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In 2001-2005, the effects of game on the condition and development of natural regeneration of a floodplain forest were studied in three permanent transects in the Vrapač National Nature Reserve (NNR). Fraxinus excelsior, Acer pseudoplatanus, Acer campestre and Acer platanoides predominated in the regeneration. The species were markedly damaged by roe deer (Capreolus capreolus) and fallow deer (Dama dama) browsing, the most affected being Acer pseudoplatanus. In spite of always newly occurring trees from self-seeding, the abundance of trees decreased during the studied period, self-seeding did not grow up from a height of 30-40 cm, the proportion of Acer pseudoplatanus decreased and that of Fraxinus excelsior increased. In addition to browsing, in 2003 and 2005 browsing damage to bark was noted in some places and in 2005 also the breaking of trees with subsequent browsing of terminal shoots, the causal agent of both types of damage being fallow deer. The development of natural regeneration is limited in principle by trophic preferences of game and by the tolerance of particular species to repeated damage. On the basis of these conditions it is necessary to consider the present game stock to be contradictory with objectives of area protection and preservation.

European larch (Larix decidua Mill.) is one of the most important tree species in substitute stands of the Krušné hory Mts. (northern part of the Czech Republic). At present, young larch stands have dynamic height growth and their canopy is closing. Therefore, the proper forest treatment with respect to all functions of these stands is an urgent issue. The aim of the study is to recognise when it is possible to start with thinning and what types of thinning regimes are more suitable in larch stands with respect to their functions as substitute tree species stands. Research was conducted on experimental series Kalek established in a larch monoculture in 1999 (stand age of 12 years) at an elevation of 780 m above sea level in the category Piceeto-Fagetum oligo-mesotrophicum - Calamagrostis villosa. The presented analysis has two main parts: (a) effect of closing canopy on growth of larch - comparison of the groups of trees from border and inside rows and (b) effect of opening canopy on growth and development of young larch stands - comparison of two partial plots (500 m² each): the one without thinning and the other with thinning (negative selection mainly from above at the age of 13 years). Comparative analyses of trees from border and inside rows showed high growth dynamics of these young larch stands, and therefore the first thinning is necessary in this stage (by 15 years of age). In spite of air pollution, the growth of experimental stands is supernormal and exceeds the data from growth tables, but 60% of individuals showed some malformations, mostly one-sided or two-sided stem curvature. Five years after the first thinning we found a significantly lower h/d ratio of mean stem on the thinned plot in comparison with the plot without thinning. On the other hand, the applied thinning had no effect (five years after realisation) on the h/d ratio of dominant trees (200 thickest trees per hectare).

In Slovakia, soil acidification remains an environmental and forestry related issue despite a sharp decrease in the S02. Recent monitoring of critical acid loads of Slovak forests show that around one third of Slovak forests are directly affected by acidification. In this situation, an increased biomass extraction from forests for energy generation purposes, considered by some decision-makers, poses a serious threat to geobiochemical cycles and may further aggravate the effect of the emissions on soils. In other parts of the country however, the drop in pH value means a soil degradation in sense of soil forming processes rather than in reference to forest production. This fact is also confirmed with the values of growing stock in Slovak forests, continually increasing since 1920.

An experimental stand was established as a monoculture by planting Norway spruce on a clear-felled area in 1925. In 1958, a research thinning experiment was established there. Control plots and the study of their development without anthropic interventions are of interest in particular. The spruce monoculture nearly disintegrated and the stand-forming role was taken over by species which occurred there originally as admixed ones. The stand became sparser and it was associated with the spontaneous regeneration of broadleaves. Out of the eight control plots three plots were selected differing significantly in stocking and extent of natural regeneration. The development of regeneration was studied in detail on these plots. The undergrowth consisted of 24 woody species in a total number of 6,000 individuals per hectare and about two thirds of them belonged to trees. The results of the study show a possibility to convert a spruce monoculture to a broadleaved commercial forest using the spontaneous regeneration of trees.

