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Reasons for performing study Ingestion of sycamore seeds ( Acer pseudoplatanus) is the likely source of hypoglycin A in atypical myopathy ( AM) but ingestion of seedlings in spring might also contribute to intoxication. Objectives To test for hypoglycin A in seeds and seedlings collected on pastures where AM cases were reported and compare its concentration in serum of affected and healthy horses. Study design Field investigation of clinical cases. Methods Whenever present, samaras (the winged nuts that each contain one seed) and/or seedlings were collected from pastures of 8 AM cases and 5 unaffected horses from different premises. Two AM cases were each co-grazing with an apparently healthy horse. Acylcarnitines and hypoglycin A were quantified in blood samples of all horses involved in the study. Results Hypoglycin A was detected in serum of AM (5.47 ± 1.60 μmol/l) but not in healthy controls pasturing where A. pseudoplatanus trees were not present. However, hypoglycin A was detected at high concentrations (7.98 μmol/l) in serum of a clinically healthy horse grazing a pasture with seedlings and samaras and also in the 2 healthy horses co-grazing with AM cases (0.43 ± 0.59 μmol/l). Hypoglycin A was detected in all samples of seeds and spring seedlings of A. pseudoplatanus. Conclusions Atypical myopathy can be associated with the ingestion of sycamore samaras and also ingestion of seedlings. Hypoglycin A can be detected in the blood of horses with no detectable clinical signs at pasture in which there is A. pseudoplatanus. Determination of hypoglycin A concentration in blood is useful for screening for exposure in suspected cases of AM. [ABSTRACT FROM AUTHOR]

The main task of the present study was to investigate the root vitality of common beech Fagus sylvatica L., sessile oak Quercus petraea Liebl. and sycamore maple Acer pseudoplatanus L. in the optimal g rowth conditions in south-western Poland. The study was carried out in 130-year-old mixed stand located within natural range of studied tree species. The density of roots (g/100 cm3 of soil) and biomass of fine roots (g/m2) in topsoil layers (0-5 cm, 5-15 cm) were determined in the tree biogroups of the same species. The mean total root density ranged from 0.248 to 0.417 g/100 cm3 in the 0-5 cm soil layer, and it decreased in the deeper soil layer (5-15 cm). There were found no statistically significant differences of total root densities between tree biogroups in topsoil layers. Diversity of fine root biomass was comparable in the tree biogroups (H' = 1.5), but common beech showed more intensive growth of fine roots in the topsoil 0-15 cm when compared to sessile oak and sycamore maple. The results of the study point out the stability of the multi-species structure of the mixed stand studied, and consequently - the ability of beech, sessile oak and sycamore maple trees to coexist in the mixed stands - in the area of natural range of these species. [ABSTRACT FROM AUTHOR]

Background Atypical myopathy ( AM) in horses is caused by the plant toxin hypoglycin A, which in Europe typically is found in the sycamore maple tree ( Acer pseudoplatanus). Owners are concerned about whether their horses are in danger if they graze near maple trees. Hypothesis/Objectives To measure hypoglycin A in the most common maple tree species in the Netherlands, and to determine whether concentration of toxin is a predictor of AM in horses. Methods A total of 278 samples of maple tree leaves, sprouts, and seeds were classified by species. Mean concentrations of hypoglycin A were compared for the type of sample, the season and the occurrence of AM in the pasture (non- AM versus AM). Statistical analysis was performed using generalized a linear model ( SPPS22). Results Almost all Acer pseudoplatanus samples contained hypoglycin A, with concentrations differing significantly among sources ( P < .001). Concentrations were significantly higher in seeds from the AM group than in seeds from the non- AM group (856 ± 677 and 456 ± 358 mg/kg, respectively; P = .039). In sprouts and leaves this was not the case. Acer platanoides and Acer campestre samples did not contain detectable concentrations of hypoglycin A. Conclusions and clinical importance Acer platanoides and campestre seem to be safe around paddocks and pastures, whereas almost all A cer pseudoplatanus samples contained hypoglycin A. In all AM cases, Acer pseudoplatanus was found. Despite significantly higher concentration of hypoglycin A in seeds of pastures where AM has occurred, individual prediction of AM cannot be made by measuring these concentrations because of the high standard deviation. [ABSTRACT FROM AUTHOR]

