WWW.ABSTRACT.XLIBX.INFO
FREE ELECTRONIC LIBRARY - Abstract, dissertation, book
 
<< HOME
CONTACTS



Pages:   || 2 | 3 | 4 | 5 |   ...   | 15 |

«Root Growth, Soil Nutrient Availability and Water Flow in Model Ecosystems of Young Oaks Subjected to Air-warming and Drought A dissertation ...»

-- [ Page 1 ] --

DISS. ETH No. 20577

Root Growth, Soil Nutrient Availability and Water Flow in Model

Ecosystems of Young Oaks Subjected to Air-warming and

Drought

A dissertation submitted to

ETH ZÜRICH

for the degree of

DOCTOR OF SCIENCES

presented by

THOMAS M. KUSTER

dipl. Umwelt-Natw. ETH

born 2nd Februar 1980 citizen of Eschenbach/SG and Uznach/SG accepted on the recommendation of Prof. Dr. Rainer Schulin, ETH Zürich Dr. Madeleine Günthardt-Goerg, Eidg. Forschungsanstalt WSL Prof. Dr. Rainer Matyssek, TU München Zürich, 2012 Table of contents Table of contents

Summary

Zusammenfassung

1. Introduction

1.1. Background

1.2. Objectives

2. Water regime and growth of young oak stands subjected to air-warming and drought on two different forest soils in a model ecosystem experiment

Summary

2.1. Introduction

2.2. Material and methods

2.2.1. Study site and experimental design

2.2.2. Measurements of soil water, leaf water potential and temperature regime........... 17  2.2.3. Biomass measurements

2.2.4. Statistical analysis

2.3. Results

2.3.1. Air and soil temperature

2.3.2. Evapotranspiration

2.3.3. Soil water regime and leaf water potential

2.3.4. Growth parameters

2.3.5. Water use efficiency

2.4. Discussion and conclusions

Acknowledgements

3. Root growth of different oak provenances in two soils under drought stress and air-warming conditions

Summary

3.1. Introduction

3.2. Material and methods

3.2.1. Study site & experimental design

3.2.2. Biomass sampling

ITable of contents

3.2.3. Statistical analysis

3.3. Results

3.3.1. Total and fine root mass

3.3.2. Effect of drought and soil properties on vertical root mass distribution............... 44 

3.4. Discussion

3.5. Conclusions

Acknowledgments

4. Root and shoot growth patterns of 1st-year Quercus robur seedlings as affected by drought conditions

Summary

4.1. Introduction

4.2. Material and methods

4.2.1. Experimental setup

4.2.2. Statistical analysis

4.3. Results

4.4. Discussion and conclusions

Acknowledgments

5. Nitrogen dynamics in oak model ecosystems subjected to air warming and drought on two different soils

Summary

5.1. Introduction

5.2. Material and methods

5.2.1. Study site and experimental design

5.2.2. 15N labelling and measurement of 15N, NH4+ and NO3- in soil, biomass and discharge water

