Previous studies indicated that the development and biogeochemistry of paddy soils relates to the parent material, thus the original soil paddies derive from. The proposed research focuses on redox-mediated changes in mineral composition and mineral-associated organic matter (OM) during paddy transformation of different soils. We plan to subject soil samples to a series of redox cycles, in order to mimic paddy soil formation and development. Soils with strongly different properties and mineral composition as well as at different states of paddy transformation; ranging from unchanged soils to fully developed paddy soils, are to be included. We hypothesize that dissolved organic matter is one key driver in redox-mediated transformations, serving as an electron donator as well as interacting with dissolved metals and minerals. The extent of effects shall depend on the parent soil's original mineral assemblage and organic matter and their mutual interactions. The experimental paddy soil transformation will tracked by analyses of soil solutions, of the (re-)distribution of carbon (by addition of 13C-labelled rice straw), of indicative biomolecules (sugars, amino sugars, fatty acids, lignin) and of minerals (including the redox state of Fe). For analyses of organic matter as well as of mineral characteristics we plan to utilize EXAFS and XPS, for Fe-bearing minerals also Mößbauer spectroscopy. This approach of experimental pedology seems appropriate to give insight into the major factors during paddy soil formation and development.
This project will provide quantitative estimates of the flow of low-salinity warm water through the Indonesian Gateway on suborbital timescales during MIS 2 and 3 (focusing on Dansgaard Oeschger (D-O) oscillations) and will assess the Indonesian Throughflow (ITF) s impact on the hydrography of the eastern Indian Ocean and global thermohaline circulation during this critical interval of high climate variability. ITF fluctuations, associated with sea level change, temperature and salinity variations in the West Pacific Warm Pool (WPWP) strongly influence precipitation over Australia, the strength of the southeast-Asian summer monsoon, and the intensity of warm meridional currents in the Indian Ocean. We will test the hypothesis that increased ITF is associated with warm interstadials of MIS 3, whereas a strong reduction in ITF occurred during stadials. We will use as main proxies planktonic and benthic foraminiferal isotopes in conjunction with Mg/Ca temperature estimates and radiogenic isotopes (mainly Nd) as tracers of Pacific water masses along depth transects in the Timor Passage and the eastern Indian Ocean. This project will provide the paleoceanographic framework that will be crucial to validate and refine circulation models of D-O events and high-frequency climate variability on a global scale.
This project is aimed at the characterization of the systemic reprogramming in barley, which modulates the compatible interaction with the biotrophic leaf pathogen Blumeria graminis f.sp. hordei upon root infestation with the mutualistic endophyte Piriformospora indica. We have recently shown that the basidiomycete P. indica - upon successful establishment in the roots - reprograms barley to salt stress tolerance, resistance to root diseases and higher yield (Waller et al., 2005). Successful powdery mildew infections in barley leaves are also disturbed by the mutualistic fungus. These processes are associated with a strong change in plant metabolism, especially with a drastic alteration of leaf and root antioxidants. On the basis of these findings we will perform an in-depth analysis of the barley metabolome (B6) and transcriptome (B7) with two specific foci: First, to elucidate the process of establishment of the mutualistic fungus within the barley roots; second, to characterize elements of the systemic response in leaves leading to an interruption or failure of compatibility processes required for successful establishment of biotrophic leaf pathogens like Blumeria. New gene candidates will be pre-selected systematically for their regulatory role in compatibility by means of transiently transformed barley leaves upon Blumeria inoculation. Stable transgenic barley and maize lines (B3) generated with verified gene candidates and genes identified by other projects (A1, A2, B5, B6) will be tested with Blumeria and P. indica. By comparing candidate genes in the different plant - microbe systems, we will identify common regulatory processes, metabolites and metabolic networks implicated in compatibility including those required for successful interactions with mutualistic fungi.
Cherry leaf roll virus (CLRV) is a plant pathogen of economic and ecologic importance. It is globally distributed in a wide range of forest, fruit, and ornamental trees and shrubs. In several areas of cherry and walnut production CLRV causes severe losses in yield and quality. With current reference to the rapid dissemination and strong symptom expression in Finnish birches and the Germany-wide distribution of CLRV in birches and elderberry, we continuously investigate and gradually reveal CLRV transmission pathways as by pollen, seeds or water. However, modes and interactions responsible for the wide intergeneric host transmission as well as for the exceptional CLRV epidemic in Fennoscandia still remain unknown. In this project systematic studies shall investigate biological vectors as a causal agent to finally derive control mechanisms and strategies to avoid new epidemics in different hosts and geographic regions. Detailed monitoring of the invertebrate fauna of birch stands/forests and elderberry plantations in Germany and Finland shall reveal potential vectors to subsequently study them in detail by approved virus detection methods and transmission experiments. Molecular analyses of the CLRV coat protein shall prove its role as a viral determinant for a virus/vector interaction. Consequently, this project essentially will contribute important answers on the CLRV epidemiology, and this will be a key element within the first network of research on plant viral pathogens in forest trees.