Atypical myopathy is an acute intoxication induced by the ingestion of hypoglycin A, a toxin contained in the seeds and seedlings of certain trees of the genus Acer (particularly Acer pseudoplatanus [sycamore] in Europe), which results in disruption of the energy metabolism. The clinical signs arise from energy depletion in the type I fibres of the postural and respiratory muscles, and lead to a specific biochemical profile that may be used to confirm a diagnosis. Since there is no cure for the condition, the emphasis is on prevention, which requires knowledge of the conditions necessary for the causative agent to exert its toxicity. This article gives an overview of atypical myopathy, discussing the mechanism involved, its aetiology and the clinical signs and management (therapeutic and prevention). [ABSTRACT FROM AUTHOR]

European beech ( Fagus sylvatica ) increases its dominance in various forest types in Central Europe. In this context we investigated a very exceptional process, in which beech have been partly outcompeted by sycamore maple ( Acer pseudoplatanus ) in unmanaged forest without severe disturbances. Main research questions were as follows: (i) How did the spatial patterns of beech and sycamore develop, and can these patterns be described by known spatial models?; (ii) What were the spatial relationships between beech and sycamore?; (iii) Does the spatial relationship of advance regeneration to gap-makers differ for the two species?; (iv) Did the presence of a road influence the spread of the sycamore population? The study was conducted in beech-dominated forest Žákova hora in the central part of the Czech Republic which has been left to spontaneous development for 85 years. We studied long-term forest dynamics using stem position maps of trees with DBH ⩾ 10 cm carried out in 1974, 1995 and 2011. We used standard methods for calculating recruitment, mortality and population change. Various types of the pair correlation function were applied to describe the development of tree spatial patterns. Our results showed that sycamore regenerated in the close vicinity of other conspecific trees. Sycamore recruits were not spatially associated to individual gap makers. Sycamore individuals had a highly clustered distribution, and the number of individuals grew mostly through the increasing of existing clusters. We successfully fitted the Matérn cluster process for sycamore spatial patterns. The radius of the model cluster ranged between 6 and 16 m. By contrast, beech recruits were negatively correlated to older conspecific trees and showed independence or positive correlation to sycamore veterans. The vicinity of the road significantly promoted sycamore recruitment (opposed to the beech). If the sycamore expansion is connected with the vicinity of the road and thickening of existing sycamore clusters only, as our results indicate, then it can be spatially and temporally limited process. [ABSTRACT FROM AUTHOR]

This investigation was undertaken to assess the level of environment pollution by biological monitoring. The leaves and bark of popular ornamental treesAcer pseudoplatanusL. andAcer platanoidesL. and soil from the sampling sites were used to perform heavy metals pollution monitoring in urban areas with different pollution sources, as well to investigate the suitability of the leaves and bark as bioindicators of Pb, Zn, Cd and Cu pollution. Plant samples were collected at nine locations classified into three pollution groups based on metal content in the soils. The chosen pollution indices were used to assess the level of contamination according to background values. Soils in the Katowice area are found to be relatively heavily contaminated with Pb, Zn and Cd. Both of the maple tree species did not statistically differ in terms of the investigated elements' concentration in leaves or bark. Only bark samples reflected the pollution level, showing differences between the sampling points, and therefore are recommended for biomonitoring purposes. [ABSTRACT FROM AUTHOR]

