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• A complex of factors at different spatial scales affects beech growth response. • The variability in responses to an identical event implies uncertainty in reconstructing disturbance histories. • A detailed examination of all important parameters of the growth reaction is suggested. Despite improvements of dendrochronological techniques in many forest ecosystems, studies describing the growth responses of trees following disturbance events including comprehensive data on factors and processes behind tree-growth release are rare, especially for European temperate forests, limiting the interpretation and generalization of dendroecological studies. Here we examine the effect of key factors on the growth reaction of Fagus sylvatica L. to disturbances in 8 old-growth forests in the Czech Republic, independently dated using three different data sources – tree censuses, dendrochronology and historical aerial photographs. Using 117 increment cores, we studied four parameters of radial tree-growth surrounding canopy gaps: magnitude, duration, abruptness and response shift, in relation to factors of different spatial scales, i.e. tree-, gap- and stand-level variables. Our results indicate that the beech growth response to gap formation strongly differs across a complex of factors at diverse spatial levels, frequently occurring in noteworthy interactions. A positive trend for the gap size * radiation interaction in the analysis of magnitude was found, suggesting that the effect of gap area differs among topographical features. As for duration and abruptness, the interaction of distance and mortality mode was identified, indicating a longer and more gradual reaction along with increasing distance of the cored tree from the gap centre, varying by the type of the gap maker's death. In addition, an altitudinal gradient was found to predict the magnitude of growth changes and the time interval between the disturbance and the reaction of nearby trees. Surprisingly, the diameter of the surviving trees was not a good predictor of radial growth, with a significant positive relationship to just abruptness. An effect of locality was not observed, facilitating the broad applicability of our findings across a wide range of beech-dominated temperate forests. Our results emphasize the general limits of dendrochronological data in disturbance spatial pattern studies, as indicated by the considerable variability in the responses of neighbouring trees to identical disturbance event. A detailed examination of the growth reaction, considering not only the response magnitude but also other important parameters, plays a key role in the precision of detecting growth releases as well as in reducing the sample size required for summary disturbance history evaluations. In focusing on this issue we believe we contribute to future dendroecological research by demonstrating the need for more precise disturbance history evaluations. [ABSTRACT FROM AUTHOR]

Post-disturbance pedogenetic pathways were characterized in three landscapes representing different degrees of weathering and leaching. Tree uprooting has been the main form of disturbance in all three landscapes. We hypothesized that the pedogenetic effect of trees due to uprooting is mainly governed by the regional degree of pedogenesis, which in turn affects soil and landscape evolution. The three regions were characterized by a chronosequence of treethrow pit-mound pairs, from fresh to almost leveled forms. Two sequences originated from the Czech Republic, one on Haplic Cambisols and one on Entic Podzols. The third and the oldest chronosequence, in Michigan, USA, was on Albic Podzols (dating back to 4080 BCE). We analyzed 38 chemical and physical soil properties for 700 samples from 42 pit-mound pairs in these regions. Ordination and regression techniques allowed us to evaluate the effect of sample depth, microsite (pit, mound, and undisturbed control position), and age of the soils formed after uprooting. Depth was the most significant variable in all regions ( p < 0.001), followed by microsite location, and then age (time since disturbance). The significance of these variables decreased with increasing weathering and leaching intensity. The results suggest that intense pedogenesis, as at the Michigan site, decreases the polygenetic impacts of uprooting on soil development pathways. On Haplic Cambisols, disturbances increased the local variability of pedogenic processes by changing melanization and hydromorphic processes, as well as by mineral alteration. Conversely, on Albic Podzols, we found comparative chemical uniformity in post-uprooting pedogenesis between microsites, despite rapid podzolization in pits and slower podzolization on mounds. The general chemical convergence of pedogenesis in these landscapes towards vertically-dominated podzolization may limit divergence of pedogenic pathways after a disturbance. The formation and translocation of labile organic matter-sesquioxide complexes in the uppermost podzolic horizons in Entic Podzolś was a key threshold, in that it changed the pedochemical, ecological and biogeomorphic role of the treethrow features in the soil and landscape evolution. Although treethrow pits were accumulation sites for soil elements in Haplic Cambisols and Entic Podzols, they were microsites of intense leaching and elemental loss in Albic Podzols. [ABSTRACT FROM AUTHOR]

