In the Earth, the dynamo action is strongly linked to core freezing. There is a solid inner core, the growth of which provides a buoyancy flux that drives the dynamo. The buoyancy in this case derives from a difference in composition between the solid inner core and the fluid outer core. In planetary bodies smaller than the Earth, however, this core differentiation process may differ - Fe may precipitate at the core-mantle boundary (CMB) rather than in the center and may fall as iron snow and initially remelt with greater depth. A chemical stable sedimentation zone develops that comprises with time the entire core - at that time a solid inner core starts to grow. The dynamics of this system is not well understood and also whether it can generate a magnetic field or not. The Jovian moon Ganymede, which shows a present-day magnetic dipole field, is a candidate for which such a scenario has been suggested. We plan to study this Fe-snow regime with both a numerical and experimental approach. In the numerical study, we use a 2D/3D thermo-chemical convection model that considers crystallization and sinking of iron crystals together with the dynamics of the liquid core phase (for the 3D case the influence of the rotation of the Fe snow process is further studied).The numerical calculations will be complemented by two series of experiments: (1) investigations in metal alloys by means of X-ray radioscopy, and (2) measurements in transparent analogues by optical techniques. The experiments will examine typical features of the iron snow regime. On the one hand they will serve as a tool to validate the numerical approach and on the other hand they will yield important insight into sub-processes of the iron snow regime, which cannot be accessed within the numerical approach due to their complexity.
Magnetic resonance tomography (MRT) on microcosm soil cores (200 mm Ø) used for CeMiX, comprising naturally stacked subsoil down to 700 mm plus topsoil from CeFiT, will be implemented at a laterally partially open Split 1.5 T magnet, with intended final in-plane spatial resolution of 200 Micro m. Three-dimensional biopore distributions and dynamics of their formation within the cores will be determined non-invasively and compared to complementing CT analyses of SP 2. One major aim is a non-invasive differentiation of the biopores into earthworm- and root system-originating ones and currently air-, water-, root- and earthwormfilled ones, based on NMR relaxation parameters. Attempts will additionally be made to classify different wall coatings of the biopores with regard to their water affinity. Dynamics of water distribution within the microcosm core and its biopore structures, starting from initial values taken from CeFiT (SP 3), will be documented with an in-plane resolution of 5 mm, in parallel to measurements of root growth dynamics for calculation of biomass and root surface area. Special emphasis will be put on the role of the plant root system for a re-distribution of water/D2O (and solutes) between different soil layers. Finally we will attempt MRT-controlled sample collection from the microcosm cores, to get - together with our research unit partners of SPs 4-8 - repeated access to minimally invasively acquired data on nutrient and microorganism distributions in concert with non-invasively collected water and root distribution data as a basis for dynamic modelling of water and solute circuits in SP 10. Beside the microcosm cores, flat rhizotrons as used in SP 3 will be employed to enable measurements of root and shoot hydrostatic pressure profiles with pressure probes, in addition to MRT measurements. In this way water distributions and corresponding driving forces and growth dynamics will be measured altogether in a minimally invasive manner.
Dairy farming across Germany displays diverse production systems. Factor endowment, management, technology adoption as well as competitive dynamics in the local or regional land, agribusiness and dairy processing sectors contribute to this differentiation on farm level. These differences impact on the ability of dairy farms and regional dairy production systems to successfully respond to pressures arising from future market and policy changes. The overall objective of the research activities of which this project is a part of, is to develop a thorough understanding of the processes that govern the spatial dynamics of dairy farm development in different regions in Germany. The central hypothesis of this research project is that management system and technological choices differ systematically across local production and market conditions. The empirical approach will focus on the estimation of farm specific nonparametric cost functions for dairy farms located in across Germany differentiated by time and location. A spatially differentiated data base with information on input use, resource availability, as well as local market conditions for land and output markets will be compiled. The nonparametric approach is specifically suited to disclose a more accurate representation of dairy production system heterogeneity across locations and time compared to parametric concepts as it provides the necessary flexibility to accommodate non-linearities relevant for a wide domain of explanatory variables. The methodology employed goes beyond the state of the art of the literature as it combines kernel density estimation with a Bayesian sampling approach to provide theory consistent parameters for each farm in the data sample.The specific methodological hypothesis is that the nonparametric approach is superior to current parametric techniques and this hypothesis is tested using statistical model evaluation. Regarding the farm management and technological choices, we hypothesize that land suitability for feed production determines the farm intensity of dairy production and thus management and technological choices. With respect to the ability of farms to successfully respond to market pressures we hypothesize that farms at the upper and lower tail of the intensity distribution both can generate positive returns from dairy production. These last two hypotheses will be tested using the estimated spatially differentiated farm specific costs and marginal costs.The expected outcomes are of relevance for the agricultural sector and the food supply chain economy as a whole as fundamental market structure changes in the dairy sector are ongoing due to the abolition of the quota regulation in the years 2014/2015. Thus, exact knowledge about differences and development of dairy cost heterogeneity of farms within and between regions are an important factor for the actors involved in the market as well as the political support of this process.