5.2.3. Soil respiration

5.2.4. Statistical analysis

5.3. Results

5.3.1. Root and shoot biomass

5.3.2. Soil respiration

5.3.3. Nitrogen in soil and microbial biomass

5.3.4. Nitrogen losses with discharge

5.3.5. Total N concentration in fine roots, stem + twigs and leaves

5.3.6. 15N tracer fractions in drainage water, soil, and tree biomass

5.3.7. 15N recovery

5.4. Discussion

5.4.1. N status of the experimental trees

5.4.2. Air-warming effects

II

Table of contents

5.4.3. Drought effects

5.4.4. Nitrate vs. ammonium uptake

5.5. Conclusion

Acknowledgements

6. Synthesis

6.1. General conclusions

6.1.1. Drought effects

6.1.2. Air-warming effects

6.1.3. Interaction of soil types with climate treatments

6.2. Which oak species/provenance is the future forest tree?

6.3. Outlook

References

Appendix

Other manuscripts of the “Querco” project

Acknowledgements

Curriculum vitae

–  –  –

IV Summary Global climate change is expected to increase annual temperatures and decrease summer precipitation in Central Europe. Being tolerant to heat and drought, oaks are considered promising trees to replace beech and spruce on forest sites that will become too warm and dry for these species. Oak provenances from dry sites are expected to be especially drought tolerant. However, little is known on how the oak species growing in Switzerland (Quercus robur, Q. petraea and Q. pubescens) will respond to the changing climate and how these responses depend on soil properties. Apart from direct drought and heat stress effects on biochemical and physiological processes, trees like other plants will also have to cope with indirect effects such as changes in soil nutrient availability. For example, nitrogen (N) availability depends on soil microbial processes, which are sensitive to soil temperature and moisture. We expected warming to increase and drought to decrease soil N availability and thus N supply to the trees.

In a 3-year factorial model ecosystem experiment, we investigated the responses of young mixed oak stands with Quercus robur, Q. petraea and Q. pubescens, growing on either acidic or calcareous soil, to air-warming (+1 to 2 °C) and drought treatments (-43% to -60% precipitation), corresponding to the IPCC climate change Scenario A2. The air-warming and drought treatments were applied separately as well as in combination on both soils.





The mild air-warming treatment had no effect on soil water availability, evapotranspiration or stand biomass, neither above nor below ground. Water limitation, which was severe during drought periods as shown in low leaf water potentials, significantly reduced the stand foliage, stem + twigs and root biomass. However, no tree died during the

–  –  –

experimental period. The drought treatment led to higher root:shoot mass ratios and only little reduction in fine root biomass compared to total root mass. Allocating relatively more biomass into structures for water and nutrient uptake than for above ground assimilation can be seen as a response to balance impeded soil water extraction with reduced transpirational water loss. Moreover, evapotranspiration increased within a few days after re-watering to predrought levels, indicating a fast recovery potential of the oaks photosynthetic activity.

Decreased evapotranspiration from the drought-exposed stands led to significantly higher air and soil temperatures, which were attributed to reduced transpirational cooling. As a major finding of our results, we point out that additional air warming did not enhance the drought effects on evapotranspiration and biomass, although more negative leaf water potentials were observed.

In an additional neutron radiography experiment, it has been shown for the first time that root-shoot growth patterns of oak seedlings are not altered by either water availability or soil properties. Independent from soil type and drought treatment, peaks and dips of shoot and root growth rates occurred at the same time. We conclude therefore that during the first year after germination, environmental conditions were overruled by endogenous growth patterns.

Moreover, it has been shown for the first time that neutron radiography is a well-suited, nondestructive method to track root growth patterns of young oak trees.

Stands not subjected to the drought treatment produced significantly less biomass on the calcareous than on the acidic soil. This was probably due to phosphor (P) or manganese (Mn) limitation. In the acidic soil, root mass was maximal in the nutrient-rich topsoil, whereas in the calcareous soil maximum root mass occurred between 0.25 and 0.5 m depth. There was no difference in biomass and water regime between the two soils under drought conditions. As another highlight of our results, we therefore emphasise that nutrient availability was governed by water availability under these conditions.

–  –  –

While total amounts, vertical distribution and availability of soil N showed substantial differences between the two soils, neither warming nor drought had a significant effect on N availability in either of them, in contrast to our expectations. Air-warming also had no effect on N accumulation in the biomass of the trees, whereas the drought treatment increased or tended to increase N accumulation, indicating that growth was not limited by N. 15N-labelling revealed that this increase was associated with a higher fraction of tracer-N accumulation deriving from 15N applied in the form of nitrate to the soil surface, while the fraction of 15N accumulated in the plants decreased when it had been applied as ammonium. As a further highlight of our study, we therefore conclude that climate change is not expected to have major effects on the N dynamics of young oak stands in central Europe.

The provenances of Quercus robur showed more vigorous growth in all treatments than those of the other two species, irrespective of soil type, air-warming and drought treatments.

