Growth, morphology, and biomass allocation of seedlings grown under different light availability levels and competition types

PhD student

Ieva Bebre

Research Outline

The effect of light on tree growth is crucial and often one of the most limiting factors of plant growth. Plasticity is a crucial trait for sessile organisms that allows adjusting resource distribution among organs of their systems to optimize the acquisition of limited resources, and it varies interspecifically. Subproject 8 sets to quantitatively assess the impact of light availability and competition type on the growth, morphology, and biomass allocation of seedlings.

The project is based on two experiments:

  • a controlled shading experiment using seven common European tree species and studying seedling growth, leaf morphology, biomass allocation, and structural complexity.

  • and a pot experiment using a light gradient and different competition types (monospecific and mixed) to assess the growth and its allocation, biomass and its allocation, and leaf morphology of European beech, Norway spruce, and Douglas fir seedlings.

The project is focused on answering questions like:

  • Does light have a positive effect on seedling growth and biomass production? And how does the effect differ between species?

  • How do height and diameter growth differ between species, and how are the differences influenced by light availability and species’ shade tolerance?

  • How does growth allocation between height and diameter change based on species’ functional group and light availability?

  • Do plants increase biomass allocation towards aboveground when the light availability is limited (i.e., balanced growth hypothesis)?

  • Does seedling structural complexity change with light availability, and are there interspecific differences?

  • Are seedlings growing in mixed pots producing more biomass than seedlings growing in monospecific pots? And how is that affected by light availability and specific mixture type?

  • Are seedlings growing in mixed pots allocating biomass among their organs differently than seedlings growing in monospecific pots?

Principal Investigator / Supervisor

Dr. Peter Annighöfer, Forest amd Agroforest Systems, Technical University of Munich (TUM)