Frost cracks which originated in birch due to bending during long-term icing in winter 1995/1996 became the place of entrance for the attack of birch stems by Piptoporus betulinus (Bull. ex Fr.) Karst. and subsequently for one of the causes of birch stand disintegration in the Krušné hory Mts. The hypothesis is substantiated on the basis of regularities of the frost crack dispersion in the stem profile, frequency of occurrence related to the stand age, altitude and cardinal points. The number of frost cracks increased with the transect profile altitude 700-850 m. One crack on the birch stem predominated (73%) while the higher number of frost cracks occurred at altitudes > 800 m. In stands younger than 20 years, frost crack damage was higher (34-47%) than in older stands (14%). Frost cracks occurred in the lower part of stems with the highest bending stress.

The article presents original results of research on the humus form dynamics in a semi-natural European beech stand in the National Natural Reserve Voděradské bučiny, in the area of Training Forest Enterprise at Kostelec nad Černými lesy (Czech University of Agriculture inPrague). The accumulation and soil chemical characteristics of particular humus forms were studied: dry matter amount, pH, soil adsorption and exchangeable acidity characteristics as well as plant available and total nutrient contents. The humus form samples were taken in four replications from the particular humus form layers (L, F, H, Ah), and the analyses were performed individually. Samplings were done in the parts of the stand with closed canopy, and they were compared with the state in gaps formed during natural and semi-natural forest regeneration (the stage of stand breaking up left to spontaneous development). The results confirmed marked changes in the quantity and quality of surface humus in the gaps. The amount of dry matter decreased by ca. 25% several years after canopy opening, especially in the H horizon, the pH, base content and base saturation increased, as well as the content of macronutrients (with the exception of total calcium). The results proved considerable changes in the humus forms during the natural and semi-natural forest cycles connected with the stand regeneration.

Forest soil acidification and depletion of nutrient cations have been reported for several forested regions in North America, predominantly in the eastern United States, including the northeast and in the central Appalachians, but also in parts of southeastern Canada and the southern U.S. Continuing regional inputs of nitrogen and sulfur are of concern because of leaching of base cations, increased availability of soil Al, and the accumulation and ultimate transmission of acidity from forest soils to streams. Losses of calcium from forest soils and forested watersheds have now been documented as a sensitive early indicator and a functionally significant response to acid deposition for a wide range of forest soils in North America. For red spruce, a clear link has been established between acidic deposition, alterations in calcium and aluminum supplies and increased sensitivity to winter injury. Cation depletion appears to contribute to sugar maple decline on some soils, specifically the high mortality rates observed in northern Pennsylvania over the last decade. While responses to liming have not been systematically examined in North America, in a study in Pennsylvania, restoring basic cations through liming increased basal area growth of sugar maple and levels of calcium and magnesium in soil and foliage. In the San Bernardino Mountains in southern California near the west coast, the pH of the A horizon has declined by at least 2 pH units (to pH 4.0-4.3) over the past 30 years, with no detrimental effects on bole growth; presumably, because of the Mediterranean climate, base cation pools are still high and not limiting for plant growth.

This paper deals with natural abundance of ¹⁵N and ¹³C in the soil and needles of the pine forest (Pinus roxburghii, Sargent) along an altitudinal gradient. The study area lies in the elevation range of 1,200 m to 2,200 m in Kathmanduvalley of Nepal. The higher altitude soil was found to be much more depleted of ¹³C than the lower altitude soil. The decreasing trend of C-isotope (as well as the trend of N-isotope) might be attributed to the lower mineralisation rate and net nitrification rate at the higher altitude. The observed differences in isotopic N- and C-contents of needles and soils across altitudinal gradients in this study are a result of the combination of environmentally induced variations in physiological and morphological differences. For example, altitudinal variation in needle δ¹⁵N and δ¹³C at the research site indicates that the needle isotopic composition is related to nitrogen availability at a site.

