Carbon dynamics and fixation in forest soils
Photo: Christina Steffens, IfB, Universität Hamburg
Temperate forests store 300 billion tons of organic carbon (C). In Europe, 800 million Mg of C are fixed annually in the forest, ~40% in the soil and ~60% in the living biomass. One goal of sustainable forestry is to ensure and increase the C sink function of the forest ecosystem. However, the factors controlling this process are not yet fully understood. The main objective of the present study is to detect the effect of important tree species (Fagus sylvatica L., Quercus robur L., Fraxinus excelsior L., Acer pseudoplatanus L., Tilia spec and Picea abies L. Karst.) on forest C-sequestration. The following sub-objectives are to be achieved:
- Quantification of the decadal change in the topsoil C stock under different tree species
For this purpose, the forest soil among the various tree species in Danish common garden experimental sites, were topsoil C stocks had last been measured in 2004/2005, will be re-sampled after about a decade. Thus, possible changes in soil C stocks can be directly quantified.
- Quantification of heterotrophic soil respiration depending on the tree species at the Mattrup site
For this purpose, soil respiration will be measured over two years and partitioned into its sources, the heterotrophic respiration (decomposition of organic substances) and the autotrophic respiration (root respiration). It will be checked whether the relative proportions of these sources to the total soil respiration are dependent on tree species and thus contribute to different carbon stocks in the forest floor.
- Quantification of the greenhouse gas balance (soil and biomass) depending on the tree species at the Mattrup site
Previous studies on tree species effects compared either C stocks in the soil or in the biomass. However, it is possible that the differences between tree species in soil and biomass (the data will provided by the cooperation partner) C stocks are not generally rectified, i.e. the available studies do not allow drawing conclusions concerning a total tree species dependent C-balance of the forest. Furthermore, the trace gases nitrous oxide (N2O) and methane (CH4) are relevant greenhouse gases, too, as their warming potential is 28 times (CH4) and 264 times (N2O) higher than that of CO2. We will check whether tree species influence N2O emission or CH4 uptake in a different way than CO2 emission. Therefore, the total greenhouse gas balance (biomass + soil) including CH4 uptake and N2O emissions will be quantified on a tree species level over a period of two years.
Employees at the Institute of Soil Science
- Postdoc: Dr. Christina Steffens
- Angela Meier (until 2017)
- Prof. Lars Vesterdal, University of Copenhagen, Department of Geosciences and Natural Resource Management