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Ash dieback caused by a non-native pathogenic fungus Hymenoscyphus fraxineus has been decimating populations of European Fraxinus species for over 30 years. Nevertheless, there is still a considerable amount of valuable ashes of this species in European cities and landscapes. Although it has been shown in many studies that the effect of H. fraxineus on adult and senescent trees tends to be rather chronic, the infection by this fungus also causes a substantial decrease in the lifespan of these trees. This research is dealing with the control of ashes using the tree injection technology. It is focused on the development of bark necroses, as this symptom results in the highest damage to a tree. Trees were first inoculated with two different strains of H. fraxineus. Trees with proven positive inoculation were injected with six different fungicides. Subsequently, over the course of nine months, the area of developing bark necroses was measured using image analysis methods. After the field part of the experiment was finished, the extent of the infection by H. fraxineus in tissues was determined and confirmed by PCR. Three out of six tested variants (Tr. 1: 7.1% propiconazole, Tr. 3: 7% propamocarb and 2.7% fosetyl, and Tr. 6: 0.015% sodium selenite) displayed significant deceleration of the growth of bark necroses compared to control. Tr. 3 demonstrated the highest effectiveness with only a very small increment of the necrosis area during the first three months after the injection treatment and a follow-up complete cessation of growth. Reisolations confirmed high mortality of H. fraxineus after this treatment. Hence the presented study can contribute to substantial prolongation of the lifespan of ashes in Europe.

Ash dieback caused by the invasive fungus Hymenoscyphus fraxineus leads to massive mortality among common ash (Fraxinus excelsior) in Europe. To select tolerant genotypes, inoculation experiments are frequently conducted with isolates of the fungus. The aim of this study was to improve the inoculation methodology for evaluating susceptibility of ash genotypes to ash dieback through (i) testing the virulence of different isolates of Hymenoscyphus fraxineus and (ii) investigating temporal lesion development using three widely applied cultivars: Altena, Atlas and Westhof's Glorie. First, an experiment was conducted with a repeated measure design in which virulence of five different isolates was tested. Second, a subset of two isolates that induced the longest downward lesion length in experiment one was used in combination with a slightly adjusted inoculum protocol. Significant differences were found between isolates for downward lesion length, but a significant interaction effect of isolates and cultivars was absent. Also, the inoculation position within the stem affected lesion length; the largest lesions were found on the highest inoculation position within the stem. Furthermore, we found that cryopreserved isolates can remain virulent over years. The timing of inoculation at the end of the growing season was effective as large lesions already occurred during winter dormancy. For future inoculation studies, we propose to use: (i) isolates that induce large lesions, as less virulent isolates induced not only shorter but also fewer lesions; (ii) a similar inoculation position to better compare inoculations within and between experiments; (iii) cryopreserved isolates for testing over years; (iv) mycelial suspensions for inoculum preparation to cover wood chips more evenly; (v) reference clone—like the studied cultivars—to standardize research outcomes between years and research groups.

Sinds 2009 worden onze essen in snel tempo aangetast door de essentaksterfte. Vooral de gewone inheemse es (Fraxinus excelsior) is zeer vatbaar. Dit wordt veroorzaakt door een minuscule schimmelsoort uit Oost-Azië, het vals essenvlieskelkje (Hymenoscyphyus pseudoalbidus)1. Naar verwachting zal minder dan 10% van de essen in bossen, lanen en parken de komst van deze invasieve exoot overleven. Dit leidt tot hoge kosten in het bos- en bomenbeheer en is ook in ecologisch en landschappelijk opzicht een verarming. 1 De gangbare naam in de internationale literatuur is nu Hymenoscyphus fraxineus, maar deze naam wordt in Nederland nog niet algemeen gebruikt.

Asken (Fraxinus excelsior) är ett av våra ädellövsslag och dess existens hotas av den vindburna svampsjukdomen askskottsjukan. Sjukdomen upptäcktes först i Polen i början av 90-talet och spreds under en 20-årsperiod till de flesta länder i Europa. Askskottsjukan orsakas av sporsäcksvampen Hymenoscyphus fraxineus som har sitt ursprung i Asien. Sjukdomen förekommer i skogar, i kulturlandskap och i städer runt om i Europa. Träd i alla åldrar drabbas men de yngre individerna tycks mest mottagliga och uppvisar snabbt symtom i form av vissnande skott och missfärgningar på stam och grenar och dör ofta inom ett par år. Studier har visat att alla arter av ask insjuknar i askskottsjukan men i olika grad. F. excelsior är den art som visat sig mest mottaglig för sjukdomen. Handel är en stor orsak till spridningen av askskottsjukan. Skötselåtgärder och beskärning anses inte tillräckligt effektiva för att stoppa smittspridningen. Forskning i Sverige och runt om i Europa pågår för att ta fram resistent plantmaterial och förhoppningen är att askens existens och möjlighet att nå hög ålder kan säkerställas. För den biologiska mångfalden har asken stor betydelse. Forskning visar att antalet arter av bland annat insekter, lavar och mossor knutna till ask är hela 483 st i Sverige. Bland dessa finns uppskattningsvis 53 st arter som är helt beroende av asken för sin existens. Vidare hyser asken tillsammans med almen, som är starkt hotad av almsjukan, 115 st gemensamma arter som endast kan leva på eller av dessa två trädslag. Om asken och almen skulle försvinna kommer många arter knutna till dem också försvinna. En utrotningskaskad är att vänta. Vikten av att träd kan bibehålla sin vitalitet och få nå hög ålder är stor för den biologiska mångfalden. Många arter knutna till träd är helt beroende av tillgång på död ved och håligheter, vilket yngre träd sällan kan erbjuda. För att säkerställa askens fortlevnad, och därmed bevara biologisk mångfald, behövs förädling av resistent plantmaterial., Ash (Fraxinus excelsior) is one of our domestic deciduous treespecies and its existence is threatened by the windborne ash dieback disease. The disease was first discovered in Poland in the early 1990s and spread over a 20-year period to most countries in Europe. Ash dieback is caused by the fungus Hymenoscyphus fraxineus, which originated in Asia. The disease occurs in forests, in cultural landscapes and in cities around Europe. Trees of all ages are affected, but the younger individuals seem most susceptible and quickly develop symptoms with wilting shoots and discolorations on trunks and branches and often die within a couple of years. Scientific research has shown that all species of ash are affected by ash dieback but to varying degrees. F. excelsior is the species that has been shown to be most susceptible to the disease. Trade is a major cause of the spread of ash dieback. Tree management and pruning are not considered effective enough to stop the spread of infection. Scientific research in Sweden and around Europe is ongoing to develop resistant plant material and the hope is that the ash's existence and opportunity to reach old age can be ensured. Ash is of great importance for biodiversity. Research shows that the number of species of for example insects, lichens and mosses associated with ash is as high as 483 in Sweden. Among these are an estimated 53 species obligated with ash. Furthermore, ash together with the elm, which is strongly threatened by elm disease, holds 115 species who can only that can only live on or by these two tree species. If the ash and elm were to go extinct, many other species would also disappear. An extinction cascade is to be expected. The importance of trees being able to maintain their vitality and reach old age is advantageous for biodiversity. Many species associated with trees are completely dependent on the availability of dead wood and cavities, which younger trees can rarely offer. To ensure the survival of the ash, and

