PhD Students

Meet our PhD candidates:


Katharina Ramskogler

Katharina Ramskogler

E-Mail: Katharina.Ramskogler@student.uibk.ac.at

Thesis title:
Short and long term feedback between vegetation and morphodynamic processess

Supervisors:
Brigitta Erschbamer, RG Population Biology and Vegetation Ecology, Innsbruck University

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Project description:

Glacier retreat, extreme events and loss of permafrost increase due to climate change. Therefore, it is important to enhance our knowledge about development of plant communities and responses of vegetation to disturbances.

Development of plant communities and responses of plants to disturbances will be studied on different scales. The first part of the PhD-project deals with analyses of plant community development along a chronosequence of a glacier foreland. The second part focuses on the response of vegetation to geomorphological disturbances, such as avalanches, debris flows or flood events. The studies are carried out along elevation gradients at test sites in three different study areas. Functional responses of plants to these disturbances will also be investigated. In a third approach, changes in vegetation since 1850 up to now are investigated. Transects will be carried out from the historical treeline to the actual subnival zone and compared with historical images.

The PhD-project is funded by the DRG (Deutsche Forschungsgemeinschaft) within the project “Sensitivity of high Alpine geosystems to climate change since 1850” (SEHAG).






Lena Nicklas

Lena Nicklas

E-Mail: Lena.Nicklas@uibk.ac.at

Thesis title:
Winners and loser of climate change in the Central and South Alps

Supervisors:
Brigitta Erschbamer, RG Population Biology and Vegetation Ecology, Innsbruck University
Sonja Wipf, WSL-Institut für Schnee- und Lawinenforschung SLF, Davos

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Project description:

Climate warming is one of the essential drivers for the ongoing vegetation changes in high altitudes. As temperatures are rising, species from lower altitudes are extending upwards. The future of the alpine biodiversity still seems unclear: scenarios are reaching from severe extinction rates to good survival possibilities of alpine species in horizontal niches. To gain empirical results, long-term monitoring studies such as GLORIA (Global Observation Research Initiative in Alpine Environment) are necessary. Within this worldwide network, vegetation changes at summits of different altitude are recorded every 5-8 years.
The PhD-project focuses on two such GLORIA regions in the Central and South Alps where monitoring data exist for 14 years. The aim of the study is to analyse recent vegetation changes and estimate the consequences for the occurring species. To understand migration processes of alpine species and predict potential invaders, additionally the vegetation at the slopes below the summits is investigated.

Publications:

Conference talks and posters:

  • Nicklas, L., Mallaun, M., Unterluggauer, P. & Erschbamer, B. (2018): Alpine biodiversity in the Central and South Alps. Quo vadis? 18. Österreichische Botanik-Tagung, Klagenfurt, 19.-21.9.2018.
  • Nicklas, L., Mallaun, M., Unterluggauer, P., Walde, J. & Erschbamer, B. (2018): Trends in alpine biodiversity and microsite variability in the Central and South Alps. 48th Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, Wien, 10.-14.9.2018.
  • Nicklas, L., Mallaun, M., Unterluggauer, P. & Erschbamer, B. (2018): Alpine biodiversity in the Central and South Alps. Quo vadis? 10. Tagung “Zoologische und botanische Forschung in Südtirol“, Bozen, Italien, 6.-7.9.2018.
  • Nicklas, L. & Erschbamer, B. (2017): Winners and losers of climate change in the Central and South Alps. Jahrestreffen des Arbeitskreises für Hochgebirge, Institut für Interdisziplinäre Gebirgsforschung, Innsbruck University, 2.-3.2.2018.
  • Nicklas, L. & Erschbamer, B. (2017): The Alpine pioneers of the Tyrolean Lech – Diversity and distribution of subalpine and alpine waterborne plants at Tyrolean floodplains. 15th International Alpine Workshop & 4th International River Conference Tagliamento 2017, Corino, Italy, 13.-20.5.2017
  • Nicklas, L., Mallaun, M., Unterluggauer, P., Walde, J. & Erschbamer, B. (2018): Are microsites essential for new colonizers at mountain summits? Annual Meeting of the International Association for Vegetation Science (IAVS), Bozeman, Montana, 22.-27.7.2018. Poster presented by Erschbamer, B.
  • Nicklas, L., Mallaun, M., Unterluggauer, P. & Erschbamer, B. (2018): Alpine biodiversity in the Central and South Alps. Quo vadis? POPBIO 2018, Innsbruck, 3.-5.5.2018
  • Nicklas, L., Mallaun, M. & Erschbamer, B. (2018): Welche Pflanzen gewinnen, welche verlieren? Lange Nacht der Forschung, Institut für Botanik, Innsbruck, 13.04.2018
  • Nicklas, L., Mallaun, M. & Erschbamer, B. (2017): Winners and losers of climate change in the Central Alps. 6th International Symposium for Research in Protected Areas, University of Salzburg, 2.-3.11.2017.
  • Nicklas, L., Mallaun, M. & Erschbamer, B. (2017): Winners and losers of climate change in the Central Alps. Workshop Long-Term Research in Mountain Areas, University Centre Obergurgl, 29.9.-3.10.2017
  • Nicklas, L. & Erschbamer, B. (2016): Alpine Pioniere an den Alluvionen des Tiroler Lechs – Verbreitungsmuster von Linaria alpina und anderen Alpenschwemmlingen. 17. Treffen der Österreichischen Botanikerinnen und Botaniker, Wien.





Dominik Kaplenig

Dominik Kaplenig

E-Mail: Dominik.Kaplenig@uibk.ac.at

Thesis title:
Adaptation and acclimation to alpine habitats viewed through anatomical and physiological traits of different populations of Arabidopsis arenosa

Supervisors:
Gilbert Neuner, RG Stress Physiology and Climate Resistance, Innsbruck University
Ilse Kranner, RG Plant Biochemistry and Metabolism, Innsbruck University
Filip Kolář, RS Plant Ecological Genomics, Charles University of Prague

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Project description:

Plants at high mountain sites experience challenging climatic conditions, including temperature extremes, higher rates of condensation and wind intensity compared to the downhill site. Especially the predicted environmental changes due to the climatic change will be challenging for some of the high alpine plants. Thus, plants in high alpine regions need functional and structural adjustments to survive the climatic conditions in their habitats. It is still not fully understood how variation in environmental factors leads to acclimation and genetic adaption. However, this habitat heterogeneity in mountain areas can exert selection pressure and therefore lead to the formation of new ecotypes in plants, which occurred in Arabidopsis arenosa (L.).
The aim of this PhD thesis is to measure anatomical, morphological and physiological traits of foothill and alpine ecotypes of A. arenosa originating from different populations grown in common gardens to elucidate stable adaptative or acclimative traits. Special focus will be laid on photosynthetic performance and its response to temperature stress (low and high temperature).






Vera Margreiter

Vera Margreiter

E-Mail: Vera.Margreiter@uibk.ac.at

Thesis title:
Germination, Establishment and Phenotypic Plasticity of Alpine Species

Supervisors:
Brigitta Erschbamer, RG Population Biology and Vegetation Ecology, Innsbruck University
Andrea Mondoni, Department of Earth and Environmental Science, Pavia University

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Project description:

The reaction of plants to changing environmental conditions is a hot topic in mountain research and plant ecology. For establishing in new or changing environments, a good germination and recruitment ability, as well as a high phenotypic plasticity are advantageous.
The PhD project includes sowing experiments with alpine plant seeds in the field along an altitudinal gradient (1), in the common garden (2), and germination in growth chambers (3) covering three major topics:

  1. Germination and survival of species along an altitudinal gradient in the Central Alps, Austria. Nine species (herbs, grasses, cushion plants) were sown from 2000 m up to 2900 m a.s.l.
  2. Effects of provenances on germination and phenotypic plasticity of the genus Saxifraga
  3. Seed traits and germination dynamics

The PhD project is part of the “Alpine Seed Conservation and Research Programme”, a project funded by “The David and Claudia Harding Foundation, Royal Botanic Gardens, Kew”.

Publications:

Conference talks and posters:

  • Germination and survival of alpine species along an altitudinal gradient in the Central Alps. Populationsbiologie-Tagung POPBIO 2018, Innsbruck, 03.-05.05.2018
  • Beeinflusst der Klimawandel die Samenkeimung und das Wachstum der Pflanzen im Gebirge? Effekte von Schutzstellen, Konkurrenz & Lebensform. Lange Nacht der Forschung, Institut für Botanik, 13.04.2018
  • Germination, Establishment and Phenotypic Plasticity of Alpine Species. Jahresmeeting "Alpine Seed Conservation and Research Network", Frankreich, Gap, 23.-25.11.2017
  • Doktoratskolleg Seminar "Alpine Biology and Global Change": Germination, Establishment and Phenotypic Plasticity of alpine species. Doktoratskolleg, 6./8.11.2017, Innsbruck
  • Germination and survival of alpine species along an altitudinal gradient in the Central Alps. Workshop Long-Term Research in Mountain Areas, Obergurgl, 29.09.-03.10.2017
  • Germination and survival of alpine species along an altitudinal gradient in the Central Alps. Populationsbiologie-Tagung POPBIO 2017, Halle 18.-20.05.2017





Špela Pungaršek

Špela Pungaršek

E-Mail: Spela.Pungarsek@gmail.com

Thesis title:
Polyploidisation as an important evolutionary mechanism in Euphorbia, Knautia and Luzula

Supervisor:
Peter Schönswetter, RG Evolutionary Systematics, Innsbruck University
Božo Frajman, RG Evolutionary Systematics, Innsbruck University

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Project description:

Polyploidy is one of the most important evolutionary pathways in flowering plants and has significantly contributed to their diversification and radiation. Recurrent formation of polyploids, (epi)genetic, transcriptomic and genomic changes as well as morphological, geographic and ecological divergence following polyploidisation are considered significant processes in the evolution of polyploids. Several ploidy levels can exist within some species and such intraspecific polyploids often have multiple origins.
Most recent studies have focused on the genetic and genomic attributes of polyploidy, but rarely on the ecological context. In my PhD I will address the following main questions connected to polyploid evolution in three different genera of flowering plants:

(1) How important was polyploidisation for diversification of Euphorbia subgenus Esula (Euphorbiaceae)?

(2) Is morphological and genetic variation reflecting current taxonomic diversity in Knautia (Caprifoliaceae) from the south-eastern Alps?

(3) How is polyploidisation and agmatopolyploidisation connected with genetic, morphological and ecological diversification in Eastern Alpine members of Luzula sect. Luzula (Juncaceae)?