In 1986 (1987) research plots were established in a forest stands on the south-western slope of Šerlich Mt., Orlické hory Mts. (Kristina Colloredo-Mansfeld - Forest Administration Opočno), at the altitude of 950 to 970 m, to study deposition, chemistry of precipitation and soil water and development of soil chemistry. The plots were established on a clear-cut area, in a young stand and a mature stand of spruce, in a mature beech stand, and in an advanced growth of spruce and European mountain ash. The content of solutes in creek water was studied at the same time. Since 1993 the concentration of substances in precipitation water intercepted in the summit part of Šerlich Mt. has been measured. Research on water chemistry in the stands terminated in 1997. Soil analyses were done in 1986 (1987), 1993 and 1999. The load of acid air pollutants in these forest ecosystems was high in the eighties. After 1991 the deposition of H⁺, S/SO₄^2-, N/NO₃^- + NH₄⁺, Mn, Zn, Al decreased. Similarly, an increase in pH was observed in soil water, and the concentrations of SO₄^2-, and N, Al compounds decreased. But in 1993 the concentrations of SO₄^2- and Al increased again under the spruce stand for several months. The concentrations of NO₃^-, Mn, Zn and Al in the stream water also gradually decreased in the nineties. On the contrary, the average values of S-ions increased compared to those of 1987 to 1991. Strongly acid soil reaction developed in deeper layers until 1993. In the second half of the nineties the pH/H₂O value somewhat increased again, however the reserve of K, Mg, Ca available cations in the mineral soil constantly decreased. The saturation of sorption complex by basic cations in the lower layer of rhizosphere did not reach even 10% in 1999. The forest ecosystems of Šerlich Mt. were also loaded by a high fall-out of Pb, and increased fall-out of Cu. The lack of balance of N-compound transformations and consumption in the soil and increased leaching of N in the form of nitrates contribute to soil acidification on the investigated plots.

The paper presents results of an institutional research aimed at assessing the effect of different technological conditions in pressing on physical and mechanical properties of plywood sheets. Spruce plywood sheets of the veneer nominal thickness of 3.0 and 3.5 mm were analyzed. The plywood sheets were produced as five-ply and BAKELITE PF B118 phenol-formaldehyde adhesives were used for there manufacture. In relation to a different pressing temperature 115, 120 and 125°C and a different specific pressure, density, bending strength, MOE in bending and glue-bond strength by a shear test were assessed. The determined values of properties were statistically tested.

Fertilization represents a measure, used as exceptional treatment managing forest stands and ecosystems as a whole. It is used since the beginning of the 20^th century worldwide, starting in the Central Europe. The beginnings were on empirical basis, later on, the scientific background was developed profoundly. Several forms and methods, as well as aims are topical at present: - Since the beginning, restoration of degraded sites and amelioration of primarily extreme soils was the aim. In the poorest regions, e.g. in the NE Germany, different means were used to increase site productivity and stability. Also in the Czech countries, amelioration played important role restoring degraded and devastated localities. - To increase site productivity, commercial fertilization was used worldwide, as well as it was applied in all continents with intense forestry practices. It became a part of the "silviculture" sensu stricto in the commercial, industrial forestry. - Supporting the growth and prosperity of forest plantations, on sites of different characters, was a broadly intended target of fertilizers application. - Since the air pollution calamity, fertilization is one of the main counter-treatments for improvement of the situation, lowering and preventing the soil acidification and nutritional degradation. Both direct as well as indirect methods are used. At the direct fertilization, nutrients in the fertilizers increase and improve the nutrient cycles over the degraded or natural level. This causes an increase in the forest ecosystem production as the main aim of such a treatment. In the indirect way, the amelioration material accelerates the bio-cycles by improving biological activities of the soil - liming is the best example of these activities. Nutrients are mobilized by enhanced activity of the soil biota, increasing organic matter mineralization and decay. This also represents the main ecological risk of these activities: the enormous and non-natural organic matter decay. Different types of fertilizer can be used: liquid, firm, powdered, pelletized, based on natural substances such as carbonates or silicate nutrient-rich (basic) rocks. In all cases, the uses of all these treatments have to be based on the detailed ecological analysis of the locality, of the site and of the forest stand. Only in this case, fertilizer effects can be optimized and the risks minimized.

