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Converting beech coppices into high forest stands has been promoted in the last decades as a management goal to attenuate the negative effects that frequent clearcutting may have on soil, landscape, and biodiversity conservation. The silvicultural tool usually adopted is the gradual thinning of shoots during the long span of time required to complete the conversion, that also allows the owner to keep harvesting some wood. This research reports and discusses, in the light of the ecological intensification approach, the results achieved from an experimental test started more than 25 years ago in a 42-year-old beech (Fagus sylvatica L.) coppice with standards in central Italy. The effects of various thinning intensities (three treatments plus a control) on the stand growth and structure are assessed by successive forest inventories. Analyses are integrated by spatial indices to assess stem density and canopy cover. Converting beech coppices into high forest through gradual thinning of shoots proves to be an effective step down the road to silvicultural systems characterized by continuous forest cover, as a tool of ecological intensification suitable to guarantee both public and private interests. Thinning has led to stands with fewer but larger stems, thus accelerating the long conversion process while maintaining both wood harvesting capability and environmental services.

Due to an increasing risk of further damage to forests, forest managers are considering introducing an alternative direction for their future development - via the cultivation of mixed forests. At middle altitudes in the Czech Republic, an oak-beech-linden stand is the most natural type, and we tried to answer three main questions: (i) How the various thinning types affect dendrometric parameters and quality of the stand; (ii) How long thinning works on this stand until it loses its effect; (iii) How the stand develops spontaneously after abandonment. This experiment was conducted at the Training Forest Enterprise in the Czech Republic in Drahanská vrchovina (highlands in central Moravia). In 1988, four plots were established in a 49-year-old stand where, in three of the plots, different types of thinning (crown, low and heavy crown) were performed, leaving one (reference plot) to develop naturally. The height, the height of the crown base and diameter at breast height (DBH) were measured, and the shape and quality of the trunk and crown were estimated on each tree. Measurements were carried out in 1989, 1994, 1999, 2005, 2010, 2015, and 2020. In the first 10 years, the DBH and height of the crown base did not show any differences, and the linden at the heavy crown plot outgrew the linden trees at the other plots in height. After these 10 years, the thickest linden, the tallest beech and linden, and the greatest height of the crown base of beech and linden were all found at the heavy crown plot. The shape and quality of the trunks and crowns of beech, oak and linden were similar in all plots (including the reference plot) during the entire experiment. After thinning, the plots were left to grow spontaneously. The heavy crown thinning removed a greater number of thicker trees at the middle level, thus supporting the trees growing in the lower part of the middle level and in the below level (i.e. the beech and linden). These trees then grew more quickly compared to the others, but their quality decreased, as did that of the others. Therefore, a forest left to grow and develop spontaneously is practically unusable for commercial purposes.

Abstract Key message Naturally regenerating populations of common beech, pedunculate, and sessile oaks develop strong spatial genetic structures at adult and seedling stages. Significant genetic relationship occurs between individuals growing up to 60 m apart. This indicates the minimum distance separating trees from which seeds used for reforestation should be harvested to avoid the adverse effects of excessive relatedness among offspring. Context Spatial genetic structure is an inherent characteristic of naturally regenerating plant populations and has practical implications in forests for the management of genetic resources. Aims We investigated the extent of spatial genetic structure in three broad-leaved forest tree species (common beech—Fagus sylvatica L.; pedunculate oak—Quercus robur L.; and sessile oak—Q. petraea (Matt.) Liebl.) coexisting in the same nature reserve, explored its variation among species and different life stages (adults/offspring), and tested its possible determinants. Methods We explored patterns of spatial distribution of individuals, and using microsatellites, we estimated parameters of spatial genetic structure based on kinship relationships, considering possible sources of variation. Results In adults, the strongest spatial genetic structure was found for Q. petraea (Sp = 0.0187), followed by F. sylvatica (Sp = 0.0133), and the weakest in Q. robur (Sp = 0.0080). It was uniform across different age classes in pedunculate oak but decreased with age in sessile oak. No apparent relationship between age and spatial genetic structure was found in beech. Offspring exhibited significant spatial genetic structure (ranging from 0.0122 in beech to 0.0188 in sessile oak). The cohorts of seedlings having both parents present within the study site had stronger spatial genetic structures than cohorts of seedlings with only one local parent. Conclusion Spatial genetic structure is strong in naturally regenerating populations of heavy-seeded forest trees. Pollen immigration from outside of a local forest stand can significantly decrease the extent of spatial genetic structure in offspring generations.

Досліджено сучасний санітарний стан бука лісового (Fagus sylvatica L.), ялиці білої (Abies alba Mill.) та ялини європейської (Picea abies (L.) Karsten) у Національному природному парку "Гуцульщина" та визначено першопричини їх ослаблення, втрати біотичної стійкості і продуктивності. З'ясовано, що сучасні екологічні виклики, зокрема такі як глобальні зміни клімату, антропогенний тиск, атаки шкідників та епіфітотійне поширення збудників інфекційних хвороб, є предикторами вразливості лісів, що призводить до порушення стратегій їхнього збереження і відновлення. Розраховано та проаналізовано середні значення показника санітарного стану за 2022-2023 рр. на підставі детального лісопатологічного обстеження 15 пробних площ, а також ідентифіковано видовий склад патологій інфекційного характеру у деревостанах дослідного регіону. Встановлено, що загальний санітарний стан лісів за участю бука лісового, ялиці білої та ялини європейської, що ростуть в умовах Національного природного парку "Гуцульщина", наразі потрібно вважати ослабленим. Середньозважений показник санітарного стану становить 2,50 з варіюванням від 1,39-3,55 (у 2022 р.) і 1,53-3,52 (у 2023 р.). Спостерігається повільне, проте стійке, збільшення площ розладнаних і загиблих деревостанів. Зафіксовано наявність дерев V і VІ категорій стану, осередки бактеріозу, мікозних хвороб і стовбурових шкідників. Під час обстежень відзначено типову симптоматику бактеріальної водянки ялиці (збудник – фітопатогенна бактерія Lelliottia nimipressuralis (Carter 1945)), раку ялиці (збудник – іржастий гриб Melampsorella cerastii (Pers.) J. Schröt. 1887), нектріозу бука (збудник – гриб-ксилотроф Neonectria ditissima (Tul., & C. Tul.) Samuels & Rossman 2006). Серед комплексу афілофороїдних макроміцетів найбільшу кількість видів зареєстровано на деревах бука європейського, найменшу – на ялиці білій. Найпоширенішою виявилася група ксилотрофних базидіоміцетів, серед яких зареєстровано збудники кореневих і стовбурових гнилей (гриби родів Heterobasidion Bref. 1888 та Armillaria (Fr.) Staude 1857, а також видів Phellinus hartigii (Allesch., & Schnabl) Pat., 1903, Fomitopsis pinicola (Sw.) P. Karst. 1881, Fomes fomentarius (L.) Fr. 1849 та ін). Відзначено, що врахування санітарного стану стає ключовим чинником під час розроблення наукових і практичних рішень для забезпечення стійкості та збереження корінних природних лісів Національного природного парку "Гуцульщина".