We identified a novel virus in diseased European ash (Fraxinus excelsior) and manna ash (F. ornus) trees exhibiting chlorotic ringspots, mottle and leaf deformation such as curling and shoestring symptoms. High-throughput sequencing (HTS, Illumina RNASeq) of total RNA isolated from diseased leaf material in combination with RT-PCR-based amplification techniques and Sanger sequencing determined five complete genome segments, each encoding a single open reading frame. Sequence analyses of RNA1–RNA5 revealed a genome organization typical for emaraviruses, i.e., (i) conserved and complementary terminal 5′ and 3′ termini of each genome segment (ii) proteins showing significant homologies to the RNA-dependent RNA polymerase (RdRP) encoded by RNA1, the glycoprotein precursor (GPP) encoded by RNA2, the viral nucleocapsid protein (N, RNA3), the movement protein (MP, RNA4), and a protein of 26 kDA (P26, RNA5) highly similar to proteins of unknown function encoded by other emaraviruses. Furthermore, we identified spherical particles (double-membrane bodies, DMB) of different sizes (70–80 nm in diameter) which are typical for emaraviruses exclusively in virus-infected leaf tissue exhibiting mottle and leaf deformation. Sequence comparison and phylogenetic analyses confirmed the identified novel virus as a new member of the genus Emaravirus. We established a species-specific RT-PCR detection protocol and could associate the observed disease symptoms with the infection of the novel emaravirus in F. excelsior and F. ornus. Therefore, we propose the name ash shoestring-associated emaravirus (ASaV). Investigation of ASaV-infected sample trees originating from different locations in Switzerland, Germany, Italy and Sweden provided a wide geographical distribution of the virus in affected ash species. To our knowledge, this is the first confirmation of an emaravirus affecting ash tree species with shoestring symptoms of leaves in Europe.

Investigation of different seed diseases of common ash has great significance due to occurrence of ash dieback across Europe caused by Hymenoscyphus fraxineus Baral, Queloz and Hosoya (T.Kowalski) and still not completely defined strategies about regeneration of this species. Species complex Diaporthe eres are familiar pathogens of common ash. During the monitoring of health condition of common ash in Montenegro Diaporthe eres was frequently isolated from common ash seeds. The aim of this research was to investigate temperature conditions that contribute to the growth of Diaporthe eres strains from Montenegro in infected seeds and histological characteristics of Diaporthe eres spread in seeds. Growth of Diaporthe eres pure cultures on tested temperatures showed the fastest growth on 25°C and the absence of growth on 35°C. Mechanical damage did not significantly contribute to occurrence of infection. Microscopic examination of heavy infected seeds showed that hyphae of D.eres were visible on outer parts of seed spreading inside the core. In this research we investigated some basic bio ecological characteristics of D. eres associated with decline of F. excelsior seed in Montenegro.

Species complex Fusarium sambucinum was frequently isolated from ash stands in Montenegro. Previous researches revealed that it is dangerous pathogen for one-year-old seedlings. The aim of this research was to investigate the influence of temeperature on growth and morphological characteristics of morphotype isolated from one-year-old common ash (Fraxinus excelsior L.) seedlings in Montenegro. Growth of Fusarium sambucinum pure cultures on different temperatures was the fastest on 25°C while the absence of growth occurred on 32.5°C. Cultures on optimum temperature were white reddish, aerial and with a lot hyaline, curved multi septate conidia. This research covers basic ecological and morphological characteristics of Fusarium sambucinum strain responsible for high pathogenicity towards one-year-old common ash seedlings in Montenegro.

Background: With the expanding ash dieback epidemic that has spread across the European continent, an improved functional understanding of the disease development in afflicted hosts is needed. The study investigated whether differences in necrosis extension between common ash (Fraxinus excelsior) trees with different levels of susceptibility to the fungus Hymenoscyphus fraxineus are associated with, and can be explained by, the differences in gene expression patterns. We inoculated seemingly healthy branches of each of two resistant and susceptible ash genotypes with H. fraxineus grown in a common garden. Results: Ten months after the inoculation, the length of necrosis on the resistant genotypes were shorter than on the susceptible genotypes. RNA sequencing of bark samples collected at the border of necrotic lesions and from healthy tissues distal to the lesion revealed relatively limited differences in gene expression patterns between susceptible and resistant genotypes. At the necrosis front, only 138 transcripts were differentially expressed between the genotype categories while 1082 were differentially expressed in distal, non-symptomatic tissues. Among these differentially expressed genes, several genes in the mevalonate (MVA) and iridoid pathways were found to be co-regulated, possibly indicating increased fluxes through these pathways in response to H. fraxineus. Comparison of transcriptional responses of symptomatic and non-symptomatic ash in a controlled greenhouse experiment revealed a relatively small set of genes that were differentially and concordantly expressed in both studies. This gene-set included the rate-limiting enzyme in the MVA pathway and a number of transcription factors. Furthermore, several of the concordantly expressed candidate genes show significant similarity to genes encoding players in the abscisic acid- or Jasmonate-signalling pathways. Conclusions: A set of candidate genes, concordantly expressed between field and greenhouse exper

Gypsy moth, Lymantria dispar L. (Lepidoptera: Erebidae) feeds on a large number of tree species, while ash, Fraxinus spp. (Lamiales: Oleaceae) species are considered resistant and are only sporadically eaten. To assess the conditions under which late instar gypsy moth larvae (GML) can temporarily use non-host common ash ( CA) (F. excelsior L.), and to evaluate their ability to recover from ingestion of this toxic food, we determined the relative growth rate, the relative consumption rate and the amount of produced feces in different laboratory feeding trials. Our report is the first to show that under specific circumstances, the resources acquired after short-term consumption of CA leaves can be utilized for larval growth. We varied the intensity of density and starvation stress prior to feeding on CA leaves. We observed that after moderate stress a group of GML was temporarily capable of coping with CA leaves. Although observed growth and consumption were much lower on CA than on the optimal host oak, Quercus cerris L. (Fagales: Fagaceae), CA-oak-switched larvae showed the ability to recover from short-term use of a toxic non-host foliage. This suggests that feeding on CA might enable GML to survive under conditions of food shortage.

