The Forest Research Plot was chosen on a typical site for the Pokljuka plateau. It is covered by a supposedly autochthonous old Norway spruce stand with rejuvenation centres. Data on the physiological parameters can be used as representation values for a subalpine Norway spruce stand. The studies include: standard site and dendrological parameters, physiological parameters (foliar analysis, antioxidants, hormones and aminoacids in spruce needs), genetical and biochemical analysis (isoenzymes and molecular markers), microbiological activity (acid phosphatase, rate of decomposition, number and occurrence of fungal decomposers of wood and litter) and studies of symbionts and pathogens of Norway spruce (mapping of fruitbodies of mycorrhizal fungi, types of ectomycorrhizae, endophytes, epiphytes - lichens and phytopathological surveys). All physiological and ecological studies are planned to be repeated at certain time periods in order to understand better the functioning of the forest ecosystems on Pokljuka.

Distribution patterns of ectomycorrhizal types and length density of finest roots were investigated in three comparable Scots pine ecosystems located along a deposition gradient of air pollutants in the new states of Germany. The plots Rosa, located near Bitterfeld and Halle, had received high depositions loads of SO2, NOX and alkaline fly ashes due to chemical industries and brown coal fired power plants in the former German Democratic Republic. Taura, located near Leipzig, was moderately affected by air pollutants. The background site Neuglobsow is located in a remonte area north of Berlin. All the three plots were dominated by only a few mycorrhizal types. Mycorrhizal projection area of these types was highest in Neuglobsow and strongly reduced at the polluted plots. The distribution patterns of mycorrhizal types differed also qualitatively. Length density of finest roots was lower in the humus layer of Neuglobsow than in the humus layer of Rosa and Taura. The results are correlated to high nutrient inputs and high rates of N-mineralization at the impacted plots.

First studies of this kind were based on mapping of cover and frequency of crustose, foliose and fructicose epiphytic lichens on trees which were assessed also for the decline symptoms. Since 1985 epiphytic lichen vegetation has been assessed by this methods and results, expressed as a lichen map of Slovenia were used as an air quality indicator for plots of forest die-back inventory. In case studies of forest decline, in collaboration with lichenologist from Graz Univ., Austria, all epiphytic lichen species were mapped in order to obtain better measure of air quality in the area studied. Very polluted and still clean and well preserved forests were investigated. From the material collected and determined a lichen herbarium has been established on the Slovenian Forestry Inst.. Possibilites of further research and use of epiphytic lichens as air quality indicators are discussed.

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.

In the paper authors review the complexity of the impacts on the forest ecosystem caused by road construction and logging operations and discuss research activities in that field. Interdiciplinary approach is emphasized and research priorities are suggested. The studies are needed where structural parameters of the soils are related to the plant vitality. This will help us understand the forests response on the impact and enable us to develop the practical techniques for soil and stand protection during further actions.

Giemsa C-banding method was applied on chromosomes in the female gametophyte tissue of Norway spruce (Picea abies (L.) Karesten). A karyogram of one single tree growing in the Botanical Garden of the University of Graz, Austria, was made by using an image analysis system. All chromosomes (n=12) showed pericentic C-bands. Chromosomes II, V and IX possed intercalary C-bands located at secondary constrictions. Telomeric C-bands appeared in chromosomes II and III on both arms.

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.

It was our aim to investigate whether the cytokinin status of Norway spruce seedlings (Picea abies L. Karst.) was changed when the plants were grown under nutritive stress. Cytokinins in shoots and roots from spruce seedlings, grown in various hydrocultural media with complete (control) or poor nutrient supply (stress), were determined by an indirect competitive enzyme-liked immunosorbent assay. The shoots of spruce seedlings grown in a poor acidic culture medium, to which aluminium ions (AlCl3, 0.8 mM) were added, showed up to 5-fold higher concentrations of zeatin riboside and isopentenyladenosine (iPa). When adding naphtylacetic acid to the nutrient medium also higher levels of cytokinin ribosides were measured in the shoots. In the roots however cytokinin riboside levels did not increase significantly under Al- or auxin treatment. Feeding experiments using tritiated iPA have shown that the metabolism of this cytokinin is strongly retarded in the roots of stressed seedlings. The experiments show that acid conditions and nutrient shortage together with aluminium ions in the rhizosphere increase the number of lateral roots in Norway spruce seedlings. It is assumed that the increased number of sites of cytokinin biosynthesis and the reduced metabolism of iPA result in the higher content of cytokinin ribosides in the shoots of seedlings.

The use of ectomycorrhizal fungi as possible indicators of ecosystem response to disturbance is discussed with emphasis on the analysis of individual species by direct observation of their mycorrhizas. Some examples of such studies are given. The possible role of fungal diversity and differential tolerance by individual species to pollutants are also discussed in relation to observed changes within ectomycorrhizal fungal communities.