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Gap dynamics are driving many important processes in the development of temperate forest ecosystems. What remains largely unknown is how often the regeneration processes initialized by endogenous mortality of dominant and co-dominant canopy trees take place. We conducted a study in the high mountain forests of the Central Western Carpathians, naturally dominated by the Norway spruce. Based on the repeated forest inventories in two localities, we quantified the structure and amount of deadwood, as well as the associated mortality of standing dead canopy trees. We determined the basic specific gravity of wood and anatomical changes in the initial phase of wood decomposition. The approach for estimating the rate of gap formation and the number of canopy trees per unit area needed for intentional gap formation was formulated based on residence time analysis of three localities. The initial phase of gap formation (standing dead tree in the first decay class) had a narrow range of residence values, with a 90–95% probability that gap age was less than 10 or 13 years. Correspondingly, a relatively constant absolute number of 12 and 13 canopy spruce trees per hectare died standing in 10 years, with a mean diameter reaching 50–58 cm. Maximum diameters trees (70–80 cm) were represented by 1–4 stems per hectare. The values of the wood-specific gravity of standing trees were around 0.370–0.380 g.cm−3, and varied from 0.302 to 0.523 g.cm−3. Microscopically, our results point out that gap formation is a continuous long-lasting process, starting while canopy trees are living. We observed early signs of wood degradation and bacteria, possibly associated with bark beetles, that induce a strong effect when attacking living trees with vigorous defenses. New information about the initial phase of gap formation has provided a basis for the objective proposal of intervals and intensities of interventions, designed to promote a diversified structure and the long-term ecological stability of the mountain spruce stands in changing climate conditions. [ABSTRACT FROM AUTHOR]

Browsing and bark peeling by ungulates is known to affect biodiversity and may constitute the main driving factor of single tree population dynamics. In Slovakia, European yew (Taxus baccata L.) is a threatened species protected by law and present in many protected areas. In the study, we emphasize that protecting land and individual plants may not be sufficient for maintaining of yew populations, unless controlling over damage by deer game is also undertaken. Our results show that in beech forests of the Veľká Fatra Mts, browsing and bark peeling constitute the main negative factor affecting yew seedling-sapling ingrowth transition, and the mortality and vitality loss of adult yew trees. We argue that ungulates may have a larger effect on biodiversity conservation than currently realized.

The study aimed to quantify annual mortality and recruitment rates on permanent research plots in the Badínsky prales old-growth forest. The data measured in four stands originate from six censuses, which together cover a 48-year period. The mean annual mortality rate reached 4.2% (DBH > 2 cm) or 2.3% (DBH > 8 cm). The mortality peaked in the first part of the observation period, probably indicating an intermediate disturbance activity, and the subsequent declining trend led to minimum annual mortality during the last 20 years. We found substantially higher fir mortality in comparison with beech, primarily during the first decades of the measurement period. Among three size categories, the stems with DBH 2-8 cm showed the highest mortality rate. We detected the minimum fir recruitment rate throughout the observation period; on the other hand, the beech recruitment rate was relatively high responding to the open canopy. Standing and lying deadwood volumes indicated similar trends like mortality did, and high values of fir standing deadwood observed during the first decades can signify that a relatively high proportion of mortality was related to the fir decline caused by air pollution. [ABSTRACT FROM AUTHOR]

Th e subject of the research is to increase the stability of beech forests (Fagus sylvatica L.) by transforming them into forests of diameter classes. At the beginning of the experiment, the stands were 80 years old. Their transformation into the selection forest or the mosaic structure begun 24 years ago. The aim of the research was to obtain the information necessary for the design of models of beech selection forest and beech mosaic stand. Th e analyzed stands had a moderately diff erentiated height structure at the beginning of the experiment. In the permanent research plots (PRP 1-2) during 24 years of conversion and application of selective thinning and later selective cutting with an intensity of 14–18%, the phase of refinement of the selection structure took place. Based on the data analysis, we derived beech forest model with a target diameter of 50 cm, an optimal volume of 307 m³ ha–1 and a basal area of 27 m² ha–1. Th e conversion of beech stand on PRP 3 to the mosaic structure resulted in the proposal of the model characterized by the Weibull diameter distribution (target diameter 50 cm, basal area 31 m² ha–1, model stand volume 392 m³ ha–1). [ABSTRACT FROM AUTHOR]

