Endophytische Pilze in Blättern und Zweigen von Quercus petraea

Endophytic fungi in leaves and twigs of Quercus petraea . Surface sterilized leaf and twig samples taken in 1989 from sessile oak (Quercus petraea) in Austria yielded host-specific as well as unspecific ubiquistic endophytes. In leaves, Aureobasidium apocryptum and Apiognomonia quercina were the most frequent taxa, while Colpoma quercinum was the dominant species in twigs. The colonization rates of individual species were subjected to seasonal variation.     

Auswaschung phytotoxischer Substanzen aus Blättern kranker und gesunder Buchen - Schäden an der Bodenflora

Leaching of phytotoxic substances from foliage of diseased and healthy beeches - damage to ground vegetation. Damage to vegetation under declining beeches gave rise to test the effects of simulated aqueous leachate of beech leaves on 7 wild flower species. In biotests under aseptic conditions leachate of declining beeches affected germination and plant development more than leachate of healthy ones.     

Endophytische Pilze in Nadeln von gesunden und geschädigten Fichten (Picea abies [L.] Karsten)

Endophytic fungi in needles of healthy-looking and diseased Norway spruce (Picea abies [L.] Karsten). Endophytic fungi were isolated from surface-sterilized, 5 to 6 year old needles of healthy-looking and diseased trees. Two fungal species could be isolated frequently: Lophodermium piceae and Tiarosporella parca. At any site neither L. piceae nor T. parca could be isolated more frequently from needles of diseased trees. The possible types of relationship between these two fungi and Norway spruce are discussed.     

Feinwurzelmasse und Mykorrhiza von Altbuchen (Fagus sylvatica L.) in Waldschadensgebieten Bayerns

Feeder root biomass and mycorrhizae of old beech trees (Fagus sylvatica L.) in bavarian forest die-back areas . The feeder root biomass (roots = 2 mm diameter) and the quantity of mycorrhizae of apparently healthy and diseased old beech trees were determined in 7 stands in Bavaria. Canopy die-back correlated with reduction of the feeder root biomass and of mycorrhizae in the topsoil. In the deeper layers of the soil (below 50 cm) there were nearly no differences between the decline classes lor these parameters. The feeder root damage described were encountered in all stand types. For that reason, such damage can be considered, at least for comparable stands, as a general symptom of above ground diseased old beech trees.     

Der Einfluß einer praxisnahen SO2-Begasung auf das 14CO2-Fixierungsmuster von Buchen (Fagus sylvatica L.)

The influence of a SO₂-fumigation on the ¹⁴CO₂-fixation pattern of beeches (Fagus sylvatica L.) under field conditions. The influence of a fumigation with a low SO₂ concentration on the metabolism of beech leaves (Fagus sylvatica L.) was investigated. Changes due to SO₂ were observed in the sulfur content, the ¹⁴CO₂-uptake and the ¹⁴CO₂-fixation pattern. The use of these parameters for the indication of air pollution effects on plants is discussed.     

Der pH-Wert und das Vorkommen niedermolekularer Fettsäuren im Naßkern der Buche (Fagus sylvatica L.)

The pH-value and the occurrence of fatty acids in wetwood of European Beech (Fagus sylvatica L.). At the border of the wetwood area pH-value of the capillary liquid was altered from acid to neutral conditions. Fatty acids frequently occurred in wetwood. Probes with pH-values higher than 6.8 often were deeply black stained.     

Feinstrukturelle Untersuchungen an Nadeln geschädigter Tannen und Fichten aus Waldschadensgebieten im Schwarzwald

Fine structural studies on the needles of damaged fir (Abies alba Mill.) and spruce [Picea abics (L.) Karst.] trees from forest dieback areas in the Black Forest . The fine structural changes in the variously damaged needles of fir and spruce trees from forest dieback areas have been investigated with special reference to cytoplasmie organization in the vascular bundles, mesophyll tissue and cuticle. The results are compared with those available for a few plants affected both by natural and artificial stress factors, especially air pollutants.     

Genetic structure of populations of beech (Fagus sylvatica L.) in Denmark

The genetic structure in Danish indigenous and introduced provenances of beech (Fagus sylvatica L.) is described. Ten stands are analysed based on variation revealed by seven enzyme systems. The present study reveals significant allele frequency differences between populations with a small absolute amount of genetic differentiation, with no pattern related to geographic distance. The genetic differentiation between indigenous populations measured by Wright's F _ST‐statistic does not deviate significantly from zero, and only 2.9% of the total genetic variation in the foreign populations was due to interpopulation differences, The allele frequencies in relatively small and isolated populations do not differ from the frequencies found in larger areas with beech forest. The low genetic differentiation of isozyme level between indigenous and foreign populations was opposed by significant differences in foliation performance measured on three pairs of neighbouring stands. Foliation performance in adjacent stands of indigenous and introduced beech indicates that quantitative characteristics must be considered separately from neutral variation at single loci.     

Zusammenhänge zwischen Kronenschäden und dem Stärkegehalt der Wurzeln bei Fagus sylvatica L.

Correlation between root starch content and crown damage of European beech (Fagus sylvatica L.). During a research project on forest decline in European beech stands the starch content of woody roots apparently of healthy and trees with dieback symptoms were examined by a histochemical method developed by Wargo . A comparison of affected and apparently healthy trees indicated no correlation between starch content of coarse roots and damage class derived from crown symptoms. However, results of these preliminary studies on distribution of starch in the root system of European beech confirmed the data reported in the literature.     