In order to gauge ongoing and future changes to disturbance regimes, it is necessary to establish a solid baseline of historic disturbance patterns against which to evaluate these changes. Further, understanding how forest structure and composition respond to variation in past disturbances may provide insight into future resilience to climate-driven alterations of disturbance regimes. We established 184 plots (mostly 1000 m 2 ) in 14 primary mountain Norway spruce forests in the Western Carpathians. On each plot we surveyed live and dead trees and regeneration, and cored around 25 canopy trees. Disturbance history was reconstructed by examining individual tree growth trends. The study plots were further aggregated into five groups based on disturbance history (severity and timing) to evaluate and explain its influence on forest structure. These ecosystems are characterized by a mixed severity disturbance regime with high spatiotemporal variability in severity and frequency. However, periods of synchrony in disturbance activity were also found. Specifically, a peak of canopy disturbance was found for the mid-19th century across the region (about 60% of trees established), with the most important periods of disturbance in the 1820s and from the 1840s to the 1870s. Current stand size and age structure were strongly influenced by past disturbance activity. In contrast, past disturbances did not have a significant effect on current tree density, the amount of coarse woody debris, and regeneration. High mean densities of regeneration with height >50 cm (about 1400 individuals per ha) were observed. Extensive high severity disturbances have recently affected Central European forests, spurring a discussion about the causes and consequences. We found some evidence that forests in the Western Carpathians were predisposed to recent severe disturbance events as a result of synchronized past disturbance activity, which partly homogenized size and age structure and made recent stands more vulnerable to bark beetle outbreak. Our data suggest that these events are still part of the range of natural variability. The finding that regeneration density and volume of coarse woody debris were not influenced by past disturbance illustrates that vastly different past disturbance histories are not likely to change the future trajectories of these forests. These ecosystems currently have high ecological resilience to disturbance. In conclusion, we suggest that management should recognize disturbances as a natural part of ecosystem dynamics in the mountain forests of Central Europe, account for their stochastic occurrence in management planning, and mimic their patterns to foster biodiversity in forest landscapes. [ABSTRACT FROM AUTHOR]

Because of some arbitrary decisions in recent dendrochronological research on forest disturbance histories, describing the actual growth responses of trees to disturbance events is still an issue of great importance. This is even more important in temperate beech-dominated old-growth forests driven by fine-scale disturbances, where a majority of growth pulses occur close to the arbitrary threshold of release detection. Recognizing this limitation, we provide a new empirically-based release detection criterion on the basis of actual reactions of trees to independently dated disturbance events interconnecting three data sets – tree censuses, dendrochronology and historical aerial photographs. The growth response of Fagus sylvatica L. was studied in detail in relation to the canopy position of surviving trees as well as regional climate responses, using 280 increment cores extracted in 8 old-growth forests in the Czech Republic. Cluster and bootstrap analysis resulted in distinguishing 2 ecoregions with site-specific growth patterns and plasticity. A boundary line (BL) method was applied to the identification and quantification of release, providing a new curve for F. sylvatica regionally valid in the mountainous regions of Central Europe. During the period investigated (1970s–1990s) 7% of trees experienced no reaction, despite clear evidence of canopy disturbances in both aerial photographs and tree censuses. 25% of growth changes were attributed to regional-scale environmental factors, in particular climate and air pollution. The magnitude of the growth response varied significantly among canopy positions, with subcanopy trees released from suppression experiencing the most intense growth rates, and individuals under permanent suppression showing a negligible response. Considering these differences we empirically inferred new criteria, subdivided into two categories according to disturbance intensity. Pulses falling within the 25–63% of the boundary line are classified as weak releases while pulses exceeding 63% of the BL are identified as major. Still, our results imply relatively high uncertainty in the detection of disturbance using dendrochronology, which can be troubled particularly in spatial analysis of past disturbances. We believe that our empirically-derived criteria represent a substantial contribution to further dendroecology research, with broad applicability to a wide range of beech-dominated temperate forests. [ABSTRACT FROM AUTHOR]

