Proportion Of Beech Research Articles

Douglas fir and Norway spruce have similar effects on small mammal density, but not survival, in Central European managed forests

In an effort to ameliorate the impacts of climate change, forest managers in Central Europe increasingly turn to conifer species that produce higher yields and are better adapted to projected future climatic conditions. Though small mammals are an important component of the forest ecosystem, the impacts of enriching native broadleaf forests with conifers on small mammal communities are not well understood. We conducted mark–recapture surveys of small mammals to ascertain differences in their community structure among stands of two conifers (native Norway spruce Picea abies and non-native Douglas fir Pseudotsuga menziesii) and the dominant broadleaf in the region, European beech (Fagus sylvatica). After estimating the density of two common species, the yellow-necked mouse Apodemus flavicollis and bank vole Clethrionomys glareolus, we found that the population density of each is positively related to the proportion of beech and negatively to the proportion of conifers in each stand, though these effects of stand composition are smaller than the positive effect of herb cover. Increasing Norway spruce proportion reduced monthly survival of small mammals, while Douglas fir proportion had a positive effect on survival. We conclude that the two conifer species have similar impacts on small mammal density, though overall small mammal survival was significantly lower on plots with Norway spruce. This suggests that increasing the proportion of Douglas fir at the expense of Norway spruce may be possible without significantly changing local patterns of small mammal population density, but further research is necessary to elucidate the exact impacts of these two conifer species on small mammal demography and behavior.

Vývoj vybraných zmiešaných ihličnato-listnatých porastov v režime bezzásahovosti

The climate change has an adverse impact on tree species and forest stands. Different tree species tolerance and changes in tree species composition are considered as one of the climate change consequences. The paper deals with assessment and comparison of tree species composition and basal area increment in mixed (spruce-fir-beech) stands, which were left to self-thinning during 45–55 years. The large-scale experimental basis of older thinning permanent research plots established, in the past, in mixed stands situated in the 5th and 6th altitudinal forest zone was used in the research. At the same time the detected changes were compared to long-range goal and tree species models specified for a given forest type. The results showed increased proportion of beech and sycamore maple contrary to decreased share of fir and spruce. At the same time, fir also recorded the highest percentage of loss by self-thinning. The comparison of the current tree species composition with the models showed slight differences in all areas in favour of spruce at the expense of beech. Similarly, the basal area increment of beech was the highest everywhere.

Spatial and temporal variation of Fagus sylvatica growth in marginal areas under progressive climate change

The escalating decline in growth trends of European beech (Fagus sylvatica) observed across its distribution area pose a major ecological and economic challenge for countries with a high proportion of beech, such as Slovenia. In this study, the effects of climate change were examined at a high-resolution scale, encompassing the large climatic, orographic, and ecological variability of beech forests in Slovenia. Using basal area increment data (BAI) from a tree-ring network (48 sites in Slovenia), modelled climate data, and generalized linear mixed models (GLMM), we found an average growth decline of 11% between the 1953–1985 and 1986–2018 subperiods, affecting 90.5% of the forest stands. Based on climate data, we defined two contrasted marginal areas of beech presence (warm and cold) and analysed the growth changes over time. The warm marginal areas, which predominate near the geographical margin of beech distribution with a sub-Mediterranean climatic regime, were most affected by growth decline, threatening the survival of beech populations in the area. In contrast, cold marginal areas, mainly at high elevations in the Alps, where beech growth had previously been limited by low temperatures, turned out to be the only ones where growth of beech increased under prevailing warming conditions. Consequently, high elevation regions harbour climatic potential for increased beech growth performance, and may represent areas of future expansion of the species.

Conversion of pure spruce to mixed spruce beech stands: Effects on alpha and beta diversity of multiple taxonomic groups

