Ash dieback in Austria – history, current situation and outlook

33-52

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200203155

Dieback of European Ash (Fraxinus spp.) – Consequences and Guidelines for Sustainable Management (2017) , 33-52

In this contribution, we aim to summarize the current knowledge on the main ash (Fraxinus) species in Austria
and on the situation of ash dieback, caused by Hymenoscyphus fraxineus. F. excelsior is of considerable
importance as a timber species. It occurs on a wide variety of sites, in different ecological contexts. Planting of
ash used to be encouraged until about ten years ago, as it seemed very suitable to replace conifer stands in
lowland areas. The species is severely affected by ash dieback, just as the more marginal species, F. angustifolia,
while F. ornus, the third ash species native to Austria, is not endangered. The progress of the disease has been
very fast, affecting practically the whole territory of Austria within very few years from approximately 2005
onwards. It now questions the continuity of timber production in forest enterprises where ash is the main species,
impairs other ecosystem services and has numerous negative ecological consequences. Likewise, it has affected
nursery plant production heavily. Landscape level effects of the impact of ash dieback are possibly reflected in
declining pollen loads in the air. In the forest, variations in disease intensity are observed from year to year, and
between moister and drier regions; yet, the disease seems to progress in most individual trees. Solitary trees in
cities and in the cultural landscape are generally less affected by ash dieback. Clones of F. excelsior in three seed
orchards have been assessed for crown damage levels over three years. These observations indicate that some
clones are more resistant or tolerant to ash dieback than others. Consequently, a resistance breeding project for
common ash has recently been initiated. There is little evidence for important genetic differentiation among
population or seed stands within Austria. Options for adapting silvicultural strategies and for conserving F.
excelsior are discussed.
Keywords: Fraxinus excelsior, Fraxinus angustifolia, Fraxinus ornus, Hymenoscyphus fraxineus, Chalara
fraxinea, noble hardwoods, silviculture, disease management, resistance, genetic differentiation, conservation
Schlüsselwörter: Fraxinus excelsior, Fraxinus angustifolia, Fraxinus ornus, Hymenoscyphus fraxineus, ChalaraFraxinea, edle Harthölzer, Waldbau, Krankheitsmanagement, Resistenz, genetische Differenzierung, Konservierung