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.
Background: Ghanas transition forests, neighbouring savannahs and timber plantations in the Ashanti region face a constant degradation due to the increased occurrence of fires. In most cases the fires are deliberately set by rural people for hunting purposes. Main target is a cane rat, here called grasscutter (Thryonomys swinderianus), whose bushmeat is highly esteemed throughout the country. The animal is a wild herbivorous rodent of subhumid areas in Africa south of the Sahara. The grasscutter meat is an important source of animal protein. Existing high-value timber plantations (mainly Teak, Tectona grandis) are affected by fires for hunting purposes. Thus resulting in growth reduction, loss of biomass or even complete destruction of the forest stands. It became obvious that solutions had to be sought for the reduction of the fire risk. Objectives: Since 2004 the Institute for World Forestry of the Federal Research Centre for Forestry and Forest Products, Hamburg, Germany is cooperating with a Ghanaian timber plantation company (DuPaul Wood Treatment Ltd.) the German Foundation for Forest Conservation in Africa (Stiftung Walderhaltung in Afrika) and the Center for International Migration with the purpose to improve the livelihood of the rural population in the surroundings of the forest plantation sites and simultaneously to safeguard and improve the timber plantations. The introduction of grasscutter rearing systems to local farmers accompanied by permanent agricultural and agroforestry practices appeared to be a promising approach for the prevention of fires in the susceptible areas. Additionally a functioning grasscutter breeding system could contribute to the improvement of food security, development of income sources and the alleviation of poverty. The following measures are implemented: - Identification of farmers interested in grasscutter captive breeding, - Implementation of training courses for farmers on grasscutter rearing, - Delivery of breeding animals, - Supervision of rearing conditions by project staff, - Development of a local extension service for monitoring activities, - Evaluation of structures for grasscutter meat marketing. Results: After identification of key persons for animal rearing training courses were successfully passed and animals were delivered subsequently. Further investigations will evaluate the effects of the grasscutter rearing in the project region. This will be assessed through the - Acceptance of grasscutter rearing by farmers, - Success of the animal caging, - Reproduction rate, - Meat quality, - Marketing success of meat, - Reduction of fire in the vicinity of the timber plantations, - Improvement of peoples livelihood.
Verschiedene Stressfaktoren führen zu oxidativem Stress im Zellgeschehen, d.h. es kommt zur Lipidperoxidation und damit zur Membranschädigung. Die Bestimmung des oxidativen Stresszustands spielt in tierischem und pflanzlichen Gewebe eine große Rolle bei der Beurteilung des zellulären Vitalitätszustandes oder des Entwicklungszustands im Krankheitsgeschehen. Eine Methode, die ohne aufwendige Analysenmethoden eine sichere Basis für die Beurteilung des oxidativen Stresszustands verschiedenster Zellgewebe liefern kann, ist die Thermolumineszenz (TL), die in diesem Vorhaben zur Serienreife geführt werden soll. Für grünes Gewebe ermöglicht diese Methode eine Beurteilung sowohl des Zustandes des Photosyntheseapparates als auch des oxidativen Stresszustandes. Die Thermolumineszenzsignale, die den oxidativen Stresszustand charakterisieren, werden nicht nur von Chlorophyllen, sondern auch von anderen Molekülspezies induziert, so dass auch tierisches Gewebe auf Lipidperoxidationen untersucht werden kann.
Recent and predicted increases in extremely dry and hot summers emphasise the need for silvicultural approaches to increase the drought tolerance of existing forests in the short-term, before adaptation through species changes may be possible. We aim to investigate whether resistance during droughts, as well as the recovery following drought events (resilience), can be increased by allocating more growing space to individual trees through thinning. Thinning increases access of promoted trees to soil stored water, as long as this is available. However, these trees may also be disadvantaged through a higher transpirational surface, or the increased neighbourhood competition by ground vegetation. To assess whether trees with different growing space differ in drought tolerance, tree discs and cores from thinning experiments of Pinus sylvestris and Pseudotsuga menziesii stands will be used to examine transpirational stress and growth reduction during previous droughts as well as their subsequent recovery. Dendroecology and stable isotopes of carbon and oxygen in tree-rings will be used to quantify how assimilation rate and stomatal conductance were altered through thinning. The results will provide crucial information for the development of short-term silvicultural adaptation strategies to adapt forest ecosystems to climate change. In addition, this study will improve our understanding of the relationship between resistance and resilience of trees in relation to extreme stress events.