The Ellenberg quotient (EQ) is a climate index defined as a ratio of the hottest month's temperature and the average annual precipitation sum. The quotient indirectly expresses the relationship between climate and vegetation, and its application is related to the ecological niche of Fagus sp. Although the quotient was curated on the grounds of field research primarily on German vegetation, the possibilities of its utilisation are not limited to the Central European region. The objective of this study is (i) to compare the EQ values calculated for the forest vegetation zones in the Czech Republic with the published data using the ecological niche of Fagus sylvatica; and (ii) to compare the new EQ-based vertical model with field empirical mapping. The study area is the Czech Republic, Central Europe. We used climate data from 1970-2000 and the data of the National Forest Inventory, 2nd cycle (2011-2015), representing an objective data design. Geospatial analytic methods, machine learning (boosting), and verification through statistical testing were performed. The results indicate higher EQ values between the two most substantial spatial frames - the Hercynicum and Carpaticum regions. By comparing empirical mapped units to their climatic potential (in the EQ), a match was found only within the Carpaticum region. The study presents a concretisation of the general climate index for a specific region, adds to the knowledge about the Fagus ecological niche in context with the Central European vegetation, and also points to the EQ's potential for evaluating the concept of vertical differentiation of forest communities, as well as a possible prediction tool for the vegetation migration in context with climate change.

Species-rich mixed silver fir (Abies alba Mill.) forests dominated in the northern Apennines, but climate and, mainly, anthropogenic land use provoked a sharp silver fir decline approximately 5000 years bp. The conservation of the silver fir in this region was mainly due to the establishment of monastic orders that preserved and even planted silver fir for its spiritual and economic value. In 1993, the best silver fir stands were included in the Parco Nazionale delle Foreste Casentinesi (FCNP), Monte Falterona e Campigna, and have been submitted to low-intensive management or strict protection regardless of past land use and cultural history. In this study, we have (1) analyzed the current structure of three silver fir forests that have had different ownership histories and (2) compared the structure of the three Italian forests among them and with two old-growth forests from the Dinaric Alps as a reference of naturalness. The results show that the current structures of the three Italian forests are very different among them and are strictly related to past land use and, mainly, to monastic legacies. Even if the Italian forests have experienced decades of low-intensity management or strict protection, they are currently structurally very different from Dinaric old-growth forests. Developing an old-growth structure in these forests can be very slow and, in some ways, unpredictable. The results also highlight the importance of recognizing protected areas as cultural landscapes that host an important biocultural diversity. The current risk is that by applying almost exclusive biodiversity-centered management and setting difficult or impossible-to-achieve biodiversity goals, total diversity will decrease, and biocultural diversity, the greatest richness of most European parks, will be lost.

A change in tree species composition in Central Europe to increase the resilience of forests when coping with climate change effects is imminent. We evaluated the present and expected future role of the European beech, (Fagus sylvatica L.), with respect to the expansion of its habitat and its stem. We assessed the current relevance of beech from data of the Austrian Forest Inventory 2007/09, and analyzed forest policies promoting the establishment of beech forests. We simulated forest growth with the model CALDIS, linked with the timber-market model FOHOW2. We used a business-as-usual (BAU) forest management strategy under moderate (RCP 4.5 BAU) or extreme (RCP 8.5 BAU) climate change. We also simulated an extreme climate change scenario with a forced change in the tree species composition (RCP 8.5 Change Species). Beech occurs in Austrian forests over the elevational gradient of 250 to 1600 m a.s.l. In low elevation, it forms beech-dominated forests, often for the supply of the domestic fuelwood demand. In mountain regions, beech enriches the diversity of Norway spruce, (Picea abies (L.) H. Karst.)-dominated forests. In a BAU setting, the habitat of beech increases only slightly in both climate scenarios. The scenario 'RCP 8.5 Change Species' increases the habitat of beech in the next 60 years considerably. With progressing warming, other broadleaved tree species gain relevance. The vulnerability to drought and pathogens are limiting factors for Austrian beech forests. The future habitat depends on many factors such as the ability of forests to cope with climate change, the confidence to arising market opportunities of beech timber in the wake of technological progress, and financial and non-financial incentives for the implementation of adaptive forest management. [ABSTRACT FROM AUTHOR]

Key message The datasets describe bacterial and fungal communities of European beech (Fagus sylvatica) leaves collected along a vertical gradient in a gallery forest throughout the growing season. They also describe communities in the surrounding environment of beech trees. Dataset access is at https://doi.org/10.7910/DVN/FFHAQU , and associated metadata are available at https://metadata-afs.nancy.inra.fr/geonetwork/srv/fre/catalog.search#/metadata/f17fe848-fc3e-4297-be11-9871b35a1be4 . Both can be used to uncover the dynamics and assembly processes of phyllosphere microbial communities in forest ecosystems.

