THE STATE OF THE FOREST ECOSYSTEM IN AN AREA OF OIL SHALE MINING AND PROCESSING
2. MORPHOLOGICAL CHARACTERISTICS
OF NORWAY SPRUCE
K. OTS
J. RAUK
M. MANDRE
Estonian Agricultural University,
Forest Research Institute
Department of Ecophysiology
18b Viljandi Road, Tallinn
11216 Estonia
| Air pollutants (oil shale fly ash, gases, organic
compounds) emitted by the oil shale industry in Kohtla-Järve, North-East Estonia, have caused
changes in the soil (pH = 4.7–7.4), subsoil water (pH = 5.9–7.2), rainwater (pH = 7.0–7.1) and
snow melt (pH = 7.3–8.7) compared with an unpolluted control area in Lahemaa National Park
(soil pH = 3.6, subsoil water pH = 5.1, rainwater pH = 6.9 and snow melt pH = 6.8). Compared
with the period before 1990 the pollution load on the area investigated has fallen drastically;
however, this has not resulted in an essential improvement in growth conditions of trees. Morphological analysis of 80-year-old Norway spruces growing on sampling plots (six) in the polluted area and in the control area showed that air pollution has had temporally (1989–1990, 1994–1996) and spatially variable effect on the parameters characterising the state of trees: length growth, weight and dry matter content of needles and shoots, number and density of needles on shoots, radial increment of trees. The length growth of needles and shoots proved to be one of the most suitable parameters indicating the influence of air pollution, although not in all sample plots investigated. The results for fresh and dry weight of needles revealed great differences between sampling plots. The biomass of shoots was notably greater in the immediate vicinity of Kohtla-Järve than in the control area. The spruces whose shoots showed inhibited length growth had greater density of needles on shoots with difference from the control being up to 16 %. The effect on the radial increment of Norway spruces was especially strong in the immediate vicinity of pollution sources (<2 km) but it fell rapidly with distance from them. |