There is increasing evidence that riparian corridors have modified thermal conditions compared to non-riparian areas. However, the biological significance of this difference is less clear. Here we tested this by investigating the response of tree phenology to riparian thermal conditions. We monitored the timing of bud burst, leaf fall and growing season of riparian and non-riparian ash ( Fraxinus excelsior L.) and sycamore ( Acer pseudoplatanus L.) in the city of Sheffield over two years. We compared the phenologies between riparian and non-riparian trees and explored the relationship between tree phenologies and thermal environments. Tree phenologies varied between riparian and non-riparian areas and the effect was species specific. Bud burst and leaf fall were earlier in non-riparian than in riparian ash, but no location effects on either bud burst or leaf fall were detected for sycamore, or in the growing season for both species. Bud burst for the two species was highly correlated to spring temperature; warmer temperature resulting in earlier bud burst in ash but later bud burst in sycamore. No significant relationship between leaf fall and temperature was found for either species. A positive correlation between growing season and temperature was observed for ash but not sycamore. [ABSTRACT FROM AUTHOR]

Background and aims: The carbon (C) sequestration potential of land-use practices is increasingly important. Trees sequester atmospheric C into biomass and above and belowground litter but may also prime the decomposition of soil organic matter (SOM). We compared the influence of Acer pseudoplatanus (Sycamore) and Larix x. europlepsis (Hybrid Larch) on soil C decomposition. Methods: We used natural abundance C to partition soil-surface CO efflux into root and SOM sources. CO was sampled from incubated root-free soil and from live tree roots using in-situ chambers. Combined surface efflux δCO was measured using dynamic chambers and cavity-ringdown spectroscopy. Results: Under Sycamore, CO emissions were dominated (80-90 %) by root respiration. SOM contributed 10-20 % with a mean residence time of centuries. Under Larch, 24-33 % of total CO efflux was root respiration, the remainder originating from an SOM pool with a turnover time of decades. Total soil C stocks were similar between the two plot types. Root-respired δCO was consistently different by c. 2 ‰ between the species. Conclusions: The decomposition rate of soil C and its mean residence time are markedly different under the two tree species. Species differences in root-respired δCO may reflect plant C allocation or respiratory fractionation. [ABSTRACT FROM AUTHOR]

In February 2021, a I Eutypella i canker was detected on a multi-trunked I A. pseudoplatanus i in a private garden (Uster, Canton Zurich, 460 m above sea level; Figure 1). Acer platanoides, Acer pseudoplatanus, Eutypella canker, fungal plant disease Keywords: Acer platanoides; Acer pseudoplatanus; Eutypella canker; fungal plant disease EN Acer platanoides Acer pseudoplatanus Eutypella canker fungal plant disease 1 2 2 06/29/22 20220401 NES 220401 I Eutypella parasitica i is an ascomycete, native to Canada and the USA, which causes perennial cankers and wood decay on I Acer platanoides i , I A. rubrum i and I A. saccharum i (Davidson & Lorenz, 1938; Kliejunas & Kuntz, 1974). [Extracted from the article]

The occurrence of polycarpous fruits on six out of 100 sycamore maples, i e. with 3, 4 and 8 fruits on one carpophore is described. Eight-carpous fruits have not been recorded to date in the region of the Serbia and Montenegro, and wider. The cause of the development of polycarpous fruits has been hypothesized.

Stringed instruments are made of high quality wood species from physical, mechanical and acoustical point of view, being carefully selected, kiln dried and processed under specific conditions that assure micro-structural integrity. Maple wood (Acer Pseudoplatanus) for musical instruments is used to getting back plates and sides for string instruments (violin family). This species of wood is valued for both acoustic qualities but mostly for aesthetic, using a natural defect of maple wood characterized by wavy grain. The paper presents the research on visco-elasticity behavior of maple wood with different types of grain deviation in wood from very curly maple to common maple. The storage modulus, loss modulus, damping capacity in varying temperature conditions and for different loading frequencies were determined using dynamical mechanical analysis (DMA). It was found that specimens characterized by very wavy grain shows a high damping capacity of frequency range between 33.33 to 50Hz, unlike specimens of common maple which do not have the capacity of frequency selectivity. [ABSTRACT FROM AUTHOR]

