Phosphorus limitation of ecosystem carbon sequestration

Supervisors: Dr Sarah Woodin (University of Aberdeen), Prof Sally Power (University of Western Sydney), Prof Pete Smith (University of Aberdeen)

The management of ecosystems to maximise their carbon sequestration has become a priority. Carbon sequestration is controlled by climate and nutrient availability; the role of nitrogen is well understood due to many studies of the effects of atmospheric nitrogen deposition, but the role of phosphorus has barely been considered. This studentship will improve mechanistic understanding of the influence of phosphorus availability on the carbon sequestration potential of natural ecosystems by undertaking research within existing nutrient experiments in contrasting P-limited systems in Scotland (montane heath, years 1&3), Australia (grassland, year 2), and the Arctic (polar heath, year 3). Skills will be gained in measurement of: species traits relating to the uptake, use efficiency and economy of P and N (e.g. type and extent of mycorrhizal colonisation, specific root lengths, root:shoot ratios and chemistry); above and below ground productivity; microorganism biomass, activity and NP stoichiometry; ecosystem CO2 fluxes and C stocks; and decomposition and mineralisation rates. Findings will be applied in a process-based soil C sequestration model, to examine the potential impacts of P limitation at regional to global scales. The student will benefit from being part of two closely-linked and vibrant research departments on opposite sides of the globe.