Th e growth response of trees to changing climate plays a key role in the effi cient management of forest ecosystems. Th e case study analyses long-term growth trends and reactions of conifer tree species (Norway spruce, silver fi r, Scots pine) on climate characteristics in mixed selection forest of the Volovské vrchy Mts. in eastern Slovakia. Th e collection of data for the analysis of stand structure was carried out in 2016 on a series of 41 circular sample plots (size 500 m2). From the selected trees in diff erent vertical layers of forest stand we collected totally 152 cores. Sampled cores were processed with standard dendrochronological methods. Based on the data acquired from the tree cores, silver fi r was confi rmed as the tree species with the best growth during the last three decades. As the only one tree species, fi r showed a positive trend of diameter growth in this period. Regarding the infl uence of climate change, the most endangered tree species was Norway spruce. Its diameter growth was limited mainly by higher summer temperatures of current and previous year and by drought. According to the acquired results we assume that silver fi r can be one of the tree species, which will replace Norway spruce in many localities. Nevertheless, questionable is how the fi r will react on the gradual increase of climate extremes and the growing competitive pressure of European beech. Regarding the diff erences between stand layers, the results confi rmed a lower sensitivity of middle layer trees to the impact of drought in comparison with the upper layer trees. [ABSTRACT FROM AUTHOR]

The study presents the changes of structure in three Norway spruce-dominated forest stands with different soil type and aspect in demonstration object Pro Silva Donovaly-Mistríky (the Low Tatra Mts., Slovakia). In surveyed stands, the conversion to single-tree selection system using the current generation is being applied for the period of 40 years. Based on the data from the full calipering in 1979 and the stand inventory (stems and natural regeneration) in 1999, 2013 and 2021 on the series of permanent research plots (0.25 ha) in investigated stands, a relatively rapid advancement in the conversion process was observed. An appropriate model of selection forest is characterized by the optimal stand volume 320 m³ ha-1 and target dbh 66 cm in protection forests on ranker soil and by stand volume 385 m3 ha-1 and target dbh 66 cm in stand with dominant production function. Under the ongoing climate change, the high proportion of Norway spruce in the stands on nutrient-poor soils and the southern aspect could lead to their fast disintegration and gradual loss of differentiated structure. Research objects of this study were three forest stands with dominant proportion of Norway spruce in demonstration object Pro Silva DonovalyMistríky in orographic unit Nízke Tatry (Slovakia). Forest stands with different soil type and aspect have been converted to selection forest using the current generation for more than 40 years. The results of full calipering in 1979 and the stand inventory in 1999, 2013 and 2021 on the permanent research plots (0.25 ha) confirm that the stands have reached the stage of structuration (compartment 1606 and 1632c) or the stage of structure achievement (compartment 1631). In the compartment 1606 with southern aspect, despite the enhanced conditions of ranker soil, we observed a rapid dieback of spruce in the upper tree layer of the converted stand. In this phase, the stability of the upper tree layer is guaranteed by silver fir, as its vitality in these ecological conditions is acceptable. During the investigated period, dynamics of regeneration processes (individuals in height range 50–130 cm) was adequate, with balanced representation of spruce (58%) and fir (42% – Tab. 3). On the other hand, a significant decrease of tree density was registered in the category of ingrowth (height ˃ 130 cm, dbh ≤ 8 cm), with the reduction from 4480 ha-1 in 2013 to 1560 ha-1 in 2021. Despite the decrease of fir proportion (77%) in favour of spruce (23%), the dominance of fir in the lower tree layer is maintained (Tab. 3). In compartment 1632c, the ranker soil played a significant role in differentiation of diameter structure and natural regeneration of spruce and fir in clusters (Fig. 1 and 2; Tab. 3). The dynamics of regeneration processes during the investigated period was continuous, with the spruce proportion in natural regeneration (height 50–130 cm) reaching 53% and the fir proportion of 38% in 2021. The decrease to the density 1720 ha-1 was observed in the category of ingrowth. Reduction of the trees in this category that provides the individuals for the diameter class 10 cm resulted from the high tree density in the diameter class 10 cm. In compartment 1631, the dynamics of regeneration processes during the surveyed period was adequate, with balanced proportion of spruce and fir. The significant decrease (by 200%) in the ingrowth category was registered also in this compartment (Tab. 3). In the investigated stands, the reduction of the annual volume increment with the gradual approaching to the selection structure was observed. On the permanent research plots in compartments 1606 and 1632c that represent the stage of structuration, the annual volume increment reached 4.5 m³ ha-1 and 4 m³ ha-1. Compartment 1631 that is in the stage of structure achievement has the annual volume increment of 7 m3 ha-1. According to the ongoing continuity of regeneration processes and the differentiation of stand structure, the model with optimal stand volume of 320 m³ ha-1 and target dbh of 66 cm proposed for the protection stands (compartments 1606 and 1632c) was confirmed as appropriate. Model with such parameters is able to maintain the sustainable fulfilment of the non-production functions as well as the high-quality timber production (resonance wood). In the stand with dominant production function (compartment 1631) it is possible to set the target diameter to 66 cm and the optimal stand volume to 385 m³ ha-1 (Tab. 3; Fig. 1). The results confirmed that on such high-productive site even in the case of significant exceeding of the optimal stand volume this does not represent the risk for the regeneration processes. [ABSTRACT FROM AUTHOR]