Grafting of Sycamore (Acer pseudoplatanus L.) was performed on to rootstock of the same species. Two phonological conditions of the rootstock were studied - dormant and active. Three methods were tested - chip budding, splice graft and cleft graft. Criteria for evaluating the results were success rate, length of the shoots, number shoots and percentage of the shoots developed from the buds applied. We recommend grafting on both "dormant" and "growing" rootstock by splice graft. The success rate in spring (dormant rootstock) was 90.00 ± 10.75% and in summer (growing rootstock) - 85.00 ± 10.75%. [ABSTRACT FROM AUTHOR]

Research on the early stages of stand dynamics in uneven-aged forests often favours regeneration over recruitment of trees into forest stands. We contrasted both regeneration (i.e. seedlings and saplings existing in a stand) and recruitment (i.e. the number of trees annually crossing the threshold of 10 cm dbh) in two main stand types of uneven-aged forests (plenter and group selection). Data from 1710 permanent plots across the Dinaric Mountains in Slovenia were used to study recruitment; on 165 plots, regeneration was additionally analysed. The zero-inflated negative binomial modelling procedure was applied to identify factors influencing regeneration and recruitment. Total regeneration (30 212 ha-1) and that of light-demanding species (14 879 ha-1) were abundant. The latter regenerated more successfully in group selection stands compared with plenter stands. A large reduction in regeneration density was determined during its growth, which was more dramatic for light-demanding species (e.g. Acer pseudoplatanus) than for shade-tolerant species (e.g. Fagus sylvatica, Abies alba). The number of recruited trees (5.83 ha-1 y-1) seemed to be sufficient to maintain the uneven structure but was less promising for light-demanding species (0.13 ha-1 y-1). However, light-demanding species have the potential to establish and recruit into uneven-aged stands with a limited target proportion in the growing stock. Both indicators--regeneration and recruitment--are indispensable for understanding patterns of stand dynamics in uneven-aged forests. [ABSTRACT FROM AUTHOR]

Accurate estimates of the wood volume or biomass of individual trees have gained considerable importance in recent years. The accuracy of wood volume estimation by terrestrial laser scanning (TLS) point cloud data may differ between individual trees due to species-specific differences in tree architecture. We selected three common and ecologically important central European deciduous tree species, which differ considerably in tree architectural complexity in early ontogenetic stages: Acer pseudoplatanus (simple), Sorbus aucuparia (intermediate) and Betula pendula (complex). We scanned six single young trees for each species (18 trees in total) under optimal scan conditions (single tree stand, leafless state, four scanning positions, high resolution). TLS-based volume estimates were derived for the total tree as well as for the two compartments; trunk and branches, using a voxel-based bounding box method. These estimates were compared with highly accurate xyolmetric (water displacement) volume measurements. Coefficients of determination between xylometric measurements and bounding box estimates were very high for total trees (R2adj = 0.99), trunks (R2adj = 0.99), and high for branches (R2adj = 0.78). The accuracy of estimations for total tree and trunk volume was highly similar among the three tree species. In contrast, significant differences were found for branch volume estimates: the accuracy was very high for Sorbus aucuparia, intermediate for Betula pendula, and low for Acer pseudoplatanus. A stepwise multiple regression showed that the accuracy of branch volume estimates was negatively related to the number of the first-order branches within diameter sizes of D ≤ 5 mm and crown surface area (R2adj = 0.61). We conclude that the accuracy in total tree and trunk volume estimates was not affected by the studied types of tree architectural complexity. The impact of the structural variability of branches and occlusion by branches was, thus, not as high as expected. In contrast, the accuracy of branch volume estimates was strongly influenced by tree architectural complexity, though not in a simple way. Because underestimations originated from different sources, the accuracy of branch volume estimates cannot be directly derived from the degree of architectural complexity. These results imply that the voxel-based bounding box method provides highly accurate total tree and trunk volume estimates, whereas further research is needed to improve branch volume estimation for young trees of different architectural types. [ABSTRACT FROM AUTHOR]

