Natürliche Isotopenverhältnisse des Stickstoffs zur Bioindikation in Kiefern-Wald-Ökosystemen

Schulz, H., Gehre, M., Russow, R.: Natural isotope ratios of nitrogen for bioindication in Scots pine forest ecosystems. - Hercynia N. F. 50 (2017): 99 – 114. The natural isotope ratios of nitrogen (δ 15 N values) were analysed in different environmental media (air, precipitation) and ecosystem compartments (pine barks, the humus layer, mosses, and pine needles). The δ 15 N values of the atmospheric N emissions ammonia (NH 3 ) and nitrogen dioxide (NO 2 ) as well as their transformations products ammonium (NH 4 + ) and nitrate (NO 3 - ) in precipitation were reflected well by the δ 15 N values of deposited NH 4 + and NO 3 - in pine barks. Bark analyses are thus well-suited for making statements about the sources of N emissions. By comparison, humus layers, pine needles and mosses where N isotope fractionations through processes of  N-mineralisation and N-assimilation are taking place are less well suited (or not at all suited) to identify the sources of  N emissions.  Key words : Air, humus layer, mosses, natural isotope ratios of nitrogen, pine needles, pine barks, precipitation