How green will the Arctic get? Understanding plant nutrient availability in Arctic ecosystems and its impacts on global climate change.

This PhD aims to understand how plant nutrient availability is changing in the Arctic, and how this will affect plant growth, ecosystem function and carbon cycling.

The Arctic is experiencing rapid change as a result of climate warming, and this includes an increase in growth and abundance of vegetation. Increases in vegetation growth have profound impacts on the functioning of Arctic ecosystems – from altered availability of forage for wildlife, to changes in hydrology and significant impacts on the carbon cycle. Research at the UoE School of GeoSciences has been crucial in providing the evidence that Arctic plant growth has increased in response to climate.

High latitude ecosystems are critical controls on future global climate change. They currently store about one half of total global soil carbon, which, if released to the atmosphere as greenhouse gases, could result in a positive climate feedback. Efforts to predict global change rely on our understanding of how much carbon will remain stored in soils in the future. In high latitude regions, this will likely be determined by the degree to which increases in plant growth can offset temperature driven increases in decomposition.

We know plant growth has increased in response to climate, but a key challenge is knowing how much further the vegetation can respond - how green will the Arctic get? Nutrient availability strongly limits plant growth in Arctic ecosystems, so we must understand how plant access to nutrients might change.

This project aims to better understand how soil nitrogen and phosphorus supply will change as Arctic soils respond to climate, and the likely impacts on plant growth and the carbon cycle.
• Which mechanisms limit plant access to nutrients in Arctic soils?
• Will the relative availabilities of different nutrient forms change under future conditions?
• What are conditions under which plant nutrient availability might be expected to be most responsive to temperature?

The research project will combine laboratory, field and modelling work. Fieldwork will be conducted in Sweden (200 km north of the Arctic circle) based at the Abisko Scientific Research Station. Research facilities at Abisko are world class, and the station supports a vibrant and international research community.

In the first year the student will develop state-of-the-art methodologies in measuring soil nutrient fluxes and apply them to Arctic plants and soils, using growth room facilities at Stirling University. The first and second year of fieldwork will involve designing and carrying out manipulation experiments to test how nutrient fluxes might change under future scenarios. This will likely include use of stable isotopes to trace nutrients to plants and microbial consumers and investigate transformations and turnover in the soil. Fieldwork will be conducted in close-association with research partners at other UK Universities (Universities of Exeter and Aberdeen) who will be conducting related research (through the NERC funded PRIME-TIME project) at the same site.

In the second and final year the student will test existing models of plant nutrient uptake against their experimental data to test the predictive ability of existing models and identify critical missing processes.