Friderike Beyer, Dr. Dietrich Hertel, Prof. Dr. Christoph Leuschner


Vitality and turnover rates of fine roots

Roots and their turnover play a vital role for individual plant growth, the interaction and competition between different tree species and the carbon and nutrient cycle in the soil. However, the knowledge about fine root physiology and their biogeochemistry is still poor. Our project analyses the interactions of different tree species in the rhizosphere. In particular the relation between longevity, branching order and nutrient availability of fine roots will be explored. Methods include a container experiment with beech (Fagus sylvatica L.) and ash (Fraxinus excelsior L.). By using the minirhizotron technique, we monitor the roots over selected time intervals. Thereby the longevity and mortality of fine roots can be viewed over a certain time period and compared through image analysing. The above- and belowground biomass production will be determined annually. In addition we are tracing the C- and N-allocation and partitioning with stable isotopes marked leaf litter. Small rhizoboxes serve as a tool to implement competition and manipulation experiments. Biochemical tests in comparison to morphological analyses will be applied to investigate root vitality and turnover. Thus we will study the allometric relationship between fine root diameter, branching order and metabolic activity. The overall aim is to uncover the role of biodiversity in soils for carbon sequestration in forest ecosystems. The results will help to understand the dynamics of root turnover, the parameters affecting the lifespan of roots and the complexity of the rhizosphere dynamics.

In a second phase of the project, we will conduct a joint diversity experiment with young trees of Fagus sylvatica, Fraxinus excelsior, Acer pseudoplatanus, and Tilia cordata under natural light and soil conditions close to Göttingen. The experiment shall help to understand facilitation and competition effects between these common European tree species, which differ markedly with regard to the mycorrhiza type (arbuscular vs. ectomycorrhizal) and the decomposability of the leaf litter. A particular focus will be on species-specific differences fine root longevity as influenced by different biotic and abiotic variables.