Plants of a coniferous forest as indicators of nitrogen enrichment in soils under the influence of atmospheric deposition

Abstract

Plants have long been used as indicators of the nutrient conditions in soils (Ellenberg, 1988). Scientists used some species present at a site as indicators of, for example, soil nitrogen supply, either using numerical indicator values from vegetation data. A frequently used method is to calculate a site value based on the indicator values assigned by Ellenberg et al. (1991). Ellenberg’s nitrogen (N) values are interpreted as showing nitrogen availability, general fertility or nutrient status of the site. The objective of this study was to identify changes of nitrogen indicator species and results were compared with Ellenberg’s N values. Species composition of pine (Pinus sylvetris L.) forests subjected to intense air pollution stress in the impact zone of one of the largest air pollution sources in Lithuania – the mineral fertilizer plant Achema – were chosen as objects of research. In order to investigate ground vegetation changes during the time period, the study sites were established at 3-22 km distances in the prevailing wind direction (70–90 azimuth to the east) from the plant. Vegetation data from 31 stands which had first been surveyed by prof. S. Karazija in 1987-1988 were available (further referred as 1988). Stands with an age of  55 years with vegetation assigned to the Vaccinio-myrtillosa site type and with similar dendrometrical characteristics were preferred and were investigated in July, 2004 [...]