PhD project: Effect of tree planting, species composition and diversity on soil organic carbon storage and turnover
International Max Planck Research School for Global Biogeochemical Cycles
In cooperation with the Friedrich Schiller University Jena, the Max Planck Institute for Biogeochemistry houses a unique and flexible research program that grants German and foreign students a broad selection of learning opportunities while still maintaining a research focus.
The IMPRS-gBGC offers a PhD program specializing in global biogeochemistry and related Earth System sciences.
Soil System Sciences (SSS)
by Marion Schrumpf , Axel Don
Forests are currently assumed to be important sinks for the greenhouse gas carbon dioxide. This extra carbon is not only bound in biomass, but also accumulating in soils. Afforestation can therefore be a potential measure for binding more carbon in soils. It is known that tree species selection has a strong impact on the amount, quality and distribution of litter entering the soil both, above- and belowground, and accordingly also soil carbon storage and turnover. Tree behaviour and litter decomposition can thereby differ between monocultures and species mixtures. Also soil management before tree planting can affect the total amount of carbon stored in soils if these are deep-ploughed before, mixing carbon-rich topsoil material into biologically less active subsoil horizons. The long-term fate of this buried carbon and its potential controls by the vegetation cover is however unresolved.
We take advantage of the unique long term, manipulative BIOTREE experiment (http://www.biotree.uni-freiburg.de/index.html), on the role of tree diversity for ecosystem functioning of temperate forests. The experimental forest plots, encompassing up to 6 species mixtures on calcareous and acidic soils, were established in 2004 on former arable land and soils of each plot were sampled and archived before tree planting. Soils were thereby deep-ploughed in rows, but left undisturbed in between. Now, almost 15 years later, forest plots with closed canopies are established, allowing studying tree species, diversity and management effects of afforestation on soil carbon storage and turnover. Besides changes in total organic carbon stocks, we would like to study carbon stability using physicochemical fractionation methods and temporal changes in radiocarbon (14C) contents as indicator for changes in soil carbon ages and turnover. The study can be supplemented by specific litter decomposition experiments and analyses of soil microbial and enzymatic parameters.
Guiding questions of the PhD could be:
- Which temperate tree species is most effective in sequestering soil organic carbon in the first years after afforestation?
- How do tree species affect soil carbon stability and turnover?
- Are diverse species mixtures gaining and stabilizing more carbon than monocultures?
- Does deep ploughing of soils have a long-term effect on soil carbon storage and what drives buried carbon stability
We are looking for a highly motivated and team-oriented PhD student interested in a scientific career. The successful candidate should have a broad interest in the drivers of soil carbon storage and turnover, and how those are linked to forest management and diversity. This project has focus on soils but requires integrated ecosystem level understanding, since not only responses at the soil, but also plant and microbial level have to be considered. Accordingly, a general background in all these disciplines, proven by a master in geoecology, environmental sciences, forestry, physical geography, biology or something related is desirable. The work ranges from soil sampling at field sites to laboratory analyses and potentially modelling of soil carbon dynamics at different forest sites. Furthermore, very good oral and written communication skills in English are required.
The Max Planck Society seeks to increase the number of women in those areas where they are underrepresented and therefore explicitly encourages women to apply. The Max Planck Society is committed to increasing the number of individuals with disabilities in its workforce and therefore encourages applications from such qualified individuals.
The Max Planck Institute for Biogeochemistry in Jena offers an exceptional dynamic, international and multidisciplinary working. The successful applicants will join a creative, international team led by Marion Schrumpf, encompassing experimental and theoretical work on the role of the biogeochemical cycles of carbon, nutrients and water at all spatial scales. The project will profit strongly from collaborations with Axel Don from the Thünen Institute in Braunschweig, who was involved in the setup of the BIOTREE experiment and the initial soil sampling. Jena is not only famous for its high-tech industry, internationally renowned research institutions and a modern university, but also for its beautiful natural setting in the Saale valley with its steep limestone slopes. The climate is mild, and a large variety of plants grow in the close surroundings, including wine grapes and wild orchids. The city of Jena has a large active student scene supporting a diverse cultural life.