The AZV (Altitudinal Zonation of Vegetation) Project was initiated in the year 2002. On the basis of a detailed regional study in continental West Greenland the knowledge about altitudinal vegetation zonation in the Arctic is aimed to be enhanced. The main objectives of the project are: a) considering the regional study: characterize mountain vegetation with regard to flora, vegetation types, vegetation pattern and habitat conditions, investigate the differentiation of these vegetation characteristics along the altitudinal gradient, develop concepts about altitudinal indicator values of species and plant communities, extract suitable characteristics for the distinction and delimitation of vegetation belts, assess altitudinal borderlines of vegetation belts in the study area. b) considering generalizations: test the validity of the altitudinal zonation hypothesis of the Circumpolar Arctic Vegetation Map ( CAVM Team 2003), find important determinants of altitudinal vegetation zonation in the Arctic, develop a first small scale vegetation map of entire continental West Greenland. Field work consists of vegetational surveys according to the Braun-Blanquet approach, transect studies, soil analyses, long-time-measurements of temperature on the soil surface and vegetation mapping in three different altitudinal vegetation belts (up to 1070 m a.s.l.).
The nature of the microbial communities inhabiting the deeper soil horizons is largely unknown. It is also not clear why subsurface microorganisms do not make faster use of organic compounds under field conditions. The answer could be provided by a reciprocal soil transfer experiment studying the response of transferred soils to fluctuations in microclimate, organic inputs, and soil biota. The subproject P9 will be responsible for the establishment of reciprocal transfer experiments offering a strong link between subgroups interested in organic matter quality, transport of organic substances, as well as functions of the soil microbial community. A single, high molecular weight substrate (13C labelled cellulose) will be applied at two different levels in the pre-experiment to understand the dose-dependent reaction of soil microorganisms in transferred surface and sub-soils. Uniformly 13C labelled beech roots - representing complex substrates - will be used for the main reciprocal soil transfer experiment. We hypothesize that transferring soil cores between subsoil and surface soil as well as addition of labelled cellulose or roots will allow us to evaluate the relative impact of surface/subsurface habitat conditions and resource availability on abundance, function, and diversity of the soil microbial community. The second objective of the subproject is to understand whether minerals buried within different soil compartments (topsoil vs. subsoil) in the field contribute to creation of hot spots of microbial abundance and activity within a period of two to five years. We hypothesize that soil microorganisms colonize organo-mineral complexes depending on their nutritional composition and substrate availability. The existence of micro-habitat specific microbial communities could be important for short term carbon storage (1 to 6 years). The third objective is to understand the biogeography and function of soil microorganisms in different subsoils. Parent material as well as mineral composition might control niche differentiation during soil development. Depending on size and interconnectedness of niches, colonization and survival of soil microbial communities might be different in soils derived from loess, sand, terra fusca, or sandstone. From the methodological point of view, our specific interest is to place community composition into context with soil microbial functions in subsoils. Our subgroup will be responsible for determining the abundance, diversity, und function of soil microorganisms (13C microbial biomass, 13C PLFA, enzyme activities, DNA extraction followed by quantitative PCR). Quantitative PCR will be used to estimate total abundances of bacteria, archaea and fungi as well as abundances of specific groups of bacteria at high taxonomic levels. We will apply taxa specific bacterial primers because classes or phyla might be differentiated into ecological categories on the basis of their life strategies.