Two provenance tests in North-Eastern Bulgaria have been studied, whose purpose is to test the response of beech provenances from Southern Germany to the drier and warmer climatic conditions in Bulgaria, in order to predict how they would perform in a warming and drying climate. The provenance tests were established in the spring of 2010 in the area of the Varbitza and Kipilovo Forest Services with 2-year-old seedlings in a 2 x 1 m scheme in 3 replications. Four provenances of common beech were studied - 2 German (Silberbach and Ebersdorf) and 2 Bulgarian (Petrohan and Berkovitza). On the 12th year after afforestation, an inventory and measurements of the height and root collar diameter were carried out. The results were processed statistically by applying one and two-factor analysis of variance, as well as Tukey’s test for multiple comparisons. A higher survival rate was found in the provenance test in Kipilovo. The Bulgarian provenances Petrohan and Berkovitza were characterized by better growth in height in both provenance tests, and in root collar diameter - provenance Petrohan. Provenance Ebersdorf could be recommended for use in drier and warmer places in Southern Germany.

Forest management has a direct influence on the structure and stability of forests. In this study, we used the 3D data from mobile laser scanning in real forest stands dominated by European beech (Fagus sylvatica L.) to simulate different silvicultural treatments and assess their impact on the structural complexity and short-term economic return. For the structural assessment, we used the box-dimension (Db), a holistic measure of structural complexity in forest. The expected net revenues of the silvicultural treatments were used as a proxy for short-term economic gain. We simulated six different treatments in 19 different real-world forest stands. The results showed that each treatment had a negative impact on the structural complexity of the stands but with varying severity. The treatments with the smallest effect on stand structural complexity showed the highest net revenue, indicating no trade-offs if a forest owner strives for small stand structural changes and high economic return. The approach used here allows quantifying the structural and economic consequences of different treatments in forest stands prior to the actual application in the real world. This holds large potential for decision making according to the forest owner's objective.

The importance of veteran trees is well recognised nowadays. The sudden breakage of some of these plants in Trentino (Italy), mainly due to Kretzschmaria deusta, prompted a survey of the veteran beeches reported in this area. Visual tree assessment was carried out in 40 sites with either single trees or groups of beeches, for a total of 115 trees evaluated. Most trees showed serious defects or problems in need of management and 19 had a high level of risk of breakage because of the presence of several structural problems. The presence of K. deusta was recorded on 50.4% of the examined trees. The pathogen was also identified in the proximity of investigated trees at 29 sites. Laboratory tests confirmed the identity of K. deusta by microbiological and molecular approaches and also identified Cosmopora berkeleyana as mycoparasite on K. deusta fruiting bodies. Isolates obtained from declining trees and old stumps showed the same pattern of growth at different temperatures. The risk evaluation emphasised how the fungus could affect the survival and safety of these veteran trees; this was confirmed by the collapse of four of the investigated trees in the last years. Therefore, K. deusta, which has been considered as a facultative parasite up to now, could play a more incisive role both in the decline of old beech trees and the natural evolution of aging beech woods.

Wood use in bio-building should be considered as one of the main pillars of sustainability. According to international standards, beech wood (Fagus sylvatica L.) is a rather less durable species as it is subject to degradation due to weathering, though it is abundantly available to a more intense use. Service life of beech products and wood products in general can be enhanced by different methods, such as heat treatments, but new chances are offered by coating technologies. However, to ensure protection from wood-destroying organisms, most commercial coatings include components that could harm human health, other organisms and the environment. Therefore, coating industry has to develop more eco-friendly solutions in order to decrease its impact on human health and environment. The objective of this article was to modify commercial acrylic varnish by adding cellulose nanocrystals (CNC) and lignin (LN) extracted from beech wood and investigate their effect on water sorption, additive dispersion in the coating matrix and coating resistance to bacterial attack. Contact angle, weight gain and colour difference were analysed and FT-IR mapping was applied. The performance of CNC was promising, as it enhanced water sorption of the modified coating. However, protection against bacterial attack was not satisfying. On the other hand, chemically unmodified lignin did not show positive effects as component in the coating formulation. Nevertheless, the currently limited usage of these two renewable and abundant resources urgently calls for their more efficient utilization, in order to create additional value with industry side-streams producing novel bio-based materials. Further experiments are needed in order to obtain better dispersion of the particles and higher resistance to bacterial attacks.

Fine roots are crucial for water and nutrient acquisition in plants; yet it is unknown how nutrient inputs and soil fertility in forests influence fine root biomass seasonal trajectories. Here, we hypothesized that standing fine root biomass increases with addition of a limited resource and shows different seasonal patterns depending on nutrient availability and phenology. We further hypothesized that the influence of climate is greater in the organic layer, causing larger responses of root biomass to climate in the organic layer and stronger responses to nutrient changes in mineral soil. We conducted our study in three European beech (Fagus sylvatica) forests representing a soil fertility gradient with high, medium, and low phosphorus (P) contents. A fully factorial fertilization regime with N and P was applied at each forest site. To test our hypotheses, we conducted soil coring in spring and fall for 2.5 years. Soil cores were fractionated into organic layer (Oe + Oa layer) and mineral soil (A horizon) and used to determine fine root biomass, soil pH and moisture, total concentrations of soil and root nutrients (basic cations, micronutrients, S, P, N, C), soluble concentrations of soil and root P. Fine root biomass in the mineral soil at the forest site with the lowest soil P content increased in response to P addition. Pheno-seasonal changes caused increases in soil P and N in spring and opposing cycling of biomass and fine root labile P contents at the P-medium and P-high sites. Contrary to our expectation, we observed stronger climatic effects on fine root biomass in the mineral soil, whereas soil moisture was more important in explaining fine root biomass variation in the organic layer. Our results show that seasonal patterns of fine root biomass are dependent on the stratification of environmental factors with soil depth and imply negative consequences for fine root biomass in the organic soil layer due to acute soil water content fluctuations and climate change effects in the mineral horizon due to long-term precipitation changes.