The use of individual-based models in the study of the spatial patterns of disturbances has opened new horizons in forest ecosystem research. However, no studies so far have addressed (i) the uncertainty in geostatistical modelling of the spatial relationships in dendrochronological data, (ii) the number of increment cores necessary to study disturbance spatial patterns, and (iii) the choice of an appropriate geostatistical model in relation to disturbance regime. In addressing these issues, we hope to contribute to advances in research methodology as well as to improve interpretations and generalizations from case studies. We used data from the beech-dominated Žofínský Prales forest reserve (Czech Republic), where we cored 3020 trees on 74 ha. Block bootstrap and geostatistics were applied to the data, which covered five decades with highly different disturbance histories. This allowed us to assess the general behavior of various mathematical models. Uncertainty in the spatial patterns and stability of the models was measured as the length of the 95% confidence interval (CI) of model parameters. According to Akaike Information Criterion (AIC), the spherical model fitted best at the range of ca. 20 m, while the exponential model was best at the range of ca. 60 m. However, the best fitting models were not always the most stable. The stability of models grew significantly with sample size. At <500 cores the spherical model was the most stable, while the Gaussian model was very unstable at <300 cores. The pure nugget model produced the most precise nugget estimate. The choice of model should thus be based on the expected spatial relations of the forest ecosystem under study. Sill was the most stable parameter, with an error of ±6–20% for ≥1110 core series. By contrast, practical range was the most sensitive, with an error of at least ±59%. The estimation of the spatial pattern of severe disturbances was more precise than that of fine-scale disturbances. The results suggest that with a sample size of 1000–1400 cores and a properly chosen model, one reaches a certain precision in estimation that does not increase significantly with growing sample size. It appears that in temperate old-growth forests controlled by fine-scale disturbances, it is necessary to have at least 500 cores to estimate sill, nugget and relative nugget, while to estimate practical range at least 1000 cores are needed. When choosing the best model, the stability of the model should be considered together with the value of AIC. Our results indicate the general limits of disturbance spatial pattern studies using dendrochronological and geostatistical methods, which can be only partially overcome by sample size or sampling design. [ABSTRACT FROM AUTHOR]

There are hundreds of scientific papers dealing with the issues of biodiversity and extinction debt in temperate forests, both of which are partly related to the absence of deadwood. Some studies have derived habitat thresholds for deadwood (according to species, size, spatial distribution) as baselines for management recommendations. But a majority of studies have one important knowledge gap – how long does it take for deadwood to decompose? To derive the residence time of deadwood, we used a 40-year time series of 4 censuses in European lowland hardwood temperate forests. The deadwood residence of 2252 logs of 5 main tree species was calculated using Bayesian Survival Trajectory Analysis. Pedunculate oak ( Quercus robur ) had the longest residence time, with the largest logs decomposing for an average of 62 years. Next was narrow-leaved ash ( Fraxinus angustifolia ) with a residence time of about 42 years. Field maple ( Acer campestre ) and hornbeam ( Carpinus betulus ) had a similar residence time – with the largest logs averaging 37–39 years. Elm ( Ulmus sp.) had the fastest decomposition of large-sized logs – estimated at 24 years. Generally, small-sized logs of all investigated species decomposed quickly. Conversely, large-sized logs of hornbeam and ash decomposed as quickly as their intermediate-sized logs. Large-sized logs of elm decayed even faster than intermediate-sized logs. An analysis of the position of field maple logs during decomposition showed that those decomposing in the air or in water decomposed slower than logs “on the ground”, with a half-life of 40 years (compared to 28 years on the ground) and a residence time of 54 years (44 years on the ground). Our results suggest that the management of deadwood should focus on (i) leaving the largest logs, which took the longest time to reach advanced decay stages, and (ii) a diversified approach regarding the individual residence time of different tree species. [ABSTRACT FROM AUTHOR]

Questions Uncertainty in detecting disturbance histories has long been ignored in dendrochronological studies in forest ecosystems. Our goal was to characterize this uncertainty in relation to the key parameters of forest ecosystems and sample size. In addition, we aimed to provide a method to define uncertainty bounds in specific forest ecosystems with known parameters, and to provide a required (conservative) minimal sample size to achieve a pre-defined level of uncertainty if no actual key forest parameters are known. Location Training data were collected from Žofínský Prales (48°40′N, 14°42′E, 735–830 m a.s.l., granite, Czech Republic). Methods We used probability theory and expressed uncertainty as the length (the difference between the upper and lower bounds) of the 95% confidence interval. We studied the uncertainty of (i) the initial growth of trees – if they originated under canopy or in a gap; and (ii) the responses to disturbance events during subsequent growth – on the basis of release detection in the radial growth of trees. These two variables provide different information, which together give a picture of the disturbance history. While initial growth date the existence of a gap in a given decade (recent as well as older gaps are included), release demonstrates the moment of a disturbance event. Results With the help of general mathematical deduction, we have obtained results valid across vegetation types. The length of a confidence interval depends on the sample size, proportion of released trees in a population, as well as on the variability of tree layer features (e.g., crown area of suppressed and released trees). Conclusions Most studies to date have evaluated the initial growth of trees with higher uncertainty than for canopy disturbed area. The length of the 95% confidence interval for detecting initial growth has been rarely shorter than 0.1 (error ± 5%) and has mostly been much longer. To reach 95% confidence interval length of 0.1 (error ± 5%) when detecting the canopy disturbed area, at least 485 tree cores should be evaluated in studied time period, while to reach a 0.05 interval length (error ± 2.5%) at least 1925 tree cores are required. Our approach can be used to find the required sample size in each specific forest ecosystem to achieve pre-defined levels of uncertainty while detecting disturbance history. [ABSTRACT FROM AUTHOR]