Gregor Pichler

Gregor Pichler

E-Mail: Gregor.Pichler@uibk.ac.at

Thesis title:
The lichen symbiosis: Metabolites involved in lichenization

Supervisors:
Ilse Kranner, RG Plant Biochemistry and Metabolism, Innsbruck University
Andreas Holzinger, RG Plant Cell Biology, Innsbruck University
Mauro Tretiach, RS Plant and Animal Ecophysiology, Trieste University

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Project description:

Flechten sind eine Symbiose zwischen einem Pilz ("Mykobiont") und einer (oder mehreren) Mikroalge(n) ("Photobiont") und können außerdem auch mit Hefepilzen sowie den verschiedensten Arten von Bakterien inter- und extrazellulär vergesellschaftet sein. Der komplexe Prozess der Flechtenbildung (Lichenisierung) zwischen Mykobiont und Photobiont ist jedoch noch weitgehend unerforscht. Eine überschaubare Anzahl an wissenschaftlichen Studien lassen jedoch vermuten, dass hierbei Phytohormone sowie auch einige andere wichtige Metabolite eine entscheidende Rolle spielen könnten. Mit umfangreichen, vorwiegend extrazellulären Phytohormon-Messungen und Metaboliten-Profiling an Myko- und Photobiont sowie den intakten Flechten und zusätzlichen Transkriptom-Analysen, soll dieses PhD-Projekt Aufschlüsse über die chemische Kommunikation und biochemischen Mechanismen der Lichenisierung aufzeigen.

Publications:





Andreas Bär

Andreas Bär

E-Mail: Andreas.Baer@uibk.ac.at

Thesis title:
Auswirkungen von Waldbränden auf adulte und juvenile Bäume alpiner Waldökosysteme.

Supervisor:
Stefan Mayr, RG Ecophysiology, Innsbruck University
Walter Oberhuber, RG Dendroecology and Tree Physiology, Innsbruck University

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Project description:

Global warming causes an increase not only in the frequency, severity and duration of drought events but also in the probability of wildfires. These phenomena affect even relatively humid regions such as the Central Alps. Knowledge of fire effects on Central European trees and forests is comparably poor but highly relevant considering the important protective function of alpine forests for human settlements and infrastructure. In case of forest fires, adult trees play an important role, as surviving specimens substantially contribute to the stabilisation of the system, while the resistance of seeds and seedlings to heat is the base for successful recruitment to replace perished trees over time.
The PhD project aims at analysing short- and long-term effects of forest fires on European tree species. Analyses on heat resistance of tissues, hydraulics and growth will be performed on adult trees, seeds and seedlings of important forest tree species. The combination of laboratory experiments and field studies will enable new insights into short- and long-term fire effects on alpine trees. The results will be relevant in both basic and applied research, as the collected data will help to improve future forest management dealing with increasing frequencies and intensities of fire and drought.

Publications:





Matthias Stegner

Matthias Stegner

E-Mail: Matthias.Stegner@uibk.ac.at

Thesis title:

Ice management in plant tissues: The influence of cell wall attributes on biophysical processes at sub-zero temperatures.

Supervisor:
Gilbert Neuner, RG Stress Physiology and Climate Resistance, Innsbruck University
Ursula Lütz-Meindl, Ultrastructure of plant cells and cellular stress, Universität Salzburg
Notburga Gierlinger, Biological materials on the nano and micro scale, BOKU Wien

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Project description:

Frost events are critical for the survival, the productivity and geographical distribution of plants. In the alpine life zone, plant species are exposed to frequent frost events, even in summer. Therefore, strategies to cope with these environmental conditions are obligatory. Ranunculus glacialis, which is able to grow even above 3000 m a.s.l in Tyrol, has ice tolerant leaves and flowers. If the occurrence of a single freezing event already causes frost damage to a plant tissue, it is considered ice susceptible. Cultivation of many important crop species, e.g. potato (Solanum tuberosum), is restricted to frost free areas or periods due to ice susceptibility.
The mechanisms causing frost damage to plant tissues and what is happening at the cellular level is hardly understood. In the frame of FWF project 30139 this question is addressed in detail. The cell wall properties appear critically important for tolerance of extracellular ice. The freezing behavior of various contrasting mesophyll tissues is studied in combination with structural and ultrastructural cell wall traits. Functional properties of cell walls are assessed by psychrometric measurements of cell wall elasticity. The potential role of cell wall elasticity on freezing behavior, freeze dehydration and cytorrhysis of cells will be analysed. For the tested species microclimate data are continuously logged to monitor the frequency and intensity of freezing events in their natural habitats in order to relate their freezing resistance strategy to the peculiar environmental strain at growing sites.

This project is funded by the FWF (project number 30139-B32).




Davide Gerna

Davide Gerna

E-Mail: Davide.Gerna@uibk.ac.at

Thesis title:
Interactions between hormones, antioxidants, and reactive oxygen species during seed germination.

Supervisors:
Ilse Kranner, RG Plant Biochemistry and Metabolism, Innsbruck University
Johanna Wagner, RG Reproductive Biology, Innsbruck University
Andreas Börner, AG Ressourcengenetik und Reproduktion, Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK)

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Project description:

Seeds are unique biological units as they contain the next plant generation in the form of the embryo, and represent a main food source for humans and livestock. Hence, seed quality and viability, which determine seed vigour, are key to agricultural productivity and food security. My research interests are in seed physiology, including redox and hormonal regulation of seed germination, their downstream effects on seed metabolism, and the biochemical bases of seed ageing. Furthermore, I am investigating the molecular signalling pathways (e.g., reactive oxygen species and plant hormones) in the interactions between seeds and bacteria, and their effects on seed germination and seedling growth. Our overall aim is to identify redox conversions and changes in metabolites that are crucial for seed viability and vigour, thus elucidating the molecular switchboards that control seed vigour.

Publications:





Marlies Außerlechner

Marlies Außerlechner

E-Mail: Marlies.Ausserlechner@uibk.ac.at

Thesis title:
Archaeobotanical Analyses of Bronze and Iron Age Burnt-Offering Sites in the Subalpine and Alpine Belt of the Eastern Alps

Supervisor:
Klaus Oeggl, RG Palynology and Archaeobotany, Innsbruck University
Gerhard Tomedi, Fachbereich Ur- und Frühgeschichte, Innsbruck University

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Project description:

The phenomenon of burnt-offering sites arose in the valley-floors of the inner-alpine regions with the beginning of the Bronze Age. In the course of the Middle Bronze Age, the ancient dwellers established burnt-offering sites also in the subalpine and alpine belt, where some of them were maintained over hundreds of years. This PhD-project focuses on the charred plant remains originating from sacred or profane fire-rites held there.
Archaeobotanical analyses of pit-fillings and soil samples of four high-alpine burnt-offering sites and one dwelling site located in the Central Eastern Alps are conducted, including carpological and charcoal-quality analyses.
The aim of this study is to gain insights into the Bronze and Iron Age land-use of higher altitudes, the timberline-situation, the subsistence strategy, and the rites of the settlers in the inner-alpine regions. Therefore, questions concerning food plants, food-supply, wood-use, and wood-supply have to be answered. Furthermore, the extent of human activities in the inner-alpine high-valleys will be evaluated.
The Vizerektorat für Foschung, Innsbruck University and the Autonome Provinz Bozen, Südtirol financially support this study.

Publications:

Conference talks and posters:

  • Außerlechner, M.; Putzer, A.; Steiner, H.; Oeggl, K.: Plant use and rites at burnt-offering sites in inner-alpine areas of Northern Italy during the Bronze and Iron Age. 18th Conference of the International Workgroup for Palaeoethnobotany (IWGP 2019), Lecce, Italien, 06.06.2019.
  • Außerlechner, M.; Putzer, A.; Oeggl, K.: Selektive Holznutzung an der Waldgrenze in der Bronzezeit? 10. Tagung Zoologische und botanische Forschung in Südtirol, Bozen, 07.09.2018.
  • Außerlechner, M.; Putzer, A.; Oeggl, K.: Bronze and Iron Age pit-fillings of high-alpine burnt offering sites. 14th Conference of Environmental Archaeology (CEA2018), Modena, 28.02.2018.
  • Außerlechner, M.; Oeggl, K.: Bronzezeitliche Pflanzenreste alpiner Brandopferplätze in Südtirol. 9. Tagung Zoologische und botanische Forschung in Südtirol, Bozen, 08.09.2016.
  • Außerlechner, M.; Oeggl, K.: Veränderungen des Kulturpflanzeninventars im Einzugsgebiet der Etsch (Südtirol) vom Neolithikum bis in die Eisenzeit. 10. HiMAT Milestone Meeting, Innsbruck, 06.11.2015.
  • Außerlechner, M.; Tecchiati, U.; Oeggl, K.: Neolithische Kultur- und Wildpflanzenfunde im mittleren Eisacktal. 9. HiMAT Milestone-Meeting, Klausen, 24.10.2014.
  • Außerlechner, M.: Karpologische Studien zur Subsistenz der neolithischen Siedlung Barbian, Eisacktal. Workshop FZ HiMAT 2014, Innsbruck, 24.02.2014
  • Außerlechner, M.; Tecchiati, U.; Oeggl, K.: Neolithische Kultur- und Wildpflanzen im mittleren Eisacktal / Neolithic crops and wild plants in the central Eisack Valley. 8. Tagung Zoologische und botanische Forschung in Südtirol, Bozen, 04.09.2014.
  • Außerlechner, M.: Die Pflanzengroßreste aus der neolithischen Siedlung in Barbian/Südtirol. 8. FZ HiMAT Milestone Meeting / 3. Milestone-Meeting der RITaK, Bischofshofen, 11.10.2013.

Project funding:

  • Subsistence of an Iron Age Blacksmith in the Eastern Alps. The Plant Macro Remains of the Settlement "Piperbühel" (South Tyrol). Tiroler Wissenschaftsförderung (TWF), 2018–2020.
  • Doktoratsstipendien aus der Nachwuchsförderung der Leopold-Franzens-Innsbruck University – Vizerektorat für Forschung, 01.11.2016 –31.08.2017 und 01.10.2017-28.02.2018.

Academic awards:

  • Award of the Society of Naturalists and Mathematicians of Modena – SNMM Award, 14th Conference of Environmental Archaeology 2018, Modena, 26.02. – 28.02.2018. (2018).
  • 1. Platz Nachwuchswettbewerb für junge Wissenschaftlerinnen und Wissenschaftler beim 9. Milestone-Meeting des Forschungszentrums HiMAT, Klausen, 25.10.2014.





Siegfried Aigner

Siegfried Aigner

E-Mail: Siegfried.Aigner@uibk.ac.at

Thesis title:
Stress responses in phylogenetically distant green algae from extreme habitats: Ecophysiological and molecular adaption in free living green algae and isolated lichen photobionts.

Supervisors:
Ilse Kranner, RG Plant Biochemistry and Metabolism, Innsbruck University
Andreas Holzinger, RG Plant Cell Biology, Innsbruck University
Ulf Karsten, Abt. Angewandte Ökologie und Phykologie, Rostock University

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Project description:

Since 2009 I have been working on photosynthetic organisms from distant linages with origination from habitats with extreme environments (e.g. high-alpine regions). Aero-terrestrial microalgae can occur in such habitats in a free-living lifestyle or as endosymbionts in lichens, whereby the latter organism consists of a fungus in symbiosis with unicellular and/or filamentous algae. These organisms can be subjected to various abiotic stress factors (including enhanced UV-radiation and/or desiccation) and my research interest is focusing on molecular adaptations and responses (e.g. induction/accumulation of UV-photoprotectants) of these organisms to such fluctuating parameters.