The primary objectives of this study were to estimate seedling abundance, spread intensity, and invasiveness of sycamore maple (Acer pseudoplatanus L.) in Lithuanian forests. The species was introduced to Lithuania in 1802, and since then has subsequently become gradually invasive. Seedling understory abundance, colonization and dispersal were investigated in six forest blocks covering the principal sycamore distribution areas in southwestern Lithuania. Seedlings height and densities in the undestory were evaluated, and seedlings assigned to four height groups. Species invasiveness was estimated applying the Pest Plant Prioritization Process (PPPP), based on the Analytic Hierarchy Process (AHP) method. Results showed the average spread distance from the parent tree was 257 m, with a mean seedling number per hectare of 2064. Sycamore maple invasive score was 0.6426 (range: 0-1), the current relative to potential distribution rating was 0.57, and the social, environmental, and economic impact score was 0.1682. Such values were used to assess the Pest Plant Score for sycamore maple, obtaining a value (0.3537) lower than expectations (0.5). Results indicated that the species exhibits invasive properties and a rapid spread in the study area. Some implications of the above results in view of the upcoming climate change and the use of sycamore maple in Lithuanian forest plantations are discussed. [ABSTRACT FROM AUTHOR]

Over the last 15 years, shoot material from wavy grain sycamore maples (Acer pseudoplatanus L.) was collected from crowns of trees which were harvested and the stems then sold for very high values. Starting with grafts from this material, cutting propagation was tested and a tissue culture method was elaborated. However, the question of whether the wavy grain structure is expressed after vegetative propagation still remained unsolved. Recently, one of the oldest cuttings (11 years) and two grafts (17 years) were cut to look for structures of wavy grain expression. Veneer was produced from the log of the cutting- derived tree. Staining experiments were carried out using veneer sheets to improve the appearance of the structures. Based on these experiments, and in using morphological comparisons with veneer from adult wavy grain sycamore, we present the first evidence for the appearance of undulating fibre structures and the beginnings of wavy grain formation even in material at around ten years of age. A hypothesis related to the formation of wavy grain in deciduous trees is discussed [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the effects of repeated pruning interventions using different pruning methods on growth and physiology of Acer pseudoplatanus L. Trees were pruned in 2008 and 2010 according to widely used pruning techniques for urban trees, such as reduction cut, removal cut and heading (topping) cut. Crown dieback, growth of the plant and of the pruned branches, leaf morphological traits and leaf gas exchange were assessed during the two growing seasons after each pruning cycle. Topping cut (i.e. the pruning treatment which suppressed the primary axis without providing a substitute) induced changes on tree growth pattern (i.e. by increasing the release of adventitious watersprouts and root suckers and decreasing stem diameter growth), which were not observed in the other pruning treatments. At the leaf level only topping cut increased leaf area at the expense of leaf mass per area, which may contribute to explain the higher occurrence of dieback on topped branches than in control and in the other pruning treatments. Also, leaves on topped branches displayed higher chlorophyll content and higher activity of Calvin cycle enzymes, which did not translate in higher CO 2 assimilation. We show here that pruning method, not only its severity (i.e. the amount of leaf area removed), modulates the morpho-physiological response of trees to pruning and that maintenance of apical control and apical dominance are key issues to preserve a structurally sound tree structure, as well as the long-term efficiency of the photosynthetic apparatus. [ABSTRACT FROM AUTHOR]

Organic films and leaves provide a medium into which organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs), can accumulate, resulting in a useful passive air sampler. In the present work, the temporal variability (weekly) in PAH concentrations and the fingerprint of films developed on window surfaces were investigated. Moreover, films and leaves of two tree species (Acer pseudoplatanus and Cornus mas) collected at the same time were used to derive PAH air concentrations and investigate their short-term variability. In general, the most abundant chemicals found in films were phenanthrene and pyrene (22%), followed by perylene (21%) and fluoranthene (16%), but the fingerprint (in contrast to leaves and air) changed over time. Leaf derived air concentrations were within a factor of 2 to 9 from measured values, while air concentrations back-calculated from films were within a factor of 2 to 53. This happened because predicted air concentrations using films and vegetation samplers (especially for low KOA chemicals) generally reflect only the last few hours (due to the fast equilibrium) of the weekly integrated samples obtained employing the high-volume sampler. This means that films and leaves can be usefully employed for predicting the short-term variability of low KOA organic contaminant air concentrations. [ABSTRACT FROM AUTHOR]