Unlike many studies on the stand structure of European beech-dominated natural forests we explicitly examined the spatial variability of six general stand characteristics: density, basal area and volume of living trees, volume of deadwood, total volume and the proportion of deadwood in the total volume. We asked whether and how these stand characteristics are spatially organized and autocorrelated, and how their spatial autocorrelation varies among particular characteristics, study sites and observation scales. The study was conducted at three forest stands dominated by Fagus sylvatica L. and co-dominated by Picea abies (L.) Karsten and Abies alba Mill., which represent the few sizable remnants of beech-dominated natural forests in central Europe. Vector stem position maps of the three sites were examined by the computer-simulated placement of differently sized square sample plots (10 x 10; 20 x 20; 30 x 30; 50 x 50 and 70 x 70 m). The six general stand characteristics were calculated for every simulated sample plot. Experimental semivariograms were calculated for all sampling plot (grain) sizes, model semivariograms were only fitted for 20 x 20 m plots. The spatial variability of stand characteristics significantly changes with the scale of observation. At the finest grain the spatial autocorrelation is mostly quite low and usually very nearly approximate the nugget model. However, autocorrelation increases with increasing sampling plot size. A peak in the first lag of the semivariograms was observed only at the finest grains, documenting the competition of large trees, whereas a recurring pattern of patches with similar stand characteristics was identified at larger observation scales. Nested structures formed by the high nugget and relatively less distinct but still apparent sill/range and fluctuation signal were detected in most of the model semivariograms, indicating different sources of variability operating at multiple scales. Moreover, significant differences among particular stand variables were demonstrated. The relative nugget varied from 61% (stand density) to 96% (stand volume) at the 20 x 20 m sampling plots; the autocorrelation ranges varied from more than 320 m to 64 m, respectively. The irregular periodic patchiness found (usually 400-1100 m² in size) may serve as a model for close-to-nature forestry, which emulates the spatial structures of natural forests. The level of positive spatial autocorrelation acknowledged for stand density should be reflected in an effective sampling design. For better estimates of the variance in this variable, sampling in a regular grid or stratified sampling is suggested. [ABSTRACT FROM AUTHOR]

Highlights: [•] Soils were studied on three sites of natural mountain spruce forests. [•] A total number of 1107 soil profiles were described within continuous areas ≥ 40ha. [•] Geostatistical techniques were used to detect soil spatial patterns from 1 to 300m. [•] The patterns were discussed in relation to different characteristics of the sites. [•] Our study enhances the understanding of the soils in mountain spruce forests. [Copyright &y& Elsevier]

Highlights: [•] Crossdating of tree uprooting events increases reliability and range of dating. 210Pb dating was used successfully for the dating of treethrow pits and mounds. [•] Pit-mound longevity can exceed 6000yrs in Michigan and 1700yrs in Central Europe. [•] Bole breakages prevailed over uprootings by 2–3:1 in (spruce)-fir-beech forests. [•] A treethrow rotation period of 1200–1400yrs is normally valid for Central Europe. [ABSTRACT FROM AUTHOR]

