Terrestrial Ecosystem Analysis Group

Master thesis

“Sermilik soil chronesequence (laboratory based)”

Background and Aim

The overall aim of this project is to investigate how the interactions between soil nutrients (carbon, nitrogen and phosphorus), microorganisms, and organic matter affect nutrient cycling and availability.

Soil samples have been collected along an Arctic soil chronosequence (at Mitdluagkat Glacier, Greenland), which is of a unique gradient of 0 to >300 year-old sediment deposits, with sediment deposition having recently accelerated due to climate change and unprecedented glacier melting. The samples will serve as a database to evaluate the effect of time and climate change on nutrient cycling and especially P cycling mediated by soil microorganisms.

The project will provide detailed understanding of soil microorganisms’ role in nutrient cycling in soil as a function of sediment deposit age, properties and vegetation establishment. The study site on a pristine natural ecosystem represent a unique opportunity to unravel the role of microorganisms in soil formation from sediments. This is a fundamental basis required to develop more sustainable agricultural systems, especially in Arctic regions that can make use of microbial P cycling to provide food security whilst simultaneously preventing losses to the environment.

Main tasks

The young soils will be characterized in the laboratory for 1) basic physical and chemical characterization (pH, nutrient content, mineralogy), 2) characterize the P pools using soil extraction methods (e.g. Olsen-P), 3) quantify the microbial biomass C, N and P using fumigation extraction, 4) characterize the soil organic matter 5) establishing a carbon source utilization profile of soil microorganisms using MicroResp

Contact

Nelly Raymond (nr@ign.ku.dk)

Master thesis

“Land reclamation after mining: nutrient cycling (laboratory based)”

Background and Aim

In natural ecosystems, microorganisms are the key driver of soil P cycling, both in short term (e.g. over a growing season) and in long term, governing changes in soil P pools as soils develop.

Promoting this role in agricultural systems to support crop production would shift reliance away from non-renewable, mineral P inputs and reduce the associated negative environmental effects. However, developing reliable strategies to achieve this goal is impeded by a poor understanding of how soil P status, soil microorganisms, and soil characteristics interactively determine P supply to plants. In this project the interactions between soil P, soil microorganisms, and soil characteristics that promote microbial P cycling and P availability to plants will be investigated, along a rare and unique managed soil chronosequence.

The chronosequence is a gradient of soil reclamation development managed by the industrial partner (RWE Power AG, Germany (RWE)). The use of this kind of site to study the dynamic effects of management practices and microbial processes over time is a world first and a highly innovative approach to deliver novel insights about how to promote microbial P cycling and P availability to plants in agricultural soils.

Main tasks

The young soils will be characterized in the laboratory for

1. basic physical and chemical characterization (pH, nutrient content, mineralogy),
2. characterize the P pools using soil extraction methods (e.g. Olsen-P),
3. do an organic matter fractionation, 4) assess microbial nutrient limitation

Contact

Nelly Raymond (nr@ign.ku.dk)

Master thesis

"The effects of mixed cultivar systems on soil exploration by roots and the acquisition of water and nutrients"

The world’s major crop-producing areas suffer from both more frequent and severe drought stress due to accelerating climatic changes. Climate change in large parts of Europe will lead to lower precipitation levels in the growing season and higher outside the growing season. This imbalance can be leveled out by utilizing previous surplus precipitation stored deep in the soil profile. In short: Growing summer crops on winter precipitation!

Mixed cultivar systems where deep and shallow-rooted cultivars are grown together have an underexplored potential to increase water use efficiency and ensure stable yields. Deeper rooting crop cultivars have access to deep stored soil moisture unavailable to more shallow-rooted cultivars. However, it appears that the presence of deep roots in moist soil does not necessarily ensure a full water supply and prevent drought stress. Thus, there is a need to identify the limiting factors for deep water uptake to improve drought tolerance.

The project

The aim of the project is to test whether mixed cultivar systems combining shallow and deep rooting cultivars are more drought resistant than single cultivar systems. We want to quantify the effects of mixed cultivar systems on soil exploration by roots and the acquisition of water and nutrients under drought. We are performing a field experiment with barley (Hordeum vulgare) to meet these aims due to its importance across Nordic countries.

The study site is in Taastrup and fieldwork will be in June and July 2023. The project can be relevant for students starting their master’s project already in block 4. 

