Wood decomposition by fungal communities plays a crucial role in regulating carbon dynamics and biodiversity within coarse woody debris (CWD), and these processes may be influenced by environmental change. However, the geographical distribution and functional roles of wood-decaying fungi are poorly explored. In the present study, we focused on CWD of Norway spruce, a dominant conifer species widely distributed in western Eurasia. Chemical analyses of 374 wood samples from six forest sites in central and southeastern Europe revealed a positive association between mean annual temperature (MAT) and dilute alkali solubility, a proxy for brown rot. DNA metabarcoding revealed associations between climatic conditions and wood-decaying fungal communities. Remarkably, the occurrence frequency of the dominant brown rot fungus, Fomitopsis pinicola, was positively correlated with MAT. These findings suggest that higher temperatures may promote lignin accumulation in Norway spruce CWD across central to southeastern Europe, potentially contributing to carbon storage in forests.

Competitive releases of understorey trees are an important pathway to canopy recruitment in unmanaged, closed-canopy forests, with significant consequences for resilience of these ecosystems. As climate and disturbance regimes progressively shift, the dynamics of canopy accession are expected to change. However, the response norms of subcanopy trees to competitive release and other developmental drivers have been understudied. To investigate the aggregate effects of multiple factors (i.e., disturbance severity, climate, ontogeny, topography, and calendar year) on growth rates and duration of growth releases, we examined growth patterns of more than 17100 tree cores of European beech and Norway spruce collected on permanent research plots located across primary forest remnants in the Carpathian Mountains. The percentage of canopy removed on the plot was the dominant extrinsic driver of growth during release events for both species, with beech exhibiting a more pronounced positive response than spruce. For both species, growth response was significantly affected by ontogeny-related factors: beech growth primarily increased with diameter at release onset, whereas spruce responded primarily negatively to age at release onset. Size at release onset also emerged as the primary predictor of release duration for both species. Additionally, both species exhibited increases in released growth rates throughout the past century, indicating a relative increase in canopy accession rates. However, it remains uncertain whether this trend will persist under a potential further intensification of disturbance regimes and shifting climatic constraints, particularly as trees on warmer and drier southern slopes already display weaker growth responses to canopy release compared to individuals on less sun-exposed sites.

Old-growth forests uniquely support biodiversity while serving as some of the planet's most important carbon stocks. The influence of tree and stand age on carbon flux dynamics remains debated-an urgent question as climate-driven disturbances may reshape forest age structures and in situ carbon storage. To clarify these relationships in Fagus sylvatica, systems, we examined a unique dataset of 3,503 tree ring series from 190 plots across some of the best preserved old-growth forests from five southern European countries. By employing a dendrochronological approach and integrating key environmental variables, including elevation, slope, temperature, and the presence of large-diameter trees (>= 60 cm), we analyzed the complex relationships between tree/stand age within a plot (represented by plot-level mean values, hereafter "stand age") and aboveground carbon stock across live, standing, and lying deadwood pools. The average stand age was 220 years, with 230 tC & sdot;ha-1 of carbon stored in aboveground biomass and necromass. We found a positive correlation between age and carbon storage at both the individual tree and plot levels. Notably, the presence of large-diameter trees was the strongest indicator of carbon stock, with carbon accumulation peaking at about 30% large-tree stems proportion before stabilising, while younger beech trees (below 100 years old) had a smaller contribution to carbon storage. We found no evidence of a decline in carbon stock with advancing stand age across the studied sites. Despite the ecological importance of old-growth forests, many of them remain unprotected and are disappearing across Europe. Our findings highlight the importance of preserving old-growth forests to maximize their role as long-term ecosystem carbon reservoirs.

