AG Terrestrische Biogeochemie

Scientific Challenges

To contribute to the understanding of processes and patterns of biogeochemical fluxes at the landscape ecosystem scale. Presently the main focus is put upon processes at the interfaces of soil, air, plants and water. We search for mechanistic relationships between geomorphology and biogeochemical processes in and between terrestrial and adjacent aquatic ecosystems. The main sphere studied by our group is the plant-soil continuum considering effects of bio- and pedodiversity. Particularly fluxes of greenhouse gases from karst landscapes, peatlands and mountain ecosystems are measured.


Members are:

• Prof. Dr. Hermann Jungkunst
  (from 04/01/2012 Professor at the University of Koblenz-Landau)


As the senior scientist my main duties are (a) to prepare the ground for new ideas within the group (b) launch pioneer studies with shorter termed thesis (c) acquire new projects for longer termed mainly PhD thesis and (d) to keep up the motivation in the team. I think we all take advantage of having related but not too similar study topics to discuss about. We all deal with the coupled carbon and nitrogen cycles. The common ground for most studies is greenhouse gas dynamics driven by varying factors like tree diversity, land use and land use change or other disturbances. We frequently meet to talk about recent shortcomings and opportunities. The external members, which principally are candidates I am actively co-supervising, hopefully benefit as well.


Presently I am particularly interested in biodiversity effects on biogeochemistry at the plant-soil interface. Furthermore I am intensifying my research activities on soil hydrogen cycling. We have done wetland research in the Drakensberg mountain range in Southern Africa which we intend to continue in close cooperation with Prof. Dr. Heinz Beckedahl, University of KwaZulu-Natal. A large BMBF Project is about to be launched in southern Amazonia in close cooperation with Prof. Dr. Eduardo Couto, UFMT, Cuiabá Area and Dr. Beata Madari, Embrapa Arroz e Feijao, Goias. Furthermore, we want to intensify our research on methane dynamics from forested and non forested peatlands in the Komi Republic, Russia headed by Jun. Prof. Dr. Lars Kutzbach, University of Hamburg.



• Dr. Felix Heitkamp (junior group leader)

Since October 2010 I participate in the group as co-group leader. Therefore my task is to add further knowledge to conceptual and methodological discussions.

Whereas Hermann Jungkunst is expert for greenhouse gas dynamics, I supplement the group with research on soil organic carbon storage and release. The focus is on effects of different land-use and environmental conditions on carbon dynamics in the soil. Coupling of knowledge from established long-term experiments (plot scale) with processes and mechanisms relevant on the landscape scale may help to understand feedbacks between land-use, management and climate change.

As a first step research activity with cooperation partners from Germany, Austria, Slovenia, Hungary and the Czech Republic are currently launched in order to increase knowledge on relations of climate, soil properties and fertilization (mineral, straw, farmyard manure) on carbon dynamics in the soil.



• Klaus Schützenmeister


I am PhD-student and scientific research assistant guaranteeing high quality results from the gaschromatograph that is used for nearly all projects of this research group. Furthermore I am coaching the candidates in completing their individual theses.

For my own thesis, embedded in the Functional Biodiversity Cluster of Excellence I am focusing on the effects of biota on the biochemistry of rhizosphere from deciduous tree species and the function of rhizosphere as a carbon sink. The rhizosphere is a region of high activity between roots, microorganisms and macrofauna. In this environment biomass turnover is extremely high. In my study I am focusing on the influences of Fagus sylvatica (beech) and Fraxinus excelsior (ash) on soil carbon and nitrogen dynamics in and out of the rhizosphere. Furthermore earthworms will be considered.

Different experimental approaches are followed to investigate the effect on pH-value, oxygen concentration, carbon dioxide, nitrous oxide, methane, root exudates and potentially other biochemical parameters of soil. The approaches include simple soil column experiments for net greenhouse gas exchange (soil with and without trees) complex rhizotron experiments with 13C labelled litter and Lumbricus terrestris in nearly undisturbed soil. In May 2011 a field experiment to label beech phloem with a 13C tracer to separate root and litter derived C in the bulk soil C will follow. I also participate in the joint diversity experiment “SPLIDRHEX” that will be set up in autumn 2010.



