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Damage on forests by large wild herbivores, especially by red deer (Cervus elaphus L.) has been increasing in Central Europe including Slovakia. Therefore, we attempted to estimate the forage potential, i.e. potentially available bark for consumption by large wild herbivores and actually consumed bark of common rowan (Sorbus aucuparia L.) and goat willow (Salix caprea L.). For these purposes, we measured basic tree characteristics and dimensions (length and width) of wounds due to bark browsing at 15 plots located in a young mixed forest stand (Javorníky Mts; Slovakia). Browsing was recorded separately for four stem sections: 0–50, 51–100, 101–150, and 151–200 cm measured from the ground level. Three stem bark browsing metrics were implemented: browsed bark area (cm2), browsed bark mass (g) and portion of browsed bark mass to total stem bark mass representing potential forage for game expressed in percent. We proved that while common rowan and goat willow were browsed in a great extent, nearly no damage occurred on stems of Norway spruce (Picea abies [L.] Karst.) and silver birch (Betula pendula Roth.). Our estimates showed that the total forage potential of stem bark at common rowan and goat willow was about 13.4 kg per 100 m2 of a forest stand. We learnt from our estimates for instance that the total available stem bark at 100 m2 of our young mixed forest might suffice (if theoretically entire potential was exploited) for red deer, fallow deer (Dama dama L.) and mouflon (Ovis aries musimon L.) for one, two and nearly four weeks, respectively. At the same, that during four years, large wild herbivores browsed nearly 2.6 kg of bark per 100 m2 area, i.e. about 1/5 of the available potential on rowans and willows. It seems like common rowan and goat willow might generate important resources of forage for large wild herbivores and would be treated as a part of biological protection of target tree species against bark browsing.

Although forest ecosystems play an essential role in climate stabilization, current climatic shifts might cause striking changes in their biological productivity, which, in turn, affects the biosphere function of forests. Studies of the relationship between the biomass of trees and stands and hydrothermal indicators (temperature and precipitation) have usually been carried out at local or regional levels. It is still unknown how climate changes affect tree and stand biomass along transcontinental gradients. Therefore, the goals of this study were (a) to test if the law of the limiting factor holds for tree and stand biomass of Picea spp. at the transcontinental level of Eurasia in relation to temperature and precipitation, and (b) to apply the principle of space-for-time substitution to document the use of the derived tree and stand biomass climate-sensitive models for predicting temporal biomass changes. The results revealed that at a tree level spruce aboveground biomass increased with a temperature increase in moisture-rich regions, whereas in moisture–deficient regions it was reduced. Similarly, precipitation reduction at a constant average January temperature caused a reduction in aboveground biomass in warm regions, while in cold regions its increase was revealed. At a stand level, we also revealed an increase in biomass with increased precipitation amount in warm regions. The study suggested that the principle of space-for-time substitution was clearly manifested on biomass quantity of spruce at both individual tree and forest stand levels.

In the period of climate change, it is necessary to have biomass models for trees of all sizes to make precise estimations of biomass forest stocks to quantify carbon sequestration by forest cover. Therefore, we created allometric models of aboveground biomass in young Norway spruce (Picea abies [L.] Karst.) trees including main components, i.e. stem, branches and needles. The models used 200 sampled trees from 10 sites located in the central part of the Western Carpathians in Slovakia. The models, i.e. allometric regression relations implemented stem base diameter (diameter d0) and/or tree height. Moreover, using the derived allometric relations and a constant annual diameter increment of 10 mm, we calculated quasi-annual aboveground biomass production with regard to diameter d0. While stem had the largest contribution to aboveground biomass, followed by needles and branches, a different situation was revealed for the annual aboveground biomass production with the largest share of needles followed by stem and branches. Finally, we implemented the allometric models in a specific forest stand, where repetitive measurements were performed within 14 consecutive years. The results showed for example nearly 650 kg of the aboveground biomass per 102 m2 at the stand age of 10 years. The new biomass models can be applied to estimate the aboveground biomass stock in Norway spruce dominating stands in the Western Carpathians. Since the models are based on both diameter d0 and tree height a user can choose which variable is more suitable for particular conditions.

The study deals with the analysis of the impact of climate and ground water table level on radial increment and defoliation of Scots pine (Pinus sylvestris L.) growing on sandy soils. The research was performed in the area of the Borska nížina (i.e. Borská Lowland, situated in southwest of Slovakia), where a substantial die-back of pine trees has been observed in the last decade. Increment measurements and defoliation assessment were performed at 150 adult trees of Scots pine growing at three permanent monitoring plots within the international network of ICP Forests during the years 1989–2018. We examined the impact of climatic and hydrological factors on selected features of pine using the methods of correlation analysis and linear mixed models. Statistical analyses confirmed that the annual radial increment of Scots pine significantly depended on the mean air temperature from June to August, and mean ground water level in the mentioned months. These two factors also significantly correlated with crown defoliation. The factors explained 26% and 32% of increment and defoliation variability, respectively. From the long-term perspective, our analyses indicated that the decrease of ground water level by 0.5 m in summer resulted in the increase of defoliation by 10%. The obtained results indicate a further increase of Scots pine die-back on easy-to-dry sandy soils in regions with low precipitation totals, particularly considering the ongoing climate change and its inherent factors.

European hornbeam (Carpinus betulus L.) is a tree species widely distributed in Europe and the Asian part of the Near East. However, since European hornbeam is not very attractive for commercial purposes, scientific interest in this species has been rather sparse. Our study focused on dense young (up to 10 years old) European hornbeam stands originating from natural regeneration from seeds in Slovakia because in future the importance of this species may increase due to the climate change. We combined previously constructed tree-level biomass models, data on basic leaf traits, i.e., weight and area, and measurements from thirty plots located at ten different sites across Slovakia to construct stand-level allometric relations of the biomass stock in tree components, i.e., leaves, branches, bark, stem under bark and roots, to mean stand diameter at stem base, i.e., at the ground level. Moreover, we calculated and modelled leaf characteristics, namely the specific leaf area (SLA), leaf area ratio (LAR) and leaf area index (LAI), at a stand level. The total tree biomass stock including all tree components ranged between 0.75 and 13.63 kg per m2, out of which the biomass of stem with bark was from 0.31 to 8.46 kg per m2. The biomass models showed that the contribution of roots (omitting those with a diameter under 2 mm) decreased with the increasing mean stand diameter at stem base, whereas the opposite pattern was observed for branches and stem biomass. Further, we found that the mean stand diameter at stem base was a good predictor of both LAR and LAI. The results indicated the high photosynthetic efficiency of European hornbeam leaves per one-sided surface leaf area. Moreover, the growth efficiency (GE), expressed as the biomass increment of woody parts per leaf area unit, of young European hornbeam trees was high. The models proved a close positive linear correlation between LAI and stand biomass stock that may be used for estimating the biomass in young stands from LAI that can be measured using non-destructive terrestrial or aerial methods. The results further indicated that young stands may sequester a non-negligible quantity of carbon; therefore, they should not be omitted from local or country-wide estimates of carbon stocks in forest vegetation.