For street trees, site-specific soil and microclimate conditions can restrict growth, health, and longevity for many species. Many urban sites are characterized by a high amount of impervious surface and paved areas resulting in a high rate of surface runoff, low infiltration into soil, and strong reradiation effects. In maintaining the ecologic and economic benefits of street trees through future decades, it is essential to establish species with a high tolerance to stressful urban environments. Researchers measured leaf-gas exchange of Acer platanoides, Acer pseudoplatanus, Platanus x hispanica, Quercus rubra, and Tilia platyphyllos to assess stomatal conductance, transpiration, and net photosynthesis at impervious urban sites in the city of Dresden, Germany. The results show significantly higher leaf-gas exchange rates for the species Platanus x hispanica and Quercus rubra, compared to the species Acer platanoides and Acer pseudoplatanus. The significantly higher mean values of water-use efficiency of Platanus x hispanica and Quercus rubra, and in particular the values during the selected periods with a high vapor pressure deficit, indicate more economical water consumption. [ABSTRACT FROM AUTHOR]

Background:The complementary use of different forms of soil nitrogen (N) might lead to a higher productivity of mixed forests than monocultures, but convincing evidence for temperate mixed forests is scarce. Aims:We searched for species differences in N uptake rates and the preference for NH4+, NO3−or glycine among five temperate broad−leaved tree species (Acer pseudoplatanus, Carpinus betulus, Fagus sylvatica, Fraxinus excelsior, Tilia cordata) in a mature mixed stand. Methods:15N tracer was added to the soil and its accumulation in fine root biomass was analysed after 10 min, 1 h and 1 d. Results:The estimated root uptake rates of the species were in the range of 5–46 µg N g−1root h−1for NH4+, 6–86 µg N g−1h−1for NO3−and 4–29 µg N g−1h−1for glycine during the first hour after tracer application.Carpinus, TiliaandAcertended to prefer NH4+over NO3−, whileFraxinusshowed equal preference for both N forms andFagusseemed to prefer NO3−. Conclusions:The five co-existing tree species differed in uptake rates and partly in their N form preference, but complementarity in the use of different N forms seems to be of minor importance in this forest because tree species appear to be rather flexible in their N form use. [ABSTRACT FROM AUTHOR]

Key message: Natural regeneration of beech, maple and fir was investigated in relation to irradiance, ground vegetation and soil features. Seedling establishment may be favoured by creating small and irregular gaps and by successive extension of gaps along the sun-exposed gap edge. Context: To successfully manage natural regeneration, it is important to understand the interactions of forest gap micro-climates and soil features. Aim: The aim of this study was to identify conditions for successful natural regeneration of European beech, sycamore maple and silver fir in mixed forests. Methods: Seedling growth and survival were recorded within and around two artificial gaps, and the relationships to irradiance, ground vegetation and soil features were examined. A simple conceptual model was applied to identify optimal micro-sites for regeneration. Results: Ground vegetation hindered the establishment of natural regeneration in the centre of the gaps. Small seedlings of maple and beech were more abundant within the small gap and along gap edges; beech had the highest density on sun-exposed edges and maple on shaded gap edges. Tall beech and maple seedlings were more abundant along sun-exposed gap edges. Greater variability of irradiance in the larger gap contributed to greater micro-site heterogeneity relative to the small gap. Conclusions: Seedling establishment may be favoured by creating small and irregular gaps and by successive extension of gaps along the sun-exposed gap edge. Circular gaps with diameters greater than stand height contribute to increased ground vegetation coverage and hinder tree regeneration, including semi-shade tolerant maple and spruce. [ABSTRACT FROM AUTHOR]