However, drought-tolerance in relation to root:shoot mass ratio, leaf stress injuries, photosynthesis and wood anatomy was higher in Q. petraea and Q. pubescens than in Q. robur. Therefore, Q. robur appeared to be the most promising species when drought periods are only short, whereas long and severe drought periods would favour Q. petraea and Q. pubescens. Within each species, provenances originating from drier sites produced more root mass than those from more humid sites. However, given that the provenances from drier sites reacted more sensitive to water limiting conditions than those from more humid sites, it remains questionable whether these provenances are better suited for a future climate. Also other aspects such as frost tolerance and wood quality must be considered in selecting provenances for future forestry. In any case, we demonstrated for the first time under controlled experimental conditions that independent from soil properties young saplings of all three central European oak species can successfully cope with severe drought periods and

–  –  –

increased air temperatures, and thus are suited from this point of view for future forestry in central Europe under conditions of climate change.

VIII Zusammenfassung Als Folge des globalen Klimawandels wird erwartet, dass bis Ende dieses Jahrhunderts in Mitteleuropa die Sommer wärmer und trockener sein werden als heute. Die in Mitteleuropa vorherrschenden Stiel-, Trauben-, und Flaumeichen (Quercus robur, Q. petraea und Q. pubescens) sind als trocken- und hitzetolerante Bäume bekannt. Damit dürften sie in Zukunft die heute vorherrschenden Buchen und Fichten in warmen und trockenen Tieflagen ersetzen. Eichenprovenienzen aus niederschlagsarmen Regionen dürften dabei besonders erfolgreich sein. Die Effekte von höherer Lufttemperatur und Trockenheit auf das Eichenwachstum sind bereits gut erforscht. Allerdings haben bisherige Studien diese Effekte getrennt voneinander untersucht, weshalb nur wenig über die Auswirkungen von Interaktionen dieser zwei Faktoren untereinander und mit Bodeneigenschaften bekannt ist.

Neben den direkten Auswirkungen von Trockenheit und Hitze auf Stoffwechselprozesse der Eichen müssen auch indirekte Effekte des Klimawandels auf Bäume berücksichtigt werden, zum Beispiel eine Veränderung der Stickstoffverfügbarkeit (N). Dabei wird erwartet, dass höhere Lufttemperaturen die Verfügbarkeit und damit das N-Angebot für Eichen erhöhen, während Trockenheit die Verfügbarkeit von N verringert.

–  –  –

Lufterwärmung (+1 bis 2 °C) und Trockenstress (-43% bis -60% Niederschlag) auf Eichenbestände mit jungen Stiel-, Trauben- und Flaumeichen auf einem sauren Boden und auf einem Kalkboden untersucht. Die Behandlungen Lufterwärmung und Trockenstress wurden entweder voneinander getrennt oder in Kombination angewendet und orientierten sich

–  –  –

dabei am IPCC Szenario A2, welches auf einem hohen Populationswachstum, einer langsamer Wirtschaftsentwicklung und einem geringen Technologiewandel basiert.

Die Lufterwärmung hatte keinen Effekt auf die Verfügbarkeit des Bodenwassers, die Evapotranspiration oder die Biomasse der Eichenbestände. Im Gegensatz dazu reduzierte

–  –  –

Trockenstressbehandlung erwies sich als ziemlich extrem, was gut sichtbar an den sehr tiefen Blattwasserpotentialen war. Trotz dieser starken Trockenstressbehandlung starb während des ganzen Experiments keine einzige Eiche. Darüber hinaus stieg die Evapotranspiration innerhalb weniger Tage nach Beendigung der Trockenperioden auf das Niveau der Kontrolle an, was auf ein hohes Regenerationspotential der Eichen hindeutet. Unter Trockenstress entwickelten die Eichen ein höheres Wurzel:Spross Verhältnis. Ausserdem waren die Effekte der Wasserlimitation auf die Feinwurzelbiomasse geringer als auf die Gesamtwurzelbiomasse.

Diese Anpassungen ermöglichten es den Eichen auch unter Trockenheit effizient Wasser und Nährstoffe aufzunehmen und gleichzeitig Wasserverluste durch Transpiration zu reduzieren.