In the last century, a synchronous beech expansion has been observed for many mixed mountain forests in southeastern Europe. This change is associated with the interaction of various disturbances. We analyzed structural changes in the Pecka old-growth forest in Slovenia during the last century, using several inventories of the tree layer, regeneration, and site factors. Throughout the observation period, the density of silver fir in the regeneration layer and in the overstory steadily decreased. In 1893, silver fir accounted for about 60% of the growing stock, whereas in 2013 it accounted for less than 13%. This is likely because of silver fir’s decline in the canopy layer due to air pollution, successive windthrows, and overbrowsing. However, climate change may also have played an important role, as silver fir also declined in southeastern European old-growth forests where air pollution was less pronounced and ungulate densities were low. A gradual decline of silver fir in the overstory resulted in a decrease of overall tree density to 231 trees ha–1, while growing stock remained relatively high at 712 m3 ha–1. Median diffuse light at 1.3 m was 3.7% and regeneration density was 19,954 ha–1. Beech was dominant (94%), followed by silver fir (4%), and sycamore maple (2%). No silver fir seedlings larger than 0.2 m were recorded. Silver fir, sycamore maple, and beech regeneration showed 87, 76, and 45% browsing damage, respectively. Regression models indicated some evidence of niche partitioning between silver fir and beech. However, many processes may be masked by the silver fir’s avoidance strategy. Given current red deer densities, climate change, and existing forest structure, the Pecka old-growth forest will likely reach an alternative stable state dominated by beech in a few decades. This calls for immediate reduction of ungulate populations. Despite the interaction of multiple disturbances, the Pecka old-growth forest has maintained a relatively high overall growing stock, a favorable microclimate, and succession pathway with shade-tolerant beech. This indicates the intrinsic resilience of natural forests. The mechanisms discussed here can be applied to the future governance of old-growth and managed montane mixed forests.

Provenance tests of forest tree species are important experiments in silviculture and tree breeding. Their results provide information about provenances' growth, adaptability, and other features. The research aimed to determine the dynamics of growth and tree shape of common beech plants per provenances in the international provenance test in Bosnia and Herzegovina to choose the best provenances considering wood production and quality. Research was conducted in the provenance test containing eight provenances from Bosnia and Herzegovina, four from Germany, three from Serbia, two each from Croatia, Romania, and Switzerland, and one from Hungary. Provenance test was established in 2007 by planting 2-year-old and 3-year old seedlings. Height and root collar diameter were measured, and tree shape was assessed in 2019. Data were processed in SPSS 26.0. Descriptive statistics, variance analysis, multiple Duncan's test for all traits, and Pearson's coefficient of corelation among morphological traits and tree shape were calculated. Variance for the height and root collar diameter showed statistically significant differences among different ages of plants and among provenances. Provenance from Croatia (Dilj Čaglinski) had the highest, and provenance from Romania (Alba-Iulia) had the lowest average height. The highest average value of root collar diameter had provenance Dilj Čaglinski, and the lowest value had provenance Sihlwald (Switzerland). The highest percentage of category 10 (ideal tree form) had provenance Bad Wildbad (Germany), and categories 1-4 (no silviculture value) had provenance Alba-Iulia (Romania). Pearson's coefficient showed that height, root collar diameter, and tree shape are highly correlated. Considering all the above, when planning forest-breeding works, it is recommended to continue the research and favor provenances with the best growth and tree shape.

The main goal of this paper was to evaluate structure dynamics in the fir-beech, old-growth forest Badínsky prales. Measurements were taken on four permanent research plots (0.5 ha each) between 1970 and 2018, typically in ten-year intervals. In order to assess long-term structure dynamics, this study used basic stand characteristics and selected structural indices - the relative density (RD), coefficient of homogeneity (H), and structural complexity index (SCI). Species composition was quantified by the relative importance value (RIV), and a detrended correspondence analysis was carried out for the visualisation of long-term changes. The long-term mean of the stand volume reached 634 ± 99 m3.ha-1, and the mean of the basal area was 36.6 ± 4.0 m2.ha-1. Calculated values of the coefficient of homogeneity (1.46-2.54) were similar to values in other old-growth forests with a comparable tree species composition. An increasing trend in beech RIV values was observed; on the other hand, fir RIV values fell by approximately 20%-25%. In 2018, maximal values of the basal area, stand volume and relative density were recorded. These high values may indicate better growth conditions due to climate change, as well as fewer disturbance events in the last few decades.

The Leaf-Area-Index (LAI) is commonly used to characterize the plant canopy and is a fundamental indication of plant vitality and photosynthetic activity. The forest health status is not only vital for economical reasons, but also has a significant impact on global carbon sequestration. The LAI has a highly dynamic character among deciduous forests and is prone to significant seasonal fluctuations. Accurate continuous LAI measurements do provide valuable information on growth characteristics, but they require considerable measurement effort. In this study, we tested a novel method that would allow for continuous low-effort LAI parameterizations. For our study we used temperature measurements from 2011 to 2019 obtained at two meteorological stations: Station one is an open land station, station two is located inside a forest stand characterized by European beech (measurements were undertaken as part of the ICP Forests program), both are located in Klausen Leopoldsdorf (Austria). We chose the difference in daily maximum temperature between the two sites for our LAI parametrization (LAIpar) since the forest canopy has a significant impact on local radiation conditions. We were able to identify phenological events such as leaf unfolding, the end of leaf growth, and the beginning and end of defoliation by examining at the average course of the year for LAIpar. The resultant LAIpar values were compared to annual values derived from hemispheric photographs taken near the stand temperature sensor. For the years 2011–2017, we found a strong correlation of 0.93 between LAI measures and LAIpar, which dropped to 0.69 after adding the year 2018 and 0.32 after adding 2019. We further compared the phenological events obtained from LAIpar to phenological observations. The impact of forests on their site climate, according to our findings, can be utilized to identify phenological and growth characteristics. The proposed method, however, is not a replacement for conventional LAI measurements.