Abstract: Interactions between pit-mound dynamics and tree species populations were studied in a natural mountain (fir)-spruce-beech forest. Pit-mounds are special habitats with unique erosion-sedimentation and microclimatic conditions, which continually influence the trees growing there. Our assumption was that these factors would impact on the competitive potential of the trees and that the interaction between the pit-mound dynamics and the tree layer would not be static, but would change depending on the ages of both the trees and the pit-mounds. Over an area of 74.2ha that was repeatedly studied in 1975, 1997, and 2008 in terms of the tree layer structure (about 23,000 trunks), pit-mound evaluation was performed on a regular network of 354 circular plots with a 23m diameter (1733 pit-mounds in total). Dendrochronological cores were drilled in 1986 samples in order to establish an age structure of the tree layer. Using tree-census, dendrochronological, and mathematical methods, direct or indirect dating of the pit-mounds was performed. The actual occurrence of trees on the pit-mounds was compared with a null model corresponding to random occurrence for various age categories of the trees/pit-mounds. The number of trees decreased smoothly with age in the respective classes. The dominant species was Fagus sylvatica, which like Picea abies and Abies alba reached an age of >450years. A multi-peak pit-mound age structure suggested the occurrence of stronger episodic disturbance events in the past. Mounds covered 8.5% and pits 3.7% of the studied area (121pieces/ha) and the average pit-mound size was 9.92m2. F. sylvatica and other marginally represented trees (A. alba, Sorbus aucuparia, Acer pseudoplatanus, Ulmus glabra) significantly preferred mounds over other microsites (χ 2 =147.37, p <0.001; resp. χ 2 =14.73, p =0.005). The preference to mounds by marginally represented tree species decreased with the age of the trees, whereas the affinity of F. sylvatica increased with age. Also, older individuals of P. abies were more frequently found on mounds compared to the null model, although the overall presence of P. abies on mounds was significantly deficient (χ 2 =11.21, p =0.024). These results suggest that the competitive potential of the trees on mounds decreases with age only in trees of initial succession stages. Mounds older than 101years were most favourable to natural regeneration. [Copyright &y& Elsevier]

Abstract: Changes to vegetation and soil were assessed in primeval forests of the Eastern Carpathians after a period of 59–68years. We hypothesized that forest ecosystems were acidified through the long-distance transport of air pollutants. A total of 141 relevés and 20 soil profiles that had been studied in 1938 in spruce- and beech-dominated forests along an altitudinal gradient ranging from 1085–1575ma.s.l. were re-surveyed from 1997 to 2006. Relevés were analyzed using multidimensional statistics and plant community characteristics (Shannon–Wiener’s index, equitability, fidelity, Ellenberg indication values – EIV); soil reaction and sorption complex properties were analyzed in soils. A total of 159 vascular plant taxa were recorded in 1938, of which 35 were not found during the repeat survey. During the later survey, 137 taxa were found, of which 13 were new findings. The upper mineral (A) as well as cambic or spodic (B) horizons were considerably acidified in both forest types. Both active and exchange soil reaction decreased by 0.1–0.3 units on average, exchangeable acidity significantly increased and the sum of base cations decreased in both soil horizons and forest types. Base saturation decreased by more than half of original values, with a maximum decrease of 68% found in the B-horizon of spruce forests. Whereas the herb layer developed along with soils in beech-dominated forests, EIV values for soil reaction increased in spruce-dominated forests, probably due to the movement of broadleaf woody species to higher elevations or due to the higher resistance of herb species to soil acidification. Significant changes to EIVs also occurred in the beech- and/or spruce-dominated forests for the factors of nitrogen, light moisture and temperature. There was an expansion of the lower tree and shrub layers, primarily Fagus sylvatica, Picea abies and Sorbus aucuparia in intermediate and higher elevations, which can be explained by reduced cattle grazing. Also, the dissipation of Juniperus communis and marked decline of Abies alba are interpreted as being related to gradual changes in landscape management along with the effect of acid deposition. Since 1938, all stands have shown a significant increase in nitrophilous taxa such as Rubus idaeus, Athyrium distentifolium, Urtica dioica, Calamagrostis arundinacea, Stellaria nemorum. Significant decreases in the number of species, Shannon–Wiener’s index and equitability were only observed in spruce-dominated forests. Neophyte taxa were not detected in either the 1930s or the 1997–2006 period. [Copyright &y& Elsevier]

