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We conducted to describe methods used to differentiate the zones of juvenile and mature wood in stems of coniferous species and to present the importance of good identification of the shares of both types of wood to ensure a rational use of the raw material and final quality of wood products. This study describes in more detail a novel method to separate the juvenile and mature wood tissue in stems of European larch using cluster analysis in the form of the k-means algorithm. Moreover, guidelines were also shortly described for forest management which could result in a reduction of the share of juvenile wood in stems of forest trees.

As the tree age increases, the formation of heartwood takes place in the central part of the tree. Since there is a large difference in the moisture content between sapwood and heartwood in conifers, the proportion of heartwood expressed in percentage is one of the most important factors influencing the average moisture of trunk wood. The aim of the research was to find out the changes in parameters of heartwood proportion and the changes in average trunk wood moisture parameters, depending on the age of the tree. To evaluate and compare the heartwood proportion in pine and spruce trunk and its moisture, sample plots were established throughout the territory of Latvia in 2011. These sample plots were established in stands of different ages (37-143 years). The total number of sample plots was 61-29 for pines with 246 sample trees and 32 sample plots for spruces with 270 sample trees. With the increase in the tree age from 60 to 140 years, the heartwood proportion increases and the average moisture content of trunk wood decreases. With an increase of the heartwood proportion in pine from 18% to 39%, the average moisture of trunk wood decreases from 108% to 86%, but with an increase of the heartwood proportion in spruce from 30% to 49%, the average moisture content of trunk wood decreases from 107% to 81%.

The out-of-roundness and pith-off-centre of Alnus subcordata, Acer velutinum and Quercus castaneifolia growing in Hyrcanian forests of Iran were investigated. Stem disks were cut from the breast height and stump height of felled trees in diameter classes of 20 cm to 90 cm. Results indicated that the pith eccentricity for Acer velutinum was significantly greater than that of Alnus subcordata and Quercus castaneifolia (P < 0.01). The pith-off-centre significantly increased with increasing stem diameter from 20 cm to 50 cm, while no significant difference were observed for pith-off-centre index from diameter class of 55 cm to 90 cm. The out-of-roundness in stems of Acer velutinum and Alnus subcordata was significantly greater than that of Quercus castaneifolia (P < 0.01). Moreover, out-of-roundness significantly decreased with increasing stem diameters from 20 cm to 45 cm except for 35 cm. There were no significant differences among diameter classes from 60 cm to 85 cm with respect to out-of-roundness. For all the species, the out-of-roundness and pith-off-centre at stump height were greater than those at breast height.

The aim of this paper is to present the results of the investigation on belowground biomass and its annual increment in a beech ecosystem (Calamintho grandiflorae-Fagetum) in Mavrovo National Park, Republic of Macedonia. Belowground biomass was estimated in three layers of the ecosystem (tree, shrub and herb layers) for seven years during the period 1997-2005. Allometric regressions were established for the relationship of root biomass from volume index (D²H, diameter squared × height) on a sample of 10 model trees and 13 model shrubs of European beech (Fagus sylvatica L.). Fine root biomass of trees and shrubs was estimated in soil samples to a depth of 145 cm and divided into live and dead fine roots and subdivided into thickness classes. Belowground biomass of the herb layer was assessed in 20 herb species. It was estimated that the total belowground biomass in the ecosystem was 57.75 .ha^-1. The contribution of shrub and herb layers was insignificant (less than 0.2%). Biomass of the live fine roots was 10.16 t.ha^-1, i.e. 18% of the total belowground biomass. Annual increment of trees and shrubs was 1.03 t.ha^-1.y^-1 and 4.6 kg.ha^-1.y^-1, respectively.

This paper presents findings of a twenty-year investigation of silviculture-production in a 40-year-old afforested spruce pole-stage stand located in a mountain region. The stand was established by four different spacing models: (i) 1.5 × 1.0 m, (ii) 2.5 × 1.0 m, (iii) 2.5 × 1.5 m, and (iv) 2.5 × 2.5 m. Three alternatives were studied for each of these spacing models. These were: (i) geometrical (line) thinning, (ii) selective thinning and (iii) no tending. During the period of our research the above-mentioned stand was affected twice by a snow-break disaster. Promising and target trees in the stand were marked and selected at the beginning of the study. The development of the above-mentioned categories of trees was analysed in relation to the initial spacing of the stand, as well as to the method of tending. Based on the 20-year research period, we conclude that the most favourable results were obtained on plots that were established at a wider initial spacing and managed by selective thinning as opposed to the denser ones tended by geometrical thinning or without any tending.