European Ash (Fraxinus excelsior) is an important species for biodiversity through-out Europe. The species is critically threatened due to an alien invasive fungus, Hymenoscyphus fraxineus. Some individual F. excelsior trees however show better resistance to H. fraxineus giving hope that the population can be saved. The under-lying mechanisms associated with this resistance however are still not clear. In ear-lier work, chemotypes could be clearly distinguished between susceptible and re-sistant ash trees. The aim of this thesis is to investigate the quantitative and qualitative differences in ash constitutive phenolics that may in part explain the observed resistance in some ash trees. Ash trees of known susceptibility to H. fraxineus from five different European countries were sampled for stem phloem tissue and phenolics were ex-tracted in a butylated hydroxyanisole methanol solution. Chemical analysis using Time-of-Flight Mass spectrometry reveals significant differences in levels of several phenolic compounds, foremost the coumarin fraxin and the secoiridoid ligustroside, which is more prevalent in trees resistant to H. fraxineus than in susceptible ones. Fraxin is also more abundant in the resistant natural host of H. fraxineus, F. mands-hurica, than in susceptible species, such as F. excelsior. This study may help in advancing breeding efforts by identifying potential biomarkers that are associated with resistance., Asken (Fraxinus excelsior) är ett viktigt träd för biodiversitet inom stora delar av Europa. Arten är nu hotad av en invasiv sjukdomsbringande svamp, Hymenoscyp-hus fraxineus. Vissa askträdsindivider visar på en bättre resistens mot H. fraxineus, vilket inger hopp för att kunna rädda arten. De underliggande mekanismerna för denna resistans är emellertid inte fullt ut förstådd än, men i tidigare arbeten har man kunnat särskilja kemotyper mellan mottagliga och resistanta askar. Syftet med denna studie är att undersöka de kvantitativa och kvalitativa skillna-derna i sammansättningen av askens konstitutiva fenoler, vilka till dels förmodas kunna förklara den observerade resistansen hos vissa askträd. Floemprover togs från kvistar på askar av känd känslighetsgrad till H. Fraxineus från fem europeiska länder och fenoler extraherades i en butylerad hydroxyanosol-metanol-lösning. Ke-misk analys med hjälp av tidsflykts-masspektrometer (en. Time-of-Flight) visade på signifikanta skillnader i nivåer av flertalet fenoler, företrädesvis kumarinen fraxin och secoiridoiden ligustrosid, som finns i betydligt större mängd i askar resistenta mot H. Fraxineus än i mer mottagliga artfränder. Fraxin förekommer också i högre nivåer i patogenen H. Fraxineus’ naturliga, och resistanta, värdart, manchurisk ask, F. mandshurica, än i mottaglia arter, såsom F. excelsior. I och med denna upptäckt ter sig försöken att genom förädlingsarbete för resistans rädda asken som ekologiskt och ekonomiskt funktionell art som mer hoppfulla.

Author Posting. © Studia Chemia, 2018. Studia Universitatis Babes-Bolyai Seria Chemia is an Open Access Journal (read, download, copy, distribute, print for research use, search, or link to the full texts of articles). The definitive version was published in Studia Universitatis Babes-Bolyai, Seria Chemia 63, no. 3 (2018): 41-48, doi:10.24193/subbchem.2018.3.03., The article reports the AMS (accelerator mass spectrometry) radiocarbon investigation results of the old common ash of Aiton. Five wood samples were collected from the trunk of the tree. The deepest ends of the samples were analysed by AMS radiocarbon. We found radiocarbon dates between 165 ± 20 BP and 240 ± 18 BP, which correspond to calibrated ages of 230 – 360 years. These results, combined with a ring counting estimate, indicate an age of 330 ± 30 years for the ash of Aiton. By this value, the ash of Aiton becomes the oldest known common ash with accurate dating results., The research was funded by the Romanian Ministry of Research and Innovation CNCS-UEFISCDI under grant PN-III-P4-ID-PCE-2016-0776, Nr. 90/2017.

Natural and urban forests worldwide are increasingly threatened by global change resulting from human-mediated factors, including invasions by lethal exotic pathogens. Ash dieback (ADB), incited by the alien invasive fungus Hymenoscyphus fraxineus, has caused large-scale population decline of European ash (Fraxinus excelsior) across Europe, and is threatening to functionally extirpate this tree species. Genetically controlled host resistance is a key element to ensure European ash survival and to restore this keystone species where it has been decimated. We know that a low proportion of the natural population of European ash expresses heritable, quantitative resistance that is stable across environments. To exploit this resource for breeding and restoration efforts, tools that allow for effective and efficient, rapid identification and deployment of superior genotypes are now sorely needed. Here we show that Fourier-transform infrared (FT-IR) spectroscopy of phenolic extracts from uninfected bark tissue, coupled with a model based on soft independent modelling of class analogy (SIMCA), can robustly discriminate between ADB-resistant and susceptible European ash. The model was validated with populations of European ash grown across six European countries. Our work demonstrates that this approach can efficiently advance the effort to save such fundamental forest resource in Europe and elsewhere.

There are relatively few studies surveying how meteorological and qualitative characteristics of tree sites in urban areas influence Hymenoscyphus fraxineus (T. Kowalski) Baral et al. ( Chalara fraxinea T. Kowalski, = Hymenoscyphus pseudoalbidus Queloz et al.) or infection by that. Based on the significance of ash trees in urban areas and the frequent use of ash species and their varieties, it becomes increasingly important to identify factors that drive the pathogen. The aim of this study was to identify the effects of both meteorological parameters and tree characteristics on the severity of the disease in the city of Leipzig, Germany. We assessed 401 ash trees along streets and in green spaces distributed across Leipzig. The assessment included scoring the level of damage by H. fraxineus, visually estimating the degree of soil sealing under a tree's crown, measuring tree height, the height of crown base and the diameter at breast height, determining sex, year of planting and species variety, as well as recording qualitative characteristics (e.g. secondary pathogens, feeding marks). Mean relative air humidity, mean annual temperature and a combined index of meteorological conditions were used as meteorological parameters. In addition, we sampled tissue of 45 ash trees for the purpose of genetically verifying the occurrence of H. fraxineus. We analysed the effects of all variables on ash dieback by using linear mixed effect models. Results show an extensive damage by H. fraxineus in the whole city area with 70% of trees being infected. Mean relative air humidity and the index of meteorological conditions show a significant positive influence on the severity of ash dieback, whereas year of planting has a negative effect. Trees with feeding marks at the trunk tend to be more damaged by the fungus. Moreover, we found a significant difference in susceptibility between F. excelsior and its variety 'Atlas'. Both meteorological conditions and the susceptibility of species

