Whether primordial bodies in the solar system possessed internally-generated dynamos is a fundamental constraint to understand the dynamics and timing of early planetary formation. Paleointensity studies on several meteorites reveal that their host planets possessed magnetic fields within an order-of magnitude of the present Earths field. Interpretation of paleointensity data relies heavily on fundamental knowledge of the magnetic properties of the magnetic carriers, such as the single to multidomain size threshold or how the saturation magnetization varies as a function of grain size, yet very little knowledge exists about these key parameters for some of the main magnetic recorders in meteorites: the iron-nickel alloys. Moreover, most meteorites have experienced some amount of shock during their histories, yet the consequence of even very small stresses on paleointensity data is poorly known.We wish to fill these gaps by magnetically characterizing Fe-Ni alloys as a function of grain size and by determining how absolute and relative paleointensity data are biased by strain levels lower than those petrologically observable (less than 4-5 GPa). For example, our preliminary work shows that an imposed stress of 0.6 GPa will reduce absolute paleointensity estimates by 46Prozent for single domain magnetite-bearing rocks. In general, paleointensity determinations possess inherent disadvantages regarding measurement precision and the inordinate amount of human time investment. We intend to overcome these limitations by extending and improving our fully automated magnetic workstation known as the SushiBar.
This project focuses on the long-term stability (or otherwise) of vegetation, based on a series of multi-proxy records in southern South America. We will build a network of sites suitable for high-resolution reconstructions of changes in vegetation since the Last Glacial Maximum, and use these to test a null hypothesis that changes in vegetation over the past 14,000 years are driven by internal dynamics rather than external forcing factors. The extent to which the null hypothesis can be falsified will reveal the degree to which we can expect to be able to predict how vegetation is affected by external events, including future climate change. The southern fringes of the South American landmass provide a rare opportunity to examine the development of moorland vegetation with sparse tree cover in a wet, cool temperate climate of the Southern Hemisphere. We present a record of changes in vegetation over the past 17,000 years, from a lake in extreme southern Chile (Isla Santa Inés, Magallanes region, 53°38.97S; 72°25.24W; Fontana, Bennett 2012: The Holocene), where human influence on vegetation is negligible. The western archipelago of Tierra del Fuego remained treeless for most of the Lateglacial period. Nothofagus may have survived the last glacial maximum at the eastern edge of the Magellan glaciers from where it spread southwestwards and established in the region at around 10,500 cal. yr BP. Nothofagus antarctica was likely the earlier colonizing tree in the western islands, followed shortly after by Nothofagus betuloides. At 9000 cal. yr BP moorland communities expanded at the expense of Nothofagus woodland. Simultaneously, Nothofagus species shifted to dominance of the evergreen Nothofagus betuloides and the Magellanic rain forest established in the region. Rapid and drastic vegetation changes occurred at 5200 cal. yr BP, after the Mt Burney MB2 eruption, including the expansion and establishment of Pilgerodendron uviferum and the development of mixed Nothofagus-Pilgerodendron-Drimys woodland. Scattered populations of Nothofagus, as they occur today in westernmost Tierra del Fuego may be a good analogue for Nothofagus populations during the Lateglacial in eastern sites. Climate, dispersal barriers and/or fire disturbance may have played a role controlling the postglacial spread of Nothofagus. Climate change during the Lateglacial and early Holocene was a prerequisite for the expansion of Nothofagus populations and may have controlled it at many sites in Tierra del Fuego. The delayed arrival at the site, with respect to the Holocene warming, may be due to dispersal barriers and/or fire disturbance at eastern sites, reducing the size of the source populations. The retreat of Nothofagus woodland after 9000 cal. yr BP may be due to competitive interactions with bog communities. Volcanic disturbance had a positive influence on the expansion of Pilgerodendron uviferum and facilitated the development of mixed Nothofagus-Pilgerodendron-Drimys woodland.