Organic nitrogen is an important but yet not very well explored component of nitrogen deposition. In this study concentrations and fluxes of organic and inorganic nitrogen in bulk precipitation in an open field (BOF) and in throughfall (THR) were evaluated at the Bílý Kříž experimental site (Moravian-Silesian Beskydy Mts., Czech Republic, 908 m a.s.l.) with a young Norway spruce stand. The results of a two-year study (2008 and 2009) were compared with the results obtained during the same time period on forest plots included in ICP Forests Programme in the Czech Republic. Total nitrogen deposition in BOF at the Bílý Kříž site amounted to about 918 mg.m^-2.a^-1, the contribution of organic nitrogen was about 8%. Total nitrogen flux with THR at Bílý Kříž was about 1,305 mg.m^-2.a^-1 during the studied years and organic N accounted for 12% of this amount. The ranges of the two-year average values found for total nitrogen flux on ICP Forests plots throughout the Czech Republic were as follows: 759-1,857 mg N.m^-2.a^-1 with 7-38% contribution of organic N in BOF and 928-3,816 mg N.m^-2.a^-1 with 7-20% contribution of organic N in THR. The share of organic nitrogen in THR nitrogen fluxes at Bílý Kříž proved clear seasonality with maxima in July. A highly significant correlation between N-NH₄⁺ and N-NO₃^- concentrations in BOF suggested the common anthropogenic source of these substances at the Bílý Kříž site. No significant correlation was found either between organic N and N-NH₄⁺ or between organic N and N-NO₃^- concentrations in BOF. Cumulative deposition charts showed different behaviour of particular nitrogen deposition components while passing through the canopy.

The effect of slope on runoff volume was evaluated on skid trails in the natural forest in the north of Iran. The objective of this study was to determine the relationship between runoff volume and slope in order to control runoff and skid trail maintenance by using water diversions. Two levels of slope > 20% and < 20% were studied in adjacent parcels in district 3 of Nav in Asalem. Treatment plots with three replications were established on skid trails after skidding and the runoff volume was recorded after duration of 3 rainfalls. The results showed that there was a positive and significant correlation between slope steepness and runoff volume, and between runoff volume and slope length (P < 0.05). Also, regression analysis results showed that there was a linear relation between runoff volume, slope length and slope steepness. Effective recommendations to control and decrease runoff volume are precise scheduling of skid trail designing, construction, maintenance and limiting skid trails to a longitudinal slope of less than 20% and rehabilitation of skid trails by using water diversions.

This paper presents research results on the performance of the Timberjack 450C skidder in timber skidding at two working sites of broadleaved trees in mountainous conditions in the Hyrcanian forest. To evaluate the current skidding system in the Hyrcanian forest in northern Iran and possibility of finding out better techniques and group organization an empirical time study has been conducted. The elements of the skidding work phase were identified and 123 cycles were recorded for short-log and long-log method. The models for effective time consumption, total productivity and unit cost of skidding in short-log and long-log method were calculated. The time consumption and productivity of skidding depend on several variables such as distances and slope, number of logs per cycle and volume. The average load per cycle in short-log and long-log method was 2.77 m³ and 3.08 m³, the average one-way skidding distance was 380 and 497 m, the average slope was 18 and 20% in the short-log and long-log method, respectively. The average travel speeds of unloaded skidder were 5.74 km.h^-1 and the average speeds of loaded skidder were 7.67 and 6.16 km.h^-1 in short-log and long-log method, respectively. The average speeds of pulling the cable were 1.71 km.h^-1, and of load winching 0.72 km.h^-1 and 0.69 km.h^-1. The average outputs in short-log and long-log method were 10.86, 11.11 m³.effective h^-1. Results indicated that hourly costs of operation were higher for the short-log method than for the long-log method (12.69 vs.12.40 USD.m^-3).