Coniferous forests in Europe have a considerable number of pests that attack trees of all ages from youngest up to oldest ones. One of them is the large pine weevil Hylobius abietis. This species is widespread in Europe and occurs from warm southern areas (Spain) up to northern countries (Sweden, Finland). Larvae of this species do not cause damage, they help in the decomposition process of stumps and roots. Adults are harmful as they consume bark of young coniferous seedlings, above all of spruce and pine. One adult can consume on average 75 mm2 of bark per day. Individuals can live up to 4 years, and during their lives they can damage and kill several tens of coniferous seedlings. Traditional chemical protection of seedlings against this pest is and will gradually be more and more restricted or forbidden. In this review, we describe this method as well as all other alternative methods including biological protection. We estimate that H. abietis causes annual damages in Europe of almost 120 million € and damages several tens of thousands of hectares of young forest stands.

The gypsy moth is one of the most serious pests in forests and fruit tree plantations over prevailing parts of the Northern Hemisphere. This work is based on a literature review, and presents history of gypsy moth Lymantria dispar L., observed in Slovak forests within the period 1945–2020. The life cycle, hosts, natural enemies, population dynamics of pests, impact of outbreaks on forests and different management methods used in the past are discussed. Since 1945, there were nine gypsy moth outbreaks in Slovakia. Between 1945 and 2020, a total of 155,034 ha of deciduous forests were touched with varying intensity, representing an average annual damage of 2,040 ha. The strongest outbreak culminated in 2004. Totally 51,479 ha were attacked in the period of 2000–2008. We have found outbreak periods that repeat with frequency of 7.8 ±2.2 years and the average outbreak phase lasts 3.1 ±1.1 years. The period between two subsequent outbreaks seems to be more or less constant and duration of the outbreak phase seems to be gradually shortened during the study period. Several factors influencing the gypsy moth population dynamics in Slovakia are discussed. The role of biological control by using entomopathogenic fungus Entomophaga maimaiga is described.

In November 2004, the windstorm Alžbeta damaged over 12 thousand ha of forests in the High Tatra Mts. It was the largest wind disaster in the modern forestry history of Slovakia. The process of forest regeneration at the post-disturbance area has to be monitored together with the effectiveness of implemented forestry measures. Therefore, we focused on tree measurements at 90 monitoring plots (MP) in 1 × 1 km net placed in the post-disturbance area in the Tatra National Park. We recorded tree species, number of trees (density) and tree heights. Besides that, stem diameters of trees with breast height diameter over 7 cm were measured. The field work was performed in the growing season of 2019, i.e. about 15 years after the wind disturbance. In total, 20 tree species, 15 broadleaves and 5 coniferous ones, were recorded at MP. The most frequent (28.9% of all trees) species was Norway spruce followed by silver birch (18.6%), rowan (16.9%) and goat willow (15.2%). Four species, i.e. European larch, wild cherry, grey alder and common alder contributed to the total number of trees between 1.8 and 4.8% each. Share of all other species together was about 5%. Tree height frequency was left-sided for the whole sampling set (all species together), as well as for individual species. Most of young trees were less than 1m high, but some of them exceeded 10 m. Further, tree density of over 100 individuals per are (100 m2) was found at 1/3 of all MPs. As many as 25% of MPs were characterized with tree densities between 61 and 90 individuals. At 23% of MPs, the number of trees was up to 30 individuals per are, and 20% of MPs had between 31 and 60 small trees per are. The results suggested that the post-disturbance forest stands in the High Tatras would be more resistant to wind storms and very probably also to bark beetles after reaching maturity than those, which were destructed and declined at the beginning of 21st century.

In the conditions of Central Europe, silver birch (Betula pendula Roth) has so far not been an important species for commercial purposes but might be relevant from ecological point of view. For instance, prompt succession by birch and other pioneer tree species at large-scale post-disturbance areas is necessary to compensate for previous carbon losses by natural disasters. Therefore, our attention was focused on 14-year-old birch trees growing at the wind-thrown area in the High Tatra Mts. (northern Slovakia). We sampled aboveground biomass of 20 silver birch trees representing four classes of crown competition: 0 – competition free crowns, 1 – crowns under mild competition, 2 – crowns under moderate competition, 3 – crowns under severe competition. We studied biomass allocated to stems, branches and foliage, and basic properties of stems and foliage. The crown-competition free birches were nearly 13 m high, and their aboveground tree biomass was 150 kg. The biomass of birches under severe competition was five times lower. Crown competition modified biomass ratios of foliage to branch as well as of branch to stem. Our results showed that birches under severe competition stress invest more in height than in diameter. At the same time, crown competition modified foliage weight and specific leaf area (SLA), which was clear mostly in the upper part of the crowns. However, foliage area was influenced by crown competition only to a negligible extent. Our main finding is that foliage position (upper, middle or lower third of crown) affected foliage properties more than intraspecific crown competition. Finally, we pointed out that silver birch is a rather productive species that is not ecologically demanding. Therefore, it might be a prospective tree species under the ongoing climate change and the present period of intensification in renewable resources utilisation.

Our research focused on the impact of post-disturbance management on the subsequent forest stands in the territory of the High Tatra Mts. situated in the northern part of Slovakia. The field work was carried out within the post-disturbance area in 2019, i.e., 15 years after the windstorm. In total, we used data from 80 monitoring plots (MP): 40 plots situated inside the managed part and 40 in the unmanaged areas. Post-disturbance management specifically consisted of logging of wind-thrown wood, therefore, the main difference between the two areas (salvaged versus unsalvaged) was the amount of coarse woody debris (CWD) left on site. We focused on the characteristics of newly regenerated forest stands: the number of trees and tree species per MP, tree height and browsing (mostly by red deer, Cervus elaphus) were recorded as was their growth substrate, i.e., soil or CWD. Higher tree densities, larger trees as well as higher tree species richness were found at salvaged plots. In addition, more evident dominance of Norway spruce (Picea abies (L) Karst.) was recorded at unsalvaged plots. Common rowans (Sorbus aucuparia L.) were frequent at both plot types. Birch trees (Betula sp.) were very frequent at salvaged plots, while only a few birch individuals were recorded at unsalvaged ones. The proportion of trees growing on CWD was 15% at unsalvaged and 3% at salvaged plots. Trees growing on the soil contained nearly double the aboveground biomass than those on CWD. Red deer browsing was approximately two times more frequent at salvaged than unsalvaged plots. While rowan was extremely prone to browsing, spruce was damaged negligibly. These main findings could have two contradictory conclusions, the positive one being that differentiated post-disturbance management within a certain area can combine both forestry and nature conservation interests. Moreover, it can generate parallel forests with different properties that might positively influence the future stability of forest ecosystems as a whole. The negative side might be that contrasting post-disturbance management can cause an uneven distribution of red deer population and intensive browsing in areas favourable for game.