Die Evapotranspiration von trockengestressten Eichenbeständen war zeitweise sehr gering, was durch eine geringe Transpirationskühlung zu höheren Luft- und Bodentemperaturen führte. Als wichtige Erkenntnis dieser Studie möchten wir hervorheben, dass die zusätzliche Lufterwärmung in der kombinierten Behandlung jedoch zu keiner Verstärkung der Trockenstressbehandlung auf die Evapotranspiration oder Biomasse der Eichen führte obwohl tiefere Blattwasserpotentiale gemessen wurden.

In einem zusätzlichen Neutronenradiographieexperiment wurde zum ersten Mal gezeigt, dass periodisches Wurzel- und Sprosswachstum von Eichenkeimlingen weder durch Wasserverfügbarkeit noch durch Bodeneigenschaften verändert wird. Unabhängig von Trockenstressbehandlung und Bodentyp traten die höchsten wie auch die tiefsten Wachstumsraten von Spross und Wurzeln immer zur gleichen Zeit auf. Wir folgern daher,

–  –  –



Pages:   || 2 | 3 | 4 | 5 |   ...   | 15 |


Similar works:

«Würzburger UNTERSTÜTZER JungChemikerForum Chem-SyStM Chemie-Symposium der Studierenden Mainfrankens Vernetze dein Wissen! Abstractband 07. Dezember 2010 www.jcf-wuerzburg.de INHALTSVERZEICHNIS Inhalt des Abstractbandes  Grußwort  Unterstützer  Abstracts der Arbeitskreise  Vortragende Appetithäppchen  Abstracts der Teilnehmer  Teilnehmerliste nach Fachbereichen aufgeschlüsselt  Notizen  Programm (Rückseite) Organisationskomitee Matthias Beyer, Nicolas Brockmann,...»

«02.089 Botschaft über die Förderung von Bildung, Forschung und Technologie in den Jahren 2004–2007 vom 29. November 2002 Sehr geehrte Herren Präsidenten, sehr geehrte Damen und Herren, mit dem Antrag auf Zustimmung unterbreiten wir Ihnen mit vorliegender Botschaft die Entwürfe zu folgenden Bundesbeschlüssen: – Bundesbeschluss über die Finanzierung der Berufsbildung in den Jahren 2004–2007 – Bundesbeschluss über die Kredite für den ETH-Bereich in den Jahren 2004–2007 –...»

«Hedging langfristiger Lieferverpflichtungen mit kurzfristigen Futures: Möglich oder unmöglich? von Wolfgang Bühler*, Olaf Korn** *Universität Mannheim und ZEW **ZEW Juni 1998 Wir danken Alexander Kempf und Marliese Uhrig-Homburg für wertvolle Anregungen und Kommentare. 1 Einleitung Im Laufe des Jahres 1993 war die Metallgesellschaft Refining & Marketing (MGRM), eine US-amerikanische Tochtergesellschaft der Metallgesellschaft AG, in großem Umfang die Verpflichtung eingegangen, langfristig...»

«DISCLAIMER The statements set forth in this guide are for information purposes only and should not be construed as the basis of a binding contract between the student and Hampton University. While the provisions of this guide will ordinarily be applied as stated, the University reserves the right to change any provision listed, including but not limited to academic requirements for graduation, without actual notice to individual students. Every effort will be made to keep students advised of...»

«Menkes van den Briel Contact Menkes van den Briel Name National ICT Australia Company Researcher Position 223 Anzac Parade, Kensington 2033, NSW, Australia Address +61 (0)2 8306 0464 Phone +61 (0)2 8306 0405 Fax menkes@nicta.com.au Email http://www.menkes76.com Homepage Summary Menkes van den Briel is an operations research scientist with a consistent track record in developing practical solutions for complex real-world problems. His work is impactful both academically and in practice. His...»