(1) Terrestrische Biota der Antarktis sind durch geografische Isolation und inselhafte Verteilung geprägt. Die isolierte Lage der Antarktis und die Beschränkung auf weit voneinander entfernte kleine Habitatflecken haben zu einem hohen Endemiten-Anteil und einer starken Regionalisierung der Fauna und Flora geführt. Genetische Differenzierung, lokale Anpassung und die Evolution kryptischer Arten sind die Folge. Die Biodiversitäts-Konvention (CBD) betrachtet genetische Diversität als einen Eckpfeiler biologischer Vielfalt und stellt sie damit in eine Reihe mit der Diversität von Arten und Ökosystemen. Durch Einschleppung ortsfremder Arten und Homogenisierung bislang getrennter Genpools bedroht der Mensch jedoch zunehmend diese Isolation und genetische Differenzierung vieler antarktischer Biota. (2) Obwohl Flechten als wichtigste Primärproduzenten antarktische terrestrische Lebensräume dominieren, fehlen zurzeit Daten zu ihrer genetischen Struktur und Diversität. Der Umfang inter- und intrakontinentalen Genflusses ist bisher völlig unbekannt. Es ist deswegen derzeit unmöglich, den aktuellen und zukünftigen menschlichen Einfluss auf antarktische Flechtenpopulationen auch nur annähernd abzuschätzen.(3) Wir schlagen vor, mittels molekulargenetischer Daten die populationsgenetische Struktur von sechs weit verbreiteten Flechtenarten mit unterschiedlichen Ausbreitungsstrategien zu untersuchen. Dabei soll die Nullhypothese überprüft werden, dass Flechtenpopulationen genetisch nicht differenziert sind. Zusätzlich wollen wir abschätzen, ob menschliche Aktivitäten zur Einschleppung ortsfremder Arten oder Genotypen und zur Homogenisierung von Genpools beitragen. Hierfür sollen Lokalitäten mit hohem und niedrigem menschlichen Einfluss verglichen werden. Das Projekt schafft damit unverzichtbare Grunddaten für die Entwicklung von Schutzstrategien in der Antarktis.
Die ursprüngliche Zielsetzung dieses Projektes war, die Hypothese zu testen, dass die meridionalen Umweltgradienten des Südozeans zur Entstehung von populationsgenomischen Gradienten und zu lokalen Anpassungen innerhalb einer Phytoplanktonart, der Diatomee Fragilariopsis kerguelensis, geführt haben. Wir haben dafür eine Kombination von genomischen und phenotypischen Ansätzen ausgewählt. Die Ergebnisse der ersten Hälfte der Projektlaufzeit haben gezeigt, dass die Zielart des Projektes ein Komplex aus mindestens drei unterschiedlichen Arten ist. Das bedeutet auf der einen Seite eine unerwartete Schwierigkeit, um unsere ursprüngliche Frage zu beantworten; auf der anderen Seite, eröffnet diese Feststellung auch neue Möglichkeiten, da wir Anpassungsprozesse sowohl in der Begleitung von Artenbildung als auch im Vorhandensein von Genaustausch, d.h., auf der ursprünglich geplanten intraspezifischen Ebene, untersuchen können. Die Verlängerung wird uns ermöglichen, beide Fragen bearbeiten zu können, und vor allem den ursprünglichen Fokus auf die Intraspezifischen Prozesse wiederherzustellen.