• Xuan Truong Vuong


My name is Xuan Truong Vuong and I come from Vietnam. In my PhD study, I want to study the effects of disturbances, land use and land use change on different soil carbon fractions. To do so, I have to separate and measure labile organic carbon and stable organic carbon in soil samples at the landscape scale. First, I have to find out the most suitable methods which can calculate labile and stable organic carbon in soil separately. Then I have to discuss advantages and disadvantages of the individual methods for the landscape scale. The methods must be quick, economical and easy to apply for many soil samples. For that, I presently analyze soil samples from Germany, Mexico, South Africa and Brazil with very different disturbance and land use history, e.g. seasonally dry wetlands, fire, old traditionally Colluvisols and formerly military (tank) land use. My studies are closely connected to the thesis of Per Schleuss.



• Per Schleuss


Forest ecosystems play an essential role in the global carbon cycle. Main functions are at least to reduce the atmospheric CO2 concentration and second to provide longer termed carbon storage. Generally carbon is stored in three different components: 1) vegetation, 2) organic layer and 3) mineral soil. In my thesis I will focus on mineral soil carbon contents and its fractions (labile & stabile pools) in association with different grain sizes (sand-, silt-, clay fractions). Investigations will be conducted for top and sub soils in the National Park Hainich (Germany/Thuringia).

The main question to answer is whether differences in carbon contents and carbon fractions are the result of different grain sizes (especially clay content) or caused by variable stand diversities. Based on the study of GUCKLAND et al. (2009) a very similar plot design is chosen, which includes varying diversity levels of monospecific stands with predominantly beech in comparison with mixed stands e.g. beech, ash, lime. I expect differences of carbon stability pools between top and sub soil as well as between diversity plots.



• Jan-Paul Krüger (now PhD-candidate in Basel/Switzerland)


During my field work in 2010 in the Drakensberg, South Africa, I investigated nitrous oxide and methane fluxes from the soils of two natural wetlands. The wetlands in the Drakensberg are drying out over the winter and getting rewetted in spring. The main results of the field work are: (a) one of the wetlands emits significant more methane than the surrounding non-wetland. (b) There is a positive (exponential) correlation between the methane emissions and the water table. The methane emissions increase abruptly above a water table of approximately 10 cm below the surface. (c) One of the wetlands reacts to the rewetting with high methane emissions within two days and the other with high nitrous oxide emissions within one day. A microcosm experiment in Göttingen is set up to simulate the rewetting effects of the soil by measuring the greenhouse gas fluxes during different water tables.

The field work in the Drakensberg was supported by the German Academic Exchange Service (DAAD).



• Hannes Haupt


During spring of 2011, I was investigating the effect of snowmelt on the leaching of dissolved organic carbon (DOC) from a boreal peatland ecosystem in the Komi Republic (Russian Federation). Boreal peatlands store tremendous amounts of carbon – about one third of the global soil carbon – and play a crucial role in the interaction between the atmospheric concentration of CO2 and terrestrial sequestration of carbon. Throughout northern Eurasia many pristine boreal wetlands are found which, despite of their significance for global biogeochemical cycles, are still underrepresented in present research and global climate models. Anaerobic conditions in wetlands of cold and continental climates reduce the rate of decomposition of organic material and lead to the historical accumulation of carbon. During the spring snowmelt period, widespread flooding occurs, causing lateral transport and leaching of DOC from the soils. My goals are (a) to estimate the effect of thawing snow cover and soil frost on the hydrology and the water balance of the peatland and (b) to quantify the budget of lateral carbon input and output during that time. These investigations are taking place within a research field trip of the Lars Kutzbach research group (University Hamburg, Institute of Soil Science) and are supported by the CliSAP Cluster of Excellence, the Komi Science Centre in Syktyvkar, Russia, and the German Academic Exchange Program (DAAD).



• Nina Hennings


“DOM comprises only a small part of soil organic matter; nevertheless, it affects many processes in soil and water including the most serious environmental problems like soil and water pollution and global warming” (Kalbitz & Kaiser 2003).
In my study I focus on the spatial dynamics of dissolved organic matter (DOM) in a boreal mire in northwest-Russia, especially during the snowmelt period.
It is important for my thesis work to distinguish different sites, so I compare measurements between the forest, minerogenous and ombrogenous parts of the peatland and also between different depths (10, 30, 60 cm).
In total 23 plots were measured twice a week and their samples were analysed either immediately with a UV-absorption method (S::can spectrolyser, s-can Messtechnik GmbH, Austria) or in the laboratory with either a combustion method (Shimadzu, Japan) or a benchtop spectrophotometer (Hach Lange LT 200). A comparison of the spring data will be made with the absorption spectra of samples taken in the fall. To identify the qualitative differences between DOM in forest, minerogous and ombrogenous snowmelt- and pore-water the UV/VIS S:can spectrolyser is used. A further goal is to document the dynamics of DOC concentrations to see whether there is an influence on the chemical character of DOM.
My hypotheses are a) The regime shift from winter to spring has a tremendous influence on DOC concentration and because of the flooding snowmelt water. DOC concentrations are rather low and b) the DOM quality varies between the different sites of the peatland and c) there is a dependence between DOC concentration and the construction of DOM.
This master thesis takes place within the Kutzbach Junior Research Group 'Regional Hydrology of Terrestrial Systems’ at the University of Hamburg and is supported by the CliSAP Cluster of Excellence, the Komi Science Center in Syktyvkar, Russia and the German Academic Exchange Programme (DAAD).