The saprotrophic, endophytic, and parasitic fungi were detected from the samples collected in the forest of the management unit East Psunj and Papuk Nature Park in Croatia. The disease symptoms, the morphology of fruiting bodies and fungal culture, and DNA barcoding were combined for determining the fungi at the genus or species level. DNA barcoding is a standardized and automated identification of species based on recognition of highly variable DNA sequences. DNA barcoding has a wide application in the diagnostic purpose of fungi in biological specimens. DNA samples for DNA barcoding were isolated from infected tree tissues, fungal fruiting bodies or fungal cultures. The ITS or ITS2 sequences of the fungal DNA were sequenced and aligned with the reference sequences in GenBank (NCBI) using BLAST. The size of ITS and ITS2 sequences were 512-584 bp and 248-326 bp, respectively. The sequences showed a high identity of 97.21%-100% at 98%-100% coverage with reference sequences in GenBank (NCBI). The exception was the species Amphilogia gyrosa that showed 95.65% identity at 100% coverage. Two fungi were determined at genus level: Cladosporium sp., and Cytospora sp., while 11 fungi were determined at species level: Alternaria alternata, Aureobasidium pullulans, Amphilogia gyrosa, Capronia pilosella, Cryphonectria parasitica, Exidia glandulosa, Epicoccum nigrum, Penicillium glabrum, Pezicula carpinea, Rosellinia corticium, and Stereum hirsutum.

Restoring the structural characteristics of secondary old-growth forests that were previously managed is increasingly debated to help increase the area of more complex forests which provide a broader array of forest services and functions. The paucity of long-term data sets in Central Europe has limited our ability to understand the ongoing ecological processes required for effective restoration programs for old-growth forests. To address this, we used repeated census data from eight permanent plots to evaluate forest structural dynamics over a 12-year period in the largest complex of European beech (Fagus sylvatica L.) forests in the Czech Highlands without intensive forestry intervention for almost 50 years. Our results showed that previously managed forests can exhibit structural qualities typically associated with old-growth forests after management has ceased for a period. The stand structural characteristics (e.g., density of large and old trees) is comparable with protected reserves of old-growth European beech-dominated forests. The average stand age was 196 years, but the oldest tree was 289 years old. The annual mortality rate was 0.43% for all species, and the U-shaped distribution indicating size-dependent mortality is likely an important process that is balanced by the turnover of new tree recruitment. During the study period, we detected that the diameter distribution tended towards a rotated sigmoid distribution. The lasting effects of the most recent forest management are evident in the scarcity of dead wood, and a prolonged process of dead wood accumulation has begun. Thus, the abandonment of all management activities in near-natural forest reserves, including dead wood removal, will ensure that the forests will develop characteristics typical of old-growth forests.

Resource allocation to different plant tissues is likely to be affected by high investment into fruit production during mast years. However, there is a large knowledge gap concerning species-specific differences in resource dynamics. We investigated the influence of mast years on stem growth, leaf production, and leaf carbon (C), nitrogen (N), and phosphorus (P) concentrations and contents in Fagus sylvatica, Quercus petraea, and Q. robur at continental and climate region scales using long-term data from the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) and similar datasets. We discussed the results in the light of opposing resource dynamics hypotheses: (i) resource accumulation before mast years and exhaustion after mast years (resource storage hypothesis), (ii) shifting resources from vegetative to generative compartments (resource switching hypothesis), and (iii) investing resources concurrently in both vegetative and generative compartments (resource matching hypothesis). Linear mixed-effects modelling (LMM) showed that both stem growth and leaf production were negatively influenced by weather conditions which simultaneously lead to high fruit production. Thus, the impact of generative on vegetative growth is intermixed with effects of environmental factors. Superposed epoch analyses and LMM showed that for mast behaviour in F. sylvatica, there are indicators supporting the resource storage and the resource switching hypotheses. Before mast years, resources were accumulated, while during mast years resources switched from vegetative to generative tissues with reduced stem and leaf growth. For the Quercus species, stem growth was reduced after mast years, which supports the resource storage hypothesis. LMM showed that leaf C concentrations did not change with increasing fruit production in neither species. Leaf N and P concentrations increased in F. sylvatica, but not in Quercus species. Leaf N and P contents decreased with increasing fruit production in all species, as did leaf C content in F. sylvatica. Overall, our findings suggest different resource dynamics strategies in F. sylvatica and Quercus species, which might lead to differences in their adaptive capacity to a changing climate.

Continuous nitrogen (N) deposition has raised concerns that temperate forest ecosystems shift from N limitation to progressing phosphorus (P) limitation under global change. According to the multiple resource limitation theory, this will not only influence P economy, but also reduce N uptake and use efficiencies of trees such that growth is equally limited by N and P. We used different global change scenarios including summer drought to test the prediction of this hypothesis for the N economy of European beech (Fagus sylvatica L.) saplings. Our study demonstrates that the N uptake efficiency (NUptakeE) of beech adjusts to soil N availability and stabilizes leaf and fine root N concentrations. By contrast, both efficiencies of N use were curtailed by increasing P limitation under elevated soil N. The photosynthetic N use efficiency (PNUE) was serially reduced with decreasing soil P availability and increasing foliar N:P ratios, while the N use efficiency (NUE) decreased with increasing fine root N:P ratios. Soil drought induced relative P deficiency alike and reduced NUptakeE, PNUE, and NUE independent from the soil N:P ratios. We conclude that not only N deposition but also increasing summer droughts might affect N:P ratios, thereby inducing P imbalances and affecting the N economy of European beech saplings under global change.

