Because of thinning of the ozone layer, there is a continual increase of ultraviolet B (UV-B) irradiation reaching the Earth. We have followed for two and a half years the influence of an artificial source of UV-B irradiation of 17685 J/m** 2 and 28010 J/m** 2 on spruce Picea abies (L.) Karst seedlings. The controls were irradiated with only normal, 6025 J/m** 2. Results show that 3 years seedlings are sensitive to irradiation, as may be first seen from their decreased mitotic activity and in lesser needle and seedling growth in their third year.

Endophytic fungi species composition in healthy needles of Austrian pine (Pinus nigra Arn.) was investigated at eight locations in Slovenia. Results from October 1994 and January 1995 isolations were compared with analyses of macronutrients, sulphur and lead content of the needles. About 80 species of microfungi were revealed. From the observations and measurements described it was not possible to discriminate between the effect of environmental factors and effect of air pollutants. The pollutants load of all measured elements is low and the environmental factors are very diverse. From the dendogram of isolation frequencies it seems that the age of the tree affects the species composition and frequencies of endophytes to the greatest extent.

Among a variety of stress indicators for early identification of Norway spruce (Picea abies (L.) Karsten) decline the sulphur content, photosynthetic pigment content, activity of the enzyme peroxidase, watersoluble thiols and ascorbic acid in 4 age classes of 5 spruce needles were analysed. The 10 sampling sites were selected according to the degree of forest decline, sea level, distances from the Thermal Power Plant Sostanj and air pollution.

Preliminary results and methodology related to the use of the fluorescence in situ hybridization technique for detection of plants hybrids are presented. Total genomic DNA probe preparation and the non-isotopic biotin probe labelling technique is presented. The use of an excess of unlabelled competitor DNA from a related plant species gives more constant results in determining whole plant genomes with in situ experiments on plant hybrids. Preliminary results of flourescence in situ hybridization for detecting alien rye chromatin and localisation on metaphase chromosomes and interphase nuclei in the bread wheat cultivar Yugoslavia are described. The methodology for detection of interspecies hybrids of common and sessile oak with flourescence in situ hybridization is given. The advantege of the use of total genomic biotin labelled probes for in situ hybridization is that it requires less effort than preparing species specific probes and the ease of interpretation of the results. The technique of fluorescence in situ hybridization is less species than other cytological techniques for higher plants and almost the same methodology can be used for detection of oak hybrids. The extraction of a high quantity of species specific DNA of high quality and probe preparation and labelling are the most important step.

Work was carried out to investigate the effect of pollution on the needle cytokinin content of mature Picea abies (L.) Karst individuals. Needles were collected from trees growing at two sites, one polluted and relatively non-polluted, in central Slovenia. After ethanolic extraction and purification, the needle cytokinin extracts were separed by reverse-phase HPLC. Cytokinin content was analysed using four direct ELISA techniques specific for Z-, DHZ- and iP-type cytokinins and the O-glucoside conjugate of Z. Results showed a trend towards the accumulation of cytokinins in needles from trees subject to high levels of atmospheric pollution, particulary with respect to ribotide derivatives. No difference was found in the (OG)Z content between polluted and non-polluted samples. The results are discussed with respect to the origins of the observed accumulation.

Types of ectomycorrhizae on Norway spruce were determined in soil cores from two differently polluted forest research plots from the emission zone of Sostanj Thermal Power Plant (TPP). The two plots are comparable regarding site characteristics, but are differently polluted by the emmissions from the TPP. During the vegetations season 1993, 21 soil cores were taken from each plot. In these all fine roots and ectomycorrhizal roots tips were counted and the percentages of different types were calculated. Additionally, soil mycorrhizae from underneath fungal fruit bodies were taken in order to characterize new types of ectomycorrhizae. Classical anatomical methods and molecular tools were applied for identification. 17 types of ectomycorrhizae were determined on 28443 root tips in soil cores from the heavily polluted plot (Zavodnje). The predominant types were Paxillus involutus, Xerocomus badius, Piceirhiza parallela and Piceirhiza inflata. On the less polluted plot (Mislinja) 24 different types were determined on 38502 root tips in equal volume and number of soils cores. The most frequent types were Hydnum rufescens, Amphinema byssoides, Piceirhiza oleiferans, Cenococcum geophilum and Lactarius lignyotus. Mycobioindication of forest site pollution through selective sensitive (here Hydnum rufescens), in comparison to unsensitive (here Paxillus involutus), fungal species in ectomycorrhizae is discussed.

This paper deals with presenting a broad range of possibilities, which can be used with computer equipment by deriving, interpreting and processing forest data. Different rates of generalized data from the forest inventory can be used as a criterion in preparing different solutions. So this data strongly influences decision making processes. The paper also presents cost analysis and multi-criteria evaluation methods.

The paper summarizes the main results of reach on heavy metal detoxification in ectomycorrhizas of Rhizopogon roseolus, Paxillus involutus, Cenococcum geophilum and Pisolithus arrhizus formed on Pinus sylvestris roots collected from heavily polluted areas in Poland. The data were obtained by methods including electron microscopy (TEM, SEM) accompanied by EELS and EDAX, cytochemical stainings and capillary electrophoresis. All of the species described in the paper are fungi highly resistant to toxic elements. As detoxification in mycorrhizas is dependent on both partners, the phenomenon was studied in fungi and in Pinus sylvestris roots. The strongest element-filtering effect was observed in R. roseolus / P. sylvestris symbiosis. This mycorrhiza type was characterized by the accumulation of heavy metals in the fungal mantle, and a gradual decrease of these elements was observed along the Hartig net towards the inside of the root. Potentially toxic elements were localized intercellularly in crystals deposited on the mantle and hyphal surface and in pigmented layer of the cell wall of the extramatrical hyphae, and the hyphae of the outer mantle layer. They were also detected intracellularly within electron-opaque depositions in the vacuoles. Much lower levels of toxic elements were detected in plant cells. The most common place for heavy metal accumulation was the phenolic material of the cortical cells.

Mechanisms of air pollution toxicity are very complex and depend on various physiological and biochemical properties of plants. These mechanisms (including formation of free radicals) are still poorly understood. In addition, physiological responses of forest plants to air pollution stress can be modified by various biotic (e.g., insects, pathogens, mycorrhizae associations, genetic variation) and abiotic (e.g., increasing CO2 concentrations, ultraviolet-B radiation, nitrogen desposition, nutrient deficiencies, drought) factors. An example of air pollution effects on forest trees may be responses of ponderosa pine seedlings to elevated concentrations of ozone: various physiological changes in trees (lowered net photosynthesis, altered carbon allocation, deterioration of photosynthetic pigments, etc.) have led to reduced growth and biomass of plants.

The concentrations of potassium were determined in: (a) the last formed wood, (b) the vascular cambial zone with conductive (noncollapsed) phloem, (c) the youngest nonconductive (collapsed) phloem and the (d) oldest nonconductive phloem, by atomic absorption flame spectroscopy in three unaffected and three heavily affected silver fir (Abies alba Mill.) trees. A commercial conditiometer and own devised Tree Tester were used to determine the electrical resistance (ER). The relationship between the ER of living tissues and K content was investigated. The tissues of unaffected trees were generally characterized by a higher K content and corresponding lower ER. In all trees the K content was highest and ER lowest in the vascular cambial zone with conducting phloem, followed by nonconducting phloem and youngest xylem.