Chitosan (CHT) is a non-toxic and inexpensive compound obtained by deacetylation of chitin, the main component of the exoskeleton of arthropods as well as of the cell walls of many fungi. In agriculture CHT is used to control numerous diseases on various horticultural commodities but, although different mechanisms have been proposed, the exact mode of action of CHT is still unknown. In sycamore (Acer pseudoplatanus L.) cultured cells, CHT induces a set of defense/stress responses that includes production of H2O2 and nitric oxide (NO). We investigated the possible signaling role of these reactive molecules in some CHT-induced responses by means of inhibitors of production and/or scavengers. The results show that both reactive nitrogen and oxygen species are not only a mere symptom of stress conditions but are involved in the responses induced by CHT in sycamore cells. In particular, NO appears to be involved in a cell death form induced by CHT that shows apoptotic features like DNA fragmentation, increase in caspase-3-like activity and release of cytochrome c from the mitochondrion. On the contrary, reactive oxygen species (ROS) appear involved in a cell death form induced by CHT that does not show these apoptotic features but presents increase in lipid peroxidation. [ABSTRACT FROM AUTHOR]

The anamorphic fungus Cryptostroma corticale (Xylariaceae) causing sooty bark disease (SBD) of Acer pseudoplatanus has been reported within the past decade in several European countries. In the last decade, severe drought conditions during summer also resulted in an outbreak of SBD in park areas in Prague (Czech Republic). Trees with the typical syndromes were recorded in four localities in Prague. Some trees were also located in the alluvial plain of the Vltava River with groundwater available all year long. We suppose that the trees were stressed by full water saturation for several months after flood in 2012 and that SBD was triggered by anoxia and subsequent phytopththora root rot. Sterile fungi isolated from one tree and one lesion were identified as C. corticale based on the similarity of their ITS rDNA sequences with strains of C. corticale in a public collection. Furthermore, C. corticale was placed in the family Xylariaceae within the genus Biscogniauxia based on phylogenetic analysis of four genes (ITS nrDNA, actin, RPB2 and β-tubulin). The closest relatives are B. bartholomei and Graphostroma platystoma. [ABSTRACT FROM AUTHOR]

Climate change is acting on several aspects of plant life cycles, including the sexual reproductive stage, which is considered amongst the most sensitive life-cycle phases. In temperate forests, it is expected that climate change will lead to a compositional change in community structure due to changes in the dominance of currently more abundant forest tree species. Increasing our understanding of the effects of climate change on currently secondary tree species recruitment is therefore important to better understand and forecast population and community dynamics in forests. Here, we analyse the interactive effects of rising temperatures and soil moisture reduction on germination, seedling survival and early growth of two important secondary European tree species, Acer pseudoplatanus and A. platanoides. Additionally, we analyse the effect of the temperature experienced by the mother tree during seed production by collecting seeds of both species along a 2200-km long latitudinal gradient. For most of the responses, A. platanoides showed higher sensitivity to the treatments applied, and especially to its joint manipulation, which for some variables resulted in additive effects while for others only partial compensation. In both species, germination and survival decreased with rising temperatures and/or soil moisture reduction while early growth decreased with declining soil moisture content. We conclude that although A. platanoides germination and survival were more affected after the applied treatments, its initial higher germination and larger seedlings might allow this species to be relatively more successful than A. pseudoplatanus in the face of climate change. [ABSTRACT FROM AUTHOR]