Th is study analyzes the structure and short-term development of the spruce old-growth forest situated in the National Nature Reserve Zadná Poľana (Slovakia) during the years 2013 and 2018. Spatial positions and measured DBH (d1.3) and height of all living and dead standing trees with DBH d1.3 >8 cm were inventoried in 20 circular permanent research plots. Th e area of one circular permanent research plot was 1,000 m². In 2018, additional measurement of trees with DBH d1.3 >2–8 cm and coarse woody debris inventory was carried out. During five years 2013– 2018, a number of standing dead trees demonstrated a relatively big difference (-20.3%). Growing stock (+2.2%) and basal area (+1.3%) of the forest stand slightly increased, diameter DBH distribution of living trees remained with no significant change. Lower mortality rate of spruce (17 pcs ha–1) more or less conserved the bimodal structure of the assessed stand. Increase in the number of juvenile trees (9 pcs ha–1) within the first diameter class compensated spruce decrease only partially. Results of our study suggest the presence of the evident changes in the number of trees even over a relatively short period. [ABSTRACT FROM AUTHOR]

Th e research deals with the description of basic characteristics of stand structure and regeneration processes according to affecting factors. Characteristics are described before and aft er large-scale bark beetle outbreak in the high mountain spruce forest of the National Nature Reserve (NNR) Kotlov žľab. In 1968, a series of three permanent research plots (PRP) with the size of 0.50 ha was established at an altitude of 1400– 1500 m. Measurements of the stand structure and regeneration processes were carried out in 1968, 1978, 1988, 1998 and 2019. Before the largescale disturbance, the high mountain spruce forest was little differentiated and was dominated by single tree layer with stagnant regeneration. Th e development in PRP 3, which had initially the lowest number of trees, the highest variability of tree diameters and was located at the lowest altitude, responded best to the effect of disturbance. However, taking into account the forest development aft er disturbance, we can state that in 2019 there was a sufficient amount of advanced spruce regeneration in all PRPs, which will ensure that development does not take place through early successional stages. In the initial stage of the forest development, rowan could be expected to fill openings among remaining spruce trees. [ABSTRACT FROM AUTHOR]