Forest succession, pivotal for biodiversity restoration after disturbance, lacks comprehensive comparisons among different taxa to elucidate mechanisms driving spatiotemporal diversity changes across trophic levels. While forest succession is generally understood, knowledge of multi-taxon succession in lowland temperate broadleaf forests is limited due to scarcity of large old-growth habitats and insufficient long-term multitrophic data. We studied successional dynamics of understory plants and saproxylic beetles (xylophages, saproxylophages, saprophages, mycetophages and zoophages) in 91 oak-hornbeam forest stands and examined species richness of functional guilds and ecological traits across a chronosequence spanning 170 years of succession. We discovered non-linear successional patterns in species richness and functional groups of both taxa. Peaks in diversity were observed in the early-and late-successional stages, with extended periods of lower diversity in the middle stages. The patterns were closely associated with fluctuations in light availability. Early-successional stages harboured light-demanding species, taller plants, and flower-visiting beetles, while middle stages were species-poorer, favoring organisms typical of shaded, moist environments. In late-successional stages, diversity increased again due to self-thinning and stand aging as succession progressed, but the values did not reach the state of early stages. In temperate broadleaf forests, biodiversity fluctuates throughout succession, with brief peaks during the post-disturbance recovery phase and again later as trees age and canopy opens due to treefall. Effective conservation strategies should aim to maintain a heterogeneous canopy structure by applying partial cutting with retained trees and preserve old-growth attributes such as large deadwood and old trees, ensuring an open canopy around these elements.

Aim Norway spruce (Picea abies) is a dominant tree species across Eurasia, and is known to regenerate on decaying logs. Understanding its regeneration dynamics is crucial for predicting forest sustainability under climate change. The decay type of the logs, indicative of fungal decay capabilities of lignin and holocellulose and traditionally categorised into white rot and brown rot, markedly influences spruce seedling density on the logs, because brown rot reduces their establishment. As fungal distribution and wood decay types are affected by macroclimate, the success of spruce seedling establishment is expected to vary continentally and may be further influenced by climate change. The goal of the present study is to examine the relationship between decay type frequencies and spruce seedling densities on decaying logs, assessing effects on regeneration success along a climatic gradient. Location Fifteen sites in six European countries. Taxa Norway spruce (Picea abies [L.] H. Karst.). Methods We collected wood samples from spruce logs naturally decaying in the forest to evaluate their decay types. Spruce seedling numbers were recorded on the logs. The occurrence of certain decay types, seedling density, and their relationships with climate, stand, and log variables were analysed using generalised linear mixed models (GLMM) and structural equation modelling (SEM). Results White rot type of decay was dominating in central Europe compared with southern and northern Europe, where brown rot was prevalent. Spruce seedling densities were positively correlated with white rot in heartwood, which was explained by high precipitation seasonality in central Europe. Main Conclusions Spruce seedling regeneration on decaying logs may be indirectly affected by climate through its influence on fungal-mediated wood decomposition. Despite predictions of northward shifts in Norway spruce distribution due to climate change, slower regeneration rates on brown rot logs may limit northern expansion, potentially leading to a contraction of the species' range.

Forest recovery following disturbances is essential for maintaining ecosystem services, especially after large-scale events where regeneration is limited by seed availability. Understanding how environmental and biotic factors influence regeneration across spatial scales is fundamental for landscape-scale management, yet the importance and spatial extent of landscape-scale effects on local recovery remains uncertain. We aimed to assess the relative influence of recovery drivers at plot, patch, and landscape scales on post-disturbance forest regeneration. Specifically, we investigated how local topography, disturbance characteristics, and the spatial arrangement of undisturbed forests affect tree regeneration after severe disturbances, namely windthrows, fires, and bark beetle outbreaks. Our study combines a comprehensive ground-based dataset of post-disturbance regeneration from temperate European forests with Landsat-derived maps of forest cover. We applied a distance-weighted regression approach to evaluate the effect of landscape (i.e., undisturbed forest in proximity of disturbance patches) on recovery, improving upon traditional buffer-based approaches. We found that ¾ of the landscape influence on forest regeneration occurred within 112 m from plot centers, with undisturbed forests nearby positively enhancing regeneration, likely due to increased seed availability. In contrast, plot-level factors, namely disturbance severity and elevation, negatively impacted regeneration, suggesting that regeneration success can be hindered by severe disturbances reducing living biological legacies, as well as harsher local climatic conditions, associated with higher elevations. Our findings underline the importance of integrating landscape-scale management with targeted local interventions to promote post-disturbance forest recovery. Management strategies should consider spatially explicit planning to enhance seed source availability and mitigate severe disturbance impacts.