The conversion from pure coniferous stands to mixed forests is a major goal of forest management strategies in the light of climate change. However, the effects of forest conversion on the associated species diversity and the factors driving diversity changes remain poorly understood. To investigate these effects, we established 54 plots in a managed forest in southern Germany, where large areas have been converted from pure spruce to mixed spruce-beech stands since the middle of the 20th century. Our sampling plots consisted of three different age classes and increasing proportions of beech, measured by the number of stems. We sampled fungi, plants, invertebrates, and birds and combined classical methods (identification by specialists) and metabarcoding for species identification. Furthermore, important forest structure and site parameters were recorded to test their influence on species alpha and beta diversity. Alpha diversity of embryophytes, and therein tracheophytes, increased with increasing availability of light, whereas fungi decreased. With increasing humus thickness alpha diversity of insects, especially dipterans and hymenopterans increased, whereas embryophytes, tracheophytes and fungi decreased. Increasing numbers of habitat trees increased the alpha diversity overall, especially in tracheophytes and hymenopterans. The proportion of beech determined the alpha diversity of one out of 12 taxa and influenced the beta diversity of 10 from 12 taxa. However, factors influencing the diversity are taxa dependent. Our study indicates that the proportion of beech had less impact on alpha diversity but impacts beta diversity. Changes in forest structures and environmental conditions occurring during forest conversion are as important as the introduction of beech for alpha and beta diversity.

Density-dependent mortality models for mono- and multi-species uneven-aged stands: The role of species mixture

The self-thinning law describes the progressive mortality of growing trees in crowded even-aged stands because of competition. In uneven-aged stands, however, density-dependent mortality is relatively poorly known. We developed density-dependent self-thinning models for mono-species and multi-species uneven-aged stands. Three models for mono-species Picea abies, Abies alba and Fagus sylvatica stands, four models for mixed conifer/broadleaf stands and a model for single tree selection stands as a specific type of uneven-aged forest were parametrized by Quantile Regression (QR) and Stochastic Frontier Analysis (SFA) using data from n = 31,612 forest inventory plots in Slovenia. The average slope of the self-thinning line in uneven-aged stands of −1.422 was statistically significantly lower than Reineke’s slope. Maximum stand density was higher in mono-species stands than in multi-species stands. The higher the proportion of beech in a stand, the higher the intercept and slope of the maximum stand density line. In single tree selection stands, the intercept and the slope of the maximum stand density line were highest and statistically different from all other types of uneven-aged forests. Species mixture had an impact on the slope and intercept of the self-thinning line. The slopes of the self-thinning lines differed between the studied types by up to 36% and 69% in the SFA and QR models, respectively, while the intercepts differed by up to 13% and 24%, respectively. However, maximum stand densities differed significantly only between compositionally very dissimilar stand types, such as Fagus sylvatica- or Picea abies-dominated mixtures versus other broadleaf mixtures (e.g., Quercus petraea, Carpinus betulus). The SFA predictions of maximum stand densities were systematically lower and less varying than the QR predictions, but not statistically different. The models can be used to constrain individual tree growth models in uneven-aged forests and to estimate the onset of inter-tree competition in irregular stands.

Diameter Growth of Silver Fir (Abies alba Mill.), Scots Pine (Pinus sylvestris L.), and Black Pine (Pinus nigra Arnold) in Central European Forests: Findings from Slovenia

The main objectives of the study were to (1) determine the response of the diameter growth of silver fir, Scots pine, and black pine in Central European seminatural forests to tree, stand, and environmental factors and (2) test for differences in their growth rate on different soils. Based on 26,291 permanent sampling plots (500 m² each), we developed a linear mixed-effects model of the diameter increment for each of these tree species. The models explained 32%–47% of the total diameter increment variability. The models differ in the set of predictors. All models suggested a non-linear effect of tree diameter on diameter increment. Nine predictors were common to all three models (stand basal area, quadratic mean diameter, basal area of overtopping trees, the proportion of beech in the stand volume, inclination, elevation, mean annual temperature, mean diurnal range, and soil unit), and six predictors were specific for one or two models (tree diameter, logarithm of tree diameter, proportion of other broadleaves, site productivity, rockiness, eastness index). Tree diameter was the most important variable for fir growth, while climatic variables explained most of the variability in pine diameter growth. The soil unit contributed from 5.3% to 7.5% to the explained diameter increment variability. Although the developed models are only locally accurate and cannot be used outside the study area without validation, the model predictions can be compared to those in other stand growth simulators and other geographical regions.