Publications:

Conference talks and posters

  • Ecophysiological and abiotic stress tolerance of aquatic, terrestrial and symbiotic Chlorella-(like) species. Aigner, S., Glaser, K., Holzinger, A., Kranner, I. & U. Karsten. Talk at the 17th Scientific conference of the Phycology Section of the German Botanical Society 2018, 11th- 14th March, Berchtesgaden/Germany
  • Zygnema sp. from arctic and alpine terrestrial habitats: adaptations to simulated UV radiation investigated by a physiological and metabolomics approach. Pichrtová, M., Albert, A., Uhl, J., Aigner, S. & A. Holzinger. Poster at the 11th International phycological congress 2017, 13th–19nd Aug, Szczecin/Poland
  • Photosynthetic performances and related UV-photoprotectants from epilithic stream algae of the genus Chamaesiphon. Aigner, S., Herburger, K., Holzinger, A. & E. Rott. Poster at the 20th Cyanophyte/Cyanobacteria research symposium 2016, 28th Aug–2nd Sep, Innsbruck/Austria
  • Pseudoscytonema sp., a calcite-precipitating macroscopic niche-forming cyanobacterium from a seepage spring in the Alps. Aigner, S., Herburger, K., Rott, E. & A. Holzinger. Poster at the 20th Cyanophyte/Cyanobacteria research symposium 2016, 28th Aug–2nd Sep, Innsbruck/Austria
  • Ecophysiological characterization and photoacclimation of the freshwater red alga Batrachospermum turfosum Bory. Aigner, S., Arc, E., Holzinger, A., Karsten, U. & I. Kranner. Talk at the 57th annual meeting of the Czech phycological society 2016, 19th-21st Sep, Prague/Czech Republic
  • Ecophysiological characterization and photoacclimation of the freshwater red alga Batrachospermum turfosum Bory. Aigner, S., Arc, E., Holzinger, A., Karsten, U. & I. Kranner. Talk at the 21st ATSPB meeting 2016, 26th-28th May, Berchtesgaden/Germany
  • Ecophysiological characterization and photoacclimation of the freshwater red alga Batrachospermum turfosum Bory. Aigner, S., Arc, E., Holzinger, A., Karsten, U. & I. Kranner. Talk at the 16th Scientific conference of the Phycology Section of the German Botanical Society 2016, 6th- 9th March, Leipzig/Germany
  • Ecophysiological characterization and metabolic stress response of the freshwater red alga Batrachospermum turfosum Bory (Rhodophyta, Florideophyceae) to enhanced UV-A and UV-AB irradiation highlight activation of ancient photoprotective mechanisms. Aigner, S., Arc, E., Holzinger, A., Karsten, U. & I. Kranner. Talk at the FBFW meeting 2015, 15th-17th April, Mondsee/Austria
  • Accumulation of unusual phenolic compounds in the purple coloured green alga Zygogonium ericetorum (Zygnematophyceae, Streptophyta) from a high alpine habitat. Aigner, S., Remias, D., Stuppner, H. & A. Holzinger. Poster at ATSPB meeting 2012, 7th-10th June, Lienz/Austria
  • Isolierung und Charakterisierung eines UV–Schutzpigmentes aus der Eisalge Mesotaenium berggrenii. Aigner, S., Remias, D., Schwaiger, S., Stuppner & C. Lütz. Poster at ATSPB meeting 2010, 3rd-5th June, Illmitz/Austria





Alumni since 2006

The following alumni have completed their Doctoral thesis at the Department of Botany:

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Clara Bertel

Thesis title:
Natural selection drives parallel morphological, anatomical and ecophysiological divergence in the mountain plant Heliosperma pusillum s.l.

Supervisor:
Peter Schönswetter, RG Evolutionary Systematics, Innsbruck University



Klaus Herburger

Thesis title:
Algal cell walls: relevance for the success of charophytes on land

Supervisors:
Andreas Holzinger, RG Plant Cell Biology, Innsbruck University
Ilse Kranner, RG Plant Biochemistry and Metabolism, Innsbruck University

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Project description:

Charophyte green algae (CGA) evolved strategies to survive on land and gave rise to the evolution of Embryophytes, which inherited fundamental traits of their algal ancestors, such as a complex polysaccharide-rich cell wall. Members of early- (Klebsormidophyceae) and late-diverged (Zygnematophyceae) CGA occur worldwide in terrestrial habitats. However, knowledge on the contribution of their cell wall properties to survive terrestrial conditions such as poor water supply is very limited. The present PhD thesis shows that filamentous terrestrial CGA modulate their cell walls in response to environmental stress and/or the developmental stage (e.g. during pre-akinete and aplanospore formation). Short-term desiccation stress induces incorporation of (1->3)-β-glucan (callose) into undulating cross cell walls of Klebsormidium spp. During desiccation-rehydration cycles, callose deposition helps preventing structural damage of Klebsormidium cells resulting in maintenance of a higher photosynthetic performance compared to Zygnema, which lacks this protection mechanism. Zygnema follows another strategy: vegetative cells develop with age into specialised resistant cells (termed pre-akinetes), which show a higher resistance against water shortage when compared with untransformed cells. Pre-akinete formation includes a reorganization of cell ultrastructure and changes the cell wall composition, e.g. by increasing the pectin fraction, which is considered to increase the water holding capacity of filaments. During cell growth, both Klebsormidium and Zygnema modify their complex hemicellulose network by transglycosylation in specific cell wall areas. In contrast, old thick-walled cells and pre-akinetes lack transglycanase activity, underpinning the pre-akinetes’ decreased metabolic activity and role as resting cells. Another adaptation to the terrestrial environment was found in the filamentous GCA Zygogonium ericetorum, which is common in acidic habitats with increased Fe and Al concentrations. Formation of vegetative aplanospores facilitates removal of excessive iron from the protoplast. Moreover, aplanospore germination enables filament growth despite high aluminium concentrations in the parental cell wall and terrestrial habitat.




Barbara Viehweider

Thesis title:
The Impact of prehistoric and historic mining activities on the vegetation in the Kitzbühel region

Supervisor:
Klaus Oeggl, RG Palynology and Archaeobotany, Innsbruck University

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Project description:

Since the Neolithic the natural landscape is influenced by humans, either by settlement activities (e.g. urban development, agriculture) or by mining activities. This interfence in natural regions induces longlasting ecological changes in the vegetation of the affected area. Here we present a study dealing with the impact of prehistoric and historic mining on the environment as well as the effects of the associated subsistence economy on the vegetation in the Kitzbühel region (North Tyrol). Thereby the reconstruction of the former vegetation and its changes over time play an essential role. The objective was to evaluate the consequences of single mining activities (exploitation, ore beneficiation, smelting), as well as associated settlement and agricultural activities on the local vegetation based on pollen analysis. In order to relate vegetation changes to mining activities,geochemical analyses were were conducted on peat deposits. Therefore three mires in the Kitzbühel region were investigated. The “Rauber” mire is located in immediate vicinity to the prehistoric exploitation site Kelchalm on 1754 m a.s.l.. The second studied mire, called “Untermoosberg”, is located at the valley bottom (858 m a.s.l.) in the surroundings of prehistoric ore beneficiation and smelting sites in Jochberg. The third mire, called “Bichlach”, is situated on the Lebenberg near the pond “Gieringer” (790 m a.s.l.), east of the town Kitzbühel and evaluates the impact of agriculture and settlement activities in connection with mining.
In total three phases of concentrated human impact are defined. A first impact on the local vegetation occurs during Bronze Age (c. 1600-800 BCE). During Early Iron Age a reduction of activities is recorded. At the end of the Laténe period (c. 200 BCE) a second phase of intense human influence on the vegetation with cultivation of cereals and livestock farming takes place. This phase continues until Middle Roman Period (c. 160 CE). A further intensification of use occurs in the High Middle Ages (c. 970 CE). Here the indicators of pasture and settlement, as well as the values of cultural plants are increasing to partly over 2 %. This anthropogenic phase and utilisation of the landscape continues until the present day. These observed phases of intense anthropogenic activities proceed relativley synchronously in the three examined mires. The antropogenic phase during the Bronze Age and the first half of the third phase during Middle Ages and Early Modern Times are characterized by mining activities in the area of Kitzbühel. This is proved by geochemical analysis of the peat and validated by archaeological data and historical sources.




Andrea Ganthaler

Thesis title:
Infection of Norway spruce by the fungal pathogen Chrysomyxa rhododendri: analysis of infection dynamics, resistance mechanisms and implications for subalpine forests

Supervisor:
Stefan Mayr, RG Ecophysiology, Innsbruck University

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Project description:

In subalpine forests of the European Alps, Norway spruce (Picea abies) is frequently attacked by the pathogen Chrysomyxa rhododendri. The rust fungus overwinters in the leaves of rhododendrons (Rhododendron ferrugineum, R. hirsutum) and infects the current year spruce needles immediately after sprouting in spring. Once entered the needle, it forms an extensive mycelium and causes needle yellowing and thereupon needle loss. Attacked trees show a reduction of chlorophyll content, photosynthesis, biomass accumulation and growth. As a consequence, reduced timber yield and increased seedling dieback were observed. Constant high infection rates during the last years concerned the forestry and ask for a better understanding of the forest disease as well as defence strategies of Norway spruce.
The main objectives of this study were (a) to evaluate the negative impact of infections on subalpine forests, (b) to identify temporal patterns of spore dispersal and needle infection and their correlation with weather conditions as well as coordination with host phenology, (c) to gain insights into the resistance mechanisms of naturally occurring resistant trees and (d) to establish a spruce population with enhanced resistance.
The analyses included a broad literature review and the assessment of available data. Infection dynamics were analysed by collecting spores continuously with a spore trap, identifying and characterising the spores with light and electron microscopy, determining the infection period by a staggered application of fungicide on selected twigs, monitoring the phenological stages during needle development, and recording weather parameters with a climate station. Norway spruce trees with enhanced resistant phenotype were identified in Tyrol and compared with control trees regarding the phenolic needle content (UHPLC-MS) and genetic variants (genome-wide SNPs). Furthermore, this spruce population was clonally reproduced by rooting of sampled twigs and resistance of cuttings was tested by infection with C. rhododendri spores.
Spore dispersal of both basidio- and aeciospores was found to be extended over a long period, enhancing an overlap with the susceptible phenological stages of the host. The time span of needle infection was limited to about three weeks, and favourable weather conditions crucial for the pathogen dispersal. This can partly explain the variable infection intensities from year to year and site to site. The phenolic profile of needles differed between susceptible and resistant trees, especially regarding the seasonal accumulation and reaction to infection. In addition, several significant genetic associations for phenolic compounds were found. Clonal reproduction was complicated by low rooting success due to the advanced age of selected trees, but enhanced resistance was proven by the infection experiment for several clones.
Repeated severe infections cause serious socio-economical as well as ecological problems due to diminished timber yield and missing rejuvenation in high elevation spruce forests. Due to the positive correlation of airborne basidiospore concentrations with long warm periods in spring, global warming may favour the further spread of the pathogen. Efficient counter strategies are needed, and vegetative reproduction of selected clones combined with resistance tests is a promising method for providing resistant plant material. Results indicate that a combination of constitutive and inducible phenolic defence confers enhanced resistance in P. abies to C. rhododendri and rapid de-glycosylation of flavonoids following infection may play a central role. Identified genetic markers associated with stilbene and flavonoid concentrations could be useful for marker-assisted breeding and selection of genotypes adapted to attack by C. rhododendri.




