Spatial and temporal small-scale variability of nitrogen mobilization in a forest ecosystem with high N deposition in NW-Germany.
For conifer stands in NW-Germany with high DIN load (23-35 kg N ha(-1) a(-1)) and a long history of nitrogen export the risk of N mobilization were investigated. Ammonium is the most mobilized N species, pointing towards either conditions not favoring nitrification or, more likely - under the dominant aerobic conditions - a very high amount of ammonium in the forest floor. Independence of net nitrification and net ammonification from each other indicates the existence of two separate systems. The nitrifying system depends very much on biotic conditions - as a function of energy and moisture - and seems not to be directly related to N deposition. In contrast, for the ammonification system (Oe horizon) a correlation with the sum of ammonium deposition three months prior to sampling was found. However, the role of disturbance, i.e. nitrogen export, during the last centuries and the role of recovery of the N balance during the last 150 years is still not clear.
Lorz
Carsten
C
Institute of Soil Science and Site Ecology, Dresden University of Technology, Pienner Str. 19, 01737 Tharandt Germany. carsten.lorz@tu-dresden.de
Eissner
Christel
C
Lethmate
Jürgen
J
Schneider
Birgit
B
D002244:Carbon / Q000032:analysis; D002852:Chromatography, Ion Exchange; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods / Q000706:statistics & numerical data*; D005858:Germany; D009584:Nitrogen / Q000032:analysis*; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D012987:Soil / Q000032:analysis; D064028:Tracheophyta; D014197:Trees
D000644:Quaternary Ammonium Compounds; D012987:Soil; D002244:Carbon; D009584:Nitrogen