Extreme disturbance activity is a signature of anthropogenic environmental change. Empirical information describing the historical normative limits of disturbance regimes provides baseline data that facilitates the detection of contemporary trends in both disturbances and community-level responses. Quantifying the attributes of historical disturbances is challenging due to their transient episodic nature, with decades-to centurieslong intervals between recurrences. Unmanaged primary forests that support centuries-old trees therefore serve as unique reference systems for quantifying past disturbance regimes. We surveyed relict stands of primary beech-dominated forests over wide environmental gradients in the Carpathian Mountains of Europe. We collected core samples from 3,026 trees in 208 field survey plots distributed across 13 forest stands in two countries. We used dendrochronological methods to analyze time-series of annually-resolved ring-width variation and to identify anomalous growth patterns diagnostic of past forest canopy removal. A 180-year record (1810-1990) of spatially and temporally explicit disturbance events (n = 333) was compiled and used to derive statistical attributes of the disturbance regime. We quantified disturbance severity (canopy area lost), patch size, and return intervals. Our analyses describe a complex regime where a background of relatively frequent, smallscale, low-to intermediate-severity disturbance was punctuated by episodic large-scale high-severity events. Even the most severe events were non-catastrophic at a stand level, leaving significant residual tree cover that supported a continuity of ecological function. We did not detect evidence for an expected climate-induced intensification of disturbance with time, but methodological limitations precluded an assessment of disturbance activity in the decades since 1990.

An observed acceleration of tree mortality rates in European forests has been attributed to the impacts of climate change and extreme disturbances. Ecosystem recovery depends on regeneration success, but the recruitment of juveniles has been recognized as bottleneck in the development of forests. We investigated the potential importance of biotic (canopy tree abundance, ungulate herbivory) and abiotic (light, soil nutrients) factors in the limitation of regeneration in montane primary forests in central Europe. We used widely distributed forest inventory data (n = 348 plots) for two forest types, multiple tree taxa, and two life stages (seedlings and saplings). Seedling densities were promoted by more abundant parent trees, but saplings were either negatively influenced or unaffected by the number of conspecific adults. Browsing intensity (per capita defoliation severity) strongly limited the density of seedlings, but not saplings, at a community level. Low understory light levels were positively associated with seedling densities, but either did not affect or depressed sapling abundance A tolerance of shading was enhanced by nitrogen availability in some taxa. Our findings reflect highly complex, context-specific regeneration processes that vary by species and life stage within species.

Forest disturbances alter hydrological, energy, and microclimatic characteristics and their extents vary with the landscape characteristics of the terrain. We evaluated changes in evapotranspiration and latent heat rate in an unmanaged, central European mountain forest (Norway spruce) after a bark beetle-induced mortality of >75 % trees, and the spatial variability in microclimate during its natural regeneration. We observed that (1) the annual mean incident solar radiation to the treeless plots was 8.2 MJ m(-2) day(-1) (95 W m(-2)), being reduced by similar to 45 % compared to its theoretical flux by high average cloudiness (70.6%) and short daily sunshine (4.3 hour day(-1)). The observed energy input to the forest floor beneath survived canopies (1.2 MJ m(-2) day(-1)) was an order of magnitude lower than solar radiation to the canopy surface. (2) The mean annual evapotranspiration and the average annual latent heat rate decreased by 155 mm yr(-1) and 385 MJ m(-2) yr(-1) (12 W m(-2)), respectively, after tree dieback. (3) The soil and air temperatures at individual plots correlated positively with the incident solar radiation and negatively with elevation. Mean soil and air temperatures exhibited similar lapse rates of 5.9-8.0 degrees C km(-1) during the growing season (May-October). The energy input (positive relationship) and elevation (negative relationship) explained 74-83 % of the between-plot variability in mean soil and air temperatures and 51-77 % of their daily amplitudes during the growing season. (4) On sunny days, the observed soil and air temperatures were significantly lower (by similar to 50 and 15 %, respectively) than ground surface temperature based on thermal satellite data (Landsat-8). The ground surface temperature explained 80-92 % of the observed variability in the soil and air temperatures. (5) The between-plot differences in daily soil and air temperatures and their amplitudes were from 24 to 70 % explained by solar radiation (positive correlation) and relative air humidity and wind speed (negative correlations).