Verticillium dahliae colonizes the xylem vessels of susceptible host plants. Hence it can be expected that the distribution of the fungus as well as disease progress will be influenced by the anatomy of the xylem of that host. Here, we studied the spatial and temporal distribution of V. dahliae in relation to recovery from disease symptoms in young European ash (Fraxinus excelsior) and Norway maple (Acer platanoides) trees that differ in vascular anatomy. Quantifying the amount of V. dahliae DNA at different heights in the stem of inoculated trees at different time points after inoculation showed that, in the year of inoculation, the speed of colonization of these two species by V. dahliae was similar. Nevertheless, in the year after inoculation disease incidence and also quantities of V. dahliae detected in maple trees were significantly higher than in ash trees, suggesting that the xylem of ash trees is much less supportive for growth and survival of V. dahliae than that of maple trees. Moreover, in this second year V. dahliae could not be re-isolated from the wood of ash trees that had recovered from disease and was only rarely detected by PCR, only in xylem of the previous year and never in the current xylem. In contrast, V. dahliae easily was detected in the wood of diseased ash and maple trees. Furthermore, despite the presence of a layer of parenchyma cells between growth rings in ash trees, in symptomatic ash trees V. dahliae was present in the xylem of the new growth ring. We also observed that V. dahliae can move downward from the point of inoculation into the root collar, which possibly provides a way for infection of new growth rings by circumventing the physical barriers within the stem xylem.

Essentaksterfte is bezig met een snelle opmars in Nederland. In 2010 werd het fenomeen alleen aangetroffen in het noordoosten van Nederland en nu is essentaksterfte al waargenomen in alle provincies. Daarmee lijkt het Nederlandse landschap na de iepziekte en kastanjeziekte nu te maken te krijgen met een nieuwe boomsterftegolf. Onder de vlag van het Bosschap zijn een groot aantal beheerders in overleg getreden om een strategie uit te zetten voor het omgaan met de essentaksterfte. De essentaksterfte komt al 20 jaar voor in midden Europa en breidt zich van daar uit.

Fraxinus species were introduced in to New Zealand as amenity trees as early as the mid-1850s. As a likely consequence of this early introduction and of their geographic isolation, Fraxinus species in New Zealand have not yet been subjected to the devastating impacts of ash decline caused by Hymenoscyphus fraxinus. This study used isolations, PCR and cloning methods to examine the endophytic fungi associated with Fraxinus excelsior and F. angustifolia on the north island of New Zealand.

European ash (Fraxinus excelsior), a tree species with both economic and ecological importance, has experienced a steady population decline in Europe since the early 1990’s due to ash dieback, caused by the pathogen Hymenoscyphus fraxineus. In 2001, the first observations of ash dieback were made in Sweden and by 2010, ash had become a red-listed species. In its origin in east Asia, H. fraxineus exists on native Fraxinus species, such as Fraxinus mandshurica, mainly as a benign associate causing little to no damage, suggesting a balanced equilibrium between host plant and pathogen. In Europe, H. fraxineus infects F. excelsior trees of all sizes, however there are several reports indicating large genotypic variation in the level of disease susceptibility among different individuals. The aim with this thesis is to evaluate heritability of ash tolerance to H. fraxineus by studying young progeny and clonal trials. The results aim to elucidate differences in susceptibility to ash dieback among individuals. This study has included a progeny trial, located in Alnarp, planted in 2014 with progeny from both known susceptible and tolerant mother trees. During 2014-2016, assessments were conducted to determine any variability among selected progeny in leaf phenology (bud burst), tree health status and stem form. Included in this thesis was also, a trial of selected ash genotypes planted in 2016, in Snogeholm, consisting of 65 clones, including susceptible and tolerant F. excelsior individuals and Asian Fraxinus species. In this trial, only health assessment was carried out. The results show that none of the ash families were unaffected by H. fraxineus but showing differences in disease severity. However, progeny from tolerant mother trees had higher survival, lower mean health class rating (HCR) and in general better stem form. This work is a first step to enable targeted genotypes to be selected for further commercial propagation, breeding and future establishment of new seed, Asken, Fraxinus excelsior, ett trädslag som är viktigt både ur ett ekonomiskt och ekologiskt perspektiv har sedan tidigt 1990-tal tydligt minskat i antal i Europa. Detta på grund av askskottsjukan, en sjukdom orsakad av patogenen Hymenoscyphus fraxineus. I Sverige fann man de första skadorna orsakade av sjukdomen 2001 och asken blev rödlistad 2010. H. fraxineus finns på inhemska Fraxinus arter som t.ex. Fraxinus mandschurica i Asien, men då oftast utan att skada trädet. Detta indikerar att det finns en utvecklad balans mellan värdväxt och patogen. För F. excelsior är läget ett annat, träd i alla storlekar blir infekterade av H. fraxineus. Men det finns rapporter som indikerar på en stor genetisk skillnad i mottaglighet av sjukdomen mellan olika individer. Målet med denna studie var att utvärdera askens tolerans mot H. fraxineus utifrån unga avkomme- och klonförsök. Resultaten syftar till att belysa olika individers tolerans mot askskottsjukan. Studien inkluderar ett försök, planterat i Alnarp 2014, med avkommor från både toleranta och mottagliga moderträd. Under åren 2014–2016 bedömdes knoppsprickning, hälsostatus, och flerstammighet för att utvärdera eventuella skillnader mellan de olika avkommorna. I studien ingick även ett försök med askkloner. Detta försök planterades 2016 i Snogeholm och bestod av toleranta, mottagliga inhemska samt asiatiska Fraxinus kloner. Inventeringarna utgjordes här endast av en bedömning av hälsotillståndet. Resultaten visar att ingen av askfamiljerna var helt opåverkade av H. fraxineus men graden av skada skiljer olika familjer. Resultaten indikerar även att avkommor från toleranta moderkloner har högre överlevnad, lägre genomsnittlig hälsoklass (HCR) och generellt mindre tendens till flerstammighet. Studien är ett första steg för att möjliggöra fortsatt urval av toleranta individer för kommande förädlingsarbete och etablering av nya fröplantager.