The production of defect-free, high quality stem wood may be promoted through pruning of branches in hardwood species, yet this practice may also lead to wood defects, such as stem discoloration. Here, models to predict stem discoloration and the time of branch occlusion were developed for Acer pseudoplatanus L. (sycamore maple) and Fraxinus excelsior L. (common ash) based on a pruning experiment in southwest Germany. The dataset consisted of 449 completely occluded branches originating from 115 destructively sampled sycamore maple and common ash trees that had been pruned either in late winter or summer, or had not been pruned and underwent natural branch shedding instead. We analyzed these data with linear and generalized linear mixed-effects models to predict (1) the time until branch occlusion, (2) the length of branch discolorations and (3) the occurrence of discolorations in the stem wood. For all treatments, the time until complete branch occlusion was negatively related to stem radial increment during branch occlusion and positively related to the branch diameter in case of green pruning or the length of the dead branch portion in case of natural branch shedding. The extent of branch discoloration was positively correlated with branch diameter (green pruning) or the dead branch length (natural shedding), which was itself correlated to branch diameter. The probability of stem discoloration after pruning increased with branch diameter and showed large interspecific differences, with a much higher risk for common ash. Thresholds for decay risk based on pruned branch diameters are reported for each species. In both branch and stem discoloration models, there was no evidence of significant effects related to the time of pruning. When analyzing a subset of the original data containing only branches with diameters up to 30 mm, we found that green pruning significantly reduced the duration of branch occlusion. The extent of branch discoloration was positively related to branch diameter and occlusion time and was not affected by pruning treatment or species. Our results indicate that pruning reduces the duration of branch occlusion and, hence, has the potential to increase the proportion of defect-free wood. Furthermore, the duration of branch occlusion after artificial pruning should be minimized in order to reduce the risk of discoloration and decay. Therefore, green pruning should start early in the life of a tree when its branches are still thin and be applied only to vigorous trees that can occlude the wounds rapidly. [ABSTRACT FROM AUTHOR]

Background and aims: Numerous microorganisms have been isolated from trinitrotoluene (TNT)-contaminated soils, however TNT tends to persist, indicating that the microbial biomass or activity is insufficient for degradation. Deep-rooting trees at military sites have been found to take-up contaminants from groundwater, and the extensive root and endosphere provide ideal niches for microbial TNT-transformations. Methods: We characterised the rhizosphere, root endosphere and endo-phyllosphere bacteria of Acer pseudoplatanus growing at a historically TNT-contaminated location, using 16S rRNA gene fingerprinting, bacteria isolation, oxidoreductase gene-cloning, in planta growth-promotion (PGP) tests, inoculation, plant physiology measurements and microscopy. Results: Based on terminal-restriction-fragment-length-polymorphism analysis, bulk soil and rhizosphere samples were highly clustered. Proteo- and Actinobacteria dominated the rhizosphere and root endosphere, whereas Alphaproteobacteria were more abundant in shoots and Actinobacteria in leaves. We isolated multiple PGP-bacteria and cloned 5 flavin-oxidoreductases belonging to the Old Yellow Enzyme family involved in TNT-reduction from 3 Pseudomonas spp., the leaf symbiont Stenotrophomonas chelatiphaga and the root endophyte Variovorax ginsengisola. Conclusions: The inoculation with a selection of these strains, consortium CAP9, which combines efficient TNT-transformation capabilities with beneficial PGP-properties, has the ability to detoxify TNT in the bent grass ( Agrostis capillaris) rhizosphere, stimulate plant growth and improve plant health under TNT stress. [ABSTRACT FROM AUTHOR]

Changes in the woody composition of Wytham Woods since 1974 are described, related to national trends in broadleaved woodland, and used to suggest the impact of future changes such as from ash dieback disease (Chalara fraxinea). Data on the tree and shrub layer from 164 permanent 10 × 10 m plots distributed in a grid across the Woods are presented from 1974, 1991, 1999 and 2012, on species occurrence, regeneration, contribution to the canopy and basal area. Variations in the current and past composition and structure of the Woods are related to past forestry management and natural succession/disturbance processes. These largely mirror changes shown by other surveys at a national level. Fraxinus excelsior has been increasing in prominence across the Woods since 1974, but its future is uncertain because of disease. The species most likely to increase if there is a severe decline in F. excelsior at Wytham appear to be Acer pseudoplatanus, Corylus avellana and Quercus robur. There are benefits from linking long-term studies at one site to wider less detailed surveys in order to explore the general applicability of the results. [ABSTRACT FROM AUTHOR]