In recent decades bark beetle outbreaks have caused high mortality in natural mountain Picea abies forests in Central Europe. This study evaluated factors affecting seedling establishment of P. abies by focusing on the role of fungal communities in decaying logs, which is an important regeneration microsite. At the control site, which was affected by lower severity disturbance, well decayed logs with moss and vegetation cover hosted many seedlings. At the disturbed site, which experienced high mortality by bark beetles, greater canopy openness suppressed vegetation on logs and lowered seedling density. Additionally, the presence of a white rot basidiomycete Phellopilus nigrolimitatus was positively associated with seedling density. In contrast, the presence of a brown rot basidiomycete Fomitopsis pinicola was negatively associated with seedling density. The relationships between these decomposer fungi and seedling density might be partly attributed to changes in wood chemical properties and associated mycorrhizal and pathogenic fungi.

Recent observations of tree regeneration failures following large and severe disturbances, particularly under warm and dry conditions, have raised concerns about the resilience of forest ecosystems and their recovery dynamics in the face of climate change. We investigated the recovery of temperate forests in Europe after large and severe disturbance events (i.e., resulting in more than 70% canopy loss in patches larger than 1 ha), with a range of one to five decades since the disturbance occurred. The study included 143 sites of different forest types and management practices that had experienced 28 disturbance events, including windthrow (132 sites), fire (six sites), and bark beetle outbreaks (five sites). We focused on assessing post-disturbance tree density, structure, and composition as key indicators of forest resilience. We compared post-disturbance height-weighted densities with site-specific pre-disturbance densities to qualitatively assess the potential for structural and compositional recovery, overall and for dominant tree species, respectively. Additionally, we analyzed the ecological drivers of post-windthrow tree density, such as forest management, topography, and post-disturbance aridity, using a series of generalized additive models. The descriptive results show that European temperate forests have been resilient to past large and severe disturbances and concurrent climate conditions, albeit with lower resilience to high-severity fire compared with other disturbance agents. Across sites and disturbance agents, the potential for structural recovery was greater than that of compositional recovery, with a large proportion of plots becoming dominated by early-successional species after disturbance. The models showed that increasing elevation and salvage logging negatively affect post-windthrow regeneration, particularly for late-successional species, while pioneer species are negatively affected by increasing summer aridity. These findings provide a key baseline for assessing future recovery and resilience following the recent occurrence of widespread disturbance in the region and in anticipation of future conditions characterized by increasing heat and drought stress. As a result of global change, forest disturbances are becoming larger and more severe, which may put forest recovery at risk, especially under a warm and dry climate. Our study shows that European temperate forests have been able to recover after large and severe disturbances and concurrent climate conditions, although with more difficulty after fires compared with other disturbance agents. The main factors negatively influencing tree regeneration after wind disturbances were increasing elevation and the removal of damaged trees from the disturbed forests.image

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Addressing the scope of biodiversity loss is a societal issue. However, consensus regarding effective management practices to attenuate species extinction is lacking. An assessment of spatial variation in species assemblages (beta-diversity) provides a promising framework for informing forest landscape planning. Within the context of recent European Union biodiversity conservation goals, this research demonstrates an application of beta-diversity theory to understand spatial patterns in the distribution of a suite of environmentally-sensitive taxa within Europe’s remaining best-preserved primary forests. We sampled the local community composition (alpha-diversity) of four taxonomic groups (birds, epiphytic and epixylic lichens, saproxylic beetles, and deadwood-inhabiting fungi) to estimate corresponding levels of beta-diversity, as well as the underlying spatial components of nestedness and turnover. To identify particularly sensitive sites on the landscape that are potentially important for multiple species, we assessed beta-diversity congruence among the taxonomic groups. To elucidate critical abiotic factors and resource attributes underpinning biodiversity patterns, we regressed observed levels of local species richness against selected habitat variables. Results show that levels of beta-diversity were high and predominantly driven by spatial turnover, particularly for dispersal-limited organisms having relationships with deadwood. Beta-diversity was lowest for the avian group, reflecting their mobility. The lichen and fungal groups were correlated in terms of beta-diversity and turnover likely due to similar resource requirements. Variation in deadwood attributes (volume, decay stage) was significantly related to the local species richness of beetle and lichen communities. We identified occurrences of several threatened (red-listed) species that were similarly associated with deadwood substrates. We suggest that the beta-diversity patterns and habitat associations revealed by our analyses provide baseline data for comparison with managed systems. In particular, our findings highlight the importance of dead trees and logs for biodiversity conservation, suggesting a need for management strategies that retain an abundant and diverse supply of deadwood in forested landscapes.