The geomagnetic field shields our habitat against solar wind and radiation from space. Due to the geometry of the field, the shielding in general is weakest at high latitudes. It is also anomalously weak in a region around the south Atlantic known as South Atlantic Anomaly (SAA), and the global dipole moment has been decreasing by nearly 10 percent since direct measurements of field intensity became possible in 1832. Due to our limited understanding of the geodynamo processes in Earths core, it is impossible to reliably predict the future evolution of both dipole moment and SAA over the coming decades. However, lack of magnetic field shielding as would be a consequence of further weakening of dipole moment and SAA region field intensity would cause increasing problems for modern technology, in particular satellites, which are vulnerable to radiation damage. A better understanding of the underlying processes is required to estimate the future development of magnetic field characteristics. The study of the past evolution of such characteristics based on historical, archeo- and paleomagnetic data, on time-scales of centuries to millennia, is essential to detect any recurrences and periodicities and provide new insights in dynamo processes in comparison to or in combination with numerical dynamo simulations. We propose to develop two new global spherical harmonic geomagnetic field models, spanning 1 and 10 kyrs, respectively, and designed in particular to study how long the uninterrupted decay of the dipole moment has been going on prior to 1832, and if the SAA is a recurring structure of the field.We will combine for the first time all available historical and archeomagnetic data, both directions and intensities, in a spherical harmonic model spanning the past 1000 years. Existing modelling methods will be adapted accordingly, and existing data bases will be complemented with newly published data. We will further acquire some new archeomagnetic data from the Cape Verde islands from historical times to better constrain the early evolution of the present-day SAA. In order to study the long-term field evolution and possible recurrences of similar weak field structures in this region, we will produce new paleomagnetic records from available marine sediment cores off the coasts of West Africa, Brazil and Chile. This region is weakly constrained in previous millennial scale models. Apart from our main aim to gain better insights into the previous evolution of dipole moment and SAA, the models will be used to study relations between dipole and non-dipole field contributions, hemispheric symmetries and large-scale flux patterns at the core-mantle boundary. These observational findings will provide new insights into geodynamo processes when compared with numerical dynamo simulation results.Moreover, the models can be used to estimate past geomagnetic shielding above Earths surface against solar wind and for nuclide production from galactic cosmic rays.
The present-day configuration of Indonesia and SE Asia is the results of a long history of tectonic movements, volcanisms and global eustatic sea-level changes. Not indifferent to these dynamics, fauna and flora have been evolving and dispersing following a complicate pattern of continent-sea changes to form what are today defined as Sundaland and Wallacea biogeographical regions. The modern intraannual climate of Indonesia is generally described as tropical, seasonally wet with seasonal reversals of prevailing low-level winds (Asian-Australian monsoon). However at the interannual scale a range of influences operating over varying time scales affect the local climate in respect of temporal and spatial distribution of rainfall. Vegetation generally reflects climate and to simplify it is possible to distinguish three main ecological elements in the flora of Malaysia: everwet tropical, seasonally dry tropical (monsoon) and montane. Within those major ecological groups, a wide range of specific local conditions caused a complex biogeography which has and still attract the attention of botanists and biogeographers worldwide. Being one of the richest regions in the Worlds in terms of species endemism and biodiversity, Indonesia has recently gone through intensive transformation of previously rural/natural lands for intensive agriculture (oil palm, rubber, cocoa plantations and rice fields). Climate change represents an additional stress. Projected climate changes in the region include strengthening of monsoon circulation and increase in the frequency and magnitude of extreme rainfall and drought events. The ecological consequences of these scenarios are hard to predict. Within the context of sustainable management of conservation areas and agro-landscapes, Holocene palaeoecological and palynological studies provide a valuable contribution by showing how the natural vegetation present at the location has changed as a consequence of climate variability in the long-term (e.g. the Mid-Holocene moisture maximum, the modern ENSO onset, Little Ice Age etc.). The final aim of my PhD research is to compare the Holocene history of Jambi province and Central Sulawesi. In particular: - Reconstructing past vegetation, plant diversity and climate dynamics in the two study areas Jambi (Sumatra) and Lore Lindu National Park (Sulawesi) - Comparing the ecological responses of lowland monsoon swampy rainforest (Sumatra) and everwet montane rainforests (Sulawesi) to environmental variability (vulnerability/resilience) - Investigating the history of human impact on the landscape (shifting cultivation, slash and burn, crop cultivation, rubber and palm oil plantation) - Assessing the impact and role of droughts (El Niño) and fires - Adding a historical perspective to the evaluation of current and future changes.
Prehistoric pits are filled with ancient topsoil material, which has been preserved there over millennia. A characteristic of these pit fillings is that their colour is different depending on the time the soil material was relocated. Soil colour is the result of soil forming processes and soil properties, and it could therefore indicate the soil characteristics present during that specific period. To the best of our knowledge, no investigation analysed and explained the reasons for these soil colour changes over time. The proposed project will investigate soil parameters from pit fillings of different archaeological periods in the loess area of the Lower Rhine Basin (NW-Germany). It aims to implement the measurement of colour spectra as a novel analytical tool for the rapid analyses of a high number of soil samples: the main goal is to relate highresolution colour data measured by a spectrophotometer to soil parameters that were analysed by conventional pedogenic methods and by mid infrared spectroscopy (MIRS), with a main focus on charred organic matter (BPCAs). This tool would enable us to quantify the variation of soil properties over a timescale of several millennia, during different prehistoric periods at regional scale and for loess soils in general. Detailed information concerning changing soil properties on a regional scale is necessary to determine past soil quality and it helps to increase our understanding of prehistoric soil cultivation practices. Furthermore, these information could also help to increase our understanding about agricultural systems in different archaeological periods.