Luftverschmutzung ist ein bedeutender Risikofaktor für die Gesundheit. Im vorliegenden Gut-achten wurde untersucht, ob eine Differenzierung der Feinstaubexposition der Bevölkerung in Deutschland nach sozioökonomischem Status möglich ist. Zur Abschätzung der Feinstaubexposi-tion wurde eine flächendeckende Darstellung der PM2.5 Hintergrundbelastung in räumlicher Auf-lösung von 2 x 2 km2 genutzt, ergänzt um höher aufgelöste Datensätze für die Städte Hamburg (Gesamtbelastung, 100 x 100 m2) und Berlin (Hintergrundbelastung, 500 x 500 m2) für zusätzli-che lokale Analysen. Als flächendeckende Indikatoren für den sozioökonomischen Status (SES) der Wohnbevölkerung wurden das jährliche Haushaltsnettoeinkommen (1 x 1 km2) sowie Miet- und Kaufspiegel in â‚ /m2 (Baublockebene) verwendet. Nach verschiedenen Schritten der Daten-aufbereitung (Baublockflächenkorrektur, Bevölkerungsgewichtung, räumliche Aggregation, SES-Standardisierung auf Gemeindeebene) wurden die jeweiligen Variablen für die drei Untersu-chungsräume verschnitten und anhand von räumlichen Regressionsmodellen sowie varianzana-lytischen Verfahren (ANOVA) auf statistische Zusammenhänge untersucht. In einigen Fällen wa-ren signifikante Zusammenhänge zwischen Feinstaub- und SES-Variablen festzustellen, aller-dings waren diese eher schwach ausgeprägt und nicht konsistent in den verschiedenen Untersu-chungsräumen. Letztlich ließen die Daten somit keine belastbaren Aussagen zur Differenzierung der Feinstaubexposition zu, denn die flächendeckend verfügbaren Variablen für den SES der Be-völkerung waren nur eingeschränkt aussagekräftig. Die Variable Haushaltseinkommen wurde zwar als inhaltlich gut geeigneter SES-Indikator bewertet, war räumlich aber zu grob aufgelöst um kleinräumige Unterschiede abzubilden. Miet- und Kaufspiegel wiederum boten zwar eine ge-eignete räumliche Auflösung, geben den sozioökonomischen Status der Bevölkerung jedoch in-haltlich nur eingeschränkt wieder. Für eine bundesweite Differenzierung der Exposition gegen-über Feinstaub nach SES bräuchten zukünftige Studien vor allem flächendeckende Datensätze in präziserer räumlicher Auflösung.
Zielsetzung: Differenzierung und Quantifizierung des Bodengefüges auf der Grundlage hochauflösender röntgen-computertomographischer Untersuchungen. Ableitung eines Gefügekennwertes aus der Standardabweichung des Meßwertes Hounsfieldeinheit bei Aggregierungs- und Disaggregierungsprozeduren. Der gewählte Ansatz lässt sich bei rasterbezogenen Datensätzen zur Beurteilung der Heterogenitätsstruktur in der Meso- und Makroskala verwenden, Messungen zur Beurteilung funktioneller Eigenschaften werden von Dr. Wendroth durchgeführt.
The production and marketing of high-value agricultural commodities - such as fruits, vegetables, and livestock products - has been an important source of cash income for small-scale farmers in the northern mountainous regions of Thailand and Vietnam. However, against the background of recent free trade agreements and market liberalization, there is increasing national and international competition, partly leading to significant price decreases. Given structural disadvantages of farmers in northern Thailand and Vietnam, it will be very difficult for them to achieve and maintain a competitive position in markets for undifferentiated high-value products. Therefore, product differentiation - in terms of health attributes (e.g., low-pesticide residues, free from diseases and pathogens), taste (e.g., indigenous livestock breeds), time (e.g., off-season production), or processing characteristics (e.g., packaging, drying, canning) - could be a promising alternative. Quality and safety attributes play an increasing role in domestic and international food trade. The additional value generated could lead to sustainable income growth in the small farm sector, but this potential will only materialize when appropriate institutional mechanisms help reduce transaction costs and allow a fair distribution of benefits. This subproject seeks to analyze how the production and marketing of high-value agricultural products with quality and safety attributes can contribute to pro-poor development in northern Thailand and Vietnam. Quality and safety attributes can only generate value when they directly respond to consumer demand. Furthermore, since they are often credence attributes, the product identity has to be preserved from farm to fork. Therefore, the analysis will cover the whole supply chain, from agricultural production to final household consumption. Interview-based surveys of farmers, intermediate agents, and consumers will be carried out in Thailand, and to a limited extent also in Vietnam. The data will be analyzed econometrically with regard to the structure of high-value markets, trends and their determinants, and efficiency and equity implications of different institutional arrangements (e.g., contract agriculture, supermarket procurement). Since in northern Vietnam, the marketing of high-value products is a relatively recent activity, markets for more traditional crops will be analyzed as well, to better understand the linkages between different cash-earning activities in the semi-subsistent farm households. Apart from their direct policy relevance, the results will contribute to the broader research direction of the economics of high-value agricultural markets in developing countries. Moreover, they will generate useful information for other subprojects of the Uplands Program.
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