Margot Kaufmann

Thesis title:
Gesteinsflechtengesellschaften im Arlberggebiet (Vorarlberg/ Tirol, Österreich)

Supervisor:
Georg Gärtner, RG Evolutionary Systematics, Innsbruck University
Roman Türk, Universität Salzburg

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Project description:

In the Arlberg region two different nappes of the Alpine stack are juxtaposed: the Northern Calcareous Alps and the crystalline Silvretta Nappe. Thus the four major rock-types relevant for the inhibition by lichen communities (silicate rocks, intermediary silicate rocks, intermediary carbonate rocks and carbonate rocks) can be studied there within a few kilometers range, in order to describe their different lichen vegetation types. 387 (of 527) vegetation surveys could be attributes to 61 rock lichens associations, which were recorded in the investigation area by the authoress for the first time. These communities (29 silicate rock lichen associations; 12 intermediary silicate rock associations; 3 transitional forms of intermediary silicate to intermediary carbonate rock associations; 6 intermediary carbonate rock associations; and 11 carbonate rock lichen associations) were all already known from the literature, but a few modifications had to be made in the syntaxonomy (Volume 1). On the other hand each single saxicolous lichen species (782 taxa of lichen and lichenicolous fungi, and additionally 133 moss taxa) is discussed in respect of its associations and diagnostic value in the investigation area compared to other areas described in the literature (Volume 2).




Benjamin Dietre

Thesis title:
10.000 years of climate and settlement dynamics in the Sivretta mountain massif between Paznaun valley (Austria) and the Lower Engadin (Switzerland)

Supervisor:
Jean Nicolas Haas, RG Palynology and Archaeobotany, Innsbruck University
Didier Galop, Université Toulouse II Jean Jaurès

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Project description:

Understanding the current mechanisms of climatic change along with the simulation of future climates depend on the accurate knowledge of past climatic events. The Holocene climate and anthropogenic land-use during prehistory had a major impact on vegetation composition and development and ultimately shaped the current cultural landscape in Europe. Given their high sensitivity to disturbances, high altitude ecosystems such as the European Alps offer an essential research area to emphasise this point. Palynology allows one to reconstruct changes of past Holocene flora and vegetation and to identify the possible origins of such alterations. Moreover, in combination with archaeological evidence, palynology also permits one to gauge the impact of the human population and of their livestock. Standard palynological methods – including micro-charcoal and non-pollen palynomorph analyses – were applied to four peat stratigraphies taken along a North-South transect through the Silvretta Massif and the Lower Engadine Valley, Switzerland. Since 2007, more than 200 archaeological sites above 1,800 m a.s.l. were detected and investigated in this area. The first archaeological evidence of human presence dates back to the Mesolithic Period (ca. 11500 cal. BP).
The palynological data from the four peat bogs investigated together cover a time span that dates back to 10450 years ago, and were published or submitted in four scientific journals. The results were also compared with the archaeological evidence known in the area, as well as with proxy data from macro-remains, denchrochronology, pedology and X-ray fluorescence analyses. These methods all help to reconstruct the timberline fluctuations in the Silvretta-Alps during the Holocene, especially the treeline lowering around 4200 cal. BP from about 2300 to 2150 m a.s.l. Other major shifts in vegetation composition due to climatic oscillations were identified, such as during the global 8.2 ka cold event, during the 4.2 ka dry-cool period characterizing the Mediterranean area, and during the 2.8 ka cold-humid phase induced by a reduction in solar radiation. First agro-pastoral activities in the area might date back to the Neolithic Period (6200–4900 cal. BP), but they were clearly intensified during the Early Bronze Age (4200–3800 cal. BP). The development of prehistorical agricultural field systems in the Lower Engadine Valley and of the Alpine pastoral areas in the Silvretta Massif most probably involved slash-and-burn techniques in order to open the dense forest vegetation. A second intensification of agro-pastoral practises occurred around 2550 cal. BP (600 BC) during the Iron Age. During the Roman Period and the Early Middle Ages the Alpine land of the Silvretta area seem to have been used less in terms of pasture, possibly due to the Bond Event 1 cold phase. On the other hand, the Medieval Warm Period (also known as Medieval Climate Anomaly) permitted the establishment of the current cultural and pastoral landscape, despite the subsequent deleterious effects of the Little Ice Age cooling (ca. AD 1350-1850) on the cultivation possibilities.




Markus Nolf

Thesis title:
Coordination of hydraulic parameters in trees, shrubs, and herbaceous species, studied with acoustic and hydraulic methods

Supervisors:
Silvia Kikuta, Institut für Botanik, Universität für Bodenkultur Wien
Stefan Mayr, RG Ecophysiology, Innsbruck University

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Project description:
Terrestrial plants face a multitude of physiological and ecological trade-offs, and require a compromise between hydraulic efficiency and safety in the water transport system, as well as a balance between gas exchange for photosynthesis and water loss. To survive in dry conditions, plants can adjust their hydraulic vulnerability to some degree, e.g. via anatomical modification, conservative stomatal regulation, or efficient repair mechanisms. However, our knowledge of the water transport system is strongly focussed on trees of temperate ecosystems, and few studies about the vulnerability of plants to drought explore the effect of within-plant coordination in hydraulic parameters.
In this PhD thesis, I studied the vulnerability to drought in trees, shrubs, and herbaceous species using hydraulic and acoustic methods, and examined its coordination with related parameters such as stomatal regulation and cellular adjustments across species, across conspecific populations, and within plants. Measurements were made in forests, meadows, and at the alpine timberline in Austria, and in tropical and temperate biomes in Australia. I also aimed to optimise acoustic emission analysis, and compared the obtained results with hydraulic reference measurements. In further experiments, I investigated the timing of important physiological events such as stomatal closure and cavitation during drought, patterns of acoustic emissions during freeze-thaw-cycles at the alpine timberline, and within-species acclimation to drought stress in an invasive species.
Based on methodical aspects of conducted studies, a novel acoustic parameter for efficient assessment of xylem hydraulic vulnerability using acoustic emission analysis was proposed, and new hydraulic data was collected for three plant groups (tropical trees, woody shrubs, and herbaceous species) that are significantly under-represented in the literature. While woody species (trees, shrubs) were similar in their hydraulic parameters, small herbs differed considerably regarding their hydraulic vulnerability and adaptation to drought stress. We showed that internal coordination helps protect plants from drought-induced hydraulic failure at moderate drought levels, and that leaves protect the more vital stems when drought further increases. These patterns and hydraulic strategies were also observed in studied trees at the timberline, an invasive herbaceous species, and in trees of temperate Australia.
Overall, this study demonstrated that drought stress is a fundamental, shaping factor for terrestrial plants, regardless of growth form. Hydraulic vulnerability and stomatal regulation are two main parameters of drought resistance, and are therefore useful characteristics to evaluate and compare the drought resistance of plants.




Roman Schuster

Thesis title:
Drought sensitivity of co-occurring conifers within a dry inner Alpine environment: a dendroclimatological and ecophysiological approach

Supervisors:
Gerhard Wieser, Fachbereich Waldgrenzenökophysiologie, Bundesforschungszentrum für Wald
Katarina Cufar, Department of Wood Science and Technology, University of Ljubljana Walter Oberhuber, RG Dendroecology and Tree Physiology, Innsbruck University

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Project description:
Computer models of global climate change predict a significant warming during next decades, changes in seasonal precipitation pattern and an increase in both the frequency and intensity of severe droughts in the future (Klein Tank & Können 2003, Beniston 2004). Even if precipitation amounts increase slightly, conditions may become drier because higher temperatures lead to increased potential evapotranspiration. Mantgem et al. (2009) reported that climate warming and consequent drought stress most likely contributed to rapid increase in tree mortality rates in coniferous forests of the western United States in recent decades. Drought triggers both, temporary declines and the mortality of susceptible or less competitive species in temperate forests (Innes 1998, Bigler et al. 2006). In the lowaltitude forests of Valais, which is an inner Alpine dry valley situated in Switzerland, a species-specific seasonal differentiation of radial growth response of Pinus sylvestris and Quercus pubescens to moisture availability was reported (Weber et al. 2007). Battipaglia et al. (2008) and Bouriaud & Popa (2009) also found a clear difference in the response pattern to drought between co-occurring coniferous species (Picea abies, Abies alba, Pinus sylvestris) at a dry site in Southern Italy and in the Eastern Carpathian mountains, respectively. Furthermore, it has to be noted that in the Alpine area climate warming in the 20th-century was 2-3 times greater than the global average (Jungo and Beniston, 2001). These and several other studies (see Bréda et al. 2006) indicate species-specific drought resistance, which will effect the development of forest ecosystems under a changing climate regime by changing species composition and inducing shifts in forest distribution.
Radial growth indices are known to be valuable long-term measures of overall tree vigor (e.g., Le Blanc 1990, Bigler & Bugmann 2006, Dobbertin 2005) and dendroclimatological methods are frequently applied to identify the climatic factors most closely associated with variations in tree-ring parameters (e.g., Fritts 1976, Hughes 2002). Based on several dendroclimatological studies conducted within dry inner Alpine valleys it is well established that radial growth of trees is primarily limited by spring precipitation (e.g., Oberhuber et al. 1998, Rigling et al. 2002) and severe drought during the growing season results in longlasting growth reductions and increased tree mortality (e.g., Oberhuber 2001, Rebetez & Dobbertin 2004, Bigler et al. 2006). Previous and preliminary dendroclimatological studies on growthclimate relationships of major coniferous forest tree species in the Alps (Pinus sylvestris, Picea abies and Larix decidua) also indicate different growth response of these species to climate variables and climate extremes at sites situated within dry inner Alpine valleys (Pichler & Oberhuber 2007).
Radial growth depends on a continuous supply of carbohydrates for cambial activity and on tree water status as a controlling factor for the metabolism of the whole tree. Tree water deficit causes stomata to close and thus photosynthetic uptake of carbon to diminish. Carbon starvation follows due to continued demand for carbohydrates to maintain metabolism (cf. e.g., Pederson 1998, Ogle 4 et al. 2000, Güneralp & Gertner 2007). On the other hand, the inhibition of cambial cell division and cell expansion of tracheids with the loss of cell turgor during drought is a well known phenomenon (e.g. Kramer 1983, Savidge 2000, Rossi et al. 2009). Species-specific differences in stomatal regulation of water status exist labeled isohydric and anisohydric regulation (Quero et al. 2011). Several hypotheses on mechanisms of drought-related tree mortality have been put forward, which were related to both, a negative carbon balance (carbon starvation hypothesis) and/or hydraulic failure, besides biotic agent demographics (for a review see McDowell et al. 2008).
To identify species-specific differences in growthclimate relationships and physiological response to drought, we analysed mixed species stands, because topography and local edaphic conditions have frequently been shown to modulate tree response to climate (e.g., Orwig & Abrams 1997, Oberhuber & Kofler 2000, Fekedulegn et al. 2003, Pallardy 2008). Within the dry inner Alpine valley of the Inn river (Tyrol, Austria) mixed stands of Picea abies, Pinus sylvestris and Larix decidua are developed, which provide the rare opportunity to compare drought sensitivity of three major coniferous species in the Austrian Alps under similar site and climate conditions.