Toxic pollution of soils is a major environmental problem in the Czech Republic. Most contemporary remediation approaches do not provide acceptable solutions. For environmental clean-up, the use of specially selected and engineered plants capable of effective restoration and stabilization of contaminated sites is an emerging technology called phytoremediation. Aspen (Populus spp.) trees represent optimal plants for absorption, accumulation, storage, and degradation of environmental pollutants such as heavy metals, pesticide residues, and other waste products. The first aim of this study was to verify possibilities of micropropagating selected elite European aspen (Populus tremula) and hybrid aspen (Populus tremula × Populus tremuloides) mature trees growing in polluted areas. The primary cultures were established from 24 years old trees from provenance plots. Dormant buds were sampled from selected trees in spring. After sterilization of dormant buds, the shoot tips were extirpated and put on nutrient media. MS medium with a higher concentration of BAP (1.0 mg/l) and IBA (0.1 mg/l) showed to be suitable for induction of organogenesis. MS medium with lower concentration of BAP (0.2 mg/l) and higher concentration of glutamine (100 mg/l) in agar medium was used for multiplication. A high number of adventitious shoots (20-30) was produced per multi-apex culture. The losses during rooting and acclimatization were minimal, around 2%. Currently, the plantlets grow on the outside bed of the experimental nursery. Twenty-five clones were established in the gene bank. Secondly, standardization of the efficient transformation of hybrid aspen was investigated with the aim to facilitate production of transformed hybrid aspen with valuable genes for increased capability of phytoremediation in the near future. Four gene constructs of Agrobacterium tumefaciens comprising different promoters (bearing two genes, NPTII coding resistance to kanamycin, and GUS coding glucuronidase synthesis allowing histochemical and fluorometrical identification) were used for transformations of aspen hybrid stem segments. A promoter suitable for transformations was selected on the basis of GUS activity assay. The highest activity was estimated in transformants with construct 148 controlled by promoter CAMV 35S.

Forestreclamation of spoil banks in mining areas in the North-West of the country started in the second half of the last century. Nowadays forest stands growing on anthropogenic substrates which are still unlike to forest soils, are getting in the phase of possible natural and/or artificial regeneration. The basic characteristics of substrate in the area and ecological attitude of used tree species are driving variables for successful regenerations. The study summarizes the vitality and growth of selected species on anthropogenic substrates in the area with the recommendations of key tree species used for forest reclamation. The results show the best adaptation to anthropogenic substrates for black alder and maple.

At the end of nineties, within the mountain forests of the Krušné hory Mts., in connection with an increased acid deposition, the symptoms (yellowing) started to be visible, characterizing magnesium deficiency in the assimilation organs, when Mg contents were laying under 300 mg/kg. In mineral soil the Mg content is mostly less than 10 mg/kg. Contents of other basic elements (Ca, K) were also very low. During four years yellowing symptoms of the spruce stands have developed in an extent area of more that 10,000 ha. Since 1999, preventive measures have been adopted to improve the nutrition status of the forest stands. Liquid magnesium fertilizers as MgNsol, Lamag Mg, MgSsol were applied during the period of 1999-2002. Since 2001, in semi-operational experiment, powder Mg fertilizer - Silvamix F4 - of higher Mg content (63.3% MgO) was applied. Application of liquid fertilizer MgNsol has helped to compensate the nitrogen deficiency in the stands of insufficient nutrition in this element. Comparing of different types of liquid fertilizers has confirmed, that the highest increase of magnesium in assimilation organs was find in combined application of MgNsol and MgSsol fertilizers. Application of 300 kg/ha Silvamix F4 has increased the magnesium content in the first needle year class in 73% in average, potassium in 33%, calcium in 16%, and phosphorus in 85%. Besides increased nutrient content in needles also improvement of the health and phosphorus in 85%. Besides increased nutrient content in needles also improvement of the health state, i.e. revitalization of the stands affected can be observed.

The paper describes the regime and dynamics of the soil moisture content of sandy soils in Záhorská lowland during different growing seasons. Research plots are situated near Kamenný mlyn, approximately 3 km from Plavecký Štvrtok and 8 km southward from the town of Malacky. Changes in the soil moisture content are described by soil moisture constants (MCC, PDA, WP) and its relation to atmospheric precipitation and to the character of undergrowth is shown. The low water-holding capacity of sandy soils and their high drainage together with dense root system do not allow the sufficient saturation of soil during the growing season. The low wilting point value (2%) leads to the consumption of all available water in the soil. The most frequent is the semiarid interval of soil moisture (PDA -WP) with reduced availability of water to plants (> pF 3.1). The arid interval (< WP) occurrence on hot summer days results in a decrease in transpiration and assimilation intensity of plants, their physiological weakening and premature fall of assimilation organs.