Abstract: The long-term development of stand characteristics and tree spatial patterns (TSP), their mutual relation, and linkage to site and tree species were studied in the Boubín primeval forest (protected since 1858). Surveys were carried out in 1851, 1961/1964, 1972, 1984/1989, 1996 and 2010 on one to six research plots sized 0.58–1.00ha. To see how results from these surveys could be generalized, results were also compared with whole-area data sets (46ha) from 1972 to 2010. The proportion of Abies alba continually decreased, from 20% in 1851 to 2–3% in 2010. This decrease started no later than at the beginning of the 20th century. In contrast, the proportion of Fagus sylvatica slightly increased. The sum of dead and living wood volume was stable during the 159year period, with deviations of only up to 5%. From 1961/64 to 2010, the number of living trees continually decreased, but the mean-tree volume and volume of dead wood increased. The distribution of dead wood always differed from the distribution of living trees. A random TSP was always most common, which seems to be typical for this type of forest. This was true even when A. alba was gradually forced out from the stand structure. Nevertheless, the pronounced decrease of A. alba found during the 1961/64 survey compared with 1851 was reflected in a tendency towards clustering, as gaps from A. alba dieback gradually closed. In these gaps, competitive pressure was lower, resulting in more clustered distributions. Regular distribution was recorded only rarely. F. sylvatica maintained a random or clustered TSP over long periods, depending on site conditions. On water-affected plots, it had a consistently higher tendency towards clustering. The only step change in TSP occurred due to Hurricane Emma in 2008. Otherwise, the most marked TSP changes over time were found for Picea abies, in which there was a gradual trend from clustered to random, connected with a decreasing number of individuals. The main reason for the decline of A. alba and the decreased number of living trees from 1961/64–2010 was the on-going effect of a high stock of red deer at the turn of the 19th and 20th centuries. The decreasing trend in the number of living trees showed no marked change, even 60years after the game pressure was strongly reduced. However, the vertical structure became increasingly homogenized due to the long-term absence of severe abiotic and/or biotic disturbances. [Copyright &y& Elsevier]

Abstract: Current knowledge of the within-site variability of major stand structural features in beech dominated natural forests is limited. Numerous studies have used just several small plots for characterizations of natural stands, but this may lead to generalizations based on unreliable results. This study shows how major stand structural features vary at the local scale, and how suitable sampling may reflect this variability. Stem position maps of three natural forests in the Czech Republic (Zofin 71ha, Salajka 19ha and Zakova hora 17ha) were used. Each vector stem position map representing all live and dead trees with DBH≥10cm was intensively analyzed using square sample plots of different sizes (10×10m; 20×20m; 30×30m; 50×50m; 100×100m; 140×140m and 200×200m). Basic statistics (mean, standard deviation, coefficient of variation, min., and max.) were calculated for every plot size and each of six major stand features: density, basal area and volume of living trees, volume of course woody debris, total volume and proportion of course woody debris in total volume. As expected, the local relative variability of major stand structural features decreased with increasing plot size. For particular stand features, the observed trend was expressed by significant regression models (y = a × x b ) with high coefficients of determination across all study sites. The results further show that even hectare-to-hectare values are still highly variable; e.g. the volume stock of living trees can range from 474 to 1049m3/ha within one study site. Hence, single samples of 1ha can be poorly representative. We also calculated the minimal number of plots and total sampled area required for estimations of major stand features to within 20% (±10%) of the mean with 95% confidence for particular plot sizes. It appears that plot sizes between 0.01 and 0.09ha would be the most efficient for sampling the above-mentioned variables in European beech-dominated natural forests. [Copyright &y& Elsevier]

Abstract: The age of single windthrows (single uprooted trees and/or pit/mound microtopographical pairs) in a natural fir-beech forest was assessed in the flysch zone of the Outer Western Carpathians. The following characteristics were evaluated for all 1562 single windthrows occurring in a 10.8ha area: dimensions; thickness of organic and upper mineral soil horizons both on mounds and in pits; and the presence of new trees taking root on the windthrows. For more recent windthrows, selected quantitative and qualitative characteristics of the uprooted trees were evaluated. A suppositional gradient of age (SGA) was constructed based on the windthrow characteristics using principal component analysis. A representative sample of windthrows was dated along the SGA with the use of dendroecological techniques and historic records from 1972 and 1995. For European beech (Fagus sylvatica L.) we were able to measure the actual threshold of release value – at 12% of growth change. The age of windthrows was determined in 37 of a total of 51 cases. The development of windthrow properties over time was studied. Age explained 33.7% of the variability in the measured windthrow characteristics (F =19.31, p =0.0002, measured characteristics see above). A multiple regression model (R 2 =0.844, F =65.62, p <1×10−6) was constructed to evaluate the age of undated windthrows. The best predictors of age were: ordinal classification of trunk disintegration and thickness of F and A horizons on the mound. In 2006, windthrows occupied 14.3% of the surface area of the studied locality, with a maximum windthrow age of 220 years. Approximately 1% of windthrows (1.5% of the windthrow area) were older than 150 years; 20% of windthrows (31% of the windthrow area) were older than 100 years, and 56% (78% of the area) were older than 50 years. The oldest windthrows with an uprooted trunk still present were 50–60 years old. The locality has not been affected by any high intensity (large scale) disturbances in the past. The period of direct soil turnover resulting from windthrows was about 1250 years. Compared with natural forests, the human caused long-term absence of windthrows in commercial forests may affect the course of soil formation. A single 100-year rotation period represents the absence of soil disturbance on 10% of the area. [Copyright &y& Elsevier]