Natural disturbances change forest habitat quality for many species. As the extent and intensity of natural disturbances may increase under climate change, it is unclear how this increase can affect habitat quality on different spatial scales. To support management tools and policies aiming to prevent habitat loss, we studied how habitat quality develops in the long run depending on the disturbance severity using a space-for-time substitution approach. We explored the effects of time since disturbance (0-250 years) and disturbance severity (20%-100% canopy removal) on structure-based habitat quality indicators in European primary Norway spruce Picea abies forests using 1000 m(2) circular plots in hierarchical design (a total of 407 plots in 35 stands). Disturbance history was reconstructed from tree cores. Habitat quality indicators were modelled as a function of the severity of the most severe disturbance and the time since this disturbance. We hypothesised that high within-stand habitat heterogeneity is formed by different successional stages after disturbances of various intensities. The results showed a U-shaped response of habitat quality to post-disturbance habitat succession on the plot scale. The decline deepened with disturbance severity. The U-shape response occurred in: large tree occurrence, amount of standing and lying deadwood, diversity of understory and understory openness. The spatial diversity in disturbance parameters increased spatial diversity of habitat quality on a stand level as expected. This high within-stand habitat heterogeneity also decreased with increasing age of the most recent disturbance. This suggests that the absence of young successional stages results in the absence of some important elements for biodiversity, for example sun-exposed snags. Synthesis and applications. Our results demonstrate that currently intensifying natural disturbance regime can consequently result in a lower habitat heterogeneity. In managed spruce forests after natural disturbances, we recommend at least the partial retention of biological legacies to preserve habitat heterogeneity and to avoid uniform and dense plantations resulting in a greater homogenisation. To emulate the natural disturbances pattern, spruce forests should be managed with a wide range of harvested patches of the size limited by a local natural disturbance regime creating spatial heterogeneity.

Forest areas infected by insects are increasing in Europe and North America due to accelerating climate change. A 2000-2020 mass budget study on major elements (C, N, P, Ca, Mg, K) in the atmosphere-plant-soil-water systems of two unmanaged catchments enabled us to evaluate changes in pools and fluxes related to tree dieback and long-term accumulation/losses during the post-glacial period. A bark-beetle outbreak killed >75 % of all trees in a mature mountain spruce forest in one catchment and all dead biomass was left on site. A similar forest in a nearby catchment was only marginally affected. We observed that: (1) the long-term (millennial) C and N accumulation in soils averaged 10-22 and 0.5-1.1 kg ha-1 yr-1, respectively, while losses of Ca, Mg, and K from soils ranged from 0.1 to 2.6 kg ha-1 yr-1. (2) Only <0.8 % and <1.5 % of the respective total C and N fluxes entering the soil annually from vegetation were permanently stored in soils. (3) The post-disturbance decomposition of dead tree biomass reduced vegetation element pools from 27 % (C) to 73 % (P) between 2004 and 2019. (4) Tree dieback decreased net atmospheric element inputs to the impacted catchment, and increased the leaching of all elements and gaseous losses of C (∼2.3 t ha-1 yr-1) and N (∼14 kg ha-1 yr-1). The disturbed catchment became a net C source, but ∼50 % of the N released from dead biomass accumulated in soils. (5) Despite the severe forest disturbance, the dissolved losses of Ca and Mg represented 52-58 % of their leaching from intact stands during the peaking atmospheric acidification from 1970 to 1990. (6) Disturbance-related net leaching of P, Ca, Mg, and K were 4, 69, 16, and 114 kg ha-1, respectively, which represented 7-38 % of the losses potentially related to sanitary logging and subsequent removal of the aboveground tree biomass.