The main goal of this study is to analyse and interpret interspecific differences in foliage biomass/area and woody parts biomass as well as the ratio between quantities of foliage and woody components (i.e., branches, stem and roots). The study was principally aimed at determining basic biomass allocation patterns and growth efficiency (GE) of four broadleaved species, specifically common aspen (Populus tremula L.), European hornbeam (Carpinus betulus L.), silver birch (Betula pendula Roth.) and sycamore (Acer pseudoplatanus L.) in young growth stages. We performed whole-tree sampling at 32 sites located in central and northern parts of Slovakia. We sampled over 700 trees and nearly 4900 leaves to quantify biomass of woody parts and foliage traits at leaf and tree levels. Moreover, we estimated specific leaf area in three parts of the crown, i.e., the upper, middle and lower thirds. We found that hornbeam had the largest foliage biomass and the lowest foliage area of all investigated species, while its biomass of woody parts did not differ from aspen and sycamore. Birch had the lowest biomass of woody parts, although its foliage properties were similar to those of aspen. Intraspecific differences of foliage were related to tree size and to leaf position along the vertical crown profile. Growth efficiency (GE), expressed as woody biomass production per foliage area unit, was evidently larger in hornbeam than in the other three broadleaves. We suggest that future GE modelling should utilize real values of stem diameter increment measured in a current year, bio–sociological position of trees and competition indicators as inputs. Such an approach would elucidate the role of stand structure and tree species mixture for ecological and production properties of forest stands.

Red deer (Cervus elaphus) are mixed feeders that consume both herbaceous and woody plants. As a consequence, intensive browsing on trees where red deer populations are particularly dense often leads to serious conflicts between the interests of forestry and hunting stakeholders. Therefore, understanding the density of deer that forest system can bear requires the ability to measure amount of potential forage provided by non-commercial tree species within a stand that serve as forage. Our objective was to build models that estimate forage potential (i.e., maximum biomass edible and accessible for consumption by red deer per tree) based on tree size [i.e., stem base diameter (d0)]. We developed models for three tree species commonly consumed by red deer in Central Europe, aspen (Populus tremula), goat willow (Salix caprea) and rowan (Sorbus aucuparia). To construct models of forage potential, we harvested 380 young (age of 2–15 years) trees on 14 sites in the Western Carpathians of Slovakia. Tree biomass was first divided into three components (stem bark, branches and foliage), each of which was subdivided into edible and non-edible portions based on branch diameter and height from the ground and then dried and weighed. We then quantified edible biomass by tree species, tree component and season (growing vs. dormant). The total amount of tree mass (forage potential) that could be consumed by red deer generally increased with tree size, but the relative contributions of different tree components varied by tree size, tree species and season. Our models predicted that the maximum forage potential per tree was ~ 500 g in aspen, 350 g in goat willow and 300 g in rowan in summer, and nearly 500 g in aspen, 300 g in goat willow and 250 g in rowan in winter. Together with theoretical knowledge and practical experience, our forage potential models can be used to help forest and wildlife managers both to better measure edible tree biomass for red deer populations and how edible tree biomass might be used to minimize the risk of deer damaging commercially valuable trees.

Climate change, especially modified courses of temperature and precipitation, has a significant impact on forest functioning and productivity. Moreover, some alterations in tree biomass allocation (e.g. root to shoot ratio, foliage to wood parts) might be expected in these changing ecological conditions. Therefore, we attempted to model fir stand biomass (t ha−1) along the trans-Eurasian hydrothermal gradients using the data from 272 forest stands. The model outputs suggested that all biomass components, except for the crown mass, change in a common pattern, but in different ratios. Specifically, in the range of mean January temperature and precipitation of −30°C to +10°C and 300 to 900 mm, fir stand biomass increases with both increasing temperature and precipitation. Under an assumed increase of January temperature by 1°C, biomass of roots and of all components of the aboveground biomass of fir stands increased (under the assumption that the precipitation level did not change). Similarly, an assumed increase in precipitation by 100 mm resulted in the increased biomass of roots and of all aboveground components. We conclude that fir seems to be a perspective taxon from the point of its productive properties in the ongoing process of climate change.

Large wild herbivores are important and natural components of forest ecosystems, but through their browsing activities have the potential to influence the structure and composition of forest communities, thus timber production and ecosystem dynamics. To examine the effects of browsing by wild herbivores on a young post-disturbance forest in the Kysuce region of northwestern Slovakia, we established two sets of 2 m radius plots, 15 within a fenced area (5.12 ha) that excluded large wild herbivores, and 15 within an adjacent unfenced area. In each plot, we recorded the species, tree height, stem base diameter, and mutual geographic positions of trees. When we compared tree community characteristics between the unfenced and fenced plots, we found fewer and smaller broadleaved tree species, except silver birch (Betula pendula Roth.) in the unfenced plots. Although common rowan (Sorbus aucuparia L.) was the dominant species within fenced plots, where some individuals were over 6.0 m tall, this species was rare outside the fenced area and usually did not exceed 1.5 m. In contrast, Norway spruce (Picea abies Karts L.) was more abundant and taller within the unfenced area, likely released from competition by suppression of broadleaved trees by herbivores. In addition, fenced plots also showed twice the tree species richness (Shannon index) of unfenced ones. Despite changes in tree communities, total aboveground biomass stock was only slightly but significantly lower in the unfenced than the fenced plots (29.6 kg per 10 m2 vs. 33.5 kg per 10 m2). Our study suggested that browsing pressure by large wild herbivores that focused on most broadleaved trees weakened interspecies competition and allowed the expansion of Norway spruce. As a consequence, converting spruce monocultures to mixed species stands is likely unrealistic when faced with heavy browsing pressure by wild large herbivores.

The aim of the paper was to compare young silver birch (Betula pendula Roth.) and Norway spruce (Picea abies L. Karst) growing at the identical site, from the point of contribution of tree components to their aboveground biomass stock, their wood density, radial increment and aboveground biomass production. Our research activities were performed in the High Tatra Mts., which belong to the Tatra National Park (TANAP), Northern Slovakia. Currently, the substantial part of the TANAP territory is covered by post-disturbance young forests which have been growing there since the large-scale windstorm episode in November 2004. Our study combined non-destructive repeated tree measurements performed at two transects in 2016–2020, with destructive tree sampling of twenty 14-year-old individuals for each species. From the gathered data, we derived models estimating standing stock and annual production of aboveground biomass in individual tree components (foliage, branches, stem bark and stem wood), using diameter at breast height (DBH) as a predictor. The results showed contrasting contributions of tree compartments to aboveground biomass stock between birch and spruce. While spruce trees had four times higher contribution of foliage than birches, the reverse situation (1.5-fold difference) was observed for stem over bark biomass. At the same time, birch trees had a 40% greater diameter increment and a 30% denser stem wood than spruce. As for aboveground biomass production, the contribution of the stem as an economically important component was greater in birch than spruce. The results suggest that, in the young growth stage, birch may be advantageous over spruce in both ecological and production properties. Therefore, we believe that strengthening research activities focused on birch ecology and production issues would bring practical recommendations for better utilization of this tree species in forestry and wood-processing industry sectors