Karin Pall

Thesis title:
Ecological quality assessment of lakes by use of aquatic macrophytes

Supervisor:
Eugen Rott, RG Hydrobotany, Innsbruck University
Seppo Hellsten, Finnish Environment Institute

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Project description:

In recent years aquatic macrophytes have come into the focus of interest as useful biological indicators for the assessment of ecological quality in lakes in the context of the implementation of the EU Water Framework Directive (WFD). Introducing this thesis an overview of past and recent scientific activities related to this subject in Europe is given. The main focus of the thesis was on the development of a WFD-compliant assessment system for macrophytes in Austrian lakes. With a multi-metric approach different aspects of the macrophyte vegetation are considered, allowing the detection of eutrophication or re-oligotrophication processes as well as of impacts by shore embankment, artificial wave action and water level fluctuations. In order to compare assessment results derived from such methods all over Europe the WFD stipulated a so called “intercalibration exercise”. The results achieved in the Lake Macrophyte Alpine Geographical Intercalibration Group (Alpine-GIG), lead by the author, confirmed sufficient comparability of the Austrian, French, German, Italian and Slovenian assessment systems.
During the lake investigations Najas flexilis, a macrophyte species new for Austria was found. Since Najas flexilis is listed in Appendix 1 of the Bern Convention and the Annexes II and IV of the European Habitats Directive, this record is also highly important for the development of the Europe-wide species protection plan. In the context of the WFD macrophyte studies, the development of a new mapping method for large lakes as well as the establishment of a macrophyte-based typology for Austrian lakes were required, as described in this thesis. Additionally, results from the first detailed macrophyte investigation in an Austrian lake, (Lake Attersee; Pall 1994) are taken as an example to illustrate possibilities for describing and evaluating macrophyte vegetation data with the aid of different numerical indices.




Manuel Pramsohler

Thesis title:
Causes of winter injury to apple trees in South Tyrol (Northern Italy)

Supervisors:
Gilbert Neuner, RG Stress Physiology and Climate Resistance, Innsbruck University
Karen Tanino, College of Agriculture and Bioresources, University of Saskatchewan

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Project description:
Frost is an economically important factor for the cultivation of apple trees in many regions of the world. Also in fruit growing areas in South Tyrol (Northern Italy) during the last two decades severe winter injury to apple trees repeatedly occurred, however the underlying causes are still unknown. Frost damage and critical winter desiccation were considered to be possible abiotic causes for winter injury to apple trees and were both studied in seasonal courses including three winter periods.
Frost resistance of different tissues was determined by controlled freezing tests and compared to frost survival of trees in the field after artificial and natural frosts. Up to now there is only little evidence how plants freeze in the field. In apple trees non-lethal xylem freezing under naturally winter conditions did not change seasonally. However, it took place at significantly higher temperatures (about 3 K) than usually observed in detached twigs investigated in laboratory experiments. Whole tree freezing started either from the peripheral twigs, or in case of soil frost and diurnally thawed stems, from the stem base. The frost damage pattern of xylem parenchyma cells (XPCs) was determined and could be related to the already known frost damage pattern in apple twigs (blackheart injury). Apple twigs showed a high regeneration capacity after frost damage to XPCs, as they were able to recuperate even after a severe frost damage to XPCs of up to 60%.
Infrared video thermography was used to proof that dormant terminal apple buds do not perform deep supercooling. In contrast, in buds after bud break supercooling could be demonstrated to occur, which has not been shown before. A decrease of the osmotic water potential of the bud primordial tissue, caused by water movement out of the bud primordial tissue, was measured upon freezing.
The results obtained in the present study corroborate by the use of new methods, that dormant apple buds show extra-organ freezing but do not deep supercool. In apple bark tissue the occurrence of dehydration and osmotic adjustment during winter was shown. In terminal buds dehydration during winter was less pronounced and osmotic adjustments were not significant. An osmotic gradient between bud and bark tissue was determined and indicated that the bud meristems are isolated from the bark tissue during winter, as they otherwise should get dehydrated. The results indicate that the determination of osmotic water potentials of tissue press saps can be a reliable method to assess tissue dehydration in deciduous trees during winter. The determination of seasonal changes of xylem sap pH showed that xylem sap alkalinisation took place from autumn till midwinter, and that re-acidification was recorded always concomitant to the phenological stage 'tight cluster' after bud break. Environmental temperatures did not show a significant effect on the xylem sap pH changes. During midwinter measurement of frost resistance indicated that aboveground tissues are not at risk to get frost damaged. However, during the periods of frost hardening and frost dehardening in autumn and spring, which in apple is mainly driven by actual temperature conditions, trees may be at a potential risk of frost damage. In particular, bud frost resistance might be insufficient for protection from frost damage. On apple trees showing winter injury in the field, it has been demonstrated that damaged trees had a damaged fine root system. The same injury symptom could be reproduced by artificially inducing frost damage to the roots.
Therefore, it is concluded that frost damage to the fine root system might be an important factor for the observed winter injury occurring to apple trees in the growing area.




Anoma Dongsansuk

Thesis title:
Photosynthesis of plants from different biomes- temperature dependency and thermal limits of photosynthetic light reactions

Supervisors:
Gilbert Neuner, RG Stress Physiology and Climate Resistance, Innsbruck University
Loretta Gratani, Department of Environmental Biology, Sapienza University of Rome



Daniela Festi

Thesis title:
Palynological reconstruction of the onset and development of alpine pasture in the Eastern Alps since the Neolithic

Supervisor:
Klaus Oeggl, RG Palynology and Archaeobotany, Innsbruck University
Didier Galop, Université Toulouse II Jean Jaurès

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Project description:
This Doctoral thesis presents the palaeoecological results obtained in the frame of a multidisciplinary study performed in the habitat of the Neolithic Iceman "Ötzi". Aim of study was the reconstruction of the former environmental and climatic situation, as well as of the land use characterizing the area since the Iceman's time.
Land use changes deal in particular with agricultural practices and the onset of transhumance and alpine summer farming. The charred macroremains and animal bones recovered at the Copper Age valley settlement of Latsch document that the valley was occupied by an agro-pastoral society based on the cultivation of cereals and legumes, and on the rearing of caprines. The most important cereals consumed at Latsch were Hordeum vulgare (hulled barley), Triticum monococcum (einkorn), T. dicoccum (emmer). Pisum sativum (pea) was the only protein rich plant recovered at the site. Macro charcoal analyses revealed that the vegetation in the valley the south facing slope was characterizes by a mixed pine and oak forest while the north facing slope was covered by a spruce forest. Pollen analyses performed at Lake Vernagt indicate that a Picea (spruce) and Pinus (pine) forest grew in the montane zone, while according to the subalpine pollen diagrams elaborated for the Schwarzboden, Laguan and Penaud mires, the timberline was formed by Larix (larch) and Pinus cembra (arolla pine). In order to reconstruct the development of ancient pasture activities in the study area, a set of pasture indicators has been created using modern pollen analogue technique. This calibration set was applied to all four pollen diagrams leading to the reconstruction of the local onset of alpine pasture. The results indicate that in the Ötztal Alps vertical transhumance and alpine summer farming started at the earliest during the Middle Bronze Age (1600-1350 cal BC).




Anton Stefan Schwarz

Thesis title:
Subsistence strategies in prehistoric and historic mining areas of the Eastern Alps

Supervisor:
Klaus Oeggl, RG Palynology and Archaeobotany, Innsbruck University
Thomas Ludemann, Geobotanik, Albert-Ludwigs-Universität Freiburg

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Project description:
This archaeobotanical doctoral thesis enlightens the supply of three settlements in the Eastern Alps (Tyrol, Austria) with agricultural products and wood from the Late Neolithic until the Late Bronze Age. The study sites have different archaeological backgrounds, but all of them are connected with prehistoric copper processing. The first site 'Kiechlberg' is a settlement with copper smelting artefacts and refers to the invention phase of experimental copper metallurgy during Late Neolithic. The second site 'Mauken' is a well operating, organised and remote smelting area of the Middle/Late Bronze Age. Finally the third location examines the Bronze Age inner Alpine settlement chamber 'Montafon'. From all sites, dry soil samples were taken and both diaspores and charcoal was analysed according to standard methods.
Recovered charred plant remains allowed - at least partially - the reconstruction of the vegetative part of husbandry. The Bronze Age settlements refer with abundant remains of hulled barley (Hordeum vulgare), emmer (Triticum dicoccum), spelt (T. spelta) but also cultivated peas (Pisum sativum) and gathered wild plants such as hazelnuts (Corylus avellana), acorns (Quercus), rowan (Sorbus), elder (Sambucus), raspberries (Rubus idaeus, R. fruticosus) and sloe (Prunus spinosa) to a balanced diet. Furthermore, the results of charcoal analyses provide information about the use of wood and timber supply. The charcoal spectra reflect the composition of the woodland and document the human impact on the vegetation in the surroundings of the sites. Moreover, physical parameters of the analysed charcoal indicate the quality and consistence of the wood taken for energy or construction purposes.




Elisabeth Breitenlechner

Thesis title:
Palaeoenvironment in prehistoric and historic mining areas of the Eastern Alps

Supervisor:
Klaus Oeggl, RG Palynology and Archaeobotany, Innsbruck University
Timothy Mighall, School of Geosciences, University of Aberdeen

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Project description:
The exploitation of ore deposits of the northern Greywacke Zone was initiated by the implementation of metallurgic technologies to the Eastern Alps thousands of years ago. The recent study aimed to detect the impact of mining activities on the environment of prominent copper deposits in Tyrol and Salzburg (Austria). This multi-proxy survey combines the results of the palynological and geochemical analyses with archaeological, archaeometallurgic, dendrochronologic and historical data.
The findings provide information about a historical analogue established for Medieval and Modern Times mining, which enables the determination of mining phases in prehistoric times. The impact of mining activities on the vegetation in particular is shown by increased pine (Pinus) and larch (Larix) values in the pollen data, growing at loose rock material at the edge of mining waste heaps. Additionally increased geochemical values (e.g. Pb, Cu, As, Sb) in the peat column are caused by mining and metalworking activities and reflect time spans with mining activities in the vicinity of the mire. Furthermore these new results combined with pollen data from the surroundings of the mining districts disclose a chronology of the settlement development and the palynological evaluation of former land-use regimes in prehistoric and historic mining sites.