Ziel dieses Projektes ist die Beschreibung von Strömungsmustern über ästuarinen Bodenformen anhand von Rinnenexperimenten und numerischen Simulationen. Bodenformen (Riffel und Dünen) sind weitverbreitete Bestandteile von Flüssen, Ästuaren, Küstengewässern- und Tiefseegebieten. Bodenformen liefern Hinweise auf Richtung und Stärke von Sedimenttransportprozessen, haben einen starken Einfluss auf die über ihnen liegende Strömung und sind zudem von großer sozioökonomischer Bedeutung, z. B. hinsichtlich ihrer Auswirkungen auf die Schiffbarkeit der Gewässer. In vielen Ästuaren bilden sich aufgrund der starken Hydrodynamik und der hohen Verfügbarkeit von sandigen Sedimenten große Bodenformfelder. Die Strömung über diesen Bodenformfeldern unterscheidet sich grundlegend von der Strömung über den bekannten, dreieckigen Bodenformen mit einem Neigungswinkel von 30°, die bisher im Fokus von Labor- und numerischen Modellierungsstudien standen. Ästuarine Bodenformen sind hauptsächlich flachgeböschte Dünen mit mittleren Luvwinkeln von 5 bis 20°. Die Strömungseigenschaften über derartigen, flachen Winkeln sind derzeit nicht genau bekannt. So ist zum Beispiel der Zusammenhang zwischen der Neigung der Leeböschung und dem Vorhandensein oder Fehlen einer intermittierenden oder permanenten Strömungsablösung noch nicht ausreichend verstanden. Außerdem haben ästuarine Dünen ein relativ flaches Tal und steile Böschungen in der Nähe des Kammes, während Flussdünen einen flachen Kamm und in der Nähe des Tals steile Böschungen haben. Die Auswirkungen dieses Unterschieds in der Dünenmorphologie auf die Strömung sind derzeit noch unbekannt. Darüber hinaus wurde der Zusammenhang zwischen einer sich in der Richtung ändernden Gezeitenströmung und der natürlichen Morphologie von Dünen, einschließlich der dreidimensionalen Variationen, noch nicht im Detail untersucht.Im Rahmen der vorgeschlagenen Studie werden mehrere Versuchsreihen in einer großen Laborrinne durchgeführt, um die Strömungseigenschaften (Geschwindigkeit und Turbulenz) über an Ästuardünen angelehnten Modelldünen aus Beton zu charakterisieren. Basierend auf Feldmessungen von Bodenformen in der Weser werden drei Dünenformvarianten untersucht: Steilgeböschte asymmetrische Dünen, flachgeböschte asymmetrische Dünen und flachgeböschte symmetrische Dünen. Darüber hinaus werden hochauflösende numerische Simulationen der Strömung über dreidimensionalen Bodenformfeldern die Rinnenexperimente ergänzen. Mithilfe der Modellsimulationen ist es möglich, die Geschwindigkeitsstrukturen der Gezeitenströmung und die Turbulenzstrukturen über natürlichen, in der Weser vorkommenden Dünenfeldern zu bestimmen. Die Ergebnisse dieses Projekts tragen zu einem besseren Verständnis der komplexen Wechselwirkungen zwischen ästuarinen Dünen und der Gezeitenströmung bei und erlauben eine bessere Parametrisierung der kleinräumigen Prozesse in großräumigen hydro- und morphodynamischen Modellen.