European forests are undergoing an important transition due to the current climate change, as monocultures are being gradually replaced by mixed forests. Understanding tree growth in mixed forests under a changing climate is challenging because of tree species’ adaptation and long-term forest planning. In this study, we evaluate the long-term behaviour of Norway spruce (Picea abies), silver fir (Abies alba) and European beech (Fagus sylvatica) from a low montane range at the Czech-Austrian border. Species-specific tree-ring width chronologies have revealed significantly decreasing growth trends since the 2000s. Temporally unstable climate–growth relationships showed an increasing negative effect of current growing season drought on spruce growth and a positive effect of dormant season temperature on fir and beech growth. Our results suggest that though species’ response to climate change differs in the mixed forest, growth reduction in the last years has been proved for all species, likely due to frequent climate extremes.

Invasions by non-native pathogens represent a major threat to managed and natural ecosystems worldwide. Although necessary for adopting preventive strategies, the identification of invasive species before they are introduced is particularly difficult. Indeed, most pathogenic species that have become established in the last decades were first described only after they became invasive. To prevent further biological invasions, not only the early identification of potential new invasive plant pathogens is crucial, but also the assessment of their potential host range. In this study, we determined the pathogenicity and the saprotrophic ability of three Cryphonectria species toward three potential hosts in the family Fagaceae. For this, seedlings and dormant stems of European chestnut (Castanea sativa), pedunculate oak (Quercus robur) and European beech (Fagus sylvatica) were inoculated with different genotypes of C. parasitica (Asian species, invasive in Europe), C. naterciae (European species), and C. japonica (Asian species, not present in Europe). Lesion growth was measured and mortality assessed for 4 months. The highest damage was caused by C. parasitica on European chestnut, while C. japonica and C. naterciae induced significantly smaller lesions on this host species. All three Cryphonectria species did not grow saprophytically on F. sylvatica and Q. robur, but successfully colonized dormant stems of C. sativa. In the context of biological invasions, our study shows that the Asian C. japonica most likely represents a much less severe threat than C. parasitica for the tested European host species. Nonetheless, the ability of C. naterciae and C. japonica to saprotrophically colonize fresh chestnut wood may suggest that they could become established in chestnut forests and eventually infect weakened chestnut trees or other hosts not tested in this study.

Reliable phenological observations are important for studying the response of trees to climate and climate change. National phenological networks were not specifically established to monitor tree phenology within forests, yet they are often used to generalise tree phenological phases at national or regional scales. Our objective was to investigate whether a phenological monitoring network using trees in open areas can accurately predict phenology of European beech (Fagus sylvatica L.) located within forests by using two models: one with correlates of environmental variables and one with interpolated monthly air temperature and sun hours. The first leaf unfolding, general leaf colouring and leaf fall dates from 2004 through 2010 were modelled using data from 47 Slovene National Phenology Network (NPN) stations in open areas and tested on phenological observations within forests using data from the UNECE CRLTAP ICP Forests network. Good agreement was found between predicted and observed first leaf unfolding in the forest, while slightly lower agreement was detected for general leaf colouring and leaf fall. Suggestions for the improvement of national phenological network are discussed in order to better predict beech phenology in forest habitats.

The accumulation of carbon in forest ecosystems supports to mitigate climate change, which makes seeking strategies for adapted forest management an urgent goal time. The European beech (Fagus sylvatica L.) is one of the main forest-forming species in Bulgaria and ensures forest areas with higher water supply, protective and recreational importance. It occupies nearly 16% of the forest territory of the country. The need for additional studies on the impact of the forestry activities on the carbon accumulation in soils of beech ecosystems is based on the importance of beech forest ecosystems for the carbon balance at national level. With that goal, 3 sampling plots were established in forest stands dominated by beech as a main forest-forming species. Forest management activities of different intensity have been carried out in the selected sites. Main soil characteristics correlated with the soil carbon stock are analyzed. The results of the analysis show that forest management activities carried out in compliance with the requirements for protection of the habitat and the functionality of the ecosystem in the studied sites have not led to significant changes in the skeletal content and bulk density of soils. А trend for an increase of carbon stocks as a result from the management activities of beech stands in the study area has been observed. [ABSTRACT FROM AUTHOR]

Populations located at the periphery of the species’ distribution range may play an important role in the context of climate change. These peripheral populations may contain specific adaptations as a result of extreme environmental conditions. The aim of this paper was to assess within population genetic diversity and among population differentiation in one of the most important forest tree species in Europe, European beech (Fagus sylvatica), at the eastern margins of its natural range. We analysed four peripheral, isolated populations and five core populations from the continuous natural range along the Carpathian Mountains using a set of microsatellite markers. Higher levels of genetic diversity as measured by allelic richness (7.34 vs. 6.50) and observed heterozygosity (0.71 vs. 0.59) were detected in core populations than in peripheral ones. Population differentiation was slightly higher among peripheral populations than among core, Carpathian populations. There was strong evidence of bottleneck effects in two out of the four peripheral, isolated populations. Both core, Carpathian populations and peripheral, lowlands populations share the same chloroplast haplotype suggesting a common geographical origin from the putative Moravian refuge area. Past long distance founding events with material from the Carpathian mountain chain might explain the occurrence of small, isolated beech populations towards the steppe in the south-east of Romania. Our genetic data may contribute to a better understanding of the evolutionary history of the remnants of beech scattered occurrences at the eastern margins of species’ distribution range.