Detailed characteristics (tree species composition, tree representation, identification features) are presented by 3^rd (i.e. geobiocenoses of Querci-fageta s. lat.) and 4^th (Fageta (abietis) s. lat.) vegetation tiers in north-eastern Moravia and Silesia. 3^rd VT occupies 45.6% of the study area - from 190 m a.s.l. up to 430 m a.s.l. Fagus sylvatica is a dominant tree (with the height of 35-40 m). Quercus robur and Quercus petraea have their ecological optimums there with the representation of up to 30%. Abies alba occurs in the crown level with the representation of up to 10%. 4^th occupies 35.2% of the study area - from 310 m a.s.l. up to 650 m a.s.l. Fagus sylvatica is dominant (the height over 50 m). Abies alba occurs in the co-dominant level (sporadically in the level exceeding the main level) with the representation of ±20% and the height of up to 50 m. Quercus petraea and Quercus robur occur only as an interspersed species with the representation of up to 10%, they do not reach the co-dominant tree level any more. Carpinus betulus is represented regularly only in the overtopped tree level.

Broadleaved-Korean pine (Pinus koraiensis) mixed forest is a dominant native vegetation type in the eastern Eurasian Continent. We intended to examine the implications of high-intensity timber harvesting (ca 70% of stand volume) for the sustainable management of a mixed forest ecosystem. We measured trees at three sites: control without cutting, older-cut site cut in 1987 and newer-cut site (cutting in 1997). There were significant differences in structure and composition between these three sites in 2003. There were 4,441 trees of 14 species with basal area 56 m² at control plot, 6,314 trees of 16 species with basal area 9 m² at newer-cut site and 8,438 trees of 21 species with basal area 31 m² at older-cut site (all on the area of 1 ha). The high-intensity timber harvesting system helped promote natural regeneration and the growth of small trees but it also allowed light-demanding tree species to invade into the forest. Dominant position and suitable diameter distribution of economically important species (Pinus koraiensis and Tilia amurensis) were maintained across the three sites. The existing timber harvesting appears to consider short-term economic values to a larger extent than long-term ecological values. To manage the broadleaved-Korean pine mixed forest for both timber production and biodiversity conservation, timber-harvesting intensity must be lowered.

Segmentation of stands by tracks is often the first phase of forest tending. However, a suitable track width is still discussed in forest practice in the Czech Republic. This article deals with the effect of track width on the growth characteristics of young spruce stands. Research involves several variants of European thinning experiment IUFRO CZ 14 Machov situated in Eastern Bohemia. Totally 3 variants were analyzed: 1 - non-segmented control plot without thinning and plots with forest tending (at top height 10 and 20 m) and with different present width of tracks (plot 3 - originally 3.5 m, plot 4 - originally 5.0 m). The significantly positive effect of stand segmentation and tracks on dbh and crown length was found only for individuals growing in the first row next to a track. As regards the stand volume and volume of mean stem, differences between variants with skidding track (3 and 4) were found minimal and insignificant. Therefore, the observation did not reveal any evident losses of production caused by different widths of skidding tracks.

The survey was conducted in three selected areas of the Czech Republic in 2008, with the results processed in 2009. Forests visitors received inquiry forms (face to face interviews, random sample). The total number of visitors on 8 survey days was 7,369. The total number of filled-in questionnaires in the three areas was 1,122. Tree planting and tree protection are considered as the most important forest operations, followed by road and stream bank maintenance. On the contrary, timber transport and harvesting are considered as the least important activities. The nature-protecting function is considered as the most important forest function, followed by soil-conservation, climatic, hydrological and health (recreational) functions. Timber production and non-timber production are the least important functions according to the respondents. 20% of respondents claimed that increased costs needed to improve non-market forest functions, used by the visitors, should be partially or fully financed from the timber sales revenues, while only 6.5% of respondents say the costs should be partially or fully financed from payments by the users of forest functions.