Relation between Topography and Gap Characteristics in a Mixed Sessile Oak–Beech Old-Growth Forest

The interest to assess the relationship between forest gap characteristics and topography features has been growing in the last decades. However, such an approach has not been studied in undisturbed mixed sessile oak–beech old-growth forests. Therefore, the present study carried out in one of the best-preserved sessile oak–beech old-growth forests in Europe, aims to assess the influence of topographic features (slope, altitude and aspect) on (i) some characteristics of canopies and expanded gaps (surface, diameter and perimeter) and (ii) the proportion of beech and sessile oak as bordering trees, gap fillers and gap makers. Through a complete gap survey on an area of 32 ha, 321 gaps were identified and mapped. The largest gaps and also the highest gap frequency (140) was found in the slope class (15.1–20°), while the gap frequency increased with altitude, with 99 gaps being recorded at 601–650 m a.s.l. The size and perimeter of the canopy and expanded gaps, as well as the number of gap makers, were negatively related to the slope and altitude. The expanded gap to canopy gap size ratio decreased with the slope and was positively related to the altitude, while a significant negative decrease in gap filler density with altitude was encountered. The sessile oak participation ratio as bordering trees forming the gap increased not only with the altitude but also with the slope. The topography plays an important role in the formation of gaps as well as in the characteristics of the future stand. This study provides valuable insights into the relationship between canopy gap characteristics and topography, which is useful information for forest owners that pursue the design of forest management toward nature-based solutions.

Chances and Limitations of Mixed Oak Regeneration under Continuous Canopy Cover—Evidence from Long-Term Observations

Traditionally, due to its light ecology, oak is regenerated on clear cuts or areas where the crown coverage is heavily reduced. Thus, the regeneration phase is relatively short. Recently, selective long-term regeneration phases avoiding large gaps in the canopy but fostering mixed-species stands have been advocated as being more in keeping with close-to-nature forestry in Central European forests. However, examples of the successful regeneration of oak in mixtures following this type of regeneration are largely missing. Here, we report the results of long-term experiments located in three different forest types, where oak was long-term regenerated under different mixing and canopy cover situations. The observation periods reached from 26 to 36 years. We focused on the dynamics of stem number reduction, as well as the height and biomass development of oaks and their interaction with interspecific competition and canopy density. The probability of oaks occurring in the regeneration basically decreased over the duration of the regeneration period. Despite this, considerable regeneration biomass growth could be observed, especially in the case of the lower standing volume of the mature stand. The development of beech as the main competitor is scarcely slowed down by the canopy cover compared to oak. Increasing canopy cover noticeably impeded oak regeneration in the considered mixed stands. The model results suggest that a reduction in competition within the regeneration by lowering the proportion of beech below 30% enhanced the success of oak regeneration in the long run even in small patches. The productivity of the remaining stand was primarily driven by standing volume. However, a negative trend of its productivity emerged with high regeneration biomasses. The study results show that small-scale oak regeneration with prolonged regeneration duration is possible in principle. However, oak regeneration requires active and continuous silvicultural assistance, which has to be adjusted to the specific site conditions.

Dominance of Fagus sylvatica in the Growing Stock and Its Relationship to Climate-An Analysis Using Modeled Stand-Level Climate Data.

In the future, climate change is expected to affect the spatial distribution of most tree species in Europe. The European beech (Fagus sylvatica), a drought-sensitive tree species, is currently distributed throughout Europe, where it is an ecologically and economically important species. In Slovenia, the European beech represents 33% of the growing stock, but such a proportion greatly varies across Europe. Whether such a variation is related to the climate environmental gradients or because of historical or management decisions is an as-yet unexplored question. For this study, we employed the Slovenian Forests Service inventory, where the proportion of beech in the forest stock has been monitored in 341,341 forest stands across the country. Modeled climate data from the SLOCLIM database, calculated for each of the stands, was also used to test the hypothesis that although beech forests have always been influenced by human activity, the dominance of beech trees in forest stands is at least partially dictated by the climate. The results showed the distribution of the main climate variables (annual precipitation, the share of summer and spring precipitation, and annual maximum and minimum temperatures) and how they affect the current dominance of beech trees at the stand level. Due to the large number and variability of forest stands studied, the results should be transferable to better understand and manage the climatic suitability and risks of Fagus sylvatica. The modeled data is publicly available in the web repository Zenodo.