The effect of commercial peat substrates (AgroCS, Gramoflor) and ectomycorrhizal (ECM) inoculations (Mycorrhiza roots, Mycorrhiza soluble, forest soil, vermiculite, vermiculite inoculum and control) on the root morphology of Norway spruce (Picea abies [L.] Karst.) seedlings was investigated. The experiment set-up was in complete randomized blocks. One block consisted of 12 combinations of inoculation (6 variants) and substrate (2 substrates). The whole experiment consisted of three blocks (repetitions). Lower root tissue density entails higher number of root tips, root forks and specific tips number per weight (STN-W). Higher root volume entails higher root length and average root diameter. Inoculation further enhanced the effect of the substrate where Mycorrhiza roots × AgroCS reached the highest root length (44.85 cm). For the number of root tips, the most significant positive effect was observed in the interaction of vermiculite × AgroCS (161). The interaction of Mycorrhiza roots × AgroCS significantly positively influenced STN-W (11 618). The number of root forks was the highest in the interaction of vermiculite × Gramoflor (173). The lowest values of root tips, root forks and STN-W (80; 85; 5109) were observed in the control × AgroCS interaction. The lowest root length (25.44 cm) was observed in forest soil × Gramoflor interaction. The conditions created by the interaction of Mycorrhiza roots × AgroCS were more favourable for morphological parameters of seedlings roots. [ABSTRACT FROM AUTHOR]

The conversion to uneven-aged, mixed-species stands represents one possible way to mitigate the consequences of disturbances in Norway spruce forests in Central Europe. A better understanding of the establishment and growth dynamics of the understory can contribute to a more effective conversion process. Here we investigate the structure of understory, light climate and growth of natural regeneration of Norway spruce and silver fir in two forest stands undergoing conversion to continuous cover forestry. Stand-wise forest inventory was conducted in 1993 and 2013. The natural regeneration was surveyed, and the light conditions and inter-tree competition were quantified in 51 sample plots established across the stands in 2013. Our results suggest that the diffuse radiation strongly affects the height growth of fir and spruce natural regeneration. We do not confirm the effect of local sapling density on the regeneration dynamics. The results further show that fir trees grow faster than spruce under less intensity of diffuse light. Most of the spruce and fir trees reached the upper limit of the lower overstory (DBH 12 cm) at approximately 50 years of age. Thus, more substantial reductions in stand density can lead to a well-differentiated structure in less than five decades. To control the prospective representation of spruce and fir in mixed-species forests undergoing the conversion, managing of light conditions is crucial. [ABSTRACT FROM AUTHOR]

Damage by herbivore grazing negatively influences the development of subsequent forest generations. Little is known about the long-term impacts of grazing and interactions between grazing and light conditions on sapling growth after the cessation of herbivory impact. In this study, Taxus baccata saplings were grown over a period of four years in artificial shading at 2, 8, 30 and 100% of full sunlight (described as initial light). These saplings were planted in fenced and unfenced plots in a mixed forest in Poland. After six years with no protection from grazing, deer pressure was eliminated by fencing. In this study, we analysed sapling growth and needle morphology five years after deer suppression. Overall, grazing had a negative significant impact on the growth rate and needle morphology of T. baccata saplings. Saplings damaged by herbivores had a height increment approximately one-third that of non-grazed saplings. The grazed yew saplings had a lower needle area and length and a higher specific leaf area (SLA) than non-grazed saplings. Initial and current light conditions did not influence tree growth rates and needle morphology. However, we found positive correlations between sapling height and both leaf area and leaf length and a negative correlation between sapling height and SLA. Browsed yews also had a greater tendency to form polycormic (multi-stemmed) individuals. Lower growth rates, smaller needles and polycormic stems indicate a strategy of "escaping" herbivory pressure even five years after elimination of deer pressure. [ABSTRACT FROM AUTHOR]