, Tilia cordata, Acer pseudoplatanus and Carpinus betulus) shall be characterised. The goal is to mechanistically model crown photosynthesis of these species depending on climate conditions (e.g. light, relative humidity, and temperature). The hypothesis that the variability of photosynthesis capacities in a tree crown relies mainly on light acclimation of leaves shall be tested by a model of 3D-structure and light. Therefore light acclimation of leaves is measured by fish-eye-photos at the position of photosynthesis measurement leaves. The measurements are performed in three different heights of the crown (bottom, middle and top of the crown) following the light gradient. The photosynthesis data are used to parameterize the photosynthesis model of Harley and Tenhunen (1991). The validation is done with independent daily course measurements. The relationship between the gas-exchange calculations are extended to the entire crown by use of the 3D-light model of project C1.
Water use efficiency of the tree species is calculated and its relevance for a potential niche partitioning with regard to CO2- and N-Assimilation is analyzed.
Methods
- Photosynthesis measurements with the LiCor6400
- Fish-eye photographs
- Mobile canopy lift for the access to the canopy up to 30m
- Delta 13C-Analysis and C/N analysis of the leaves
- Photosynthesis modelling on the basis of the photosynthesis model of Harley and Tenhunen 1991