The influence of light on growth, biomass partitioning and tree architecture of free grown Fagus sylvatica, Acer pseudoplatanus and Fraxinus excelsior seedlings
This project focuses on light as the most important factor modulating growth of beech, sycamore and ash seedlings, trying to analyse how it drives processes at different levels. This means trying to assess a species growth strategy towards light, i.e. defining its shade tolerance.The general objective of the present work is to provide information on the light-induced growth reaction in free grown beech (Fagus sylvatica), sycamore (Acer pseudoplatanus) and ash (Fraxinus excelsior) seedlings under contrasting light conditions. Thereby we aim at verifying whether reaction at physiological level goes into the same direction as at morphological level and at distinguishing between real plasticity (due to light) and apparent plasticity (due to ontogenetic status). Three particular goals can be individuated:
- Photosynthetic performance and leaf traits The Farquhar photosynthesis model was parameterised with measured assimilation curves. C, N, chlorophyll concentration and LMA (leaf mass per area) were measured on the same leaves used for photosynthetic measurements. We hypothesise that the most important photosynthetic parameters are strongly correlated to N content and to LMA.
- Foliage structure and light interception Three-dimensional images of the seedlings (showing both foliage and architecture) were produced after data collection with a digitising device. These data allowed to calculate total leaf area and to simulate light interception (quantified by STAR, Silhouette to Total Leaf Area Ratio) which depend on leaf density, insertion angle and distribution.
- Biomass partitioning and tree architecture Total leaf area, biomass partitioning [LAR (leaf area ratio), LMR (leaf mass ratio), SMR (stem mass ratio)] and architecture parameters (branchiness, crown geometry) were measured on seedlings growing under different irradiance levels and different size classes.
|Projektleitung:||Prof. Dr. J. Bauhus|