Since the early 1990s, ash dieback due to the invasive ascomycete Hymenoscyphus fraxineus is threatening Fraxinus excelsior in most of its natural range. Previous studies reported significant levels of genetic variability in susceptibility in F. excelsior either in field or inoculation experiments. The present study was based on a field experiment planted in 1995, 15 years before onset of the disease. Crown and collar status were monitored on 777 trees from 23 open-pollinated progenies originating from three French provenances. Health status was modeled using a Bayesian approach where spatiotemporal effects were explicitly taken into account. Moderate narrow-sense heritability was found for crown dieback (h2 = 0.42). This study is first to show that resistance at the collar level is also heritable (h2 = 0.49 for collar lesions prevalence and h2 = 0.42 for their severity) and that there is significant genetic correlation (r = 0.40) between the severities of crown and collar symptoms. There was no evidence for differences between provenances. Family effects were detected, but computing individual breeding values showed that most of the genetic variation lies within families. In agreement with previous reports, early flushing correlates with healthier crown. Implications of these results in disease management and breeding are discussed.

Mechanical parameters of ash wood (Fraxinus excelsior) subjected to compression in radial direction, before and after its thermal modification and measured at moisture content close to the equilibrium moisture content of wood exposed in and outside (4 and 12%) were compared. Thermal modification of wood was performed at 190°C or 200°C for 2 h in industrial conditions. During the measurements, the moisture content of the modified and control samples was identical. The parameters compared included: modulus of elasticity, stress at proportionality limit, relative linear strain at proportionality limit and accumulated elastic energy. Changes in the mechanical parameters of wood induced by its thermal modification were found to depend on the modification temperature and wood moisture content.

Essenzaadbronnen op de Rassenlijst Bomen hebben een hoge genetische diversiteit. Dat is een belangrijk kwaliteitsaspect van teeltmateriaal en speelt een cruciale rol in het aanpassingsvermogen van soorten aan een veranderend klimaat en nieuwe ziekten en plagen. De huidige generatie essenbossen heeft te kampen met de veelal desastreuze gevolgen van essentaksterfte. Uit onderzoek blijkt dat resistentie tegen deze ziekte genetisch bepaald is, en dat een klein deel van de essen goed bestand is tegen de ziekte. Deze genetische basis biedt hoop om een nieuwe generatie essen te selecteren die bestand is tegen de ziekte, met behoud van de genetische diversiteit.

The current database is part of the FEM growth and yield database, a collection of growth and yield data from even-aged monocultures (douglas fir, common oak, poplar, Japanese Larch, Norway spruce, Scots pine, Corsican pine, Austrian pine, red oak and several other species with only a few plots like grand fir, even-aged mixed species forest plots, uneven-aged natural forest, uneven-aged selection forest and roadside plantations of poplar). The FEM growth and yield data base is currently supervised by Jan den Ouden and Frits Mohren.

The current database is part of the FEM growth and yield database, a collection of growth and yield data from even-aged monocultures (douglas fir, common oak, poplar, Japanese Larch, Norway spruce, Scots pine, Corsican pine, Austrian pine, red oak and several other species, with only a few plots, even-aged mixed species forest plots, uneven-aged natural forest, uneven-aged selection forest and roadside plantattions of poplar. The FEM growth and yield data base is currently supervised by Jan den Ouden and Frits Mohren.

This study aimed at investigating gene expression patterns in resistant and susceptible clones of Fraxinus excelsior L. (European ash) in response to infection with Hymenoscyphus fraxineus. A further objective of this study was to investigate the role of ABA8-hydroxylase genes (ABA8H) in European ash under infection with H. fraxineus. To address the first aim, bark of susceptible and resistant clones were infected with H. fraxineus and samples were taken after 9 months from the margins of necrosis. Total RNA was extracted and sequenced by next generation Illumina sequencing technique. To identify differentially expressed genes (DEGs), sequences were aligned to the European ash draft genome before analyzing in the Cufflinks pipeline. The DEGs were then annotated in Blast2go. More than 87,000 transcripts were presented in the library. In the inoculated susceptible clones, up-regulation of the 2-hydroxyisoflavanone dehydratase-like (HID) gene, associated with formation of secondary metabolites, was observed. The over expression of caffeoyl- o- methyltransferase (COMT) and farnesyl diphosphate synthase was also detected in the inoculated susceptible clones. In the inoculated resistant clones, the defense response genes such as 1-aminocyclopropane-1-carboxylate oxidase (ACC), some of the ethylene-responsive transcriptional factors (ERFs) and WRKY- transcriptional factors (TFs) were up-regulated. The peroxidase-like and pathogen- related protein (PR) genes, secoisolariciresinol dehydrogenase-like, flavonol syn- thase flavanone 3-hydroxylase-like, phenylalanine ammonia-lyase and shikimate chloroplastic-like genes were up-regulated but ERFs were down-regulated in both susceptible and resistant clones in response to H. fraxineus inoculation. Shikimate chloroplastic-like acts in the secondary metabolite pathway just like flavonol syn- thase flavanone 3-hydroxylase-like. To address the second aim, susceptible genotypes of the European ash were subjected to biotic stress which

Asketoptørre medfører økonomiske tab. Dette speciale beregner det økonomiske tab for Danmark., Following ash dieback, a substantial economic loss is expected. This thesis calculates the loss for Denmark.

Heat treatment is an attractive method to enhance wood durability, and valorize local hardwood species with naturallow durability. Yet no standard allows the certification of such products.This study first aims to observe the influence of heat treatment on the different mechanical properties. The standard mechanical tests; bending,tension parallel a nd perpendicular to grain, compression parallel and perpendicular to grain and shear, have been performed on native and heat - treated woods samples. The measurements are then compared to values of EN 338 standard. Results reveal that shear strength is the property most affected by heat treatment and that the modulus of elasticity perpendicular to grain is increased. The values given by EN 338 standard are generally safe with the exception of shear strength which is underestimated by current relationships. It is suggested that new relationships have to be provided for heat - treated wood, taking into account the loss of shear resistance.

The evolution of laws on the use of biocide products has led to important changes in the field of wood preservation leading to an increasing interest for non "biocidal treatments" like thermal or chemical modifications. While thermal modifications become more and more common on industrial scale, development of chemical modifications progresses slowly. One reason for the challenges encountered is probably the difficulty to use actual vacuum pressure plant to impregnate wood with solutions of reactive chemicals aimed to react with or within the wood. In this context, the presented research focuses on a new alternative called axial impregnation, derived from Boucherie process, for impregnation of treatable non durable hardwood species. This process consists of low-pressure impregnation of green wood logs through its lower extremity with treatment solution transiting via natural pathways of vessels. In order to evaluate the feasibility of the method, logs of different hardwood species were impregnated with a copper based preservative solution and the distribution of copper within the wood was determined. Results indicated that treatable wood species like beech, hornbeam and birch can be easily and homogeneously treated using axial impregnation method, while ash known for its weak impregnability remained untreated.

