Impact of long-term N deposition on nitrogen transformations and translocation in a northern peatland
DFG BL563/14-1From 06/2007 to 11/2008
Principal Investigator: Christian Blodau, Jan Fleckenstein
Staff: Yangping Xing, Dimitre D. Dimitrov
Large areas of peatlands have been exposed to elevated atmospheric N deposition. When sustained chronic inputs of N lead to “nitrogen saturation”, N is lost from the soil, and environmental pollution will inevitably occur. Ombrotrophic, Sphagnum-dominated peatlands are exclusively fed by wet and dry atmospheric deposition and are very sensitive to increased atmospheric N input. It is thus of great scientific interest to examine the changes in N mass balances and cycling induced by anthropogenic N input. Little is currently known about the changes in the fate and mobility of N following chronic N pollution. The proposed project seeks to clarify the pathways of N transformations and N mobility in different pools under different long-term nutrient fertilization and changing plant cover through combined application of 15N as an isotopic tracer and HYDRUS modeling. The mechanisms of N retention by soil and plants will be elucidated and N saturation thresholds will be estimated by empirical analyses and modeling. Results from this study will improve our understanding of the fate of N under increasing N load, thereby enhance our ability to predict the future response of the N balance and cycle in northern peatlands.