Although forest disturbances have become more frequent and severe due to ongoing climate change, our understanding of post-disturbance development of vegetation and tree&ndash, herb layer interactions remains limited. An extreme windstorm, which occurred on 19 November 2004, destroyed Picea abies (L.) H. Karst dominated forests in the High Tatra Mts. Here, we studied short-term changes in diversity, species composition, and aboveground biomass of trees and herb layer vegetation, including mutual relationships that elucidate tree&ndash, herb interactions during post-disturbance succession. Assessment of species composition and tree biomass measurements were performed at 50 sample plots (4 &times, 4 m) along two transects 12, 14, and 16 years after the forest destruction. Heights and stem base diameters of about 730 trees were measured and subsequently used for the calculation of aboveground tree biomass using species-specific allometric relationships. Aboveground biomass of herb layer was quantified at 300 subplots (20 &times, 20 cm) by destructive sampling. Species richness and spatial vegetation heterogeneity did not significantly change, and species composition exhibited small changes in accordance with expected successional trajectories. While aboveground tree biomass increased by about 190%, biomass of annual herb shoots decreased by about 68% and biomass of perennial herb shoots was stable during the studied period. The contribution of trees to total aboveground biomass increased from 83% to 97%. After 16 years of forest stands recovery, tree biomass represented approximately 13% of forest biomass before the disturbance. Herb layer biomass, particularly the biomass of annual herb shoots, was more closely related to tree cover than to tree biomass and its decline could be assigned to gradual tree growth. Our study provides clear evidence that short-term successional processes in post-disturbance vegetation are much better detectable by biomass than by diversity or compositional measures and emphasized the importance of light conditions in tree&ndash, herb competitive interactions.

This study reports on an investigation of fine root and foliage productivity in forest stands dominated by European beech (Fagus sylvatica L.) and exposed to contrasting intensities of mature forest harvesting. The main aim of this study was to consider the long-term effects of canopy manipulation on resource acquisition biomass compartments in beech. We made use of an experiment established in 1989, when five different light availability treatments were started in plots within a uniform forest stand, ranging from no reduction in tree density to full mature forest removal. We measured fine root standing stock in the 0&ndash, 30 cm soil layer by coring in 2013 and then followed annual fine root production (in-growth cores) and foliage production (litter baskets) in 2013&ndash, 2015. We found that the plot where the tree density was reduced by 30% had the lowest foliage and the highest fine root production. In 2013, this plot had the highest fine root turnover rate (0.8 year&minus, 1), while this indicator of fine root dynamics was much lower in the other four treatments (around 0.3 year&minus, 1). We also found that the annual fine root production represented around two thirds of annual foliage growth on the mass basis in all treatments. While our findings support the maintenance of source and sink balance in woody plants, we also found a long-lasting effect of tree density manipulation on investment into resource acquisition compartments in beech forests.

Global climate change also influences the forest damaging agents occurrence and thus a forest health. Forest trees that are damaged by agents are in managed forests processed by salvage felling. The amount of an annual salvage felling represents the occurrence of a damaging agents occurrence in a certain year. In 2015, the area of forests in Slovakia reached 2.014 mil. ha. Within the 20 years (from 1998 to 2017), the total felling reached 162.52 mil. m3, out of this 47.99 % were ascribed to a salvage felling. Abiotic agents were the most damaging agents (42.28 mil. m3 of damaged wood), out of it a wind was the most important one. Biotic damaging agents were the second important group (32.165 mil. m3), whereas bark beetles on spruce were the most important. The third group and the less damaging one was anthropogenic agents group (3.555 mil. m3) with an air pollution as the most important damaging agent. There was no statistically significant difference in the volume of processed trees within salvage felling caused by abiotic and biotic damaging agents. However, these two groups caused significantly higher damages than the third group of anthropogenic damaging agents. There were two major wind damages, Alžbeta in 2004 and Žofia in 2014 with damaged wood 5.3 mil. m3 and 5.2 mil. m3, respectively. They occurred in southern, central and northern part of Slovakia. As damaged wood was not processed from strict nature conservation areas, the secondary damaging agents, mostly Ips typographus on Norway spruce reproduced as much that after some years it cumulatively reached or even exceeded damages from those two major windthrows episodes.

Our research of common aspen (Populus tremula L.) focused on the forested mountainous area in central Slovakia. Forest stands (specifically 27 plots from 9 sites) with ages between 2 and 15 years were included in measurements and sampling. Whole tree biomass of aspen individuals was destructively sampled, separated into tree components (leaves, branches, stem, and roots), and then dried and weighed. Subsamples of fresh leaves from three crown parts (upper, middle, and lower) were scanned, dried, and weighed. Allometric biomass models with stem base diameter as an independent variable were derived for individual tree components. Basic foliage traits, i.e., leaf mass, leaf area, and specific leaf area, were modelled with regard to tree size and leaf position within the crown. Moreover, biomass stock of the woody parts and foliage as well as the leaf area index were modelled using mean stand diameter as an independent variable. Foliage traits changed with both tree size and crown part. Biomass models showed that foliage contribution to total tree biomass decreased with tree size. The total foliage area of a tree increased with tree size, reaching its maximum value of about 12 m2 for a tree with a diameter of 120 mm. Leaf area index increased with mean stand diameter, reaching a maximum value of 13.5 m2 m&minus, 2. Since no data for biomass allocation for common aspen had been available at either the tree or stand levels, our findings might serve for both theoretical (e.g., modelling of growth processes) and practical (forestry and agro-forestry stakeholders) purposes.

In Slovakia, the contribution of young stands to the total forest area has been increasing in the last decade. However, scientific attention to these stands was previously very sparse and they were usually not included in local and country carbon stock estimates. Therefore, we focused on the calculation of tree biomass and necromass in young beech and spruce stands as well as on their development during the period of nine years (aged from 4 to 12 years). For the calculation, we implemented allometric equations using tree diameter and height as independent variables. The results showed very dynamic changes in biomass (carbon) stock. Specifically, tree biomass increased in the period of 9 years from about 2,000 g to 15,000 g (i.e. cca 1,000 to 7,500 g of carbon) per m2in beech, and from 4,500 to 12,000 g (cca 2,300 to 6,000 g of carbon) per m2 in the spruce stand. At the same time, the amount of biomass (fixed carbon) was only slightly larger than the accumulated quantity of necromass (carbon loss from living trees). It means that a large portion of carbon was allocated to necromass. We found that not only the foliage fall but also the mass of dead trees, a result of intensive competition, was an important path of carbon flux to necromass. The results proved that although young forests fix much less carbon in their biomass than old stands, they can represent large carbon flux via annual increment of necromass. This indicates that young stands should not be omitted in forest carbon balance estimates of the country.