The aims of the paper were as follows: (1) to assess the applicability of speckled alder for pioneer stands on the mountainous clear-cut tracts and (2) to evaluate the effects of slow-release fertilizer on the survival and growth of speckled alder under harsh environmental conditions. On the basis of seven-year results we can presume that speckled alder is a convenient pioneer species that can be cultivated on harsh mountain sites where the climatic extremes need to be alleviated and a layer of surface humus renewed. The initial slow-release fertilization is, nonetheless, highly desirable. As contrasted to the control the surface and planting hole applications of amendment reduced the total seven-year mortality rate by 9.5% and 20.1%, respectively, and the periodic annual height increment (2003-2009) was promoted by 47% and 59%, respectively. Analogous results were obtained when the values of basal stem diameter and crown diameter were compared. As for the method of application, the placement of the slow-release amendment in the planting holes seems to be more efficient mainly in terms of survival promoting. The surface application is, nonetheless, less laborious and also yielded satisfactory results.

In this study, productivity rate and operation cost of farm tractor were evaluated in a mountainous natural forest. Data for the study came from a detailed time study in the Research and Educational Forest of Tarbiat Modares University (REFTMU) and was used to develop a multiple linear regression model to predict the skidding cycle time. The results showed that effective independent variables of skidding time were skidding distance and slope of skid trail (P = 0.01). Average productivity rate ranged from 2.43 to 2.60 m².h^-1. Total time and effective time, respectively. Total cost of the system was 10.24 USD.h^-1 whereas 4.58% of the cost of skidding resulted from personal delay. The cost and productivity resulting from this study emphasized the importance for foresters to consider a farm tractor when designing skidding operations in young stands or prescribing a combination of two machines in mature stands.

The effect of Scots pine admixture in European beech stand on the leaching of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), nitrate nitrogen (NO₃-N) and ammonium nitrogen (NH₄-N) from organic and humic horizons of Dystric Arenosols was studied in northern Poland in 2008-2009. Three zero-tension lysimeters under organic and humic horizons were installed in pure beech and mixed pine-beech stands. Water samples were collected after each rainfall, measured volumetrically, filtered and analysed. In each sample pH and concentrations of DOC, DON, NH₄-N and NO₃-N were analysed. Stronger acidification of leachates was observed in mixed stand compared to pure beech. About twice higher concentration of DOC and its fluxes per unit area were determined in mixed stand. The fluxes of DOC from unit mass of soil were less varied. In general, lower concentrations of DON, NH₄-N and NO₃-N as well as fluxes of the components (calculated in mg.kg^-1DM.year^-1 and mg.m^-2.year^-1) were observed in mixed stand.

Phytophthora alni is responsible for a devastating disease in alder and changes in the environment of riparian and alder carr ecosystems. One of the main approaches to solve this problem is to find naturally resistant genotypes using a series of artificial inoculation experiments, to preserve and use them in programmes for resistance breeding. However, the results of artificial inoculation experiments (screening for natural resistance) can be affected by several factors. The potential effect of the social status of the host, the presence of naturally occurring P. alni infections, the season and the size of the sections of branches used were studied in a series of infection experiments. It was found out that the development of lesions was significantly affected by the year season (the largest lesions were found in summer) and by the presence of naturally occurring P. alni infections in the sampled trees (the lesions were five times larger in healthy trees and trees recovered from natural P. alni infections compared to trees with active disease development).

The paper presents results of an assessment of needle age classes in Scots pine partial populations in the period of three and five years after outplanting in a lowland site in relation to conditions created by climatic elements. The method is based on Skuhravý's (1987) description when the state of needle age classes of the third whorl (from the apex) is evaluated just once. Five-year summary of meteorological data was assessed according to the criteria of determination of periods of heat waves and dry spells. Differences in numbers of living needle age classes in the groups of Scots pine populations in the period of three and five years after their outplanting in permanent lowland sites proved the highest total number of living needle classes in the group of local lowland populations. On the contrary, the lowest total number of living needle classes was found out in the group of mountain populations. Critical climatic periods are overlaps of heat waves and dry spells that illustrate the complexity of moisture and temperature conditions of lowland sites. Although the Scots pine is a xerophytic species, it responded to the cumulation of adverse factors by accelerated needle senescence. Its physiological response to heat and dry stress consists in needle shedding, i.e. reduction in the assimilating area. As mountain populations are not usually exposed to heat waves, the impact of this phenomenon on them was the highest. On the other hand, the local (lowland) populations carrying information on the patterns of local climate from the reproduction period do not undergo any marked reduction in needle age classes.