• Marco Gronwald


In my master thesis, which is embedded in the Project B5-Rhizosphere chemistry (Klaus Schützenmeister) within the Functional Biodiversity Cluster of Excellence, I want to investigate the influence of photosynthesis on greenhouse gas-emissions from Beech- (Fagus sylvatica) and Ash- (Fraxinus excelsior) planted soils.

A pre-study of the AG showed, that (a) the N2O-emissions of the Ash soils were lower under light-conditions than in beech soils. (b) Ash soils have a higher methane uptake and (c) a higher CO2 release than the Beech soils.
The very interesting point is the influence of the tree species on the quantity of N2O emissions. That implies the questions what the influence of the root-activity is and how species-specific metabolism characteristics impact emissions.

To confirm & enlarge the AG's results, I measure and compare the greenhouse gas-emissions (1) from a soil column experiment which are planted with beeches and ashes and (2) with same-planted plots in the field experiment "SPLIDRHEX".

Since march 2012, we get the opportunity to enhance the experiment with a special- influence-factor: silver nanoparticles. The question for us is: how do silver nanoparticles alter ecosystem processes with the main focus on greenhouse gas emission from soils if nano particles are released into the pedosphere.

Moreover I will be briefed on the use of the gaschromatograph (Shimadzu 14b) and support the 13C-tracer experiment of the B5- Project. In this experiment we label beech phloem with a 13C-tracer to separate the C that is exhale from the roots or from the soil.
Furthermore I’m student assistant for general works in the department.



• Stephanie Kätsch


My master thesis deals with the effects of inter- and intraspecific competition on tree growth and biomass production. I try to investigate whether different dominance patterns in tree mixtures and different densities in tree spacing influence above-ground biomass production.

In order to do so, I conducted tree measurements in an experimental afforestation site near Kaltenborn in Thuringia, Germany. The Simplex experiment, which I worked in, consists of 36 plots with different mixtures of European beech (Fagus sylvatica L.), Sessile oak (Quercus petraea Liebl.), Norway spruce (Picea abies (L.) H. Karst.) and Douglas fir (Pseudotsuga menziesii (Mirb) Franco). Heigth and diameter at 30 cm of each tree were measured in order to estimate their biomass using allometric equations.
I want to find out, if the tree species in certain mixtures are more productive than in others and if there is any evidence for complementary effects between the different species. Furthermore different spacing densities might influence biomass production and growth allocation as well.

In addition to the mere investigation of ecological aspects, these questions are particularly important in the light of climate change. Large amounts of carbon are stored in the living biomass of the forests. Hence the results of this study could also contribute to the research on mitigating strategies against rising CO2-levels in the atmosphere. Furthermore, because of investigating tree species with considerable economic value, the experiment outcome will as well be relevant for forestry purposes.
The Simplex experiment is part of the BIOTREE experiment (BIOdiversity and ecosystem processes in experimental TREE stands), which was finally set up in 2004 to study long-term biodiversity –ecosystem functioning. This experiment is a joint project of the Max Planck Institute for Biogeochemistry in Jena, the Thuringan State Institute for Forestry, Game and Fishery (Thüringer Landesanstalt für Wald, Jagd und Fischerei) and the German Federal Forest Service, District Thuringian Forest (Bundesforstamt Thüringer Wald).