Katline Charra-Vaskou

Thesis title:
Conifer needles: hydraulic efficiency and safety in the context of tree hydraulic architecture

Supervisor:
Stefan Mayr, RG Ecophysiology, Innsbruck University
Steven Jansen, Systematik Botany and Ecology, Universität Ulm

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Project description:
The hydraulic architecture of trees, the specific patterns in hydraulic efficiency and hydraulic safety, determine the plant's water relations. Leaves, representing the distal section of the soil-plant-atmosphere continuum, are exposed to lowest water potentials and thus highest drought stress intensities within the plant. While many studies dealt with angiosperm leaves, insight into the hydraulic architecture of conifer needles is poor. This PhD thesis focused on efficiency and safety of conifer needles.
For the analysis of the hydraulic conductivity of Picea abies and Pinus mugo needles, a new method was developed and used. Vulnerability to drought induced embolism (pressure at 50% loss of conductivity P50) was analysed with the cavitron technique on axes and needles of Pinus pinaster and on axes of Picea abies and Larix decidua as well as of Fagus sylvatica and Sorbus aucuparia. Further measurements based on ultrasonic acoustic emissions were performed on P. abies, P. mugo and P. pinaster. Hydraulic conductance of the entire needle was determined via rehydration kinetics analysis, and Cryo-SEM and x-ray tomography allowed to analyse changes in needle structure.
Conductivity in needle xylem was similar or lower than in corresponding axes sections of P. abies and P. pinaster. Within P. mugo needles, only 24% of total needle resistance was situated in the xylem. In the three studied conifer species, axes xylem (P50 between -3.0 and -3.5 MPa) was more resistant to drought induced embolism than needle xylem (P50 between -1.2 and -2.6 MPa) and entire needles were even more vulnerable (P50 of -0.5 MPa). No altitudinal trend in P50 of axis xylem at the inter- or intraspecific level was observed in conifers. At the timberline, needle conductance varied between 0.46 and 1.35 mmol m-2 s-1 MPa-1 in P. abies and between 0.50 and 3.04 mmol m-2 s-1 MPa-1 in P. mugo with lowest values in mid winter. In P. pinaster needles dehydrated to pressures between -0.2 and -3.5 MPa, cavitation and collapse were observed in xylem tracheids, while gaps appeared in living tissues around the xylem, and particularly in palisade parenchyma.
This study demonstrates that hydraulic pathway in needles contributes a major part to the overall hydraulic resistance of conifers and exhibits low hydraulic safety. Within needles, the extra-vascular pathway probably has lowest efficiency and safety so that the risk of conductivity losses is highest at the most distal sections of the transport pathway. Future studies should focus on observed embolism repair and structural changes on drought.




Maria Elena Beltrami

Thesis title:
Benthic diatoms for ecological water quality assessment in Italy, with special reference to the alpine ecoregion

Supervisors:
Eugen Rott, RG Hydrobotany, Innsbruck University
Francesca Bona, Department of Life Sciences and Systems Biology , Universita di Torino

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Project description:

This PhD thesis was carried out with the aim of increasing scientific knowledge on diatom ecology, taxonomy and distribution in Italy, and in particular in the Alpine area. Understanding species ecology and biogeography is essential for the development of methods for ecological quality assessment of rivers, because species distribution patterns should be characterized by their correlation to environmental parameters. Our data set was mainly composed of samples collected in Trentino Alto Adige / Südtirol region (Northern Italy), a geographic area representative of the Alpine Ecoregion. In this study we obtained basic information on the species present in Trentino Alto Adige / Südtirol region and characterized species assemblages typical of different stream types under degraded and nature near reference conditions. In particular the ecology and distribution of the species Didymosphenia geminata was investigated, and some recently described diatoms were recorded, for which we added relevant unknown information on biogeography. Regarding ecological water quality assessment, the reliability of different diatom indication methods for the Alpine Ecoregion was tested and possible tools were suggested to improve the performance of methods using diatoms, such as regional calibration of indices, considering the presence of specific environmental and geographic conditions (geology, altitude, flow regime) and different levels of human impact.
In this PhD a detailed taxonomic study was made in addition on samples collected in Latium region (Central Italy) and in South East of France, resulting in the description of a diatom species new for science: Gomphonema vidalii Beltrami & Ector.




Lewis Sitoki

Thesis title:
Phytoplankton and eutrophication in Nyanza Gulf (with special reference to toxic cyanobacteria and planktonic diatoms)

Supervisor:
Eugen Rott, RG Hydrobotany, Innsbruck University
Leopold Füreder, RG Alpine Freshwater Research, Innsbruck University

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Project description:
Phytoplankton community composition, microcystin (MC) concentrations and environmental conditions were investigated from July 2008 to September 2009 monthly from Kisumu Bay and for four seasons from two additional central gulf stations, Rusinga channel and one main lake reference station to characterize the trophic status of Nyanza Gulf. The study showed increased eutrophication in Kisumu Bay and the two central stations of the gulf with a drastic reduction in transparency, changes in phytoplankton composition and increased nutrient concentrations. The dominating group of phytoplankton in the gulf was cyanobacteria whereas diatoms were more important at Rusinga channel and the main lake station. In the gulf Microcystis accounted for the largest part (>50 90 %) of cyanobacterial biovolume with two highly toxic tropical species (Microcystis panniformis, Microcystis protocystis) dominating the phytoplankton most of the time in Kisumu Bay. MCs (1- 90 µg l-1) were detected in most of the samples dominated by Microcystis in the gulf stations. Occurrence of MC could only be associated with Microcystis.
Within the more common diatoms of the main lake stations, we detected two planktonic Nitzschia species new for science (Nitzschia kavirondoensis and Nitzschia victoriae). Lakewide comparisons on the status of the environment showed that inshore areas have higher eutrophic status than offshore sites in particular with regard to physico-chemical conditions such as Secchi depth, chlorophyll a, conductivity and nutrient concentrations.




Günter Haselwanter

Thesis title:
Schutz- und Managementkonzept für ausgewählte Moore im Alpenpark Karwendel

Supervisor:
Sigmar Bortenschlager, Innsbruck University

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Project description:

The cumulative existence of mires in the area of Achenwald Bächental is a natural characteristic of the entire alpine park Karwendel. Only five of the 14 mires included in STEINER'S report (1992: Brettersberg-Mittelleger-, Halslkopf-, Pitzkopf-, Raberskopf- and Rosskopf-Moor) were selected, to put in practice extensive management measures. After a general survey of the investigation area, especially the climate with focus on precipitation, apart from geology, was dealt with. In the retrospective monitoring historical changes of the mires were reconstructed. After a lot of research in the Tiroler Landesarchiv and in specialized libraries, in historical maps and aerial picture interpretations, many historical utilisations like drains could be dated accurately. In an extensive field research the actual state was documented by means of vegetational-ecological methods (maps of vegetation, map of indicator values of relevees, permanent plot). In doing so, especially current dangers were treated. PH-measurement and the investigation of the thickness of the peat layer with Ground Penetrating Radar (GPR) as well as probing were constituent parts of the fieldwork. The use of GPR in Austrian mires was an innovation and provided a lot of facts about peat and peat layer. Based on this, a management plan with a target state was developed, which contained a historical comparison of the past and the present state, a zonal concept and a catalogue of measures to achieve the target state. Because of the long-term investigations several practical management plans in the way of concrete regeneration projects were already mentioned. Additionally, a hydrological and vegetational-ecological monitoring and a photo monitoring were started for evaluation.
Finally measures that could be practically applied.




Gerlinde Steinacher

Thesis title:
Pollen tube growth and pistil receptivity of high mountain plants under extreme climatic conditions

Supervisor:
Johanna Wagner, RG Reproductive Biology, Innsbruck University

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Project description:

The reproductive phase is one of the most critical phases in the life cycle of a plant. Especially processes occurring during flowering are highly vulnerable to the prevailing environmental conditions including temperature. Temperature clearly affects stigma receptivity, ovule longevity, pollen germination and pollen tube growth. These functions are bound to a certain temperature range beyond which reproductive success is increasingly reduced or absent. The microclimate that plants experience at higher elevations is very different from the macroclimate and shows a high temporal variability with ample diurnal variations of temperature. On cloudless summer-days short-time floral temperatures around 30°C can be reached whereas in the night or during cold snaps plants may experience near-freezing or even subzero temperatures. Thus, the influence of temperature on the processes occurring from pollination to fertilization - especially the thermal thresholds (minimum, maximum temperature) and the optimum temperature range for pollen germination and tube growth were investigated in alpine (Gentianella germanica, Ranunculus alpestris, Saxifraga caesia, S. moschata) and nival species (Cerastium uniflorum, Ranunculus glacialis, Saxifraga bryoides). The investigated species showed a high flexibility concerning all the processes and functions during the progamic phase. Anthesis (and thus receptivity of the stigma, the style and the ovules) could be considerably prolonged in case of absent pollination. Under favorable weather conditions (no precipitation, temperatures between 15-25°C) postpollination processes functioned very effectively and guaranteed fertilizations within a few hours. On the other hand, also cold snaps were tolerated very well and the investigated species were able to maintain sexual functions.




Barbara Beikircher

Thesis title:
Water relations of woody species: water transport and transpiration, and their relevance for the recultivation of dry sites

Supervisor:
Stefan Mayr, RG Ecophysiology, Innsbruck University

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Project description:

The hydraulic architecture of woody plants, determined by specific patterns in hydraulic efficiency and hydraulic safety, as well as transpiration influence the plants water relations. Both aspects are strongly linked and play an important role for the survival and distribution of plants. Plant water relations may be a central aspect in practical applications, e.g. for the recultivation of dry sites.
In this PhD thesis, interrelationships between hydraulics, growth form and environmental conditions were analysed on different woody species.
Juniperus communis ssp. communis enabled an intraspecific comparison of the hydraulic architecture of shrubs and trees. Measurements revealed a remarkable correlation between hydraulic architecture and growth form as hydraulic efficiency patterns in shrubs and trees of Juniperus differed significantly. During the transition from shrub to tree, a highly conductive xylem in the stem is formed and patterns in Huber value (HV) are optimised. On the other hand, the comparison with other tree species indicated that the reorganisation in hydraulic architecture of dendriform juniper is still insufficient to allow for the development of taller growth forms. Besides growth form, also environmental conditions can influence hydraulics and related anatomical parameters. While Juniperus communis and Pinus sylvestris showed only little plasticity in hydraulic safety, drought tolerance increased significantly in Ligustrum vulgare and Viburnum lantana when plants were subjected to drought. The increase in hydraulic safety was strongly related to structural modifications in the xylem, but, in parallel, also differences in stomata behaviour were observed. This acclimatisation potential may be of importance for the recultivation of dry sites. In some species a preconditioning prior to...