The energetic efficiency of C4 photosynthesis is strongly affected by bundle sheath leakiness, which is commonly assessed with the 'linear version' of the Farquhar model of 13C discrimination, and leaf gas exchange and 13C composition data. But, the linear Farquhar model is a simplification of the full mechanistic theory of ? in C4 plants, potentially generating errors in the estimation of leakiness. In particular, post-photosynthetic C isotope fractionation could cause large errors, but has not been studied in any detail. The present project aims to improve the understanding of the ecological and developmental/physiological factors controlling discrimination and leakiness of the perennial grass Cleistogenes squarrosa. C. squarrosa is the most important member of the C4 community which has spread significantly in the Mongolia grasslands in the last decades. It has an unusually high and variable discrimination, which suggests very high (and potentially highly variable) leakiness. Specifically, we will conduct the first systematic study of respiratory 13C fractionation in light and dark at leaf- and stand-scale in this C4 species, and assess its effect on discrimination and estimates of leakiness. These experiments are conducted in specialized 13CO2/12CO2 gas exchange mesocosms using ecologically relevant scenarios, testing specific hypotheses on effects of environmental drivers and plant and leaf developmental stage on discrimination and leakiness.
In freshwater sediments, iron oxidation is dominated by phototrophic and chemotrophic (aerobic and nitrate-reducing) Fe(ll)-oxidizing microorganisms. Although these biogeochemical processes have been investigated in detail in laboratory studies, not much is known about their spatial distribution, interactions (e.g. competition) amongst each other, as well as their response towards environmental perturbations (i.e. temperature, geochemical variations (nutrient, organic matter input)). This research proposal aims to investigate the activity, abundance and resource competition between different chemotrophic (aerobic and (autotrophic/mixotrophic) anaerobic nitrate-reducing) and phototrophic ironoxidizing microorganisms. In order to better understand the spatial distribution of nitrate-reducing iron oxidizing bacteria, microbial nitrate-producing and competing, nitrate-depletion processes will also be studied throughout the sedimentary redox gradient. In addition, the activity and abundance of the ironoxidizing processes will be quantified with (geo)microbiological, molecular and novel spectral imaging techniques. Using high resolution geochemical measurements (microsensors) we will characterize the environmental conditions these bacteria experience in order to determine the role of spatial and functional niche competition in microbial iron oxidation and the interconnection to the N-cycle. Iron mineral formation will be investigated as a function of the microbial spatial and temporal activity, depending on environmental perturbations. The proposed research study will strongly improve the understanding of iron cycling, the interconnection to the N-cycle, as well as interactions and competition between phototrophic and chemotrophic metabolisms in aquatic environments.
Die Erforschung von Artbildungs- und Anpassungsprozessen ist zentral, um zu verstehen, wie Biodiversität entsteht und auf wechselnde Umweltbedingungen reagiert.. Ein idealer Ort für solche Studien ist das Südpolarmeer: Es beherbergt eine reiche und hochgradig endemische Fauna. Neuere Studien zeigen, dass viele benthische Arten aus Gruppen von genetisch distinkten Kladen bestehen, die als früher übersehene Arten pleistozänen Ursprungs interpretiert werden. Diese kryptischen Arten können durch molekulare Methoden (z. B. DNA-Barcoding) und z.T. auch durch morphologische Analysen unterschieden werden. Es wird angenommen, dass die Artbildung per Zufall erfolgte, als ehemals große Populationen während glazialer Maxima in kleinen allopatrischen Refugien isoliert wurden, wo sie starker genetischer Drift ausgesetzt waren. Alternative Artbildungsmodelle wurden bislang wegen fehlender molekularer Methoden kaum erforscht. Studien aus anderen Ökosystemen zeigen, dass ökologische Artbildung, d.h. Aufspaltungsereignisse durch unterschiedliche Selektion, ein naheliegendes alternatives Artbildungsmodell ist. In dem hier vorgestellten Projekt sollen erstmals hochauflösende genomische Methoden zusammen mit morphologischen Analysen benutzt werden, um konkurrierende Artbildungsmodelle für das Südpolarmeer zu testen. Als Fallstudie sollen hierfür Muster genetischer Drift und Selektion in einer besonders erfolgreichen Gruppe benthischer Arten des Südpolarmeeres untersucht werden, den Asselspinnen (Pycnogonida). Aufbauend auf vorangehenden Studien sollen genomische Muster neutraler und nicht neutraler Marker bei zwei Artkomplexen untersucht werden: Colossendeis megalonyx und Pallenopsis patagonica. Diese beiden Artkomplexe von Asselspinnen sind aufgrund mehrerer Merkmale hervorragende Modelle für die Themen dieses Antrages: 1) Es existieren zahlreiche genetisch divergente kryptische Arten, 2) erste morphologische Unterschiede wurden gefunden, 3) die weite Verbreitung der Vertreter sowohl auf dem antarktischen Kontinentalschelf als auch in weniger von den Vereisungen betroffenen subantarktischen Regionen, 4) ihre geringe Mobilität. Sollte eine durch genetische Drift bedingte allopatrische Artbildung in glazialen Refugialpopulationen der Hauptantrieb der Evolution sein, ist zu erwarten, dass Zufallsfixierung neutraler Allele und Signaturen von Populations-Bottlenecks in stark vereisten Gebieten am höchsten sind. Wenn andererseits natürliche Selektion der Hauptantrieb der Artbildung war, so sind starke Signaturen von Selektion auf Geno- und Phänotyp zu erwarten. Diese sollte am stärksten bei sympatrischen Arten sein (Kontrastverstärkung). Die Variation entlang von Genomen soll untersucht werden, um das Ausmaß zufälliger bzw. nicht zufälliger Variation einzuschätzen. Das vorgeschlagene Projekt wird ein wichtiger erster Schritt einer systematischen Erforschung der relativen Bedeutung von genetischer Drift und Selektion für die Evolution im Südpolarmeer sein.