«QUEST, 1992.44.304-316 Integrating Sport Into the Physical Education Curriculum in New Zealand Secondary Schools Bevan C. Grant Schools are important in shaping the values and beliefs of young people. One value claimed to be important to New Zealanders is participating in sport. New Zealand has an impressive international sporting record for a country with a small population, and many forms of recreation and sport are deemed to be socially and culturally significant and positive contributors to...»

«Das Markusevangelium Portfolio Das Markusevangelium Portfolio von René Knipschild Copyright © 2008 René Knipschild Seite 1 von 11 Das Markusevangelium Portfolio Inhaltsverzeichnis 1. Zusammenfassung des Markusevangeliums 3 1.1 Der Beginn des Wirkens Jesu Christi 3 1.2 Jesus liebt die Menschen 3 1.3 Das Reich Gottes 4 1.4 Jesus stillt den Sturm 4 1.5 Die Speisung der Fünftausend 4 1.6 Das wichtigste Gebot 5 1.7 Jesu Tod und der Missionsbefehl 5 2. Fragen an das Markusevangelium 7 2.1 Warum...»

«EUROPÄISCHE KOMMISSION Brüssel, den 9. November 2005 SEK (2005) 1423 Kosovo (gemäß der Resolution 1244 des Sicherheitsrats der Vereinten Nationen) Fortschrittsbericht 2005 {KOM (2005) 561 endg.} A. EINLEITUNG 1. VORBEMERKUNG 2. HINTERGRUND 3. BEZIEHUNGEN ZWISCHEN DER EUROPÄISCHEN UNION UND KOSOVO B. UMSETZUNG DES STABILISIERUNGSUND ASSOZIIERUNGSPROZESSES 1. POLITISCHE LAGE 1.1 Demokratie und Rechtsstaatlichkeit 1.2 Menschenrechte und Minderheitenschutz 1.3 Regionalfragen und internationale...»

«PERCEPTIONS OF THE SERPENT IN THE ANCIENT NEAR EAST: ITS BRONZE AGE ROLE IN APOTROPAIC MAGIC, HEALING AND PROTECTION by WENDY REBECCA JENNIFER GOLDING submitted in accordance with the requirements for the degree of MASTER OF ARTS in the subject ANCIENT NEAR EASTERN STUDIES at the UNIVERSITY OF SOUTH AFRICA SUPERVISOR: PROFESSOR M LE ROUX November 2013 Snake I am The Beginning and the End, The Protector and the Healer, The Primordial Creator, Wisdom, all-knowing, Duality, Life, yet the terror in...»

«Элизабет Халл Кен Джексон Джереми Дик Разработка и управление требованиями Практическое руководство пользователя (Второе издание) II Об авторах и книге Elizabeth Hull, BSc, PhD, CEng, FBCS School of Computing and Mathematics, University of Ulster Newtownabbey, Co Antrim, UK Kenneth Jackson, BSc, MSc, MBCS Telelogic UK Ltd., Oxford, UK Jeremy Dick, BSc(Eng), ACGI,...»

«Prediction Tests Tests For Predicting VO2max Maximal Tests 1.5 Mile Run. Test Population. This test was developed on college age males and females. It has not been validated on other age groups. Test Procedures. A 1.5 mile level running surface is used. The 1.5 miles is covered in as fast a time as possible. It is best to run at an even pace until near the end, just as in a race. It is best to have at least one trial run before the test to establish a pace-sense for this distance. Only the time...»

«THE STAGES OF THE PEPTIC HYDROLYSIS OF EGG ALBUMIN. By JENNIE McFARLANE, VIOLET E. DUNBAR, HENRY BORSOOK, Am) B.ARDOLPH WASTENEYS. (From the Department of Biochemistry, University of Toronto, Toronto, Canada.) (Accepted for publication, October 18, 1926.) Numerous investigators have studied the stages in peptic digestion. The conclusions at which they have arrived may be grouped under two main heads. On the one hand, Kiibne (1) and Neumeister (2) concluded that the products of digestion arise...»





 
<<  HOME   |    CONTACTS
2016 www.abstract.xlibx.info - Free e-library - Abstract, dissertation, book

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.