The aim of this study is to identify a period of time over which smaller, less costly tree transplants can reach the height of larger tree transplants and thus offset their performance. The following Central European native tree species were used: Quercus robur L., Carpinus betulus L., Fraxinus excelsior L., Acer campestre L., Acer pseudoplatanus L., Tilia cordata Mill. and Prunus avium L. In the period after planting, the best growth was observed for small tree transplants. These transplants reached the height of the medium-sized tree transplants for all species except C. betulus. However, the large transplants of A. campestre, F. excelsior and P. avium were still significantly taller than the medium-sized transplants ten years after planting. In contrast, slow growth was observed for the large tree transplants of C. betulus and Q. robur. During the monitoring period, the height of the medium-sized transplants of C. betulus even exceeded the height of the large transplants of this species. These differences suggest that the differences in the establishment rates of individual species are reflected in the growth rates of their plantations during longer periods after planting.

Information on the historical background of the present forest conditions is needed for proper decisions on forest management. Disturbances play a major role in the formation of forest structure and composition. This paper compares the present break-up of mountain spruce stands in the Bohemian Forest (in the Šumava Protected Landscape Area) with conditions during their initiation using dendrochronological techniques. On three selected localities we established two study plots within relatively old stands of unknown origin. Stands were recently broken up by a windstorm. The present situation was described by diameter and decay class distribution. To describe the situation at the stand initiation, we cored at least 40 stems on each plot to get the age structure and growth series of trees. Disturbances were marked by discovering synchronous releases on tree-ring series. Main population waves were initiated in association with severe disturbances during a relatively short period, leading to the establishment of relatively even-aged, homogeneously looking stands. The disturbances were synchronized between plots and accounted for by historically known windstorms or bark beetle outbreaks; notwithstanding, logging as a disturbance factor is also particularly possible.

The objective of research was, on the basis of the exactly predefined input parameters of upper soil horizons of selected forest soils, to perform accurate measurements of the impact of soil loading by tested forestry machinery using the dynamic penetration test. The measurements by the dynamic penetration test in conditions changed by the wheel traffic of forestry mechanization were performed at three localities of the Křtiny Training Forest Enterprise, Masaryk Forest, a special-purpose facility of Mendel University in Brno. The dynamic penetration test was performed with a lightweight dynamic penetrometer. The methodology of the research is based on assessing the ability of soils to resist dynamic penetration of a rod with a cone, in relation to their lithological composition and physicomechanical properties; the measurement itself is defined by the ISO 22476-2 (2005) standard. Penetrometer measurements were repeated in the period after a harvesting operation and again 6 months later, i.e. in October 2007, April 2008 and October 2008. The results of the field dynamic penetration test and the results of laboratory testing of main soil physical parameters are presented in figures and tables. Besides the naturally variable soil compaction on geologically different substrates, the obtained original results document differences in the impact of particular forestry machines. In conditions of the identical geological substrate, the results indicate that the universal wheeled tractor had a more negative influence on the compaction of surface soil horizons compared to the multi-axle harvester and the forwarder.

The paper presents the evaluation of data on precipitation totals and on SO₄^{2 -}concentrations and S-SO₄^{2 -} fluxes in lysimetric waters in a submontane beech stand. The records cover continually a 19-year period. The site is situated in the Kremnické vrchy Mountains, belonging to the West Carpathians Mountains. The material was sampled on two plots. The first had been clear cut immediately before the research started (1989), the second was covered with the original forest stand. In total, the highest SO₄^{2 -} concentrations on the open plot were measured four years after the intervention (1993) at the soil depth of 0.25 m (40.50 mg.l^-1). The lowest values were recorded in 1989 on the control plot at the soil depth of 0.25 m (4.54 mg.l^-1). The sulphate sulphur deposition was the highest in 1995 in the surface humus layer on the open plot (51.8 kg.ha^-1.year^-1). A very significant influence of precipitation totals on sulphur amounts deposited in the particular soil horizons was also confirmed. No interannual differences in SO₄^{2 -} concentration and S-SO₄^{2 -} fluxwere proved.

