Hopp til hovedinnholdet

Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

1998

To document

Abstract

Enhancement of the atmospheric N deposition is a serious threat for the structure and function of ecosystems. Here we evaluate the ecological effects of excess N with respect to changes in vegetation and soil biota in a series of experiments along a N gradient across Europe. The aim of this project (NITREX: N saturation EXperiments) is to assess the risk of N saturation and the reversibility of N saturation. At the experimental sites with a low-to-moderate input, N was added (n = 3), while at sites with a high input, N was removed by means of a transparent roof (n = 4). The experiments started between 1989 and 1991. Across the N gradient a positive correlation was found between the N concentration in deposition or soil solution with the N concentration in the needles and in general a negative correlation with the base cations K and Mg. In the N-addition plots there was a tendency towards a decreasing nutrient status of the needles, whereas at one site N-removal led to an improvement. Addition of N hardly affected fine-root biomass production, whereas signs of growth increase were recorded when the input was reduced. Tree growth was accelerated upon input reduction at two of three sites. Manipulation of N input did not alter the decomposition rate, although significant differences between sites were noted. Manipulation of the N input hardly affected the biomass of fungi and bacteria, but a negative relation between the N-addition and part of the soil fauna may be present among sites.

1997