Harald Geir

Thesis title:
Invasive Neophytes in the Eastern Alps: a case study on the example of North and South Tyrol (Austria/Italy)

Supervisor:
Sigmar Bortenschlager, Innsbruck University

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Project description:
Despite the large amount of studies on different aspects of neophyte flora in Europe, we still know quite little about its effects in the (Eastern) Alps.
Which consequences do arise out of the increasing infestation of semi natural habitats? The present study offers some answers to this question. North Tyrol (Austria) and southern adjacent region South Tyrol (Italy) have been chosen as study area. The whole area encompasses about 18000 km², out of them ca. 10 600 km² belong to North Tyrol. Here, 80% of the area is located more than 1 200 m a.s.l, however the neophyte flora is almost restricted to the area below this sea level. This leads to a high neophyte concentration in the remaining 20% of the area. The total flora of North Tyrol consist of about 2300 taxa, of which almost 22% are neophytes.
The study focuses on the invasive taxa Buddleja davidii, Fallopia japonica, Fallopia sachalinensis, Fallopia x bohemica, Impatiens glandulifera, Impatiens parviflora, Senecio inaequidens, Solidago canadensis and Solidago gigantea. Based on the data of the biotope mapping of North Tyrol (initiated by Tyrolean provincial government, done by Inst. of Botany/University of Innsbruck), the North Tyrolean floristic data base (Tiroler Landesmuseum Ferdinandeum, W. NEUNER) and the data of South Tyrol collected by WILHALM et al. (Naturmuseum Bozen), semi-natural habitats infested with neophytes have been selected.
Therefore pairs of infested and not infested sites of the same biotope type were chosen. The field work on the 683 sites was done during vegetation periods of 2006 and 2007. Flora and vegetation of the study sites were analysed floristically and by using the Braun-Blanquet scala.




Sybille-Belina DeCarli

Thesis title:
Einfluss des jahreszeitlichen Klimas auf Ultrastruktur und wichtige Inhaltsstoffe in den Blättern von Loiseleuria procumbens L. (Desv.)

Supervisor:
Cornelius Lütz, Innsbruck University

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Project description:

Loiseleuria procumbens (Ericaceae), a procumbent growing evergreen dwarf-shrub, colonizes small to large areas between 1800 and 3000 m a.s.l.. The shrubs develop, beneath green, also yellow and red coloured vital leaves. The red colour, which is caused by anthocyanins in the vacuole, disappears in summer from July to August. Over a period of 2,5 years it has been investigated how the fast changing and extreme alpine environmental conditions are reflected in the content of starch, soluble carbohydrates, plastid pigments, flavonoids and in the ultrastructure of the leaves and how the green leaves differ from the red and yellow ones. Therefore leaves have been examined via electron microscopy, photometer and High Performance Liquid Chromatography. The leaves showed differences in the ultrastructure between the different coloured leaves and between the seasons. The yellow leaves can be found on branches, which are exposed to strong sunlight and drought.
They contained many large starch grains, large plastoglobuli and less thylakoids in the chloroplasts and a lot of oleosomes in the cytoplasm.
Red leaves had a similar general ultrastructure to the green leaves, in spring and autumn mitochondria appeared frequently, microbodies, dictyosomes and chloroplast-protrusions rarely. In summer the thylakoids were dilated, the chlorophyll content was lower than in spring or autumn. There were major differences between the cells in winter and during the vegetation period. In winter the organelles of the upper palisade parenchyma-cells accumulated at the basal part of the cells.
The number and size of plastoglobuli increased. The organisation of thylakoids changed completely, the number and size of the plastoglobuli increased, most notably in the yellow leaves.
The content of carotenoids and chlorophylls correlated positive with the temperature in the population. Lutein seemed not to be affected by temperature, the greatest yield was measured in the green leaves, the smallest in the yellow ones. [alpha]-tocopherol, which is known to act as antioxidans and scavenger, has its greatest occurrence in the yellow leaves, red leaves contain less [alpha]-tocopherol. The xanthophyll-cycle pigments correlated negative with temperature and the FV/FM-ratio. Single flavonoids reacted different to the changing climatic conditions. All showed an increase in February, when the plants were exposed to sunlight and cold because of missing snow cover. Sucrose was the most common soluble sugar in Loiseleuria, followed by glucose and fructose. Sucrose showed no significant changes during the year, glucose and fructose had a maximum appearance in winter, minimum in summer. Starch was absent in winter, the maximum was measured in summer.




Angelov Blagoy

Thesis title:
Aeroterrestrial algae from Pirin Mountain (Bulgaria)

Supervisor:
Georg Gärtner, Innsbruck University



Biva Aryal

Thesis title:
Leaf wettability of plants from different altitudinal origin

Supervisor:
Gilbert Neuner, RG Stress Physiology and Climate Resistance, Innsbruck University

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Project description:
Leaf wettability of a total number of 792 leaf surfaces from 396 plant species (representing 85 families) from three different mountain systems and continents of the world was investigated. Measurements of water droplet contact angle and droplet run off were made for both adaxial and abaxial leaf surfaces of the most predominant native plant species. The main goal of this study was to analyze the influence of natural environmental conditions on the development of specific leaf wettability. Plants from high altitude, open places and semi-arid growing sites were usually highly non-wettable. In contrast, plants from low altitudes, the understorey of forests and humid regions had often highly wettable leaf surfaces. The structural properties of non-wettable leaf surfaces appeared to be an important functional trait to prevent a number of the negative effects adhering surface water may have.
Additionally, 5.1 % of the investigated leaf surfaces showed super-hydrophobicity or philicity, i.e. promising features for a potential transfer to technical surfaces.




Peter Schmid

Thesis title:
Refilling in Koniferen an der alpinen Waldgrenze: Dynamik, Einflussfaktoren, Bedeutung

Supervisor:
Stefan Mayr, RG Ecophysiology, Innsbruck University

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Project description:

Conifers growing at the alpine timberline can suffer from severe losses in hydraulic conductivity because of frost drought and frequent freeze-thaw cycles during winter. There is evidence to suggest that affected conifers are able to refill embolised conduits. In the present study the dynamics of the refilling process and the impact of various factors, especially the uptake of water via the surface of twigs, were analysed.
In Norway spruce (Picea abies), European larch (Larix decidua), stone pine (Pinus cembra), mountain pine (Pinus mugo) and juniper (Juniperus communis) the seasonal courses in water potential and loss of conductivity at the alpine timberline and on sites in the valley were investigated. In Norway spruce, refilling was also analysed in different crown parts, and field and laboratory experiments were conducted to study the water uptake via the surface of twigs. Along altitudinal transects loss of conductivity and frost drought damage were correlated.
The impact of artificially induced embolism on sap flow and transpiration was experimentally studied on young spruce trees. Main methods used in this study were the Scholander pressure chamber technique to analyse the water potential and the Sperry technique to meassure conductivity. Embolism was artificially induced by a pressure collar and the effects were recorded by sap flow meters and a portable photosynthesis system.
At the alpine timberline, up to 100% loss in xylem conductivity was found in Norway spruce, juniper and mountain pine. Conductivity losses were repaired in late winter and spring at moderate air temperatures before new tracheids were developed. Refilling started after the water potential had risen to about -1 MPa subsequent to winter minima. During the main part of the refilling period, the water potential stayed




Jürgen Hacker

Thesis title:
Ice propagation in plants visualized by infrared thermography

Supervisor:
Gilbert Neuner, RG Stress Physiology and Climate Resistance, Innsbruck University

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Project description:

In temperate regions wild plants and crop species have to deal with freezing temperatures. The low temperatures itself are not harmful for plants of this region, only freezing resulting in the formation of ice within the plant can cause damage. Freezing of various intact plants was monitored by infrared thermography and an imaging chlorophyll fluorescence system to gain a better understanding of the freezing processes in plants. The use a digital infrared camera combined with a close-up lens and IDTA (Infrared Differential Thermal Analysis) enabled the measurement of freezing on the plant tissue level. The freezing process in leaves consisted of three phases: (1) ice nucleation, (2) ice propagation in the vascular tissue, and (3) freeze dehydration of the mesophyll cells. After freezing is induced by ice nucleation, ice propagated within the vascular tissue visualizing the leaf venation pattern. The rate of vascular ice propagation differed between species and increased significantly with the degree of supercooling (up to 24 cm s-1). Ice propagation reflected the vascular structure, for instance the independent freezing of graminoid leaves due to their leaf bundle organization. The extracellularly formed ice withdrew water from the cells, due to its lower water potential. Hence freezing resulted in a dehydration of cells what may potentially cause damages. The physiological response was an increase of chlorophyll fluorescence, which was observed after a distinct time lag, when the water status of mesophyll cells has reached a critical value. Infrared thermography and chlorophyll fluorescence imaging have shown to be efficient methods to investigate freezing in plants.
In temperate regions wild plants and crop species have to deal with freezing temperatures. The low temperatures itself are not harmful for plants of this region, only freezing resulting in the formation of ice within the plant can cause damage. Freezing of various intact plants was monitored by infrared thermography and an imaging chlorophyll fluorescence system to gain a better understanding of the freezing processes in plants. The use a digital infrared camera combined with a close-up lens and IDTA (Infrared Differential Thermal Analysis) enabled the measurement of freezing on the plant tissue level. The freezing process in leaves consisted of three phases: (1) ice nucleation, (2) ice propagation in the vascular tissue, and (3) freeze dehydration of the mesophyll cells. After freezing is induced by ice nucleation, ice propagated within the vascular tissue visualizing the leaf venation pattern. The rate of vascular ice propagation differed between species and increased significantly with the degree of supercooling (up to 24 cm s-1). Ice propagation reflected the vascular structure, for instance the independent freezing of graminoid leaves due to their leaf bundle organization. The extracellularly formed ice withdrew water from the cells, due to its lower water potential. Hence freezing resulted in a dehydration of cells what may potentially cause damages. The physiological response was an increase of chlorophyll fluorescence, which was observed after a distinct time lag, when the water status of mesophyll cells has reached a critical value. Infrared thermography and chlorophyll fluorescence imaging have shown to be efficient methods to investigate freezing in plants.




Wolfgang Hofbauer

Thesis title:
Aerophytische Organismen an Bauteiloberflächen: Diversität und Taxonomie der Primärsukzession an Außenbauteilen unter Einbeziehung ökophysiologischer Grundlagen

Supervisor:
Georg Gärtner, Innsbruck University



Silvia Marcante

Thesis title:
Life history traits an population dynamics of glacier foreland species

Supervisor:
Brigitta Erschbamer, RG Population Biology and Vegetation Ecology, Innsbruck University



Christina Oppeneiger

Thesis title:
Einfluss von klimatischen Faktoren auf den Primär- und Sekundärstoffwechsel von Dryas octopetala L.

