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The aim of the project "Adaptation of autochthone and culturally valuable Austrian Pine Forests to future climatic conditions with special reference to aspects of forest pathology and interspecific genetic variation", which is described in detail in the project application of the BFW to the Austrian Ministry of Sustainability and Tourism, is to investigate measures of adaptation of ecologically valuable forest ecosystems dominated by Austrian Pine to climatically-induced epidemics of Diplodia shoot dieback (Diplodia sapinea). For that purpose the intraspecific variation of susceptibility of Pinus nigra to Diplodia sapinea should be tested and utilized. Within this project the following aspects will be adressed by the tasks carried out at the Institute of Forest Entomology, Forest Pathology and Forest Protection, BOKU, Vienna: • Laboratory investigations with regard to the selection and phenotyping of resistant mother trees of Pinus nigra (working package 1) • Providing assistance and support on investigations aiming to evaluate the resistance of clones or ramets from the clone archive (working package 2). • Development and implementation of a new seed control protocol taking into account infections by Diplodia sapinea (working package 3). • Assistance in the course of the revision of the currently approved seed lots for Pinus nigra in Austria (considering the genetic resistance of pine provenances to Diplodia sapinea) (working package 4). • Documentation of the above described tasks via protocols and scientific reports; data analyses and electronic data procession; provision of data to the BFW
Research project (§ 26 & § 27)
Duration : 2018-10-01 - 2021-09-30

Ash dieback is a serious disease of ash (Fraxinus) species caused by the ascomycete fungus Hymenoscyphus fraxineus, which is native to East Asia and an invasive alien species in Europe. In Austria, symptoms of ash dieback were first recorded in 2005, and due to the successive spread of the causative agent, the disease now occurs in entire Austria. Besides the highly susceptible common ash (Fraxinus excelsior), which is severely damaged throughout most of its distribution range in Europe, narrow-leaved ash (Fraxinus angustifolia), which is in Austria mainly distributed in floodplain forests along the river March, is highly susceptible to the ash dieback pathogen. As observed for F. excelsior, there are individual F. angustifolia trees in young and mature forest stands which are only slightly affected by the disease. Such trees possibly possess a genetically heritable high resistance towards H. fraxineus. In order to preserve the autochthonous occurrence of F. angustifolia in floodplain forests along the March, which is threatened by ash dieback, undamaged or only slightly damaged ash trees across all age classes will be selected in the natural distribution range of the species. These trees will be incorporated in a clonal collection and in a progeny trial, in which their disease resistance levels will be evaluated. Heavily damaged afforestations of narrow-leaved ash which have been established during the last 10 to 15 years will be inspected, and undamaged or slightly damaged plants will be selected and vegetatively propagated, first by grafting and later by rooted cuttings. For the older age classes, seeds will be collected from undamaged or slightly damaged ash trees, from which plants will be grown. With the vegetatively and generatively propagated plant material two field trials will be established. In these trials, the level of resistance of the various genotypes will be tested. Simultaneously, the experimental sites shall serve for the ex situ preservation of narrow-leaved ash. Thereby, the present project will in the long-term lay the foundation for the establishment of seed orchards with disease resistant specimens of this ash species.
Research project (§ 26 & § 27)
Duration : 2018-07-01 - 2022-06-30

Extreme climatic events are main triggers of pest outbreaks, and an improved mechanistic understanding of drought effects on interactions of the Eurasian spruce bark beetle (Ips typographus) and its host Norway spruce is highly demanded. The proposed drought manipulation study deals with the problem of resource allocation in Norway spruce with specific regard to secondary metabolism. To what extent is constitutive and induced defence against bark beetle attack, such as resin flow and hypersensitive reaction on blue stain fungus inoculation, influenced by tree drought stress? In particular, patterns in the composition and concentration of monoterpenes in spruce bark as well as in volatile emissions are addressed. Response of bark beetles in terms of tree attack is tested in the field, in terms of direct repellent or attractive effects of different bouquets on male beetles in the lab. The in situ drought manipulation experiment will provide novel empirical evidence of effects of water deficiency on Norway spruce secondary metabolism important for risk assessment. Study results will be incorporated in a previously developed, comprehensive model framework addressing the complex interplay between drought stress intensity, induced and constitutive defence responses, and insect infestation. At the drought manipulation site, sample trees are embraced by rain-out shelters in the size of 5x5 m, further trees are chosen for control. Climate parameters and tree water status in terms of pre-dawn twig water potentials are recorded. Constitutive and induced defence is examined by resin flow, hypersensitive reaction on blue-stain fungus inoculation, and jasmonic acid concentrations in the bark. Volatile compounds emitted from the tree stems and bark extracts are analysed by Gas Chromatography and Mass Spectrometry. Using the novel attack box approach, bark beetle attack under controlled test conditions is regularly observed. Local bark beetle activity is checked by pheromone-baited flight-barrier traps and trap trees outside the forest stand. By use of an olfactometer, behavioural response is tested for various blends of monoterpenes identified in the course of the field experiment.

Supervised Theses and Dissertations