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

Knowledge of the structure and dynamics of near-natural mixed forests is a key factor for ecologically oriented management of forest ecosystems. The development of these model forests mostly takes place continually without any pronounced disturbances. Natural regeneration can be locally limited by ungulate browsing. The paper was focused on the structure and development of forest stands with emphasis on natural regeneration in relation to ungulates in Černý důl Nature Reserve and Trčkov National Nature Reserve situated in the Orlické hory Mts., Czech Republic. The case study was conducted in a spruce-beech-fir forest stand on four permanent research plots (PRP) of 0.25 ha in size. PRP are situated in the same stand and in comparable site and stand conditions, but two PRP has been protected against game by fencing since 1985-1989. The stand volume ranged from 478 to 565 m3 ha−1 in age 143 - 156 year. The results showed that the diversity of tree layer was higher by 19.8% (48.0% in species richness) in the stands protected by fence. In the phase of natural regeneration, the species composition, stand structure and number of recruits were poorer on unfenced PRP (7,990 recruits ha−1) compared to fenced PRP (13,160 recruits ha−1). Admixed silver fir and rowan were completely eliminated by browsing (to 94 - 100% of individuals). Growth analyses statistically confirmed that ungulates were a significant limiting factor for successful forest development (P < 0.001).

Impact of tending on dvelopment of beech (Fagus sylvatica L.) pole timber stands was analysed using different variants of the free crown thinning, i.e. the original method developed in Slovakia at the end of 1950s. Four variants of this method were compared: (i) - the free crown thinning on the whole area, the method of promising trees, later the method of target trees at stand age of 58 years. (ii) - the free crown thinning on non-whole area, tending realised inside of growth space of target trees only, the method of target trees, salvage cutting on the whole area. (iii) - the free crown thinning on non-whole area, the method of promising trees (the method of target trees at stand age of 58 years) realised on circular plots with diameter 4 m and spacing 8 m (distance between centre of circular plots). (iv) - combined selective method, thinning from below and the free crown thinning by method of target trees was used by the first thinning, in next thinning only the free crown thinning on whole-area was used, method of target trees. The structure (diameter and height) of the stand, the quantitative production parameters had been observed for a period of 30 years. Small differences were found in diameter and height structure between the variant (iv) and other three ones. Comparison of quantitative production pointed out minimum differences in favour of the variant (iv) compared to the other ones. The same results were also obtained in the qualitative production, especially for selective quality (target trees).

The study examined the influence of ultraviolet radiation on the colour of thermo-mechanically modified beech (Fagus sylvatica ) and oak (Quercus robur). The wood colour parameters were measured using the mathematical CIE L*a*b* and L*C*h colour space models. The higher the temperature of thermo-mechanical treatment, the least susceptible beech and oak wood was to a change in L*, a* and b* under the influence of light irradiation. The greatest changes in the colour of non-densified and densified beech and oak wood occurred after 20 h of light irradiation. The higher the temperature of thermo-mechanical treatment, the smaller were the total changes in the colour of beech and oak wood under the influence of ultraviolet radiation. The total changes in the colour of beech densified at temperatures of 100°C and 150°C that took place under the influence of ultraviolet radiation were twice as high as in the case of densified oak wood. The colour of oak wood modified at a temperature of 200°C did not change significantly in 300 h of light irradiation.

Heterogeneity in soil characteristics promotes and maintains coexistence between a diverse set of species. In forests, trees have species-specific impacts on soil abiotic characteristics and mixing of tree species is being promoted as a tool to ensure high levels of diversity and functioning. Yet, limited knowledge is available on the effect of tree species composition and spatial clustering on heterogeneity in soil characteristics. In this paper we derived heterogeneity of key characteristics of the leaf litterfall, the forest floor and the mineral topsoil (C, N and base cation concentration, C:N ratio and mass) in 53 plots of 7 different tree species compositions. We found that heterogeneity increased from the leaf litterfall, through the forest floor down to the mineral topsoil. Mixing tree species did not lead to an increased heterogeneity in the forest floor and topsoil compared to monocultures. However, we did find that mixed plots where conspecific trees stand in groups are more heterogeneous than plots where species are intimately mixed. Our results imply that heterogeneity in soil characteristics does not necessarily increase with tree diversity, but that within mixed stands the spatial organization of tree species should be considered in relation to the scale at which heterogeneity is desired. [ABSTRACT FROM AUTHOR]

The increasing frequency and severity of extreme weather events, especially droughts, arising from on-going climate changes negatively affect productivity and stability of forest ecosystems. Understanding species responses and suitable ecotypes that are able of adapting to new environmental conditions is increasingly important. The objective of this study was to quantify the relationships between the inter-annual stem circumference increase (SCI) of five European beech (Fagus sylvatica L.) provenances and weather variability during 2012-2014 in a provenance trial located in central Slovakia. SCIs were extracted on daily and weekly scale from hourly data of circumference changes. To detect the main environmental factors influencing SCI seasonal dynamics, intra-seasonal moving correlation functions were calculated. All five provenances responded synchronously to weather conditions, with high correlations among them during the growing season on both daily and weekly scale. The photoperiod exhibited a synchronizing effect on the seasonal peak of SCI as a sign of tree adaptation to long-term seasonal variations in climate. Temperature was the most significant factor influencing SCI dynamics at the beginning of the season. During the summer months, a precipitation deficit, heat waves and the consequently decreased soil water potential significantly affected the SCI of young beech trees, despite the fact that the provenance plot was situated in an area of optimum beech growth. Not only the severity and duration were important but also the timing of drought within a season. Within all seasons, the lowest SCI values were recorded for the provenance from the lowest altitude and the most oceanic climate (northern Germany). A comparison of daily and weekly SCI with first derivatives of growth functions indicated that SCIs were closely related to theoretical incremental processes, especially on a weekly scale. In young beech trees, SCI seemed to represent an appropriate proxy for studying intra-seasonal incremental processes. A newly designed SASB (self adjusting sharp beginning) function fit these processes better than the Gompertz function.