Bark beetle disturbances are a critical event in the life cycle of Norway spruce forests. However, our knowledge of their effects on ectomycorrhizal fungi (EMF), which play a key role in forest productivity and nutrient cycling, is still incomplete. Special attention has been paid to the dynamics and diversity of EMF communities in managed forests, but studies dealing with disturbed natural stands are underrepresented. We conducted a study in an unmanaged natural spruce forest in the Bohemian Forest (Czech Republic), which suffered severe forest dieback caused by bark beetle. Approximately a decade after the disturbance, the character of the forest structure in the study area (∼60 ha, 41 study plots) ranged from sites with open canopy and sparse tree cover to areas with dense spruce regeneration to patches of closed-canopy forest. We found that relative EMF abundance in soils was positively related to surviving tree and regeneration density. The number of surviving trees also positively affected species EMF richness and tended to support preservation of late-successional EMF species. Our results suggest that trees that survive bark beetle disturbance are key for the fate of the EMF community in natural forests.

Canopy accession strategies reveal much about tree life histories and forest stand dynamics. However, the protracted nature of ascending to the canopy makes direct observation challenging. We use a reconstructive approach based on an extensive tree ring database to study the variability of canopy accession patterns of dominant tree species (Abies alba, Acer pseudoplatanus, Fagus sylvatica, Picea abies) in temperate mountain forests of Europe and elucidate how disturbance histories, climate, and topography affect canopy accession. All four species exhibited high variability of radial growth histories leading to canopy accession and indicated varying levels of shade tolerance. Individuals of all four species survived at least 100 years of initial suppression. Fir and particularly beech, however, survived longer periods of initial suppression, exhibited more release events, and reached the canopy later on average, with a larger share of trees accessing the canopy after initially suppressed growth. These results indicate the superior shade tolerance of beech and fir compared to spruce and maple. The two less shade-tolerant species conversely relied on faster growth rates, revealing their competitive advantage in non-suppressed conditions. Additionally, spruce from higher-elevation spruce-dominated forests survived shorter periods of initial shading and exhibited fewer releases, with a larger share of trees reaching the canopy after open canopy recruitment (i.e. in absence of suppression) and no subsequent releases compared to spruce growing in lower-elevation mixed forests. Finally, disturbance factors were identified as the primary driver of canopy accession, whereby disturbances accelerate canopy accession and consequently regulate competitive interactions. Intensifying disturbance regimes could thus promote shifts in species composition, particularly in favour of faster-growing, more light-demanding species.

Protecting structural features, such as tree-related microhabitats (TreMs), is a cost-effective tool crucial for biodiversity conservation applicable to large forested landscapes. Although the development of TreMs is influenced by tree diameter, species, and vitality, the relationships between tree age and TreM profile remain poorly understood. Using a tree-ring-based approach and a large data set of 8038 trees, we modeled the effects of tree age, diameter, and site characteristics on TreM richness and occurrence across some of the most intact primary temperate forests in Europe, including mixed beech and spruce forests. We observed an overall increase in TreM richness on old and large trees in both forest types. The occurrence of specific TreM groups was variably related to tree age and diameter, but some TreM groups (e.g., epiphytes) had a stronger positive relationship with tree species and elevation. Although many TreM groups were positively associated with tree age and diameter, only two TreM groups in spruce stands reacted exclusively to tree age (insect galleries and exposed sapwood) without responding to diameter. Thus, the retention of trees for conservation purposes based on tree diameter appears to be a generally feasible approach with a rather low risk of underrepresentation of TreMs. Because greater tree age and diameter positively affected TreM development, placing a greater emphasis on conserving large trees and allowing them to reach older ages, for example, through the establishment of conservation reserves, would better maintain the continuity of TreM resource and associated biodiversity. However, this approach may be difficult due to the widespread intensification of forest management and global climate change.