The formation of biogeochemical interfaces in soils is controlled, among other factors, by the type of particle surfaces present and the assemblage of organic matter and mineral particles. Therefore, the formation and maturation of interfaces is studied with artificial soils which are produced in long-term biogeochemical laboratory incubation experiments (3, 6, 12, 18 months. Clay minerals, iron oxides and charcoal are used as major model components controlling the formation of interfaces because they exhibit high surface area and microporosity. Soil interface characteristics have been analyzed by several groups involved in the priority program for formation of organo-mineral interfaces, sorptive and thermal interface properties, microbial community structure and function. Already after 6 months of incubation, the artificial soils exhibited different properties in relation to their composition. A unique dataset evolves on the development and the dynamics of interfaces in soil in the different projects contributing to this experiment. An integrated analysis based on a conceptual model and multivariate statistics will help to understand overall processes leading to the biogeochemical properties of interfaces in soil, that are the basis for their functions in ecosystems. Therefore, we propose to establish an integrative project for the evaluation of data obtained and for publication of synergistic work, which will bring the results to a higher level of understanding.
(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.
Introduction: In Malaysia, excessive nutrients from livestock waste management systems are currently released to the environment. Particularly, large amounts of manure from intensive pig production areas are being excreted daily and are not being fully utilised. Alternatively, the excess manure can be applied as an organic fertiliser source in neighbouring cropping systems on the small landholdings of the pig farms to improve soil fertility so that its nutrients will be available for crop uptake instead of being discharged into water streams. Thus, there is a need for better tools to analyse the present situation, to evaluate and monitor alternative livestock production systems and manure management scenarios, and to support farmers in the proper management of manure and fertiliser application. Such tools are essential to quantify, and assess nutrient fluxes, manure quality and content, manure storage and application rate to the land as well as its environmental effects. Several computer models of animal waste management systems to assist producers and authorities are now available. However, it is felt that more development is needed to adopt such models to the humid tropics and conditions of Malaysia and other developing countries in the region. Objectives: The aim is to develop a novel model to evaluate nutrient emission scenarios and the impact of livestock waste at the landscape or regional level in humid tropics. The study will link and improve existing models to evaluate emission of N to the atmosphere, and leaching of nutrients to groundwater and surface water. The simulation outputs of the models will be integrated with a GIS spatial analysis to model the distribution of nutrient emission, leaching and appropriate manure application on neighbouring crop lands and as an information and decision support tool for the relevant users.
Perennial fodder cropping potentially increases subsoil biopore density by formation of extensive root systems and temporary soil rest. We will quantify root length density, earthworm abundance and biopore size classes after Medicago sativa, Cichorium intybus and Festuca arundinacea grown for 1, 2 and 3 years respectively in the applied research unit's Central Field Trial (CeFiT) which is established and maintained by our working group. Shoot parameters including transpiration, gas exchange and chlorophyll fluorescence will frequently be recorded. Precrop effects on oilseed rape and cereals will be quantified with regard to crop yield, nutrient transfer and H2-release. The soil associated with biopores (i.e. the driloshpere) is generally rich in nutrients as compared to the bulk soil and is therefore supposed to be a potential hot spot for nutrient acquisition. However, contact areas between roots and the pore wall have been reported to be low. It is still unclear to which extent the nutrients present in the drilosphere are used and which potential relevance subsoil biopores may have for the nutrient supply of crops. We will use a flexible videoscope to determine the root-soil contact in biopores. Nitrogen input into the drilosphere by earthworms and potential re-uptake of nitrogen from the drilosphere by subsequent crops with different rooting systems (oilseed rape vs. cereals) will be quantified using 15N as a tracer.
In the Bavarian Forest National Park a brief, but intense storm event on 1 August 1983 created large windfall areas. The windfall ecosystems within the protection zone of the park were left develop without interference; outside this zone windfall areas were cleared of dead wood but not afforested. A set of permanent plots (transect design with 10 to 10 m plots) was established in 1988 in spruce forests of wet and cool valley bottoms in order to document vegetation development. Resampling shall take place every five years; up to now it was done in 1993 and 1998. On cleared areas an initial raspberry (Rubus idaeus) shrub community was followed by pioneer birch (Betula pubescens, B. pendula) woodland, a sequence well known from managed forest stands. In contrast to this, these two stages were restricted to root plates of fallen trees in uncleared windfalls; here shade-tolerant tree species of the terminal forest stages established rather quickly from saplings that had already been present in the preceeding forest stand. Soil surface disturbances are identified to be causal to the management pathway of forest development, wereas the untouched pathway is caused by relatively low disturbance levels. The simulation model FORSKA-M is used to analyse different options of further stand development with a simulation time period of one hundred years.
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