The paper focused on the estimation of aboveground biomass and its carbon stock in the vegetation cover on the territory of the High Tatras twelve years after a large-scale wind disturbance. Besides biomass quantification of main plant groups (i.e. trees and ground vegetation) we considered plant components with special regard to carbon rotation rate. The measurements were performed on two transects each containing 25 plots sized 4 × 4 m. Height and stem diameter of all trees on the plots were measured and used for biomass estimation. To quantify the biomass of ground vegetation, six subplots sized 20 × 20 cm were systematically placed on each plot and the aboveground biomass was harvested. The plant material was subjected to chemical analyses to quantify its carbon concentration. The study showed that while the wind disturbance caused dramatic decrease of carbon stock, young post-disturbance stands with abundant ground vegetation, represented large carbon flux via litter fall. Twelve years after the wind disturbance, the trees contributed to carbon stock more than the ground vegetation. However, the opposite situation was recorded for the carbon flux to litter that was related to the dominance of annual plants in the above-ground biomass of ground vegetation. The carbon stock in the biomass of young trees and ground vegetation represented about 8,000 kg per ha. The young stands manifested a dynamic growth, specifically the aboveground biomass increased annually by one third. The results confirmed different carbon regimes in the former old (pre-disturbance) and sparse young (post-disturbance) stands.

Since forests can play an efficient role in the mitigation of greenhouse gas emissions, objective information about the actual carbon stock is very important. Therefore, the presented paper analysed the carbon stock in the living merchantable trees (with diameter at breast height above 7 cm) of the Czech forests with regard to groups of tree species and tree compartments (wood under bark with diameter above 7 cm, wood under bark with diameter below 7 cm, bark, green twigs, foliage, stump and roots). We examined its regional distribution and relationship to the number of inhabitants and the gross domestic product. The data used for the analysis originated from 13,929 forest plots of the first Czech National Forest Inventory performed between 2001 and 2004. The total tree carbon stock was obtained as a sum of the carbon stock in the individual tree compartments estimated from the biomass amount in the compartments multiplied by the relative carbon content. Wood biomass amount was calculated by multiplying a particular part of tree volume with species-specific green wood density. The total amount of carbon stored in forest trees in the Czech Republic was over 327 mill. t, which is about 113 t of carbon per ha of forests. The highest carbon amount (160 mill. t, i.e. 49.0% of the total amount) was fixed in spruce. The minimum carbon amount fixed in the forest cover (14.35 mill. t) was calculated for Ústecký kraj (region), while the maximum carbon amount (51.51 mill. t) was found in Jihočeský kraj.

Wind is both an ecological provider and disturbance facilitator influences trees and other organisms in forests. Impacts of wind on induvidual trees and forests mainly depend on the strength (or intensity) of the wind and the stability of the trees. Wind causes large-scale damage to forests and serious economical losses for the forestry sector within Europe. Therefore, knowledge of interactions between wind and trees and/or forests provides the baseline for developing adequate prevention or mitigation of the negative consequences associated with wind disturbances in forest ecosystems. Herein, we analyse the wind as an ecological and disturbance factor in forests in Europe, emphasising forests in Slovakia. Here, strong winds destroy mostly spruce dominated forests in the following regions; Orava, High and Low Tatra Mountains, Great Fatra Mountains, Pohronie, Poľana Mountains and Slovak Ore Mountains. Increasing volumes of timber damaged by windstorms have been documented since 1961, with the maximum damage recorded in 2004. Yearly volumes of damaged timber of approximately 2.5 mil. m3are predicted from 2016 to 2030. This highlights the data requirement regarding wind disturbances for integrated forest protection against dangerous winds and other disturbance agents in forest ecosystems in Slovakia and other European countries.

European beech (Fagus sylvatica L.) and Norway spruce (Picea abies Karst.) are two of the most ecologically and economically important forest tree species in Europe. These two species co-occur in many locations in Europe, leading to direct competition for canopy space. Foliage characteristics of two naturally regenerated pure stands of beech and spruce with fully closed canopies were contrasted to assess the dynamic relationship between foliage adaptability to shading, stand LAI and tree growth. We found that individual leaf size is far more conservative in spruce than in beech. Individual leaf and needle area was larger at the top than at the bottom of the canopy in both species. Inverse relationship was found for specific leaf area (SLA), highest SLA values were found at lowest light availability under the canopy. There was no difference in leaf area index (LAI) between the two stands, however LAI increased from 10.8 to 14.6 m2 m−2 between 2009 and 2011. Dominant trees of both species were more efficient in converting foliage mass or area to produce stem biomass, although this relationship changed with age and was species-specific. Overall, we found larger foliage plasticity in beech than in spruce in relation to light conditions, indicating larger capacity to exploit niche openings.

Large-scale disturbances under the conditions of Slovakia, caused especially by storm and bark beetle, bring dramatic decline in carbon budget of the country, besides other negative consequences. The largest disturbance in modern history of the Slovak forestry was the storm damage that occurred in November 2004. The Tatra National Park (TNP) was one of the most affected regions. Thus, in this territory, two transects (T1 – the Danielov dom site and T2 – near the Horný Smokovec village) were established to survey basic dendrometric properties of trees in young stands established after the disaster. The standing stock of aboveground biomass in tree cover for the spring and autumn 2014 was calculated using the recorded variables, i.e. tree height and diameter measured at the stem base, together with the region-specific allometric relations. Then, the Aboveground Net Primary Production (ANPP) in tree cover was estimated with respect to its components (stem, branches and foliage). ANPP was 315 g m−2 per year (Transect T1), and 391 g m−2 per year (Transect T2). The differences in the structure of ANPP, i.e. contribution of tree components, were found between transects T1 and T2. They were caused by the contrasting tree species composition, specifically the ratios between Norway spruce and broadleaved species. Broadleaves allocated more biomass production to foliage than spruce. This phenomenon together with higher turnover (once a year) of foliage caused that broadleaves manifest higher share of fast-cycling carbon in comparison to the amount of carbon sequestrated in woody parts (stem and branches). High variability of ANPP was found within the transects, i.e. among the plots (microsites). As for the representative estimation of the standing stock of aboveground part of tree cover as well as ANPP at the post-disturbance area in the TNP territory, the survey should be performed on a net of research plots. Only this approach enables reliable estimates of carbon amount sequestrated in woody parts, eventually carbon yearly absorbed by young forest stands.

Salvage felling is one of the indicators of the forest health quality and stability. Most of the European Union countries monitor forest harmful agents, which account for salvage felling, in order to see trends or functionality between factors and to be able to predict their development. The systematic evidence of forest harmful agents and volume of salvage felling in Slovakia started at the Forest Research Institute in Zvolen in 1960. The paper focuses on the occurrence of the most relevant harmful agents and volume of salvage felling in the Slovak forests over the last decade. Within the 10 years period (2004–2013) salvage felling in Slovakia reached 42.31 mil. m3 of wood, which was 53.2% of the total felling. Wind and European spruce bark beetle Ips typographus damaged 78.4% of salvage wood, i.e. they were the most important pest agents. Norway spruce (Picea abies) was the most frequently damaged tree species that represented the amount of 35.6 mil. m3 of wood (81.2% of total volume of salvage felling). As Norway spruce grows mostly in mountains, these regions of Central and Northern Slovakia were most affected. At the damaged localities new forests were prevailingly established with regard to suitable ecological conditions for trees, climate change scenarios and if possible, natural regeneration has been preferred. These approaches in forest stand regeneration together with silvicultural and control measures are assumed to gradually decrease the amount of salvage felling over long term perspective.