The effects of soil conditioners Frisol, TerraCottem, Bi-algeen, and fertilisers Silvamix Forte and Cererit on the welfare of Austrian pine were observed in a seven-year experiment on Loket spoil bank. Simultaneously the economic aspects of growing the Austrian pine until the stage of established plantation were examined. The application of products one year and a half after planting did not cause seedling mortality. The elongation growth of young plants conditioned by the application of Silvamix Forte and Frisol was statistically significant whereas these effects manifested themselves in the second year: they persisted till the end of the experiment for Silvamix Forte, and for three years in total for Frisol. The other products - TerraCottem, Bi-algeen and Cererit - also showed generally better, though statistically insignificant results as compared to those of the control plants. The elongation growth for all products culminated in the fifth year and then declined. The stem diameter growth for the best products reached its maximum in the second year. Regarding the overall height growth after seven years, the average number of the highest plants on the experiment location was on plots treated with Silvamix Forte; these plants exceeded the control plants by 46.2 cm. Pines treated with Frisol were higher by 23.4 cm. However, the application of soil conditioners and fertilisers to the given location proved economically ineffective because there was no need to improve the soil at the location, the same applies to mowing and hoeing since almost no forest weed grew there and the substrate surface remained well-aerated and porous.

The investigations were conducted in the frame of EU Research project Wood for Energy - a Contribution to the Development of Sustainable Forest Management (2001-2005). The integrated wood ash experiment was set up in a 38-year-old Scots pine (Pinus sylvestris L.) stand on Arenosols in SW part of Lithuania. Raw (not hardened) wood ash and nitrogen fertilizers were applied in 6 variants: 1.25 t ash/ha; 2.5 t ash/ha; 5.0 t ash/ha; 180 kg N/ha; 2.5 t ash + 180 kg N/ha and control (no treatment). The changes of soil pH, the content of some nutrients, heavy metals in Arenosols and soil solution, the abundance of ammonifiers, nitrifiers and denitrifiers in forest floor and mineral topsoil after the application of wood ash are presented and discussed in this paper.

The study deals with the influence of the structure, texture and dynamics of a spruce-beech primeval forest on the bird community in Skalná Alpa National Nature Reserve in the Veľká Fatra Mts. (West Carpathians, Slovakia) in the years 1982-2002. The abundance of Norway spruce (Picea excelsa Lam.) was highest both in the optimum and decomposition stage. In the growth stage the number of Norway spruce (Picea excelsa Lam.) trees was quite low. The texture of spruce-beech virgin forest was very variable. Percentage ratios of individual stages on the area of 42.16 ha were as follows: growth stage 38.3%, optimum stage 20.1% and decomposition stage 41.6%. Altogether 46 bird species were represented in the bird community during the spring season. Mean total density was 85.8 ind/10 ha. The bird community consisted of 52 species in the summer season, 45 in the autumn migration season, 34 in the winter season, and of 47 in the spring migration season. The highest density was found in the bird community during the autumn migration season (109.8 ind/10 ha), the lowest in the winter season (24.6 ind/10 ha). During the spring migration season, both the spectrum of bird species and total density of bird community increased by the number of migratory species that came back from winter habitats.

The second part of the paper summarizes results of an institutional research aimed at the determination of physical and mechanical properties of different sets of plywood sheets pressed under different conditions. The first part dealt with the determination of compressibility or values of decreasing the thickness of pressed plywood sheets. In this second part, results are summarized of the analysis of physical and mechanical properties of the set of whole-beech plywood sheets of the nominal thickness of veneers amounting to 1.5 mm. The plywood sheets were manufactured as seven-ply and urea-formaldehyde resin DUKOL S was used for their production. The sheets were pressed using a pressure of 1.5 and 1.7 MPa. Following parameters were analyzed: moisture, density, bending strength, MOE in bending and shear strength.

Damage to forest stands and their decline in the Czech Republic evoked a necessity to elucidate the function of soil in these processes. Main factors affecting acidification of forest soils are assessed in the paper. On the one hand, it refers to natural factors such as properties of soil-forming substrates and species composition of forest stands, on the other hand, to the effects of anthropogenic character such as influences of man-made spruce monocultures and effects of acid depositions. Special attention is paid to the development of forest soils in the Krušné hory Mts., where the effects of acid depositions are highest.