Site conditions more than species identity drive fine root biomass, morphology and spatial distribution in temperate pure and mixed forests

AimThe establishment of broadleaved - conifer mixtures has had positive effects on productivity. However, it is still not clear the degree to which belowground space occupation contributes to these effects and how root traits of the respective species differ between mixed and pure stands. Thus, the aim of this study was to examine how enrichment of beech forests with conifer species impacts fine root biomass and other root traits across variable site conditions. MethodsWe studied 20 mature pure and mixed stands of European beech (Fagus sylvatica), Norway spruce (Picea abies), and Douglas-fir (Pseudotsuga menziesii), and determined differences in biomass, spatial distribution, and morphology of fine roots (≤2 mm, to 60 cm soil depth) among beech – conifer mixtures and pure stands of the respective species in two regions with differing site conditions in Northern Germany. ResultsSite conditions had strong effects on fine root biomass (FRB) and fine root area index (RAI). Both FRB and RAI were significantly higher across all stand types on the sites with lower belowground resource availability. On the less favorable sites, FRB significantly increased with increasing beech proportion. In contrast to specific root area (SRA) and RAI, specific root length (SRL) was not affected by site conditions but differed significantly among species. No overyielding was observed when FRB was plotted against basal area and/or area potentially available (APA), which reflects the aboveground horizontal space configuration. Spatial fine root biomass patterns of all species in both monospecific and mixed stands changed along the vertical soil profile at both sites. FRB decreased with increasing soil depth, with the exception of beech in mixed stands. ConclusionOur data suggest that both amount and distribution of tree fine roots in pure and mixed stands are highly variable and depend primarily on-site conditions and secondarily on tree species identity. By disentangling soil and species identity effects, we conclude that beech has a remarkable potential for adjusting fine root biomass to cope with unfavorable conditions as compared to spruce and Douglas-fir.

Revealing hidden drivers of macrofungal species richness by analyzing fungal guilds in temperate forests, West Hungary

We explored the most influential stand-scaled drivers of ectomycorrhizal, terricolous saprotrophic, and wood-inhabiting (main functional groups) macrofungal species richness in mixed forests by applying regression models. We tested 67 potential explanatory variables representing tree species composition, stand structure, soil and litter conditions, microclimate, landscape structure, and management history. Within the main functional groups, we formed and modeled guilds and used their drivers to more objectively interpret the drivers of the main functional groups. Terricolous saprotrophic fungi were supported by air humidity and litter mass. Ectomycorrhizal fungi were suppressed by high soil nitrogen content and high air temperature. Wood saprotrophs were enhanced by litter pH (deciduous habitats), deadwood cover, and beech proportion. Wood saprotrophic guilds were determined often by drivers with hidden effects on all wood saprotrophs: non-parasites: total deadwood cover; parasites: beech proportion; white rotters: litter pH; brown rotters: air temperature (negatively); endophytes: beech proportion; early ruderals: deciduous stands that were formerly meadows; combative invaders: deciduous tree taxa; heart rotters: coarse woody debris; late stage specialists: deciduous deadwood. Terricolous saprotrophic cord formers positively responded to litter mass. Studying the drivers of guilds simultaneously, beech was a keystone species to maintain fungal diversity in the region, and coniferous stands would be more diverse by introducing deciduous tree species. Guilds were determined by drivers different from each other underlining their different functional roles and segregated substrate preferences. Modeling guilds of fungal species with concordant response to the environment would be powerful to explore and understand the functioning of fungal communities.

Stand inventory data from the 10-ha forest research plot in Uholka: 15yr of primeval beech forest development.

Forests dominated by European beech (Fagus sylvatica L.) are among both the most widespread in Europe and the most intensely exploited globally. One of the largest remnants of unmanaged beech forests in Europe is the Uholka-Shyrokyi Luh forest in Transcarpathia, Ukraine, covering 8,800ha of primeval forest. In 2000, a permanent forest plot of 10ha has been established in the Uholka massif. All living and dead trees with a diameter at breast height (DBH) ≥ 60mm were identified to species, DBH measured, stems tagged and mapped. Since then, the plot has been remeasured in 2005, 2010, and 2015. In total, 4,820 individual trees were measured with 14,116 individual measurements throughout all four inventories. In spring 2018, an Airborne Laser Scan was carried out, covering the Uholka-Shyrokyi Luh forest. This data setallows us to derive a high-resolution digital elevation model (DEM) of the plot area. European beech covers a share of ≈ 95% of the basal area (BA) of all living stems. While BA was relatively stable throughout all inventories (≈ 38m2 /ha), the number of stems increased considerably between 2010 and 2015 from 290 to 430 stems/ha. Additionally, the proportion of beech stems decreased from 95% in 2010 to 86% in 2015. The continuity of the share of beech on BA and the decrease in number of stems can be traced back to disturbance events, which led to an increase of more light demanding species in the recruitment but did not alter the distribution of BA as these small trees contribute very little to BA. The data setallows for important insights into the development and the spatial and temporal dynamics of primeval beech forests. It can be used to quantify the demographic processes growth, mortality, and recruitment, and to study inter- and intraspecific effects on demographic rates, stand structure, and species composition. No copyright or proprietary restrictions are associated with the use of this data set other than citation of this Data Paper.