The decline of spruce stands caused by bark beetle outbreaks is a serious economic and ecological problem of forestry in Slovakia. In the preceding period, the decline affected mainly secondary spruce forests. Over the last decade, due to large bark-beetle outbreaks this problem has been observed also in natural spruce forests, even at high elevations. We dealt with this issue in a case study of short-term development of larch-spruce stands in the High Tatras (at a site called Štart). We compared the situation in the stand infested by bark beetles several years after the wind-throw in 2004 with the stand unaffected by bark beetles. We separately analysed the development of the mature (parent) stands and the regeneration. The results indicated that forest decline caused by bark beetles significantly depended on the stand structure (mainly tree species composition), which affected the period of stand disintegration. Mortality of spruce trees slowed down biomass accumulation (and thus carbon sequestration) in the forest ecosystem. In the new stand, pioneer tree species dominated (in the conditions of the High Tatras it is primarily rowan), although their share in the parent stand was negligible. The results showed different trends in the accumulation of below-ground and above-ground biomass in the declined and living stands. In the first years after the stand decline, rowan accumulated significantly more biomass than the main tree species, i.e. spruce. The reverse situation was under the surviving stand, where spruce trees accumulated more biomass than rowan. The different share of spruce and pioneer tree species, mainly rowan, affected the ratio between fixed (in woody parts of trees) and rotating (in foliage) carbon in the undergrowth. Forest die-back is a big source of carbon emissions from dead individuals, and the compensation of these losses in the form of carbon sequestration by future stands is a matter of several decades.

Science of The Total Environment, 615, ISSN:0048-9697, ISSN:1879-1026

Growth intensity of particular tree components is controlled by a variety of factors and as a consequence, biomass allocation also changes over time. Since the allocation of biomass controls the carbon regime in a forest stand, tree standing stock and biomass structure, with regard to tree components: fine and coarse roots, stem, branches and needles, were estimated in a young Norway spruce stand based on repeated tree sampling, soil coring and allometric equations (modelled for 2009 and 2013, i.e. for 12- and 16-years-old trees). Large differences were found between the two models in the contribution of the tree components to aboveground biomass. Between the first and fifth year of the experiment, below - ground to aboveground biomass ratio as well as short-lived to long-lived tree part ratio manifested decreasing tendencies. At the same time, the stand possibly reached the maximum standing stock of both needles and fine roots. It is concluded that for biomass allocation estimates in young stands, not only stand-specific but also time-specific allometric relations should be constructed and implemented. Further, there appears to be a canopy closure threshold beyond which biomass allocation is different from the situation in sparse young spruce stands.

The study focuses on two young stands of European beech (Fagus sylvatica) and Norway spruce (Picea abies) of the same age (12-yearold) with similar sized trees grown at near identical sites. After performing a destructive sampling technique which included all tree compartments except fine roots; allometric equations were constructed for all tree components. Diameter at stem base (do) was utilized as an independent variable for the equations. The models expressed not only biomass of woody parts (branches, stem and coarse roots) and foliage but also foliage area and specific leaf area (SLA). Results indicate that the basic morphological properties of foliage vary in both species along the vertical crown profile. In spruce, contrasting values of needle area and SLA were recorded among needle sets (based on year of establishment). On a tree level, both spruce and beech had similar foliage areas however, beech had a larger biomass comprising of woody parts while spruce biomass was dominated by foliage. Therefore the leaf mass ratio (LMR) defined as the ratio between foliage biomass and total tree biomass, as well as leaf area ratio (LAR) defined as the ratio between leaf area and total tree biomass were much larger in spruce than in beech species. On a stand level, spruce manifested a higher value (18.64 m2.m−2) of leaf area index (LAI) than beech (12.77 m2.m−2). Moreover, while the biomass of foliage was 4.6 times higher in spruce than in beech, total biomass of woody parts were similar in both stands. These contrasts indicate very different growth strategies and biomass allocations between beech and spruce at the young growth stages

In November 2004, the Alžbeta windstorm hit the mountainous areas of northern and central Slovakia. The most affected area was Tatra National Park, where downslope wind damaged 12,000 ha of forest, mostly Norway spruce (Picea abies [L.] Karst.). In the areas with the highest level of nature conservation, about 165,000 m3 of damaged wood was left uncleared. These uncleared sites triggered a serious bark beetle outbreak, where Ips typographus (L.) was among the dominant species. The aim of our work was to quantify and map forest damage resulting from this windstorm and subsequent insect outbreak in Tatra National Park. The objective of this article is also to present simple geographic information system (GIS) techniques available to forest managers for the detection and mapping of bark beetle infestations. The infested areas were studied using GIS and a series of color-infrared aerial photographs taken in 2005–2009. More than 50% of all damage was recorded within 300 m, and more than 75% within 500...

The paper presents information on the projected drought exposure of Central Europe, describes the anticipated dynamics of the regional forests, and identifies measures facilitating the adaptation of forests to climate change-induced drought risk. On the basis of an ensemble of climate change scenarios we expect substantial drying in southern Slovakia and Hungary, while such trends were found to be less pronounced for the Czech Republic and Austria. In response to these climate trajectories, a change in species composition towards a higher share of drought tolerant species as well as the use of drought resistant provenances are identified as paramount actions in forest adaptation in the region. Adaptation to aggravating climate change may need to use artificial regeneration to enrich local gene pools and increase the drought tolerance of stands. Increasing risks from pests, pathogens and other disturbances are expected as a result of more frequent and severe droughts, underlining the need to put a stronger focus on risk management principles rather than on indicators of productivity in silviculture and forest planning. A consolidation of disturbance monitoring systems and a broader use of pest dynamics and hazard rating models are paramount tools to facilitate this adaptation process in forest management. The effectiveness of all the suggested measures needs to be controlled by efficient forest monitoring systems, the consolidation of which seems to be a timely task. Systematic and long-term implementation of the presented measures should increase forest stability and resilience, and further secure the sustainable provision of ecosystem services under climate change.

We investigated the seasonal dynamics of height increment, as well as total annual height increment, in 2009-2013 on young stands of beech and spruce grown at the same site. The results showed that the inter-annual dynamics of basic stand characteristics, especially tree density, were more obvious in spruce than in beech stands. Much higher tree mortality in spruce was explained by a lower light intensity under the spruce stand canopy and higher tolerance of beech to shade. Large interspecific differences were also found in the timing of height increment. Specifically, the height increment of beech trees started earlier than those of spruce. Moreover, the terminal grew for longer in spruce (nearly 70 days) compared to beech (about 45 days). The comparisons between the courses of the height increment and the ambient factors suggested that global radiation played a principal role. In the beech stand, the maximum height increment rate occurred during the same days as the maximal global radiation in 2009 and 2011, while a decline of the height increment occurred simultaneously with a depression in global radiation in 2012. As for the spruce stand, its one-peak maxima in height increment were related to the maximum of global radiation in 2009 and in 2012. On the other hand, double-peak courses of height increment in 2010 and 2011 may have been related to sudden declines in global radiation. Interspecific differences in height increment timing might play a certain role in cases of unfavourable weather conditions, e.g. drought episodes in the middle part of the growing season when the height increment would be accomplished in beech but would still be ongoing in spruce.