The pine stand in the Havraní Skála locality in the Bohemian Switzerland National Park was affected by an extensive mixed-severity wildfire in summer 2006. The fire severity, fire type and fire extent were assessed by various fire severity measures collected in the field (mean bole char height on stems on sample plots, content of oxidizable C and total N at a soil depth of 0-5 cm), as well as by classification and filtering of green canopy cover from time series of aerial photographs acquired before the fire (2005), soon after the fire (2006) and one year after the fire (2007). The specific image analyses made it possible to uncover the spatial and temporal pattern of the stand defoliation. The central part of the site was mainly affected by the crown fire and thus defoliated substantially right during the fire. On the contrary, the peripheral part of the site was mostly affected by low-severity ground fire and therefore defoliated progressively one year later. All the fire severity measures used were well related.

Soil properties can be affected by heavy equipment used for skidding but these impacts vary greatly with site conditions and operational practices. We assessed the effects of ground-based skidding on site disturbance and soil physical properties. We also tested the effects of skid trail slope and traffic frequency on soil compaction, total porosity, and moisture content. On average, about 30% of all harvested area was disturbed to varying levels. Intact forest floor (undisturbed) and light slash were the dominant surface conditions, covering an average of 68.9% of harvested area. Deep disturbed soils accounted for only just over 1.1% of observations. Results showed that dry bulk density, total porosity and moisture content were affected considerably on skid trails by traffic frequency and skid trail slope. Measurements of soil properties in the surface layer (0-10 cm) showed that bulk density is 57% higher and total porosity is 31% lower on the skid trail compared to the undisturbed area. Average moisture content has been measured as 35% on the skid trail versus 47% in the undisturbed area.

As a part of International Cooperative Programme on Assessment and Monitoring of Air Pollution Effect on Forests (ICP Forests), defoliation of forest stands has been assessed in the Czech Republic since 1986. Defoliation is one of the principal parameters reflecting the health of forest stands that is assessed on monitoring plots within this programme. Monitoring plots are distributed evenly according to woodiness of the area in a regular schematic network all over the Czech Republic. Even though there has been a long-term reduction of air pollution in most European countries, forest ecosystems reflect these changes with some delay. In the Czech Republic the trend of total defoliation of coniferous and deciduous forest stands has been increasing very moderately in the last 10 years. This trend appears to be partially analogous with some neighbouring countries. Compared to the whole of Europe the trend of defoliation of broadleaves is very similar, but differences have occurred in conifers in the last 10 years. There are significant differences in defoliation levels among the particular countries; in this comparison the Czech Republic is classified as one of the worst. Differences in these levels are very evident especially among the neighbouring countries. To partly eliminate these differences, regular international calibration courses are organized.

The paper deals with the analysis of price changes of roundwood (spruce, fir and beech sawlog, fuelwood) and energy wood in Slovakia, Czech Republic and Austria during the period of 2008-+September 2011. At the beginning of the article, the authors identify the major factors influencing timber price trends such as legislation regarding technical standards for the quality grading of round wood, global economic recession, incidental felling and political influence. Consequently, detailed analysis of timber price changes in selected European counties is provided by means of line graphs. The results of the analysis revealed that demand for wood and wood products began to decrease in mid-2008. The most critical situation was in 2009, primarily in the softwood market, when prices bottomed out. However, recent trends indicate a gradual rise in timber prices. In the future, a slight increase of timber prices is expected, however other factors (such as economic development, lobbyist pressure, incidental felling and many others) may influence prices, which makes it difficult to predict their trend.

The results of a fifteen-year period of investigations conducted on Norway spruce in the upper plateau of the Jizerské hory Mts. were summarised. The objectives were to evaluate the growth performance of an experimental plantation under harsh environmental conditions and assess the effects of amendments as well as the influence of the forest site variability on growth performance and survival of young spruces. The following treatments were distinguished: (1) lower control, (2) limestone and (3) amphibolite treatments on a less exposed slope of the ridge and (4) upper control on a summit of the mountain ridge. Principle characteristics such as mortality rate, height, annual height increment, stem base diameter, crown diameter and nutritional status were summarized and evaluated. Significant differences between treatments were recorded in heights. The trees fertilized with amphibolite were significantly taller than the control ones in thirteen out of the fifteen evaluated years and the applied limestone improved heights in ten years out of the fifteen evaluated years. A positive effect of amphibolite treatment on stem base diameter was proved in three of the four assessed years and was persisting till 2007 (last measurement of this characteristic), the positive effect of limestone was lasting up to 2006. The considerable role of the site variability was apparent from a comparison between the upper and lower control although they were in a very close position to each other, growth increment of the spruces on the ridge was significantly lower. Temporarily lower N concentration was recorded in the fertilized treatments in comparison with their respective control. The concentration of P was low and decreased to the limit of deficiency in all treatments, P seems to be the most limiting macroelement in the area.