Irrigation in the Yanqi Basin, Sinkiang, China has led to water table rise and soil salination. A model is used to assess management options. These include more irrigation with groundwater, water saving irrigation techniques and others. The model relies on input data from remote sensing.The Yanqi Basin is located in the north-western Chinese province of Xinjiang.This agriculturally highly productive region is heavily irrigated with water drawn from the Kaidu River. The Kaidu River itself is mainly fed by snow and glacier melt from the Tian Mountain surrounding the basin. A very poor drainage system and an overexploitation of surface water have lead to a series of environmental problems: 1. Seepage water under irrigated fields has raised the groundwater table during the last years, causing strongly increased groundwater evaporation. The salt dissolved in the groundwater accumulates at the soil surface as the groundwater evaporates. This soil salinization leads to degradation of vegetation as well as to a loss of arable farmland. 2. The runoff from the Bostan Lake to the downstream Corridor is limited since large amount of water is used for irrigation in the Yanqi Basin. Nowadays, the runoff is maintained by pumping water from the lake to the river. The environmental and ecological system is facing a serious threat.In order to improve the situation in the Yanqi Basin, a jointly funded cooperation has been set up by the Institute of Environmental Engineering, Swiss Federal Institute of Technology (ETH) , China Institute of Geological and Environmental Monitoring (CIGEM) and Xinjiang Agricultural University. The situation could in principle be improved by using groundwater for irrigation, thus lowering the groundwater table and saving unproductive evaporation. However, this is associated with higher cost as groundwater has to be pumped. The major decision variable to steer the system into a desirable state is thus the ratio of irrigation water pumped from the aquifer and irrigation water drawn from the river. The basis to evaluate the ideal ratio between river and groundwater - applied to irrigation - will be a groundwater model combined with models describing the processes of the unsaturated zone. The project will focus on the following aspects of research: (...)
The magnetosphere of a planet is controlled by a number of factors such as the intrinsic magnetic field, the atmosphere and ionosphere, and the solar wind. Different combinations of these control factors are at work at the terrestrial planets Mercury, Venus, Earth, and Mars, hence they form a very suitable set for quantitative comparative studies. A significant intrinsic dipolar magnetic field is present only on Earth and on Mercury. However, the configuration at Mercury differs considerably from that at Earth because Mercury does not support an atmosphere and ionosphere, the dipolar field is much weaker, the solar wind denser, and the interplanetary magnetic field stronger. Both Mars and Venus have atmospheres but lack a global planetary magnetic field, with regional crustal magnetization being present on Mars. This proposal aims at investigating and comparing electrical current systems in the space environments of terrestrial planets using magnetic vector data collected by orbiting spacecraft such as Venus Express, Mars Global Surveyor, CHAMP (Earth), and MESSENGER (Mercury). We propose to construct data-driven and physically meaningful representations that reveal and quantify the influence of various control factors. To achieve this, we will tailor Empirical Orthogonal Function (EOF) analysis and other multivariate methods to the specifics of planetary magnetic field observations. In contrast to representations that build on predefined functions like spherical harmonics, basis functions in the EOF approach are derived directly from the data. EOFs are designed to extract dominant coherent variations for further interpretation in terms of known physical phenomena, and then, in a regression step, for modeling using suitable control variables. The EOF methodology thus allows quantifying the relative importance of control factors for each planet individually, and thus contributes to the solution of topical science questions. The resulting empirical models will facilitate comparative studies of current systems at the terrestrial planets.
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