Supervisor:
Cornelius Lütz, Innsbruck University



Angelika Tschaikner

Thesis title:
Soil algae and soil algal crusts in the alpine regions of Tyrol (Ötztal, Austria)

Supervisor:
Georg Gärtner, Innsbruck University

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Project description:

Orographic and harsh climatic conditions in the alpine and nival zones of the Alps result in many areas with sparse or absent cover of vascular vegetation. The open spaces between the higher plants are generally not bare of autotrophic life, but often covered with soil crusts, soil surface communities consisting of algae, cyanobacteria, lichens, microfungi and mosses.
Soil crusts cover extensive portions of arid and semiarid regions all over the world and are an important feature in stabilizing soils. In the past research mainly concentrated on soil crusts in hot deserts, information regarding soil crusts in alpine ecosystems is very rare.
To broaden the state of knowledge of soil crusts in high altitude areas in the Alps the algal flora of soils and soil crusts from alpine grasslands, dwarf - shrub heathland and ski slopes of 11 sites in the alpine region near the village Obergurgl (Ötztal, Austria) was investigated from the surface down to a depth of 2.5 cm. In total 54 algal taxa were recovered, Chlorophyta (34 taxa) were by far the most diverse group, followed by Cyanophyta (9 taxa), Xanthophyta (8 taxa), Bacillariophyceae (2 taxa) and 1 taxa of Eustigmatophyceae were encountered. 5 species are new to science:
Coelastrella aeroterrestrica TSCHAIKNER, GÄRTNER ET KOFLER, a coccal green algae, characterized through a fine network of cell wall ribs only visible in SEM, already has been described as new species. Descriptions of until now two unknown Chlamydomonas species, one Botrydiopsis- and one Diplosphaera species are in preparation.




Andreas Heiss

Thesis title:
Weizen, Linsen, Opferbrote - Archäobotanische Analysen bronze- und eisenzeitlicher Brandopferplätze im mittleren Alpenraum

Supervisor:
Klaus Oeggl, RG Palynology and Archaeobotany, Innsbruck University

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Project description:

Burnt-offering places are an archaeologically heterogeneous group of finds in the Alps, predominantly occurring during Late Bronze Age and Iron Age. Plant macrofossil and charcoal analyses were carried out at nine of these sites, targeting at the assessment of the offerings and the firewood used for the altars. A total of 99 taxa are represented by carbonised remains. One constant component in the finds are fragments of a cereal product, characterised by small-grained (< 300 µm) cereal bran and close structural resemblance to archaeological bread finds.
Further classification (grain-paste, porridge or bread) was however not possible. In opposite to the processed cereals, grain finds (mainly hulled barley, hulled wheats, broomcorn millet) are rather scarce. Older sites (LBA) show the under-representation of main crops as documented for contemporary settlements. Finds of legumes were found mainly in north Italian sites. Oilseeds occur punctually. The useful plants spectrum, together with the archaeozoological record, confirms an "agrarian" character of the rituals postulated earlier: domesticated plants and animals dominate over gathered plants and game. Four hypotheses are suggested to explain the role of wild plants in the rituals, however not allowing definite conclusions. Fuel wood choice was guided by local availability, only two sites indicating specific selection. Dendrological and taphonomical parameters of the charcoal point to a predominance of gathered deadwood. Both aspects (deadwood use, no specific selection) clearly differentiate the Alpine burnt-offering from the ancient Greek ritual, which is often used as a basis for comparison.




Doris Gesierich

Thesis title:
Benthic algae in springs and streams of the Alps and Alpine Forelands

Supervisor:
Eugen Rott, RG Hydrobotany, Innsbruck University

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Project description:
The present doctoral thesis focuses on the diversity of benthic algae and their main driving variables, based on 4 publications:
Publication 1 comprised samples from 12 high-altitude running water sites in an alpine catchment, 10 km2 in size, located in the central part of the Alps. Publication 2 consisted of samples from 7 main sites within a 0.22 km2 calcareous fen complex in lower altitudes in the Alpine Foreland. Publications 3 and 4 were based on samples from 23 rheocrene springs and 4 spring streams within an area of 2000 km2 at the western slopes of the Eastern Alps.




Klaus Pfeifer

Thesis title:
Klimahistorische Auslegung extremen Koniferenwachstums in rand- bis inneralpinen Hochlagen der Ostalpen

Supervisor:
Walter Oberhuber, RG Dendroecology and Tree Physiology, Innsbruck University

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Project description:

Two new multi-centennial long Norway spruce (Picea abies (L.) Karsten) tree ring proxies for alpine summer temperature have been developed. Chronologies are based on historical and living wood from upper mountainous and lower subalpine regions of the Montafon (470 samples, AD 14311987) and Tannberg (162 samples; AD 12472003) in Vorarlberg (Austria) in the western part of the Eastern Alps.
Additionally, 6 ring width chronologies of Cembran pine (Pinus cembra L.) were developed from living trees at timberline sites (2.0002.080 m a.s.l) facing different aspects (112 samples; AD 17952000) on Mt.
Patscherkofel (Tyrol, Austria), which is situated in the inner-alpine dry region of the Central Austrian Alps.
These studies were focused on a reconstruction of summer temperature (JuneJuly) for the intermediate alpine region and on the climatological interpretation of distinct radial growth as well as wood anatomical features (> 3.100 tree rings with conspicuous wood anatomical features were analysed, i.e. about 5 % of all measured tree rings).
Growth-climate relationships between ring width chronologies (residual chronologies) and climate variables were explored using Pearson product-moment correlations. Current year summer-temperatures (JuneJuly) were found to be the primary climate factor that controls radial growth of Picea abies and Pinus cembra at all sites.
Above average temperature in April (Montafon) and May (Tannberg) and a well-balanced soil moisture in spring (depending on previous year autumn precipitation) forced the production of earlywood at northern intermediate- and northern outer-alpine regions, respectively. At the inner-alpine timberline low precipitation in late winter (March), i.e. a minor snow cover, negatively affected the growth of Pinus cembra, which might have.




Corinna Raffl-Wallinger

Thesis title:
Comparative analyses of the primary succession on Central Alpine glacier forelands on inter- and intraspecific levels

Supervisor:
Brigitta Erschbamer, RG Population Biology and Vegetation Ecology, Innsbruck University



Klaus Loacker

Thesis title:
Die Ausbreitung von Juglans regia L. im Ostalpenraum im Zuge der Klimaerwärmung

Supervisor:
Walter Oberhuber, RG Dendroecology and Tree Physiology, Innsbruck University

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Project description:

Since the Roman time, the walnut tree (J. regia L.) has been cultivated in gardens and orchards in Tyrol, Vorarlberg (Austria), South Tyrol (Italy) and other Alpine regions in Central Europe. Recently, however a striking increase of growing sites and individuals of wild J. regia trees has been detected within the above mentioned regions. To examine more closely, if influence of climate warming - especially since 1970 - favoured spread of J. regia, a dendroecological and phytosociological study at representatively selected study sites in the central alpine Region of Tyrol, in the border alpine Region of Vorarlberg and the south alpine Region of South Tyrol was initiated. Analysis of climate conditions in years of germination revealed a striking correspondence between the number of germinated trees and winter (DecemberFebruary) minimum temperatures, which can be related to frost sensitivity during seed and seedling stage. In summary, the provided data strongly indicate that climate warming after 1970 favoured establishment and growth of frost sensitive seeds and seedlings of J. regia within eastern alpine regions.




Ilse Larl

Thesis title:
Flower development in high mountain saxifrages

Supervisor:
Johanna Wagner, RG Reproductive Biology, Innsbruck University

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Project description:

Morphogenesis of floral structures, dynamics of reproductive development from floral initiation until fruit maturation, and leaf turnover in vegetative short-stem shoots of High-Mountain Saxifrages (S.oppositifolia, S.biflora, S.moschata, S.caesia) were studied in three consecutive years at an alpine site (2300 m) and at an early- and late-thawing subnival site (2650 m) in the Austrian Alps. Two different strategies in flower development could be distinguished: The "one-season strategy" found in the alpine species S.caesia, which accomplishes flower development and anthesis within one year and the "two-season strategy" of the alpine-nival plants S.oppositifolia, S.biflora, and S.moschata, which extend flower formation over two growing seasons.
Flower buds of S.oppositifolia and S.biflora entered winter dormancy in a highly differentiated, but still premeiotic state. In S.moschata, flower development stops in an early stage of flower primordia initiation. The length of the prefloration period negatively correlated with the degree of flower bud preformation of the previous year. In total, the period of active flower development amounted to 2 months in all investigated Saxifraga-species. Correlation analyses showed that temperature was not a limiting factor for floral development, and developmental processes could not be accelerated by higher temperatures.
Though daylength hat no effect on the date of flowering, it seems to play a crucial role in floral initiation. There was no strict synchronisation between flowering and seed development on the one hand and new flower bud development on the other hand.
Vegetative growth and leaf expansion started immediately after snowmelt and lasted until late autumn. The average rates of seasonal leaf initiation in S.oppositifolia and S.caesia at early thawing sites (16 and 25 leaves per shoot, respectively) were reduced by 1/3 at late thawing sites. Nevertheless, vegetative short-stem shoots performed in most cases full leaf turnover within one growing season.




Daniel Remias

Thesis title:
Vergleichende Ecophysiology der Schneealgen der Alpen und polarer Gebiete

Supervisor:
Cornelius Lütz, Innsbruck University

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Project description:

Snow algae live in persisting old summer snow fields and can cause green, yellow or red colorations. From 2003 to 2006, over 50 samples were taken from different locations in the Alps, the Arctic and in Antarctica for species characterisation and for physiological measurements. The aim of this work is to gain knowledge about the occurrence and surviving strategies of these cold-adapted micro-organisms and to compare populations from mountains in temperate zones with those growing in polar coastal areas. Field material of these algae, which are adapted to high irradiance and low nutrients stress, were analysed by light- and electron microscopy; chlorophyll-fluorescence and photosynthesis were measured and the content of primary and secondary pigments was investigated. The red coloration of all investigated snow algae species is caused by the secondary carotenoid astaxanthin and of its esters. A native cis-isomer of astaxanthin provides additional screening in the near UVA.
In Antarctica, green snow was found which contained no secondary pigments. From surfaces of alpine glaciers, a Mesotaeniaceae is reported, whichs secondary, purple pigmentation is not identified so far.
Photosynthetic measurements have shown that all investigated species were able to produce oxygen at ambient temperatures close to zero degrees. At elevated irradiation, no photoinhibition takes place.
However, at temperatures from 10 to 20 degrees on, the respiration is significantly increased and as a consequence, the overall productivity is much lower.




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