• Jens Nienaber


The northwestern part of Germany is characterized by intensive agricultural land use. It is of great importance for the regional economy and for the self conception of the local population. Intensive agricultural systems, however, do have negative environmental. These negative impacts are manifold e.g. decrease of biodiversity and dangers for human health and are particularly related to fertilizations needed to achieve high yields. They affect the water quality of adjacent streams, lakes and groundwater. Therefore it is of great importance to find methods which are able to decrease the loads of nitrogen and phosphor in water systems. One possibility is complete denitrification in open water bodies low in oxygen and high in carbon content. For this, I will take water samples inside of an anthropogenic generated recreation area called the Ahlhorner Fischteiche, an area with many different lakes mainly provided by one stream called Lethe in the northwestern region of Germany. These water samples will be investigated in order to find differences in the load of dissolved nitrous oxide, nitrat and phosphor in order to make conclusions about denitrication processes inside the area. The samples will be taken at the Lethe which flows through the area and provides the lakes with water. Additionally samples will be retrieved at several lakes which are used for fish breeding or are not used by humans at all.

External members:

• Ann-Catrin Fender

PhD studies on biogeochemical cycles as affected by the rhizosphere of deciduous tree species.



• Jens Altmann

PhD project on biomarker methods to differentiate root derived from other sources of soil organic matter.



• Lisa Schüler

PhD studies to reconstruct former and to predict future landscape dynamics on Mt. Kilimanjaro.

Former members:

Marlen Gritschke

Karst ecosystems are very vulnerable landscapes particularly with respect to nitrogen input. Usually nitrate is used to find out whether karst ecosystems are saturated or even supersaturated with nitrogen. I want to investigate the role of dissolved nitrous oxide N2O and dissolved molecular nitrogen N2 as an indicator for nitrogen supersaturation. Nitrous oxide forms as an intermediate of denitrification of nitrate and as a byproduct of nitrification of ammonia.
For this purpose I take samples from springs of karst landscapes of Triassic limestone region of Göttingen and of gypsum karst in the region of Nordhausen and Herzberg (Harz). These two types of karst will be compared to find out whether the parent rock material influences the chemistry of spring water.

Miriam Hurkuck

Traditionally, methane (CH4) is thought to be produced under strictly anaerobic conditions, e.g. in wetlands. However, recent investigations show that CH4 can be even emitted under aerobic conditions without microbial activity.
During an exchange semester in Lund, Sweden, I reproduced the Keppler et al (2006) study “Methane emissions from terrestrial plants under aerobic conditions”. In most cases his results could be confirmed. However, these results are still intensely debated and remain controversial, so that there is further need of research.
Based on the work in Sweden my thesis deals with the non-methanogenic formation of CH4 in soils, especially in main components of this soil. For this purpose different complete soil samples will be investigated. The reaction in terms of CH4 emissions towards changes in water content and increasing temperature will be compared. In a further step, three main soil components – Vermiculite, Lepidocrocite and Hemicellulose – will be wetted, dried and observed in the same way.
The measurements are supported by the Max-Planck-Institute for Chemistry, Mainz, and are conducted under the supervision of Kepplers research group.

Andreas Dahm

Climate variability is predicted to increase. Consequently trees most likely have to cope with more extreme dry, wet, hot and frost periods. This is particularly true for saplings. For example, the winter of 2008/2009 was very frosty in Göttingen and the saplings of the Hainich Experiment suffered severely and many died off.
During my studies I want to elaborate which of the five deciduous tree species (beech, ash, lime, maple and hornbeam) proved to be frost-resistant. Is there a species effect and a diversity e.g. species composition(1 species, 3 species and 5 species) effect with respect to soil frost? My focus will be on the root system but aboveground biomass (quantity and quality) will be considered as well.
My studies potentially add a little to the knowledge needed to plan an optimized future forest in Central Europe in terms of economy and ecology.

• Ulrike Wolf



In summer 2008 I spent three months for my diploma thesis in the Republic of Komi, Russian Federation to investigate the methane dynamics of Ust-Pojeg peatland, a patterned boreal peatland ecosystem.

During the field work, my focus was on closed-chamber-measurements of methane fluxes. Furthermore I sampled soil water for the analysis of dissolved methane and the concentration of dissolved organic carbon (DOC).

The main results were: (a) significant differences between the three different relief types (hummock, lawn, flark) and (b) CH4 emissions were exceptionally high. The maximum value was 1614 mg m-2 d-1. The mean value of all measurements was 316 mg m-2 d-1. The values exceed by far the average of 5-80 mg CH4 m-2 d-1 for the boreal zone (Blodau 2002). For more details refer to my poster [PDF].

The work for my diploma thesis was realized within the project “Eurasian peatlands in a Changing Climate” (EURAPECC) of the working group “Ecosystem Dynamics” of the Ernst-Moritz-Arndt University of Greifswald.