Seven ectomycorrhizae on oak (Quercus robur L.) from a Slovenian forest stand are described, five of them for the first time in detail. Four of these species could be identified (Lactarius chrysorrheus (Fr.) Fr., L. serifluus DC. ex Fr., Xerocomus subtomentosus (L. ex Fr.) Quel., X. armeniacus (Quel.) Quel., one unidentified species was given a preliminary name ("Quercirhiza squamosa"). Two identified species, already comprehensively characterized on other tree species, are presented shortly (Laccaria amethystina (Bolt ex Hooper) Murr., Cenococcum geophilum Fr.). Whereas some of the encountered species show considerable host specifity with oak (Lactarius chrysorrheus, L. serifluus and, in a lesser degree Xerocomus armeniacus), other species have a broader host range and can even grow with conifers (Xerocomus subtomentosus, Laccaria amethystina, Cenococcum geophilum). A key for all species was established. A possible use of ectomycorrhizal species as bioindicators is discussed.

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.

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.

The haploid chromosome set of Norway spruce consists of 12 chromosomes. Most of the chromosomes are very similar in their morphology (length, arm ratio, secondary constriction). For the CGBI it is necessery to recognize all chromosomes. Therefore we used different banding methods to solve this problem. We used the root meristem and the dividing cells of the macrogametophyte as test objects. We discussed morphology of chromosomes of these two different dividing tissues. The use of image analysis equipment made it possible to get in a relatively short time a great number of data for statistical analysis. Another method was, to use an expert-system for data analysis. Finally 3-D models of interphase nuclei were reconstructed.

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.

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.

Forest soil was sampled on two different observation plots by following well described methodology. Sampling sites had been chosen in place with typical soil conditions for the observed forest site. To make sampling easier some natural forest site characteristics were considered. Mg, Zn and Cd were determined by atomic absorption spectroscopy in all samples. Results were statistically evaluated and different sources of variance were estimated. It was also estimated whether the number of samples was sufficient for our requirement for accuracy of analytical results.

It is often difficult to predict how synergistic effects work and how dieback may be expected to spread through an area over time. On the other hand concepts and methods for compensation of acid deposition, melioration and restauration of acidified forest areas represent a major management problem. The following examples show how GIS may be used to find answers to these questions.