Tree mortality, driven by natural disturbance agents and climate, represents a crucial process shaping forest dynamics also influencing forest structure. The mortality rates and composition of mortality agents in primary mixed-species forests dominated by Fagus sylvatica L. were examined on different spatial scales using an extensive set of sample plots located in the Carpathian Mountains (i.e., 13,915 living trees on 227 plots within 16 stands). The determined overall annual mortality rate (i.e., 0.89%) was well within the previously published range of background mortality. Species-specific annual mortality rate was 0.76% for Abies alba, 0.88% for Fagus sylvatica, and 1.1% for Picea abies. Although the annual mortality rates below 2% were detected on 90% of plots, the mortality rates of 5% per year were exceeded only for conifers on 5% of plots. Plot-level mortality varied; lower rates were observed in the western Carpathians, compared to other regions, and significant differences were found in species-specific mortality between coniferous species and F. sylvatica. Most trees that had recently died were found in the smallest diameter classes with their counts continuously decreasing towards the bigger size classes. Individual mortality agents had different distributions across the size classes, highlighting the complexity of the mortality process in the primary forests. Most study stands experienced drought stress; however, the climatic extremes were recorded as the major mortality agent only in a limited number of cases. While competition and various forms of abiotically caused physical damage were the major mortality agents for F. sylvatica and A. alba, insect infestation was the most frequent mortality agent for P. abies suggesting insects to have a crucial role in tree species dynamics emphasising the importance of structural and compositional heterogeneity even in the stands with low overall mortality and relatively low abundance of P. abies. Conservation of these remaining European beech-dominated primary forests is critical due to their significance in preserving local biodiversity and avoiding irreversible losses.

&lt;p&gt;Primary beech-dominated forests are rare in Central Europe, while the knowledge of natural processes of these ecosystems is crucial for understanding the forest dynamics providing complex of ecosystem services. In order to understand these ecosystems better, which were one of the most widespread in this region, we decided to study their disturbance regimes and their long-term and recent trends driven mostly by natural disturbances.&lt;/p&gt;&lt;p&gt;The study was conducted within the region of Carpathian Mountains including 14 stands and 210 permanent study plots. All living and dead trees were inventoried on these plots, while selected trees were cored. Disturbances were reconstructed by examining individual tree growth patterns: (1) rapid juvenile growth rate (open canopy recruitment), and (2) abrupt, sustained increases in radial growth (release). From these disturbance patterns we reconstructed other disturbance parameters as disturbance severities, patch sizes and plot proportions of disturbed plots on the stand scale characterizing disturbance regime. Further, generalized linear mixed effect models were used to asses long-term and recent trends in these disturbance parameters.&lt;/p&gt;&lt;p&gt;Studied ecosystems were driven by mixed severity disturbance regime. The disturbance events revealed continuous gradient from low-severity, small-scale events to higher-severity, larger-scale events, and this gradient was progressively increasing with the rotation period. The low severity class was the most frequent, but it had similar canopy area disturbed (23.9 %) as moderate and high severity class (34.4 %, 27.1 %), respectively. The very high severity class had the longest rotation period and it affected only 14.7 % of overall canopy area disturbed. Long-term and recent trends in disturbance severities and patch areas were not detected. Plot proportions of disturbed plots on the stand scale had slightly declining trend in time over last two centuries, but the recent trend was not detected.&lt;/p&gt;&lt;p&gt;Analysis of the recent trends in disturbance characteristics have not shown increasing trend, as it was reversely observed in Europe proving the value and stability of these ecosystems under pressure of climate changes. Based on our findings we highly recommend to localize and protect primary and old-growth forests for their high conservation values, high and stable carbon stock, and provision of other ecosystem services. For enhancement of the managed forests&amp;#180; stability we could recommend to support natural species composition and nature-based forest management mimicking natural disturbance regimes as retention silvicultural system combining irregular shelterwood and selection systems with occasional clear cuts.&lt;/p&gt;