• Canopy trees altered forest floor by litter and deadwood production and uprooting. • Deep beech litter accumulations prevented regeneration of spruce, but not of beech. • Deadwood and uprooting mounds were the best microsites for spruce regeneration. • Soil wetness became more limiting for beech regeneration in larger size classes. • Canopy trees of both species showed the ability to support their own regeneration. Natural regeneration of European beech (Fagus sylvatica) and Norway spruce (Picea abies) plays a crucial role in the future of many European mountain forests. It is affected by various soil and stand-related factors whose relative importance, especially in mixed stands, is still not known. In this study, we assessed the importance of stand composition, soil wetness, disturbances and different microsites and seedbeds for regeneration of beech and spruce in a mixed old-growth mountain forest. We also focused on how the effects of these factors change as regeneration gets older. We sampled all regeneration in 563 plots from different microsite types (deadwood, intact soil, treethrow pits and mounds), distinguishing three seedbeds (mosses, beech litter, bare substrate) for seedlings. We used soil survey and tree census data with generalized linear mixed models and variance partitioning to identify the main factors driving tree regeneration and their relative importance. Although beech was slightly less abundant in the canopy than spruce, it strongly outnumbered spruce in regeneration. Beech regeneration showed an affinity for beech litter-rich microsites and drier soils, while spruce was more common on deadwood and moister soils and its response to the seedbed was microsite-specific. The regeneration of both species was positively related to the proportion of their own species in the canopy, but more so in seedlings than in older regeneration cohorts, where soil wetness was more important. The overall pattern of tree regeneration thus resulted from a complex interplay between site conditions and their alterations by current and former generations of canopy trees through the creation of new microsites (deadwood, uprooting mounds) or litter production. Where beech regeneration is not suppressed by excess soil wetness, it is much more successful than spruce due to its shade tolerance and ability to be established in the beech litter that dominates the forest floor. On the other hand, spruce regeneration is mostly restricted to elevated microsites with lower litter accumulation, such as deadwood and treethrow mounds. Our results indicate that both species exhibit an ability to modify their environment in favor of their own regeneration, but under current conditions, beech is more successful than spruce and can be expected to increase its dominance in the future. [ABSTRACT FROM AUTHOR]

• Entic Podzols under trunks had more nutrients, higher CEC and pH compared to control. • Convergence of soil properties below trunks prevailed over divergence and chaos. • Lying trunks affected soil characteristics at a maximum about 25 yrs after the fall. • Convergence in mineral soils typically terminated circa 53 yrs after trunk fall. • The effects of decomposing trunks was modelled to depths of over 60 cm. • There is some threshold between trunks and soils limiting changes in the microbiome. The biochemical effects of trees may significantly influence local pedogenesis as well as pedocomplexity, biodiversity and forest dynamics on both stand and landscape scales. One such effect is the decay of tree trunks, which is driven by organisms, and especially by the microbiome. Decomposition modifies soil formation, which due to the existence of many feedbacks affects the composition of the decomposer community. We aimed to uncover general trends in the evolution of Entic Podzols as well as individual trajectories of soil properties below decaying beech trunks in an old-growth mountain forest. In particular, we used mathematical models to distinguish soil convergence, divergence and chaotic behaviour to enhance a general theory of pedogenesis. We further aimed to calculate the depth and time of convergence if this scenario is prevailing in the study plot. Pedogenetic pathways were assessed regarding the changing composition of fungal and bacterial communities in soils to obtain a complex picture of the decaying trunk-soil microbiome system. We sampled the decaying wood layer under 24 lying beech trunks and corresponding organic horizons on adjacent control microsites occupied by decaying beech leaves. At the same time we sampled underlying mineral soil horizons at both microsites (wood vs. leaves), all on Entic Podzols and granite (in total 192 soil samples). Individual trunk fall events were dated using precise dendrochronology, with the resulting chronosequence covering trunks lying for 8–52 years. We analysed decomposition processes (with a wide spectra of organic acids and ions analysed), soil chemistry (28 additional soil properties assessed), and the microbiome composition in both decaying organic matter and soils (relative abundances of the 200 most common bacterial and fungal OTUs analysed). During the first stage of trunk decay, underlying Entic Podzols responded with a significant increase of nutrients, pH, and CEC, and the maximal divergence compared to control sites was reached between 12 and 60 years after the trunk fall. Subsequently, a majority of soil properties slowly converged over a few decades to match the soil properties of control sites. The modelled convergence point occurred at ages between 39 (SO 4 2−) and 229 (Al w) years, with a median convergence time of 53 years. The majority of soil properties converged within 20 cm below the trunk, but mathematical models predicted footprints of some soil properties down to depths of ca 60 cm. In addition, 11 soil properties did not converge at any depth, and for some properties the models even diverged. Differences in bacterial and fungal communities between below-trunk and control positions were relatively minor. Pedochemical drivers of fungal and bacterial communities (nutrients content, N tot , C ox , Al, Fe, Mn forms) changed significantly in the mineral soil below trunks, and the microbiome partly reflected these depth-related changes. However, we propose that there is a threshold between organic and mineral soil horizons limiting the impacts of trunk decay and pedogenesis in changes to the microbiome. [ABSTRACT FROM AUTHOR]