The objective of this study was to identify optimal growing conditions for the production of high-quality mini-plug seedlings of black locust (Robinia pseudoacacia [L.].). Two seed origins (Greek and Hungarian), two growing media (enriched peat and stabilized medium) and four mini-plug densities (975; 1,460; 1,820 and 3,500 mini-plugs.m^-2) were tested in two phases, in growth chambers and in a nursery after transplanting the mini-plugs into larger containers. Measurements included seedling survival, growth traits (root length, shoot height, leaf area, root dry mass, shoot dry mass, root/shoot ratio) and root growth potential (RGP). In addition, the ratio of variable to maximal fluorescence (F_v/F_m) and the effective quantum yield of photosystem II (ΔF/F'_m) were measured. It was found that growing medium produced significant effects mainly in the first phase and seed origin in the second phase while mini-plug density was important in both phases. The F_v/F_m ratio was found to be significantly affected by growing medium while the effective quantum yield was influenced by density. Early survival of seedlings was closely correlated with fluorescence and growth traits (particularly with plant height) suggesting that these parameters might be useful for the grading of black locust seedlings prior to transplanting.

Conversion of coniferous monocultures to more stable mixed stands is one of the crucial tasks of present forestry in the Czech Republic. One of the factors hampering this process is the activity of small rodents that can cause severe damage to young plantations in winter. Little knowledge is still available of the ecology of small mammals in the forest environment and of the factors influencing their distribution and extent of damage. In order to acquire relevant information on rodent impacts on forest regeneration, we mapped the cumulated damage to forest plantations in 13 regions within the Czech Republic in 2007 and 2008. We checked 19,650 trees of eight species on 393 plots. Broadleaves were affected by browsing much more than conifers (20% and 4%, respectively). Of the monitored species, beech was damaged the most frequently (26% individuals). Browsing intensity differed among the regions (6-60% browsed individuals). The least damaged were the plantations at the altitudes below 400 m a.s.l.; on higher located plots the browsing intensity showed no trend. The proportion of damaged trees increased with plantation age up to 6 years, then it did not vary significantly. This study has confirmed that rodents are an important factor with a negative influence on the regeneration of broadleaves. Bark browsing in young trees is affected by several factors and the prediction of damage is complicated. Further research should improve the prediction of the bark browsing threat to young plantations and at the same time the efficiency of protection against rodent-caused damage.

The forests located in the northern areas of Iran are known as Hyrcanian Forests and are distributed across three provinces, namely Gilan, Maznadarn and Golestan. These provinces are situated in the north of Iran near the Caspian Sea. Timber products in the said forests during the last two decades were markedly different so that the total timber harvested in the first decade was 1.6 million m3 on average, however, in the second decade it nearly amounted to 1 million m³. Two major timber products of Iran are studied and compared in this research, namely logs and squared timber. Squared timber products averaged 10.7% during the first decade, but they fell to 7.3% over the second decade. Apropos of log products, they reached 20.9% and 29.2% over the first and the second decade, respectively. Analyses of the data indicate the following converse linear equation between squared timber products and log products during the 20 years of study: Y =-0.359X + 18.065 (Y = log products, X = squared timber, R² = 0.768).Accordingly, any increase in log products at a time caused the squared timber products to decrease at the same time.

The efficiency of two types of pheromone dispensers (ECOLURE classic and ECOLURE tubus) was compared in 2008. Pheromone-baited traps were checked 13 times in 10-day intervals (this guaranteed the efficiency of ECOLURE tubus all time). ECOLURE classic trapped more beetles on average in all samples. Differences among the first 4 samples (checkings) were statistically insignificant, differences among another 9 samples were significant (used statistic tests - two choice t-test, α = 0.05 from data with normal distribution, Wilcoxon matched pairs test in the case of other data distribution).