PhD defense Emily Pickering Pedersen
On Wednesday 29 September, Emily Pickering Pedersen defended her PhD thesis. In the thesis entitled “Secrets below the surface: Patterns and processes of plant nitrogen uptake in a changing Arctic”, Emily studies the impacts that increased soil nitrogen availability has on plant uptake and growth.
Higher temperatures and thawing permafrost have the potential to increase the amount of nitrogen available to plants in Arctic ecosystems. Emily’s PhD project investigates plant species specific uptake of newly available N across multiple dimensions of N release (depth, space, time) and according to species characteristics, plant-microbe competition and environmental change. Throughout all studies, stable isotope labelling was used to simulate naturally occurring processes of N release and to track plant and microbial N uptake and turnover over time.
This work demonstrates that arctic plants successfully acquire both surface-released and permafrost-released N. Thus, arctic plants can take advantage of both increased decomposition and permafrost thaw for new N supply. While most plants prefer top-soil N, the ability to access deep-soil N pools renders permafrost-released N an important new nutrient source to arctic plants. Even in sloping terrain, plants can capture permafrost-N both locally and downslope from the point-of-release, which may contribute to landscape-scale plant community change.
Emily has done her research at CENPERM under the supervision of Anders Michelsen and Bo Elberling.