The biogeochemical model MAGIC was applied to simulate long-term (1880–2050) soil and stratified soil solution (30 and 90cm depth) chemistry at a spruce dominated site in the western Ukraine (Pop Ivan, 1480m a.s.l.) to evaluate the effects of acid deposition on soil acidification in a less polluted region of Europe. Since 2008, sulphur (S) deposition of 9kgha−1 year−1 and nitrogen (N) deposition of 8.5kgha−1 year−1 have been measured at Pop Ivan. The recent deposition of S and N is about 30% and 50% of those values estimated for the early 1980s, respectively. Acidic deposition caused the depletion of base cations (Ca, Mg, Na, K) from the soil cation exchange complex, which resulted in a decrease of calcium and magnesium saturation between 1935 and 2008 in the top mineral soil (0–30cm) and deeper mineral soil (30–80cm) by 67% and 88%, respectively. Base cation leaching acted as the major buffer mechanism against incoming acidity, therefore the measured inorganic aluminium (Al) concentration in soil solutions is ca. 10μmolL−1 and the subsequent molar (Ca+Mg+K)/Al ratio above 1. Recovery of the soil solution pH and Al is expected within the next 40 years, whereas the soil base saturation will only increase slowly, from 6% to 9.8% in the top soil and from 5.5% to 11% in the deeper mineral soil. Since the 1960s, modelled inorganic N leaching (as NO3) has started to increase following the trend in N deposition. Modelling and experimental evidence suggest that N availability from mineralization and deposition exceeds the rate of microbial and plant immobilization. Thus, soil N accumulation since the 1960s has been limited. A significant increase in nitrophilous species as well as a decrease of herb layer diversity was observed between 1936 and 1997. [Copyright &y& Elsevier]

Abstract: The precipitation chemistry, deposition, nutrient pools and composition of soils and soil water, as well as an estimate of historical deposition of sulphur (S) and inorganic nitrogen (N) for the period 1860–2008, were determined in primeval deciduous and coniferous forests at the sites Javornik and Pop Ivan, respectively. Measured S throughfall inputs of 10kgha−1 year−1 in 2008 were similar to those estimated for the period 1900–1950 at both sites. The highest estimated S inputs were in the 1980s. Measured bulk deposition of N in 2008 was lower at Pop Ivan (5.6kgha−1 year−1) compared to Javornik (12kgha−1 year−1). Significantly lower NO3 deposition was both estimated and measured at Pop Ivan. Higher soil base cation concentrations were observed at well-buffered Javornik underlain by flysch (Ca pool of 2046kgha−1 and base saturation of 29%) compared to Pop Ivan underlain by crystalline schist (Ca pool of 186kgha−1 and base saturation of 6.5%). The soil pool of organic carbon (C) was higher at Pop Ivan (212tha−1) compared to Javornik (127tha−1). The C concentration was positively correlated with organic N in the soil (p <0.001) at both sites, but the mass average C/N ratio in the forest floor was lower at Javornik (22) than at Pop Ivan (26). High N leaching of 17kgha−1 year−1 at the 90cm depth was measured in the soil water at Javornik, suggesting high mineralization and nitrification rates in old growth deciduous forests in the area. Despite relatively low Al concentrations in the soil water, a low soil water Bc/Al ratio (0.9) (Bc=Ca+Mg+K) was found in the upper mineral soil at Pop Ivan. This suggests that the spruce forest ecosystems in the area are vulnerable to anthropogenic acidification and to the adverse effects of Al on forest root systems. [Copyright &y& Elsevier]