Vanaf ca. 2010 slaat de essentaksterfte in Nederland op grote schaal toe. Tot dusver vooral in bossen en wat minder in laanbeplantingen. Hoe het zich verder ontwikkelt, is nog onduidelijk, maar het einde lijkt nog niet in zicht. In sommige regio’s is binnen enkele jaren de conditie van bomen zwaar achteruit gegaan of zijn bomen geheel afgestorven. Voor bosbeheerders en boseigenaren een ware ramp. Gedane investeringen ‘verdampen’. Sommigen vrezen zelfs dat de es geheel uit het Nederlandse bosbeeld zal verdwijnen. Echter, met gerichte bosbouwkundige maatregelen, lijken er mogelijkheden de es te behouden. In deze bijdrage van gastauteurs Jitze Kopinga en Sven de Vries wordt aangegeven welke strategieën daarbij denkbaar zijn en wordt aangegeven welke de meest kansrijke lijken te zijn.

Essentaksterfte is een veelbesproken onderwerp, maar volgens Iben Margrete Thomsen van het Deense instituut voor geowetenschappen verschilt de beste aanpak per locatie van de betreffende bomen. In de openbare ruimte kan men zieke essen met een gerust hart laten staan, zo is de ervaring in Denemarken.

Nederland heeft al sinds 2010 te maken met essentaksterfte. In 2011 is een eerste landelijk advies uitgebracht door het voormalig Bosschap. Dit advies gaf aan hoe het best met essentaksterfte om te gaan. In 2013 volgde een verbeterde versie: Praktijkadvies essentaksterfte. Begin 2015 heeft de auteur van dit artikel binnen het kader van zijn afstudeerproject onderzocht hoe de zaken er anno 2015 voor staan wat betreft het beheer van deze lastige ziekte. Een en ander resulteerde in het afstudeerwerkstuk Literatuuronderzoek essentaksterfte.

Dossier met filmpjes en kernpublicaties over essentaksterfte. Het dossier bevat informatie over de symptomen van essentaksterfte, de gevoeligheid van soorten, praktijkadvies voor groenbeheerders hoe om te gaan met essentaksterfte en informatie over landbouwkundig onderzoek naar de essentaksterfte.

In 2012 zijn opnames uitgevoerd in essenproefvelden van het CGN en zaadgaarden van het Staatsbosbeheer naar de mate waarin de daar aanwezige essen inmiddels zijn aangetast door essentaksterfte, veroorzaakt door de schimmel Chalara fraxinea. Doel van dit onderzoek was om een indruk te krijgen van genetisch bepaalde verschillen in mogelijke resistentie / tolerantie voor deze ziekte. Een aantal handelsklonen profileerden zich in 2012 reeds als bovengemiddeld qua resistentie. Geknotte of sterk gesnoeide bomen zijn significant gevoleiger voor bladaantasting en twijgsterfte dan niet gesnoeide bomen.

Ditn verhaal gaat over het waarnemen van wat je, lopend in de bossen en onderweg in de auto, aan aantastingen in de essen ziet. Het waarnemen zonder in de valkuil te lopen dat je dàt ziet wat je graag wilt zien. Waarnemingen vanuit Nederland, en enigszins uit België, Duitsland en Engeland. Verder staan enkele wetenswaardigheden uit recente Duitse publicaties centraal

In recent years, some papers about the volatile composition of no .,oak heartwoods have been shown in scientific literature, with a view to their use in cooperage, although only oak and chestnut are approved by OIV to wine aging. Many volatile compounds were identified in seasoned and toasted no oak heartwoods, among them lignin and carbohydrate and lipid derivatives. On the whole, compared to oak, toasted acacia and chestnut woods showed a very high richness of these compounds, as lignin as lipid and carbohydrate derivatives, while cherry and ash werericher than toasted oak wood in lignin derivatives, but poorer in lipid ahd carbohydrate derivatives, showing sorne compounds that could be considered chemical markers for each one of these woods. In the present work, the wood related volatile composition of six wines (four red, one white, and one rosé) aged using barreis and chips of cherry, chestimt, false acacia, ash and oak wood was studied by GC-MS, to know if the volatile compounds that no oak woods contribute to wines can be used as chemical markers, and to classify the wines according to aging method. A total of more than 80 volatile compounds were studied, among furanic compounds, lactones, enolone stmctures, simple phenols, mono, di and trimethoxyphenols, phenolic aldehydes, ketones, ethers, acids, alkyl esters and alcohols. Most of them have been previotisly described in different varietal wines aged in oak, but some were only detected in wines aged in contact with other wood specie. As a rule, some differences in the wood related volatile composition ofwines were detected regarding both, the levels of compounds provided by each wood species and the different evolution in wines during aging in banels or in contact with chips.

The phenolic composition of heartwood extracts from Fraxinus excelsior L.;F. americana L.;both before and after toasting in cooperage, was studied using LC-DAD/ESI-MS/MS. Low-molecular weight (LMW) phenolic compounds, secoiridoids, phenylethanoid glycosides, dilignols and oligolignols compounds were detected, and 48 were identified, or tentatively characterized, on the basis of their retention time, UV/Vis and MS spectra, and MS fragmentation patterns. Some LMW phenolic compounds like protocatechuic acid and aldehyde, hydroxytyrosol and tyrosol, were unlike to those for oak wood, while ellagic and gallic acid were not found. The toasting of wood resulted in a progressive increase in lignin degradation products with regard to toasting intensity. The levels of some of these compounds in medium-toasted ash woods were much higher than those normally detected in toasted oak, highlighting vanillin levels, thus a more pronounced vanilla character can be expected when using toasted ash wood in the aging wines. Moreover, in seasoned wood, we found a great variety of phenolic compounds which had not been found in oak wood, especially oleuropein, ligstroside and olivil, along with verbascoside and isoverbascoside in F. excelsior, and oleoside in F. americana. Toasting mainly provoked their degradation, thus in medium-toasted wood, only four of them were detected. This resulted in a minor differentiation between toasted ash and oak woods. The absence of tannins in ash wood, which are very important in oak wood, is another peculiar characteristic that should be taken into account when considering its use in cooperage. Copyright © 2012 John Wiley & Sons, Ltd.

Nieuwsuitzending van RTL journaal om half acht (avond) van 15 juli 2012

De afdeling Ziekten en Plagen van BTL Bomendienst is momenteel bezig aan onderzoek naar de essentaksterfte (ETS). Hierbij wordt gebruik gemaakt van wetenschappelijke inzichten. Deze inzichten wil BTL Bomendienst implementeren in de praktijk. Dit doet zij door samen te werken met gemeenten om samen tot beheeroplossingen te komen. Ron Schraven vertelt over de inzichten die tot nu toe zijn vergaard.