Environmental drivers of the forest regeneration in temperate mixed forests

As modern silviculture in natural forests is based on natural regeneration, finding the most important drivers of regeneration is crucial for forestry as well as conservation. We explored the relationship between numerous environmental and land use history variables and the species richness, cover and composition of the regeneration layer, and also the cover of the dominant species of the regeneration (sessile oak, hornbeam and beech) in coniferous-deciduous mixed forests. We identified the key factors which forest management can influence to support the regeneration of mixedwoods.Thirty-four stands were sampled, representing different tree species combinations and stand structures. We used redundancy analysis to explore the effects of the explanatory variables on the regeneration’s species composition, and general linear modelling to examine their effects on its species richness and cover.The most important drivers of species composition were tree species richness, the amount of relative diffuse light, the proportion of beech in the overstory, and the heterogeneity of the diameter of trees. The cover of the regeneration layer was positively related to the density of large trees and to the amount of relative diffuse light. Its species richness was most strongly influenced by light and tree species richness. For the cover of a particular species in the regeneration, the proportion of the conspecific species in the overstory was determinant for every species, but other, various drivers also played a role in the case of the different species.According to our results, the community variables of the regeneration are mainly driven by the characteristics of the current forest stands, thus they are strongly influenced by management. Compositional heterogeneity of the overstory, various tree size distribution and the presence of large trees play key roles in the maintenance of a heterogeneous regeneration layer. The shelterwood forestry system is partially capable of providing these conditions, but continuous cover forestry is much more suitable to achieve them. Besides the stand structural variables, among the drivers of the individual species, various variables of forest site, landscape and land use history also occurred. Therefore, we conclude that maintaining the landscape-scale heterogeneity of forest types and management systems may promote the coexistence of various species in the region.

Дослідження причин всихання деревостанів ялиці білої (Abies Alba Mill.) в Українських карпатах

Вивчено типологічну роль ялиці білої в Українських Карпатах. Виявлено та описано характер всихання дерев ялиці білої. Складено карту поширення осередків всихання ялиці білої на території НПП "Гуцульщина". Відібрано 25 модельних дерев ялиці білої у трьох найпоширеніших типах лісу у деревостанах різного віку, повноти, висоти н.р.м., експозицій схилів. Здійснено відбір зразків для досліджень ходу росту дерева, фізико-механічних властивостей здорової та пошкодженої деревини, кількісного вмісту фотосинтезуючих пігментів хвої дерев. Ялиця біла формує 26 типів лісу в свіжих, вологих та сирих сугрудах і вологих та сирих грудах, в 11 з яких є головною породою та в 15 – супутньою. Масове всихання ялиці відбувається у тих типах лісу, де вона виступає головною породою. Здійснено комплексну діагностику інфікованої деревини ялиці білої для встановлення причини всихання дерев. Проведено дослідження для визначення зараження дерев стовбуровими нематодами, бактеріями і фітопатогенними грибами. За результатами аналізів дерева ялиці білої із ознаками всихання інфіковано комплексом патогенів. Серед них виявлено фітопатогенні бактерії, за допомогою ПЛР-аналізу ідентифіковано в стовбуровій деревині гриби роду Fusarium та Heterobasidion parviporum. За допомогою лабораторних досліджень встановлено причини всихання, послідовність інфікування дерев різними патогенами та описано сценарій розвитку хвороби.

Can bark stripping cause red heartwood formation in beech stems?

Injuries to standing trees caused by logging and the subsequent changes in biochemical composition and anatomy of affected tissues lead to wood quality loss, thus lowering the commercial value of roundwood. In this study, we investigated the influence of various factors that could help mitigate or prevent the spread of infections in the stem caused by injuries. A total of 112 beech logs (tree age: 42-143 years) from ten forest stands at three different sites in central Slovakia were examined, and the extent of discolouration and decay zones in each stem was measured, along with cambial age, stem diameter, injury width, and injury closure period. The results showed that the width of physiologically active wet sapwood and the width of the inactive dehydrated zone in the stem are important factors influencing red heartwood formation. We found no significant differences in the extent of discolouration and decay among different stands and sites. Stem diameter and injury width did significantly affect the penetration of infection through sapwood, and red heartwood formation was significantly affected by cambial age and injury width, while stand age, site slope, beech proportion in the stand and injury closure did not show any significant effect. Binary logistic models were applied to assess the probability of pathogen penetration through sapwood into the stem dehydrated zone as a function of injury width and stem diameter, as well as the probability that this could lead to red heartwood formation based on injury width and cambial age of beech stems.