Contact

Camilla Ruø Rasmussen crr@ign.ku.dk
Carsten W. Müller cm@ign.ku.dk

Arctic tundra processes in relation to climate change

The Arctic environment is severely impacted by changes in global climate . We need to study the consequences for importanct functions and characteristics of the tundra ecosystem

Project 1

• Impact of tundra wild fires on soil processes and greenhouse gas emissions.
• Global warming leads to increased frequency of wild fires in Arctic . The project emphasizes the consequences of tundra fires for alterations in soil nutrient pools, vegetation regrowth and emission of greenhouse gases.
• The project includes laboratory work with analysis of soil and vegetation samples.

Project 2

• Disclosing the secrecy of the tundra nitrogen cycle.
• The arctic tundra is characterised by a relatively closed nitrogen balance with small pool sizes, low inputs and low outputs. However , changes in climate (permafrost thaw , increased temperature) may increase the availability of N and lead to increased greenhouse gas emissions.
• The project includes laboratory work with application of advanced stable isotope techniques to study soil biogeochemistry and GHGs.

Contact

Per Ambus, Center for Permafrost
IGN , peam@ign.ku.dk
http://cenperm.ku.dk

Nitrous oxide emission from contrasting agricultural landscape

Nitrous oxide (N2O) is the most powerful among the long lived greenhouse gases and contributes ca . 6% to anthropogenic climate forcing and is the dominant ozone depleting substance emitted in the 21st century. However global estimates are still incomplete and distinct sources are associated with large uncertainties.

The project

Disclosing soil nitrous oxide production and emission along topogradients

Microbial activity in soil surface layers commonly explain terrestrial N2O production, and this surface emission is regulated by soil and climatic factors. Recent research reveals that surface fluxes of N2O is intimately linked landscape topography. Hence, in order for a accurate estimate of surface fluxes combined analysis of soil biogeochemical properties, landscape topography and surface fluxes is needed.

The project includes field and laboratory work with collection and incubation of soil samples. Usage stable isotope techniques is a central element in the project , and will include application of a new high end N2O isotope laser. Field work in Denmark in 2021.

Contact

Per Ambus, Center for Permafrost
IGN, peam@ign.ku.dk
http://cenperm.ku.dk

A selection of previous master projects for inspiration.

Climate and vegetation

• Reduction of global GHG emissions (TF)
• Modelling temperature gradients in Greenland (BH)
• Global radiation in mountainous areas (BH)
• Automatic animal trail recognition in a Danish wetland using satellite and drones (AWN)
• North American boreal forest fires (GS)
• Multi-criteria GIS analysis as decision support tool for finding nature restoration (TB)
• Vegetation and sheep farming in South Greenland (BE)
• Kitchen middens and vegetation changes (BE)
• The effect of climate change on Sorghum yields in Burkina Faso (GS)
• Modeling biomass production in Greenland (BH)

Soil

• P-retention capacity in soils - in the future an environmental problem? (HBM)
• Biochar & glacial flour as fertilizer in tropical soils (HBM)
• Methane uptake in dry landscapes (BE)
• Methane emissions from Arctic peatlands (GS)
• Effects of permafrost depletion in a subarctic landscape in Northern Sweden (TF)
• Impacts of tundra fire on soil nutrient mobility and GHG emissions (PA)
• A chronosequence study on C and N acquisition in a recently deglaciated forefield, W-Greenland (PA)
• Plant available nutrient and growth with warming (BE)
• The effect of glacial flour on soil water retention and irrigation strategy in sandy tropical soils (HBM)
• Soil Water chemistry changes after snow addition (BE)
• Emissions of nitrous oxide from arctic tundra in response to climate warming (PA)
• Modelling active layer thickness in Greenland (BH)
• Soil quality and yields in organic and conventional cultivation systems in East Uganda (TBB)
• Palm oil expansion in the Amazon: Implications for soil organic carbon and future development (TBB)

Water

• Arc-Malstroem and Malstroem: Applications for flood risk modelling in urban and rural areas (TB)
• SeaFlood: Flood assessment in coastal areas caused by stowage of sea water (TB)
• Kagså climate adaptation and assessment of extreme precipitation events in next generation climate scenarios (TF)
• Improved techniques to measure snow volume using drones (AWN)
• Data standardization and data modelling in compliance with the European Water Framework Directive (TB)
• A method for automated generation of stream networks in rural areas (TB)
• Changes in methane oxidation after watering (BE)
• Water use efficiencies from different land use managements in Skjern River catchment (TF)

(supervisors: AWN – Andreas Westergaard-Nielsen; BE – Bo Elberling; BH – Birger Hansen; GS – Guy Schurgers; HBM – Henrik Breuning-Madsen; PA – Per Ambus; TB – Thomas Balstrøm; TBB – Thilde Bech Bruun; TF – Thomas Friborg)