The quantification of stems (under- and overbark), foliage and fine roots in 14-year-old stands of Eu - ropean beech and Norway spruce grown on the same site were evaluated. Therefore, 60 trees of each species were sampled, dry masses of stems and foliage were established and expressed by allometric equations with stem diameter as an independent variable. The spruce allocated a much larger portion of biomass into the foliage than beech. The equations on a tree level were constructed also for specific leaf area and one-sided projected leaf area. Moreover, the quantity and morphological characteristics of fine roots in both stands were surveyed through soil coring. While standing stocks of fine roots were similar in the stands of both tree species, significant interspecies differences oc - curred in morphological properties of roots. Growth efficiency, expressing annual stem production on a variety of foliage and fine root parameters was calculated. The largest differences, specifically fivefold in favour of spruce, were found in growth efficiency based on a number of root tips.

This study was aimed at modelling seasonal variation of stem circumference increments in a mixed stand composed of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.). Moreover, we focused on the quantification of the main climatic factors governing the increments. The measurements were performed at a site established at about 970 m a.s.l. from the locality of Vrchslatina (Central Slovakia). Data was collected from 20 European beech trees and 20 Norway spruce trees, from 2009 to 2012. The increments (measured at 130 cm above ground level) were recorded circa biweekly using manual band dendrometers. Lognormal function was used for the modelling of the seasonal trend of the increments. Hourly-based records of climatic variables such as air temperature, precipitation, and derived vapour pressure deficit were used for the modelling. The effect of climatic parameters on the seasonal variations of the increments was tested by including them directly into the lognormal function. The results suggest that while the sum of precipitation was a better predicting factor for spruce, the mean temperature was the better predictor for beech. In addition, both temperature and vapour pressure deficits also had an effect on the increments of spruce, but these parameters did not contribute to the explanation of the variability of increments for beech. Overall, the variability clarified by the final model was 72% for spruce and 78% for beech. At the same time, climatic parameters as a part of the model helped to explain 10% of the variability for the spruce (precipitations) and 3% of the variability for the beech (temperature). We also found lower variability in the increments of beech compared to spruce. This suggests that for the specific site conditions spruce are more sensitive to environmental conditions than beech

V tejto práci sme pomocou kombinácií kontinuálnych meraní a deštruktívnych odberov vzorníkov sledovali a porovnali zásobu nadzemnej biomasy a ročnú primárnu produkciu (NPP) v prirodzene obnovených mladých porastoch buka a smreka. Na vybranej lokalite predpokladáme, že zmenené klimatické podmienky budú lepšie vyhovovať buku pred v súčasnosti prevládajúcim smrekom. Lokalita Vrchslatina sa nachádza v južnej časti Veporských vrchov v nadmorskej výške 977 m nad morom (48° 38΄ 50΄΄ N, 19° 36΄ 07΄΄ E). Priemerné ročné zrážky sa pohybujú okolo 900 mm, priemerná ročná teplota je 5,2 °C. Na sledovanej lokalite sme pozorovali odlišný priebeh rastu buka a smreka. Pri buku bola pozorovaná menšia medziročná mortalita, udržiaval sa až prehustený zápoj, v ktorom sa aj podúrovňové stromy snažili dostať do úrovne. Toto sa prejavilo na tvare kmeňov, ktoré sú tenké a vysoké. Štíhlostný koeficient sa pri stromoch so strednou hrúbkou a strednou výškou postupne zvyšoval od 1,19 do 1,40. Pri smreku dochádza k vyššej mortalite, vrastavé a podúrovňové stromy odumierajú z dôvodu nedostatku svetla. Stromy rastú viac do hrúbky, čo sa odráža aj na štíhlostnom koeficiente, ktorý bol po celé obdobie viac-menej konštantný a pohyboval sa v rozpätí 0,89 až 0,93 (tab. 1). Zásoby kmeňa sú pri smreku v jednotlivých rokoch o 3 - 10 m3.ha-1 väčšie ako pri buku (tab. 3). Po prepočítaní na sušinu je vplyvom rozdielnej objemovej hmotnosti (obr. 5) celková zásoba sušiny drevných častí (kmeň a konáre) väčšia pri buku (tab. 3). Najväčší rozdiel medzi drevinami je v zásobe asimilačných orgánov, ktorá je pri smreku viac než trojnásobná (tab. 3 a 4). Počas rastu dochádza pri obidvoch drevinách k zvyšovaniu podielu kmeňa a znižovaniu podielu asimilačných orgánov (obr. 2). Hlavný medzidruhový rozdiel pri pomerne vyrovnaných hektárových zásobách je v rozdelení nadzemnej biomasy medzi komponenty, kde buk alokuje do kmeňa viac asimilátov ako smrek (obr. 2 - 4). Pri porovnaní ročnej NPP asimilačných orgánov a konárov neboli zistené žiadne signifikantné rozdiely medzi sledovanými drevinami (obr. 6). Ukázali sme, že zásoby nadzemnej biomasy ako aj NPP buka a smreka boli v mladých plnozakmenených porastoch z prirodzeného zmladenia na danom stanovišti podobné (tab. 3 a 4).

V ostatnom období sa výskum venuje jemným frakciám koreňových systémov drevín najmä z dôvodu ich výrazného prínosu pri obehu uhlíka v lesných ekosystémoch. Naše štúdium jemných koreňov (tieto sa definovali maximálnou hrúbkou 2 mm) sa sústredilo do bučín a smrečín v štádiu mladina, rastúcich na výskumnom objekte Vrchslatina. Pomocou dvoch metód, konkrétne pôdne vývrty (v hĺbke pôdy 0 - 50 cm) a vrastavé valce (v 0 - 30 cm) sa zis tila zásoba biomasy a nekromasy, ako aj produkcia jemných koreňov. Z týchto údajov sa odvodil ich obeh (vyjadrený ako pomer medzi produkciou a zásobou biomasy) a mortalita. Takéto sledovania sa vykonali počas štyroch rokov (2009 - 2012), pritom sa zohľadnili aj klimatické pomery, tzn. priemerné teploty vzduchu a úhrny zrážok. Výsledky poukázali na pokles zásoby biomasy jemných koreňov s hĺbkou pôdy, pritom výraznejší bol pri smreku (tzn. plytšia distribúcia jemných koreňov) než pri buku. Zásoba jemných koreňov bola mierne vyššia v bučine (priemer za roky 2009 - 2012 bol 6,57 t na ha) než v smrečine (6,01 t na ha), pritom medziročne výrazne varírovala. Ročná produkcia jemných koreňov bola veľmi podobná v obidvoch porastoch (priemer za roky 2009 - 2012 bol 1,37 t na ha za rok v bučine a 1,29 t na ha za rok v smrečine), pritom aj tu sa zistili veľké medziročné rozdiely. Kým v roku 2010 prevládala produkcia jemných koreňov nad ich mortalitou, opačná situácia bola v roku 2011. Zásoba, produkcia a mortalita jemných koreňov pravdepodobne súvisela s klimatickými pomermi v jednotlivých rokoch. Zvýšenú mortalitu jemných koreňov spôsobili najpravdepodobnejšie epizódy sucha. V obidvoch porastoch sa zistili podobné obehy jemných koreňov (približne jedenkrát za 4 roky). Pri porovnaní našich výsledkov s inými prácami sa konštatovali vysoké zásoby jemných koreňov, avšak nízke hodnoty ich obehu. Tento stav jemných koreňov pravdepodobne súvisí s mladým vekom sledovaných porastov, resp. s priaznivými pôdnymi pomermi na stanovišti.