The potential use of beech (Fagus sylvatica Linnaeus) sawn timber for structures has been investigated. Beech stands in transition from coppice to high forest after thinning interventions have been sampled from different Italian sources. A sample of 160 beams of two different cross sections was extracted and tested, according to the normalized procedures for the characterization of wood for structures. The specimens were visually graded considering the strength relevant defects, according to the Italian standard. To determine the mechanical properties of the timber (namely strength and stiffness), four-point bending tests were performed and the main characteristic values were derived. The results of the study reveal that knot ratio was the principal defect that influenced both resistance and yields. The potential strength class D30 was achieved with the resulting characteristic values, although, due to the small number of samples tested, the reached class could not be formally assigned. To improve the effectiveness of the grading rule in the Italian standard, some modifications and a new grade were proposed for the beech sawn timber. Finally the D40 strength class could be theoretically reached, but with reduced yields.

Two drought stress indices were applied to managed as well as old-growth beech forests and gaps for the 2001 to 2013 period to aid in the development of an efficient tool for field water supply diagnosis. The relative extractable soil water (REW), which was calculated from the soil water content in the root zone, and the transpiration index (TI), calculated as the ratio between the actual and potential transpiration were used. Both indices were calculated on a daily basis using the water balance model BROOK90, which was fitted and tested using measured data on throughfall and soil water content. A sensitivity analysis apportioned to the input parameters of the drought stress indices was conducted to assess uncertainty. Both drought stress indices showed the greatest drought stress in the years 2009, 2003 and 2011, as also indicated by the Standardized Precipitation Evapotranspiration Index (SPEI) at the nearest meteorological station. However, drought stress intensity and duration differed between the indices and study sites. Greater water supply stress was shown in the forests than the gaps. Furthermore, the agreement among the indices was smaller for gaps compared with forests, which implies that careful index selection is needed when comparing water supply stresses in different stages of forest stand development. Due to the low amount of input data required and the parameters that can be measured with relative ease in the field, REW might be an efficient tool for field water supply diagnosis when analyzing the drought stresses of similar forest types and at unique stages of development. REW satisfactorily indicated drought stress in forests but to a lesser extent in gaps. TI demonstrated more consistent differences in drought stress between forests and gaps and therefore proved to be the appropriate index for a detailed analysis of drought stress variation between different stages of forest stand development. However, due to a greater number of required input data and more demanding parameters, TI appears to be a more complex tool than REW for field water supply diagnosis in forests.

The practice of salvage logging dead and damaged timber following large high severity disturbances has raised much controversy, partly because of the negative ecological effects that such practices have on forest ecosystems. Many of the studies on salvage logging effects, however, have been done on sites damaged by large, severe disturbances. Less is known about the ecological consequences of salvage logging following intermediate severity disturbances that cause partial canopy damage at smaller scales. We examined the response of the herbaceous layer and tree regeneration to salvaged and non-salvaged treatments following small-scale intermediate severity disturbances in eight mixed beech (Fagus sylvatica L.) dominated forest stands in Slovenia. The cover and diversity of herbaceous vegetation, as well as the density and diversity of tree regeneration were similar between treatments across the study sites. The only notable differences between the treatments were that salvaged sites had a larger proportion of shade intolerant tree species in the regeneration layer, while non-salvaged sites tended to have a more well-developed regeneration layer in taller height classes. The results suggest that salvage logging following small-scale intermediate severity disturbances may not hinder forest recovery in mixed beech dominated forests.

Biscogniauxia nummularia is a xylariaceous fungus known as a common endophyte of European beech, living in plant tissues without development of symptoms, or even inducing strip-cankers and wood decay on trees stressed by drought. We studied the presence of the fungus in apparently healthy beech trees, growing in two different bioclimatic zones characterized by Continental and Mediterranean climates. Asymptomatic twigs were collected in each zone over the season and evaluated for the presence of B. nummularia infections using both cultural and qPCR methods. Results from qPCR indicated differences in the detection of B. nummularia among the seasons and between the study sites. In both sites the highest frequency of detection was in summer. B. nummularia was more frequently detected in the Mediterranean bioclimatic area, where drought is more common. These results suggest that B. nummularia may be a possible bioindicator of beech health stands.

A broad interest exists in developing structure-based indicators to use as proxies for other attributes that are difficult to assess, such as biological diversity. Summary variables that account for stand-scale forest structural complexity could facilitate the comparison among stands and provide a means of ranking stands in terms of their potential contribution to biodiversity. We developed an index of structural heterogeneity (SHI) for beech forests in southern Italy: (i) we established a preliminary list of 23 structural variables obtained from data routinely collected in forest inventories; (ii) we quantified these variables in a set of 64 beech-dominated stands encompassing a wide range of variability in the Cilento, Vallo di Diano and Alburni National Park; (iii) we identified a core set of attributes that take into account the main sources of structural he­terogeneity identified in reference old-growth forests; and (iv) we combined these core attributes into a simple additive index (SHI). We identified eight core attributes that were rescaled to the range 0 to 10 using regression equations based on raw attribute data. The SHI was calculated as the sum of these attribute scores and then expressed as a percentage. The index performance was evaluated against ten reference old-growth beech stands in the Apennines. The index ranged between 38 and 79.1 (median=59.4) and was distri­buted normally for the calibration dataset. The SHI successfully discriminated between old-growth (range=71.9-99.9, median=85.1) and early-mature to mature forests. Furthermore, the SHI linearly increased with stand age and was higher in multi-layer high forests than in single- and double-layer forests. However, a large variation was detected within both management types and age classes. SHI could be helpful for foresters as a tool for quantifying and compa­ring structural heterogeneity before and after a silvicultural intervention ai­med at restoring the structural complexity in second-growth stands.