Seasonal changes of the Hazel Grouse Tetrastes bonasia habitat requirements in managed mountain forests (Western Carpathians)

We studied the differences between spring and winter sites of Hazel Grouse Tetrastes bonasia in a managed, temperate forest in the Beskid Mountains (Western Carpathians, Poland). The study of seasonal requirements of this species in this type of habitat was innovatory. Spring territories must provide birds with appropriate conditions for breeding and winter ones must give good habitat for wintering. The environmental variables of spring and winter sites were collected in three layers in a 100 m radius from the place of recording of the Hazel Grouse: canopy, understory and undergrowth. According to our study, the proportion of deciduous trees was greater in spring territories in comparison to winter territories in all studied layers. Conversely, greater species richness in the undergrowth and understory in spring sites of Hazel Grouse was found in comparison to winter sites. Moreover, a greater proportion of birch, poplar, willow, wild cherry and bird cherry were found in the spring sites of Hazel Grouse in comparison to winter sites. Generalized Linear Model models showed that the occurrence of overgrown clearings, clearfellings with deadwood and higher richness of grass and herbs and their cover in the forest were important habitat factors for Hazel Grouse in both spring and winter sites. Sites of Hazel Grouse were strongly affected by the proportions of beech, sycamore, fir, spruce and larch in the canopy layer in both seasons. Moreover, a greater proportion of tree species producing nuts, drupes or winged seeds was important in both spring and winter sites. Bush cover was important for winter sites of the Hazel Grouse. Food resources, mainly in winter sites are important factors for habitat selection. Summarizing, we found habitat differences between spring territory and winter sites of Hazel Grouse. In both seasons, higher habitat heterogeneity was an important factor for occurrence of this species.

Effect of water stage and tree stand composition on spatiotemporal differentiation of spring water chemistry draining Carpathian flysch slopes (Gorce Mts)

The purpose of this study was to identify the factors affecting spring water chemistry in different tree stands and to measure the influence of water stage on the physicochemical parameters of spring waters in a small Carpathian catchment. Water samples were collected three times per year at various stages of the water: after the spring thaw, after a period of heavy rain and after a dry period in 2011 and 2012. Water samples were left in the laboratory to reach room temperature (19–20°C) and analyzed for EC (reference T=25°C) and pH. After filtration through 0.45μm PTFE syringe filters, the water samples were analyzed by means of ion chromatography using a DIONEX ICS 5000 unit. The following ions were analyzed: Ca2+, Mg2+, Na+, K+, HCO3−, SO42−, Cl−, and NO3−. Multivariate analysis (PCA) allowed the identification of two factors of spring water chemistry: factor 1, water stage and factor 2 tree stand composition. Seasonal variation of spring water chemistry showed that, higher pH values and mineralization as well as higher concentrations of Ca2+ and Mg2+ were measured during low water stage periods while lower EC and pH values were noted after spring snowmelt and rainfall, when higher concentrations of NO3− and SO42− were also found. Higher concentrations of Ca2+ and Mg2+ and higher pH of spring waters located in beech-fir stands and in those mixed with a large proportion of beech as well as a lower concentration of Ca2+, Mg2+ and HCO3−, pH, conductivity and mineralization of these spring waters, in which the alimentation areas were covered by upper subalpine spruce stands were noted.

Evaluation of the genetic diversity of selected Fagus sylvatica L. populations in the Czech Republic using nuclear microsatellites

Fagus sylvatica Linnaeus (European beech), the ecologically and economically most important broadleaved tree species in the Czech Republic, was strongly reduced in the past. Today there are efforts to increase the proportion of beech to ensure optimal forest tree species composition. When extensively reintroducing beech, it is important to acquire more detailed knowledge of genetic diversity. Thirteen important beech populations in different stands in the territory of the Czech Republic were genotyped using 12 polymorphic nuclear microsatellite markers. The genotypic data from adult trees imply genetic differences between the populations. The estimated genetic diversity expressed as Shannon’s information index ranged from 1.73 to 1.92. Thirteen beech populations showed excess homozygotes, as indicated by positive fixation index (F) values (F = 0.005–0.115). The pairwise F<sub>ST</sub> values indicated low genetic differentiation between the 13 Czech beech populations, because they were greater than zero, that means they confirmed the presence of population structuring in Czech European beech. Not significant linear correlations were observed between genetic and geographic distances of the 13 beech populations studied on the basis of microsatellite markers. Twelve microsatellite markers were verified as highly polymorphic and suitable for genotyping of European beech populations.