General information on forest growth and development as well as different approaches of forest management are presented in the introduction of the paper. Furthermore, it shows an analysis of the development of tree species composition in the Slovak forests during the last 50 years. Historical data base for the analysis originated from the forestry records (especially Permanent Forest Inventory). Our attention was focused on reforestation with respect to tree species, tree species composition in young forest stands by age classes and relations between these forest characteristics. The next section of the paper describes new proposals for regulation of forest regeneration and reforestation with the aim to achieve desired tree species composition in all age classes, not only in accordance with natural conditions but also respecting human demands in the future.

A rain shelter experiment was conducted in a 90-year-old Norway spruce stand, in the Kysucke Beskydy Mts (Slovakia). Three rain shelters were constructed in the stand to prevent the rainfall from reaching the soil and to reduce water availability in the rhizosphere. Fine root biomass and necromass were repeatedly measured throughout a growing season by soil coring. We established the quantities of fine root biomass (live) and necromass (dead) at soil depths of 0-5, 5-15, 15-25, and 25-35 cm. Significant differences in soil moisture contents between control and drought plots were found in the top 15 cm of soil after 20 weeks of rainfall manipulation (lasting from early June to late October). Our observations show that even relatively light drought decreased total fine root biomass from 272.0 to 242.8 g m-2 and increased the amount of necromass from 79.2 to 101.2 g m-2 in the top 35 cm of soil. Very fine roots, i.e. those with diameter up to 1 mm, were more affected than total fine roots defined as 0-2 mm. The effect of reduced water availability was depth-specific, as a result we observed a modification of vertical distribution of fine roots. More roots in drought treatment were produced in the wetter soil horizons at 25-35 cm depth than at the surface. We conclude that fine and very fine root systems of Norway spruce have the capacity to re-allocate resources to roots at different depths in response to environmental signals, resulting in changes in necromass to biomass ratio.

Nitrogen deposition affect fine-root dynamics, a key factor in forest carbon and nutrient dynamics. This study aimed to elucidate the effects of increased soil inorganic nitrogen (N) levels on the fine-root dynamics of Cryptomeria japonica, which is tolerant to excess N load. An ammonium nitrate solution (28 kg ha−1 month−1) was applied for 3 years to plots (1 m × 2 m) in a C. japonica plantation. The elongation and disappearance of the fine roots were examined using the minirhizotron technique. The N fertilization increased soil inorganic N content and lowered the soil pH. Fine-root elongation rates increased with fertilization, whereas patterns of their seasonal changes were not affected. The ratio of cumulative disappearance to cumulative elongation of fine roots was lower in the N-fertilized plots than in the control plots. The mean diameter of the fine roots was not affected by N fertilization. Our results suggest that C. japonica can respond to increased levels of soil inorganic N by increasing both the production and residence time of the fine roots. However, the effects of the changing soil N content are less evident for the phenology and morphology of the fine roots in C. japonica.

Sebeň, V., Boseľa, M., Konopka, B. 2012: Damage to spruce stands in the Kysuce and Orava region determined from the National Forest Inventory. – Beskydy, 5 (1): 9–18 An analysis of the status of spruce stands in the Kysuce and Orava region was performed and their health condition was compared to the spruce forest constitution in the rest of Slovakia. For this purpose, the inventory plots established within the first circle of National Forest Inventory (NFI) in 2005 and 2006 were used. The Kysuce and Orava regions significantly differ from the rest of Slovak forests by its high proportion of spruce. The health status of the spruce stands in these regions, according to the salvage felling as a result of the damage caused prevailingly by stem rotting and bark beetles appears worse than in the rest of Slovakia. The analysis showed that not only the acute damage of spruce stands (insects) but also the chronic damage of trees (rotting, mechanical damage during logging) is more serious in these regions than in the rest of Slovakia. The browsing caused by deer game (data does not include young stands) in both regions as well as in the rest of Slovakia seems to be low and not so serious compared to the previously mentioned types of damage. Other sorts of damage (stem breakage, standing dead trees, or damage by insect) have also small proportion. More detailed analyses of NFI data with acceptable precision were possible only for most frequent kinds of damages such as stem rotting and damage by logging. The results showed the frequency of rotting tended to be higher with increasing stand age. Influence of altitude on the frequency of the damage was not evident. Since variability of selected types of damage on spruce forest in the target regions was high, all results are presented with the precision at 68 % confidence interval. Keyword: age classes, forest survey, harmful agents, Picea abies, standing stock

Summary Biomass allocation to above- and belowground compartments in trees is thought to be affected by growth conditions. To assess the strength of such infl uences, we sampled six Norway spruce forest stands growing at higher altitudes. Within these stands, we randomly selected a total of 77 Norway spruce trees and measured volume and biomass of stem, aboveand belowground stump and all roots over 0.5 cm diameter. A comparison of our observations with models parameterized for lower altitudes shows that models developed for specifi c conditions may be applicable to other locations. Using our observations, we developed biomass functions (BF s ) and biomass conversion and expansion factors (BCEF s ) linking belowground biomass to stem parameters. While both BF and BCEF are accurate in belowground biomass predictions, using BCEF appears more promising as such factors can be readily used with existing forest inventory data to obtain estimates of belowground biomass stock. As an example, we show how BF and BCEF developed for individual trees can be used to estimate belowground biomass at the stand level. In combination with existing aboveground models, our observations can be used to quantify total standing biomass of high altitude Norway spruce stands.

An increasing importance is assigned to the estimation and verification of carbon stocks in forests. Forestry practice has several long‐established and reliable methods for the assessment of above‐ground biomass; however, we still miss accurate predictors of below‐ground biomass. A major windthrow event exposing the coarse root systems of Norway spruce trees allowed us to assess the effects of contrasting soil stone and water content on below‐ground allocation. Increasing stone content decreases the root/shoot ratio, while soil waterlogging leads to an increase in this ratio. We constructed allometric relationships for below‐ground biomass prediction and were able to show that only soil waterlogging significantly impacts model parameters. We showed that diameter at breast height is a reliable predictor of below‐ground biomass and, once site‐specific parameters have been developed, it is possible to accurately estimate below‐ground biomass in Norway spruce.