In the paper we evaluate the influence of crown thinning with positive selection, different intensity (moderate PRP III and heavy PRP IV) and 5-year frequency on development of growth, production, quality and leaf area index of black walnut (Juglans nigra L.) monocultures growing on the series of three permanent research plots (PRP) Sikenica (Levice Forest Enterprise, Levice Forest District) as observed in 1978-2003. The trends of development of mean stem, basal area, standing volume and aboveground dendromass (in dry matter) were mainly influenced by heavy crown thinning. The index of growth was as follows: basal area 169.01%, standing volume 262.12%, aboveground dendromass (in dry matter) 324.48%. At the age of 64 years the black walnut monocultures tended by heavy crown thinning had the following parameters: basal area 31.03 m²/ha, standing volume 463.88 m³/ha and aboveground dendromass 194.98 t/ha. Mean periodic increment reached the values: basal area 0.51 m²/ha/year, standing volume 11.48 m³/ha/year and dendromass 5.39 t/ha/year. The index of increment percent growth was: basal area + 31.75%, growing stock + 30.85% and dendromass + 0.79%, compared to the control. The total production was also significantly influenced by heavy thinning. At the stand age of 64 years the tended stands had the total basal area of 4.92 m²/ha, total volume production of 572.77 m³/ha and total weight production of 246.04 t/ha. The total mean increment of basal area is 0.67 m²/ha/year, of volume 8.95 m³/ha/year and of weight 3.84 t/ha/year, which is by 24.07%, 23.96% and 16.01% more than on the control plot. The leaf area index at the age of 64 years ranges from 6.54 ha/ha (PRP III) to 7.82 ha/ha (PRP V). Dendrochronological analyses revealed minimum widths of annual rings in the years 1952, 1961, 1968, 1971, 1975, 1981, 1983, 1985, 1993, 2000, maximum ones in 1951, 1957, 1959, 1967, 1974, 1979, 1982, 1984, 1989, 1999.

Dothistroma needle blight Mycosphaerella pini E. Rostrup and its anamorphic stage Dothistroma septospora (Dorog.) Morelet was detected for the first time in the territory of the Czech Republic in a consignment of imported plants of Austrian pine Pinus nigra Arnold in 1999. In 2000, it was also found on Pinus nigra in an open planting in a plantation of Christmas trees by the village of Jedovnice near Brno in South Moravia. In the Czech Republic, Dothi-stroma needle blight was identified on 13 species of pine. Pinus nigra Arnold and Pinus mugo Turra are the most frequent hosts. In addition to these species, Dothistroma needle blight was observed on Pinus ponderosa Douglas ex Lawson, Pinus jeffreyi Grev. et Balf, Pinus banksiana Lamb., Pinus contorta Douglas, Pinus rotundata Link, Pinus leucodermis Ant. and Pinus sylvestris L. Finds on Pinus aristata Engelm., Pinus rigida Mill., Pinus heldreichii H. Christ. and Pinus cembra L. var. sibirica (Du Tour) G. Don. are a certain rarity. These species are not mentioned anywhere as potential hosts of Dothistroma needle blight. As for the species of other genera Picea pungens Engelm., Picea abies L. Karst. and last but not least Picea schrenkiana Fisch. & C. A. Mey were also observed as hosts. The host range of Dothistroma needle blight recorded in papers is noted as well.

Holorganic layers belong among the key ecosystem components of forest soils at higher altitudes. Increased biological activity of the surface humus is very often observed after forest decline and/or forest cut and removal at these sites. The forest removal or tree layer extinction was studied in the flat, water affected terrain: its effects on the soil chemical characteristics and on the soil respiration, ammonification and nitrification activities. The standard methods of analyses were used. The study proved the increased intensity of nitrification and ammonification in stands with decreased ecological as well as environmental function potentials, further decreased concentrations of magnesium. Due to the concentration effects, the concentrations of some macroelements - nitrogen, calcium - increased in these stands (in the humus form layers), as well as the base content and base saturation.

The red turpentine beetle, Dendroctonus valens LeConte (Coleoptera: Scolytidae), was found for the first time in China in Yangcheng and Xinshui counties, Shanxi province in 1998, and in Hebei province in 1999. The beetle mostly attacks the oil pine Pinus tabulaeformis Carriére. By 2003 the beetle was found in 85 counties of three provinces in north China and the area of infested pine forests covered more than 700,000 ha. The elevation above sea level of forests infested is more than 800 m. The beetles most frequently attack trees on hilltops and at the forest edge, fewer attacks occur in the centre of the stand. This correlates with the damage done to the trees by wind or man. Weak and dying trees are more vulnerable to attack than healthy ones. The most attractive breeding sites are fresh stumps. The population density of the beetles is higher in the forests on northern slopes than on southern slopes. Most of the bores in the trunk are less than 0.5 m above ground; the galleries are found also on roots.