Climate modifies tree interactions in terms of basal area growth and mortality in monospecific and mixed Fagus sylvatica and Pinus sylvestris forests

Net interactions between trees vary depending on environmental conditions and other factors such as stand density, age, or between-species complementarity and/or facilitation. According to the stress gradient hypothesis, positive or facilitative interactions are more frequent in high-stress environments whereas negative or competitive interactions occur in benign environments, although recent studies highlight the influence of species composition, type of stress, ontogeny, etc. on the interaction–stress gradient pattern. The aim of this paper is to analyze whether site climatic variables are a key factor in tree interactions in mixed stands of beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.). To test how site climatic conditions modify the effect of inter-specific competition on tree basal area growth and tree mortality, growth and mortality models were fitted using monospecific and mixed sample plots located in matching site conditions selected from the Spanish National Forest Inventory in the Navarra Province. Tree competition status was broken down into four terms according to size-symmetry (size-symmetric vs. size-asymmetric) and species identity (intra-specific vs. inter-specific). The results showed that the size-symmetric inter-specific component was non-significant on beech basal area growth and had a negative effect on pine growth. The effect of size-asymmetric inter-specific competition was always non-significant, resulting in a higher basal area growth when the admixed species are of a larger size. The interaction between annual precipitation and this inter-specific competition effect was much more pronounced on beech than on pine. Inter-specific competition had a negative effect on pine growth under better climatic conditions and a positive effect at dryer sites, while beech always benefited from the presence of pine, although the benefit was greater where climatic site conditions were better. In tree mortality models, pine mortality increased with the proportion of beech, while beech mortality was lower as the proportion of pine increased. Precipitation modified the inter-specific competition effect on tree mortality although the site influence was less relevant than on tree growth. For pine mortality, the negative effect of beech admixture was stronger at lower mean annual precipitation, while in the case of beech the positive effect of pine increased at higher levels of precipitation. The influence of climate on the effect of competition, the variation in their strength depending on the mode of competition (size-symmetric or size-asymmetric), along with the inter-specific competition component, highlight the importance of considering the effect of site conditions on between-species interactions when modeling tree growth and mortality. The species-specific patterns of variation in tree interactions along climatic gradients and the differences in tree growth and mortality corroborate the need to consider the nature of stress-limiting factors and species composition and the importance of analyzing both dynamic processes simultaneously.

Interchangeable sets of complementary habitat variables allow for flexible, site-adapted wildlife habitat management in forest ecosystems

Integrating biodiversity conservation into forest management is a major goal in sustainable forestry. Hence, target values for forest structural and compositional stand characteristics are required to ensure wildlife habitats of sufficient extent and quality. Yet, the possibility to meet these targets depends on the patch conditions, notably their initial state and future trajectory. Shaped by succession, site conditions and management regime, not all forest stands can be readily converted into a particular state, which calls for flexible management prescriptions. Using the example of two forest grouse species, capercaillie and hazel grouse, we sought complementary variable combinations – with quantitative thresholds for any given crucial habitat feature – which would likewise offer suitable habitat. Habitat variables were mapped in sampling plots within occupied and non-occupied 1km2 grid cells distributed across three Swiss mountain regions. Generalized linear mixed models (GLMM) were combined with conditional inference trees (CIT) to identify species-relevant variable combinations and variable thresholds. Important features for both species were the proportion of bilberry (Vaccinium myrtillus) and the number of basal-branched trees, as well as a low proportion of beech (Fagus sylvatica) in the canopy layer. Hazel grouse additionally favoured rowans (Sorbus aucuparia) as feeding trees and a high percentage of herbs in the ground layer, while the presence of inner forest edges was additionally important for capercaillie. Thresholds were not clear-cut: different values applied for a particular variable depending on other, functionally similar habitat variables present at the site. By delivering information about relevance, interactions and the required amount of crucial variables, we provide alternative options for flexible species habitat management which allows accounting for the prevailing stand conditions.