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Research project (§ 26 & § 27)
Duration : 2022-05-01 - 2024-09-30

Drought stress response has become an integral part of adaptive forest management and its understanding is required for estimating the consequences of climate change on prospective tree species range shifts. The dominant tree species in the Vienna Woods is European beech (Fagus sylvatica). Other species like oak, hornbeam, larch, red and black pine, silver fir, Norway spruce, Douglas fir, false acacia and Norway maple make up a relatively small percentage of the forest cover. European beech is a species, which is particularly vulnerable to soil drought and higher temperatures are assumed to increase the frequency and intensity of these droughts. The proposed study tries to link site factors, dendrochronology, dendrochemistry and eco-hydrological modeling with a worldwide unique set of soil and foliage data (up to 97 forest sites) of 1984 and 2012. We propose to measure stable isotopes of carbon (13C/12C-ratios) in dated tree rings for evaluating drought periods. Reduced stomatal conductance causes photosynthetic discrimination against 13CO2, indicated by decreased 13C/12C-ratios in leaves and tree rings. Our related research questions are: i) How drought sensitive is beech in comparison to other optional tree species of the Vienna Woods: oak, hornbeam, larch, Scots pine, black pine, silver fir, Norway spruce, Douglas fir, false acacia and Norway maple? ii) Are dendrochemical parameters useful for estimating transpiration fluxes of the studied trees? iii) How do forest site factors (climate, soil, terrain) affect the ranking of tree species by drought sensibility? iv) Do our experimental data agree with modeled data on the stand’s vulnerability and resilience towards soil drought, and if so, can we assess temperature driven changes? The final objectives are drought sensitivity characterizations of the previous experiences with the existing tree species and recommendations for future tillering and their management with regard to climate change.
Research project (§ 26 & § 27)
Duration : 2022-03-01 - 2024-09-30

The mechanisation of forest managementis of great importance for the sustainable provision of the renewable raw material wood. The coordination of the technology with the ecological framework conditions is decisive for the care of the utilisation. The particularly productive, often ‘heavy’ soils of the flysch and molasse zone are susceptible to compaction and therefore pose a challenge for mechanisation. Soil compaction by driving changes the soil structure and thus the infiltration capacity, the plant-available water storage capacity, the water balance of the ecosystem and the soil air balance. Site properties such as rootability, tree species suitability, productivity, but also other soil functions such as the source and sink effect of the soil for greenhouse gases or the habitatfunction for soil organisms are closely related to the soil structure. A site-adapted use of technology is therefore a basis for forest management on soils susceptible to compaction. The aim of this projectis to create a database for the assessment of the effects of different wood harvesting technologies on forest sites with compaction-prone soils for the currently prevailing and expected future climatic conditions. On the basis of documented timber harvesting operations of the lastten years and the utilisations carried out under controlled conditions during the project period, the effects of differenttechnologies used (type, design) under defined soil conditions (water content, soil frozen or not, etc.) are examined. The indicators allow a statement on the impact of different harvesting measures on soil functions, the remaining stand as well as regeneration. Water availability, controlled by the ratio of surface runoff to infiltration, water storage capacity and root penetration of the soil, is of particular importance for the following stand. This comparison is intended to provide forest managers with a practical decision matrix that clarifies the opportunities and risks of the various technologies in additi‐ on to the expected harvesting costs. The aim is to derive recommendations for the choice of the most suitable harvesting technology depending on location and weather conditions. Demonstration plots will be established for education and further raining.
Research project (§ 26 & § 27)
Duration : 2021-09-01 - 2024-11-30

Austrian forests are experiencing severe climate change impacts, both directly through the shifts of abiotic conditions and habitat suitability, as well as indirectly through the increased frequency and intensity of disturbances such as wind throws and bark beetle outbreaks. Successful restoration of the affected areas will require afforestation or natural recruitment, both of which depend on the quality and quantity of seed production by climate resilient tree species. Because seed production in most temperate forest trees varies strongly over time in a synchronized manner, a phenomenon termed masting, available seed quantities for replanting and natural regeneration vary extensively between years. A forward-looking strategy for the restoration of Austria’s forests therefore requires a thorough understanding of the mechanistic drivers of the quantity and quality of seed production to develop strategies that optimize seed harvests, both in certified seed stands as well as in seed orchards. The goal of this research project is to investigate the drivers of seed production, seed quality and seed genetic diversity of Austria’s forest tree species, to determine the effects of climate change thereon, and to assess strategies that improve the reliability and quality of seeds available for afforestation. The project will test and apply innovative seed orchard management practises to improve seed production for oak and silver fir. Furthermore, natural recruitment dynamics and their limitations throughout the seed and seedling phase will be quantified to evaluate “hands-off” management approaches. The project will aim to include small-scale forest owners, whose seed harvesting efforts could help mitigate national shortages, while their involvement also increases awareness for forest management issues in the changing climate. In close coordination with practitioners, we aim to derive recommendations and methods to increase yields and maintain genetic diversity of seed crops.

Supervised Theses and Dissertations