The paper summarises main ideas concerning the structure of natural forest ecosystems at middle altitudes and documents the changes of humus forms and their chemistry in the natural forest of Žákova hora National Nature Reserve, in typical selected parts with different tree species composition: European beech - Norway spruce. The species composition, age and spatial structure are discussed and analysis of the uppermost soil layer is done in particular parts of the natural forest regeneration cycle, of different stages respectively. We compared the amount and layer composition of surface humus and basic pedochemical characteristics of holorganic and upper mineral horizons. The results document changes in the character of humus forms as a consequence of the tree species change. On the contrary, a high portion of uncertainty as for the species, age and spatial structure follows from discussion about the structure of natural forests at middle altitudes.

The paper documents the effects of forest stands of different species composition on the humus form state and soil profile chemistry. It compares the situation in mixed broadleaved (ash, oak, hornbeam), basswood and spruce stands. Spruce demonstrates the site degradation effects: raw humus accumulation, soil acidification, negative effects on nutrient dynamics. Both broadleaved stands were similar as for site effects, lower litter accumulation, more rapid organic matter mineralization and more rapid nutrient cycling and intense uptake were documented in the basswood stand.

The effects of soil conditioners TerraCottem, Frisol, Bio-algeen and fertilisers Silvamix Forte and Cererit on the survival rate and growth of European ash seedlings until the stage called established plantation were observed on two experimental plots with different anthropogenic substrates. Eight-year experiments showed that under the given conditions the tested agents fulfilled the declared effects only partially. The application of TerraCottem was statistically insignificant both in the survival rate and in the growth. In the applied dose, Frisol manifested itself as an agent that may cause problems with the survival of plants, but at the same time also as a preparation improving the overall growth of young plants statistically significantly. Its effective dosage largely depends on the soil character. Bio-algeen had a very good effect on the survival rate of plants, but it did not surpass the control plants in the initial growth of plants. Silvamix Forte did not cause the mortality of seedlings and influenced the growth of plants statistically significantly for 1-3 years. In the applied dose, Cererit caused a high mortality of seedlings. The application of soil conditioners and Silvamix Forte did not markedly accelerate the growth and development until the stage of the established plantation. Until that time, the costs of the application of conditioners were higher by 4-13% as compared with the costs in the control plants.

A decline of macromycetes, especially of ectomycorrhizal species, has been described in the last decade in various parts of Europe. These changes are attributed to direct or indirect effects of air pollution. In Central Europe these changes correlate with visual damage of forest. Many ectomycorrhizal fungi seem to be very suitable bioindicators of the disturbance of forest ectotrophic stability. Stages of this disturbance can be linked directly to particular phases of impoverishment of ectomycorrhizal mycocoenoses. These conclusions have been obtained from long-term research on permanent plots (1,000-2,500 m²) in spruce and oak forests in the Czech Republic, but it seems that they are valid generally. For the quantification and study of mycorrhizal activity a special method has been developed and applied. The analyses of mycorrhizas from the same plots in the period 2000-2002 indicate large mycorrhizal dynamics. These data correlate with data obtained from a fruiting bodies survey. Both the percentage of ectomycorrhizal species and the ratio of active mycorrhizas are highly sensitive to outer impacts (air pollution, acidification, fertilization). Their decrease is in correlation with the strong defoliation of trees and can be used for the prediction of further development in comparable stands.

Observations of the beech assimilatory apparatus in different levels of a model tree were realised from 1993 to 1999 in a research demonstration plot situated in Poľana. Different observations of the natural ecosystem condition were carried out. A model beech tree was chosen and marked as No. 228 for the above-mentioned analyses. The different ecophysiological and morphological characteristics of beech leaves were analysed in three (or two) tree crown levels. The results confirmed significant differences in these characteristics in dependence on three crown levels of mature beech tree. The differences in the mentioned characteristics were also shown in the course of particular years of research. In this paper we have presented the results of analysed beech leaves, their average maximum length, width, their average area, thickness, chlorophyll fluorescence during the research period.