De afdeling Ziekten en Plagen van BTL Bomendienst is momenteel bezig aan onderzoek naar de essentaksterfte (ETS). Hierbij wordt gebruik gemaakt van wetenschappelijke inzichten. Deze inzichten wil BTL Bomendienst implementeren in de praktijk. Dit doet zij door samen te werken met gemeenten om samen tot beheeroplossingen te komen. Ron Schraven vertelt over de inzichten die tot nu toe zijn vergaard.

Stand van zaken van een onderzoek naar essentaksterfte dat in 2012 gestart is door Praktijkonderzoek Plant & Omgeving Wageningen UR.

The phenolic composition of heartwood extracts from Fraxinus excelsior L. and F. americana L., both before and after toasting in cooperage, was studied using LC-DAD/ESI-MS/MS. Low-molecular weight (LMW) phenolic compounds, secoiridoids, phenylethanoid glycosides, dilignols and oligolignols compounds were detected, and 48 were identified, or tentatively characterized, on the basis of their retention time, UV/Vis and MS spectra, and MS fragmentation patterns. Some LMW phenolic compounds like protocatechuic acid and aldehyde, hydroxytyrosol and tyrosol, were unlike to those for oak wood, while ellagic and gallic acid were not found. The toasting of wood resulted in a progressive increase in lignin degradation products with regard to toasting intensity. The levels of some of these compounds in medium-toasted ash woods were much higher than those normally detected in toasted oak, highlighting vanillin levels, thus a more pronounced vanilla character can be expected when using toasted ash wood in the aging wines. Moreover, in seasoned wood, we found a great variety of phenolic compounds which had not been found in oak wood, especially oleuropein, ligstroside and olivil, along with verbascoside and isoverbascoside in F. excelsior, and oleoside in F. americana. Toasting mainly provoked their degradation, thus in medium-toasted wood, only four of them were detected. This resulted in aminor differentiation between toasted ash and oak woods. The absence of tannins in ash wood, which are very important in oak wood, is another peculiar characteristic that should be taken into account when considering its use in cooperage.

Essensterfte heeft vorig jaar ons land bereikt en begint inmiddels serieus om zich heen te slaan onder met name de gewone es (Fraxinus excelsior). Bosbouwkundigen van Staatsbosbeheer en van Alterra pleiten voor onderzoek naar vatbaarheid per genetische variëteit en naar de relatie tussen weersomstandigheden en de vatbaarheid voor essensterfte. Maar waarom het wiel opnieuw uitvinden? Kunnen we niet beter eerst bestaande Europese publicaties over essensterfte doornemen, of een belletje plegen met het buitenland, waar men jarenlang kampt met de essensterfte en een schat aan onderzoeksgegevens heeft verzameld.? Vakblad Boom in Business pleegt een aantal van dit soort belletjes.

Het Nederlandse landschap lijkt te maken te krijgen met een nieuwe boomsterftegolf. Na de iepziekte en kastanjeziekte is nu essentaksterfte bezig met een snelle opmars in Nederland. In 2010 werd het fenomeen alleen aangetroffen in het noordoosten van Nederland en nu is essentaksterfte al waargenomen op belangrijke essengroeiplaatsen in de IJsselmeerpolders en langs de grote rivieren. Onder de vlag van het Bosschap is een groot aantal beheerders in overleg getreden om een strategie uit te zetten voor het omgaan met de essentaksterfte. Hier wordt kort een eerste advies gegeven, zodat iedereen die in het beheer en beleid te maken krijgt met essentaksterfte zich hierop kan voorbereiden.

Deze FAQ-sheet heeft als doel om beheerders van essenbossen een handvat te bieden in het beantwoorden van persvragen. De beheerder kan deze algemene informatie aanvullen met gebiedsspecifieke kennis.

La prevalencia de los trastornos metabólicos está creciendo a nivel mundial. Botánicos, como el romero (Rosmarinus officinalis L.) y las semillas de fresno (Fraxinus excelsior L.), pueden ser una alternativa para mejorar estos trastornos. El objetivo de esta tesis doctoral fue generar extractos industriales de las partes comestibles de estas plantas, identificar sus compuestos por HPLC, HPLC-MS y RMN, y determinar su eficacia y seguridad. Se desarrollaron tres extractos de romero - estandarizados al 20% de ácido carnósico, 20% de ácido rosmarínico, y 40% de ácido ursólico. El extracto rico en ácido ursólico mostró la menor capacidad antioxidante en modelos ORAC y FRAP in vitro, mientras que los otros dos extractos tuvieron capacidades más elevadas. Sin embargo, el extracto rico en ácido carnósico (RE) fue superior en la inhibición de la oxidación de LDL ex vivo, y fue el único seleccionado para estudios posteriores. Se desarrolló un extracto de semilla de fresno (FE) de acuerdo a su uso tradicional en Marruecos, siendo identificados salidrosido y 9 glucósidos secoiridoides, dos de ellos fueron descubiertos por primera vez: Excelside A y Excelside B. En estudios in vitro, RE y FE activaron receptores nucleares que regulan la homeostasis de la glucosa y la energía, y actuaron sobre mecanismos contra la obesidad y la dislipidemia - RE activa PPAR? e inhibe la lipasa pancreática, y FE estimula PPAR? y evita la diferenciación de preadipocitos. La eficacia de ambos extractos para el control de trastornos metabólicos fue confirmada en ratones C57BL/6J administrados con una dieta baja en grasa, una dieta alta en grasa, o una dieta alta en grasa más 0.5% RE (HFD.RE) o 0.5% FE (FED) durante 16 semanas. HFD.RE limitó el aumento del peso corporal y grasa en el epidídimo en un 69% (P<0.01) y 79% (P<0.001), respectivamente. HFD.RE también redujo la glucemia (72%, P<0.01) y los niveles de colesterol (68%, P<0.001). FED redujo la glucemia (76.52%, P<0.001), insulinemia (53.43%, P