Observations on the Condition of Beech (Fagus sylvatica L.) in Britain in 1990

In 1990, the Forestry Commission's main monitoring programmeassessed the condition of 864 beech trees across 36 sites inBritain. Sites were located throughout the country, with thenorthernmost site being near Inverness and the southernmostnear Exeter. The initial crown density data suggested that asmall deterioration had occurred. However, further investigationrevealed that the spatial pattern of crown density changed in1990, with trees in southern sites deteriorating markedly. Otherindices of crown condition also changed, with the amount ofdieback, the amount of mast, the incidence of small leaves andthe amount of leaf-rolling all being high in the south of thecountry. In addition, the radial growth of many trees was depressed.Most of the changes in 1990 are thought to have been causedprimarily by the 1989 drought, with the 1990 drought only havingan effect on parameters such as leaf-rolling. Further effectsin 1991 and possibly later years are anticipated.     

DNA sequence variation and development of SNP markers in beech (Fagus sylvatica L.)

European beech (Fagus sylvatica L.) is one of the most important deciduous tree species in Central Europe. The potential of beech to adapt to climate change, higher temperatures, and less precipitation in the summer months is still unknown. Most studies in beech used microsatellite, AFLP (amplified fragment length polymorphism), or isozyme markers, which have only a restricted potential to analyze adaptation. Only few studies investigated genes probably involved in the adaptation to drought stress and bud phenology in beech. In this study, SNP (single nucleotide polymorphisms) markers were developed in order to analyze adaptation and their technical advantages compared to microsatellites and AFLPs were discussed. Partial sequences of ten candidate genes probably involved in drought stress and/or bud phenology were identified at the genomic level, and SNPs and indels (insertions/deletions) in coding and non-coding regions were analyzed. Plant material was sampled along a precipitation gradient in Germany. In total, 8,145?bp were sequenced and analyzed, 4,038?bp were located in exon and 4,107?bp in intron regions. 63 SNPs and 11 indels were detected, which are differently distributed over the studied gene regions. The nucleotide diversity ranged from 0 to 6.62 (π?×?10^?3) and is comparable to other tree species, whereas the mean nucleotide diversity (2.64) for F. sylvatica is comparatively low. These results will help to investigate the genetic basis of drought stress and bud burst and to conduct association mapping in natural populations. Furthermore, the detected SNPs can also be used for population genetic studies.     

Climate-sensitive modelling of site-productivity relationships for Norway spruce (Picea abies (L.) Karst.) and common beech (Fagus sylvatica L.)

The aim of the presented research project is to fit a site index model capable for predicting changes in site-productivity in a changing climate. A generalized additive model is used to predict site index as a function of soil and climate variables. The climate parameter values are estimated using the regional climate model WETTREG, based on global climate simulations with the global circulation model ECHAM5/MPI-OM for the reference period from 1961 to 1990. The climate values are further regionalized on a 200 m × 200 m grid. The generalized additive model quantifies the partial linear and non-linear effects of the predictor variables on site index. The model is parameterized for Norway spruce (Picea abies (L.) Karst.) and common beech (Fagus sylvatica L.) in Lower Saxony, Germany. Two case studies investigate the model's ability to generate information in order to support forest management planning decisions under a changing climate. One example analyzes the possible shift in site index of spruce along a precipitation gradient under the International Panel on Climate Change (IPCC) emission scenario A1B in the period from 2041 to 2050. The other case study shows possible future changes in site index of beech along a temperature gradient.     

Genetic structure and variability of phenological forms in the European beech (Fagus sylvatica L.)

? Microsatellite markers were used to describe the genetic structure and variability of early, intermediate and late phenological forms of European beech (Fagus sylvatica L.). Two hundred and seventy individuals from three populations located in southern Poland were divided into three forms according to the phenological criterion — bud burst, and analyzed for allelic variation at five highly polymorphic microsatellite loci.

? Population differentiation was moderate and differed significantly among phenological forms. Average values of F _ST and R _ST decreased across phenological forms and amounted to F _ST values of 0.135, 0.110 and 0.108 and R _ST values of 0.365, 0.231 and 0.098 for early, intermediate and late forms of beech, respectively.

? Analysis of Molecular Variance (AMOVA) revealed different genetic structures characteristic of respective phenological forms of beech. The amount of within-population variability increased with the delay of the beginning of vegetation and amounted to 64%, 77% and 90% of total variability, depending on phenological form. A similar trend was found in average pairwise genetic distance between individuals belonging to a given phenological form (11.78, 11.85 and 12.22, from early to late forms).

? Our results demonstrate the importance of late spring frosts as a factor influencing the genetic structure of beech, and as a cause of the decrease in genetic variability as well as the increase in population differentiation proportional to the degree of phenological earliness.

     

Identification of moisture-induced stresses in cross-laminated wood panels from beech wood (Fagus sylvatica L.)

The crosswise bonding of the layers in laminated solid wood panels results in internal stresses when the humidity varies. The layers hinder one another as a result of the anisotropy of wood. The purpose of this study was to determine the internal stress state in free and constrained swelling. The expansion properties in the three panel directions were measured. Furthermore, the swelling of samples was constrained while the resulting forces were recorded. Hygroscopic warping experiments were carried out inducing a climate gradient within the panels. Afterwards the stresses were calculated from released deformations and non-destructive measurements of the Young’s modulus. The materials used were untreated and heat-treated beech wood, the latter modified in two levels. In addition to homogenously structured panels, treated top layers were combined with an untreated middle layer. Swelling, swelling pressure, warping and internal stresses considerably decreased from untreated to treated wood. If layers from treated and untreated material were combined, stresses and deformations increased as compared to the variants produced only from treated wood. It was concluded that the lower equilibrium moisture content of heat-treated beech wood improves its dimensional stability, which results in smaller deformation differences between the layers. Hence, the stresses were less distinctive.