Hamling och andra former av lövtäkt för utfodring av tamboskap, var tidigare mycket vanligt men har minskat betydligt fram till våra dagar. Arter, som under åtminstone ett par tusen år anpassat sig till ett liv i, eller i anslutning till de hamlade träden, hotas idag av utrotning. För att kunna säkerställa fortlevnaden för dessa arter samt för de hamlade träden och hamlingen som tradition, krävs kunskap, dels om hamlingsförfarandet i äldre tider, dels om förekomsten av hamlade träd i dagens landskap. Genom att samla in och datera grenprover, kartlade jag i detta arbete senaste hamlingstidpunkt i Bråbygden, i Oskarshamns kommun. För att bedöma hamlingens utförande och potentialen för ytterligare hamling i området, studerade jag också förekomsten av döda träd med hamlingsspår, grova (brösthöjdsdiameter över 30 cm) askar, lindar och lönnar utan hamlingsspår, samt tillgången på tänkbara nya hamlingsträd. En enkät ställd till markägarna i området samt en omfattande litteraturstudie över hamlingens praktik och historia i Sverige ingick också i studien. På de 72 fastigheter som besöktes, tog jag prover från 406 träd. Knappt hälften, 46 procent, av de studerade träden hade hamlats för mindre än 5 år sedan, vilket visar att det i Bråbygden finns förutsättningar att upprätthålla en hamlingstradition med intervall inom de historiskt förekommande intervallen på 2 till 10 år. Jag fann inget klart samband mellan grenarnas diameter och ålder. Detta visar att man inte ska ”stirra sig blind” på de historiska hamlingsintervallen, utan även ta hänsyn till växtplats och andra faktorer som kan påverka grentillväxten, när man bestämmer tidpunkt för nästa hamlingsingrepp. Löv var i äldre tider inte ett nödfoder, utan åtminstone för får och getter ett alldagligt foder, som insamlades i stor mängd och på olika sätt i hela vårt land. Lövtäkten minskade kraftigt från slutet av 1800-talet i samband med jordbrukets rationalisering och lövet gick från att år 1830 värderas som prima hö till att s, Pollarding and other forms for gathering of leaves, twigs and branches for foddering of live¬stock, was formerly common practice but has declined considerably until our time. Species adapted to a life in, or adjacent to, pollarded trees, is therefore largely threatened with extinction. To ensure the survival of pollarded trees with their threatened species, as well as the tradition of pollarding itself, we need to gain knowledge about pollarding in older times, but also about the occurrence of pollarded trees in today’s landscape. I used branch samples to identify the last pollarding event in Bråbygden, south-eastern Sweden. To evaluate earlier use of pollarding and the potential for new pollarding, I also studied the presence of dead trees with traces of pollarding, the occurrence of large (diameter at breast height exceeding 30 cm) ashes, limes and maples without traces of pollarding and potential new pollarding trees. A questionnaire about their pollarding activities was sent to landowners in the area. This work also contained an extensive literature study of pollarding in Sweden in general. 72 properties were visited and samples were taken from 406 trees. Nearly half, 46 percent, of the studied trees were pollarded less than five years ago, which is well within historically known pollarding intervals of 2 to 10 years. I didn’t find any clear relationship between age and diameter of the branches. This shows that you should not only look at historical pollarding intervals when deciding time for the next event, but rather also take into account site productivity and other factors that influence the growth of the branches. In former times leaf fodder was not only used in shortage of other fodder but rather used on an everyday basis, at least for sheep and goats. It was gathered in huge quantities in all parts of Sweden. During the structural rationalization of Swedish agriculture in the late 1800 hundreds, the use of leaf fodder fell sharply. In 1830 it was valued a

Het stond al enige jaren te gebeuren, maar afgelopen augustus is essensterfte, ofwel Chalara fraxinea, officieel aangetoond in Nederland. Boomadviesbureau De Groot uit Veenendaal wist dit als eerste te melden op zijn website. Communicatie rondom de nieuwe ziekte is echter verre van optimaal. Tot op dit moment heeft de PD nog geen melding van de ziekte op haar site staan. Zowel boomkwekers als groenbeheerders tonen zich geïrriteerd over het gebrek aan transparantie en duidelijkheid vanuit de PD.

This paper discusses determinants of the historical and current spatial extent of the floodplain forest in Leipzig as well as its tree species composition using a GIS-data based delineation model and historical forest inventories for the floodplain forest in the district of Leipzig in Germany from the 19th to the 20th century. We found that the spatial extent of the floodplain forest remained considerably stable in spite of an overall decline in the entire floodplain area from the period where the city first experienced industrialisation in the 19th century to now. However, with river regulations and the alteration of forest management from coppice-with-standards forest to high forest in the 19th century, major changes can be found in the tree species composition of the floodplain forest. Comparing these findings with references from other European floodplain forests we discuss the impact of historical and current forest management as well as the city location''s influence on the extent and tree species composition of urban floodplain forests. For urban forest management in particular there is a great need to integrate biophysical, historical and forestry knowledge when predicting future developmental trends.

This study is concerned with larger areas of floodplain forests that still exist today along the Rivers Danube, Elbe, Rhine, Oder as well as the rivers Weiße Elster/Pleiße/Luppe in the district of Leipzig. The historical development of these floodplain forests since the Holocene has been described for an early period (period of Holocene and older artificial floodplain areas 11.000 B.C. to 17th Century) and a more recent period (period of younger artificial floodplain areas ca. 1650 to present). The main focus was on the development of the hardwood floodplain forests. It could be shown that not only the well-known tree species of floodplain forests such as Carpinus betulus, Quercus robur, Tilia cordata and Ulmus spec. belong to the natural tree species of Central European floodplain forests but also Acer pseudoplatanus, Fagus sylvatica, Fraxinus excelsior and Pinus sylvestris. Anthropogenic influence of the earlier pristine floodplain forests of the Holocene period had been greater than previously assumed. Since the Middle Ages individual cases of changes to river courses have been reported. In the period of younger artificial floodplain areas, a severe encroachment on the floodplain forests already existed before the rivers were regulated in the 19th century. Existing fluvial systems such as that of the Upper-Rhine were shifted for example. Dykes changed the use of the floodplain areas permanently and under agricultural pressure hardwood floodplain forests were very often converted into fields and the structure of the remnant floodplain forests drastically changed forever. For some river sections the loss of floodplain forests could be quantified from 1700 to 1840. There has been a longer tradition of biotopes for the hardwood floodplain forests of the river Elbe and in the District of Leipzig compared to the Upper-Rhine and the river Danube near Neuburg. It was only the correction of the Upper-Rhine and Danube river courses that resulted in today's floodplain fores

We examined the influence of tree- and stand-level conditions on lichen diversity on 143 ash trees, varying in age from 11 to 140+ y, in 5 deciduous stands in southern Sweden. The number of lichen species per tree varied from 2 to 30 and was primarily explained by tree trunk diameter and to a lesser extent by tree age, crown cover, lichen cover, and stand identity. The positive relationship between species richness and lichen cover seems compatible with a random placement of species and suggests that similar factors affect both lichen growth and establishment. Species richness did not increase on trees above 65 y of age, while species composition changed with tree age. Together with the positive linear effect of trunk diameter, these results suggest a slight overall positive effect of area, but that species richness over time depends more on species turnover. In addition, we examined if lichens occurring on trees of different ages differed in life history traits, e.g., spore size, thallus height, and pH preference. The results indicate that lichens that most frequently occurred on old trees had larger spores and thicker thalli than other species, suggesting that lichen species' response to tree age can be understood to some extent from their life history traits. However, in this respect lichen ecology is still in its infancy.