Water is an intrinsic component of ecosystems acting as a key agent of lateral transport for particulate and dissolved nutrients, forcing energy transfers, triggering erosion, and driving biodiversity patterns. Given the drastic impact of land use and climate change on any of these components and the vulnerability of Ecuadorian ecosystems with regard to this global change, indicators are required that not merely describe the structural condition of ecosystems, but rather capture the functional relations and processes. This project aims at investigating a set of such functional indicators from the fields of hydrology and biogeochemistry. In particular we will investigate (1) flow regime and timing, (2) nutrient cycling and flux rates, and (3) sediment fluxes as likely indicators. For assessing flow regime and timing we will concentrate on studying stable water isotopes to estimate mean transit time distributions that are likely to be impacted by changes in rainfall patterns and land use. Hysteresis loops of nitrate concentrations and calculated flux rates will be used as functional indicators for nutrient fluxes, most likely to be altered by changes in temperature as well as by land use and management. Finally, sediment fluxes will be measured to indicate surface runoff contribution to total discharge, mainly influenced by intensity of rainfall as well as land use. Monitoring of (1) will be based on intensive sampling campaigns of stable water isotopes in stream water and precipitation, while for (2) and (3) we plan to install automatic, high temporal-resolution field analytical instruments. Based on the data obtained by this intensive, bust cost effective monitoring, we will develop the functional indicators. This also provides a solid database for process-based model development. Models that are able to simulate these indicators are needed to enable projections into the future and to investigate the resilience of Ecuadorian landscape to global change. For the intended model set up we will couple the Catchment Modeling Framework, the biogeochemical LandscapeDNDC model and semi-empirical models for aquatic diversity. Global change scenarios will then be analyzed to capture the likely reaction of functional indicators. Finally, we will contribute to the written guidelines for developing a comprehensive monitoring program for biodiversity and ecosystem functions. Right from the beginning we will cooperate with four SENESCYT companion projects and three local non-university partners to ensure that the developed monitoring program will be appreciated by locals and stakeholders. Monitoring and modelling will focus on all three research areas in the Páramo (Cajas National Park), the dry forest (Reserva Laipuna) and the tropical montane cloud forest (Reserva Biologica San Francisco).
Background and Objectives: The project area is located in the Ashanti Region of Ghana / West Africa in the transition zone of the moist semideciduous forest and tropical savannah zone. Main land use in this region is subsistence agriculture with large fallow areas. As an alternative land-use, forest plantations are under development by the Ghanaian wood processing company DuPaul Wood Treatment Ltd. Labourers from the surrounding villages are employed as permanent or casual plantation workers. Within three forest plantation projects of approximately 6,000 ha, DuPaul offers an area of 164 ha (referred to as Papasi Plantation) - which is mainly planted with Teak (Tectona grandis) - for research purposes. In return, the company expects consultations to improve the management for sustainable timber and pole production with exotic and native tree species. Results: In a first research approach, the Papasi Plantation was assessed in terms of vegetation classification, timber resources (in qualitative and quantitative terms) and soil and site conditions. A permanent sampling plot system was established to enable long-term monitoring of stand dynamics including observation of stand response to silvicultural treatments. Site conditions are ideally suited for Teak and some stands show exceptionally good growth performances. However, poor weed management and a lack of fire control and silvicultural management led to high mortality and poor growth performance of some stands, resulting in relative low overall growth averages. In a second step, a social baseline study was carried out in the surrounding villages and identified landowner conflicts between some villagers and DuPaul, which could be one reason for the fire damages. However, the study also revealed a general interest for collaboration in agroforestry on DuPaul land on both sides. Thirdly, a silvicultural management concept was elaborated and an improved integration of the rural population into DuPaul's forest plantation projects is already initiated. If landowner conflicts can be solved, the development of forest plantations can contribute significantly to the economic income of rural households while environmental benefits provide long-term opportunities for sustainable development of the region. Funding: GTZ supported PPP-Measure, Foundation
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.
The German dairy value chain is subject to profound structural change resulting in increasingly dominant agents at all stages of the chain, i.e. at the farm level, at the processors' level and at the retailers' level. In particular, the consolidation of retailers has increased retailers' bargaining power vis-à-vis their suppliers. Against this background, the overall objective of this subproject is to analyze the structural change in the dairy sector, particularly at the processors' level, by taking into account firms' strategic interactions along the entire dairy value chain. So far, there exists no theoretical workhorse model that allows for the analysis of interdependencies in a three-layer structure where imperfect competition is considered at all three stages. We aim to close this gap to understand how an increasingly dominant retail industry influences strategic decisions at the dairy processors' level which, in turn, may affect dairy farmers. Building upon a three-layer approach, we first examine whether processors have merger incentives to counter the retailers' bargaining power. We then analyze the differences between cooperatives and for-profit firms concerning their decision on product quality and the number of dairy suppliers. Finally, we assess the implications for upstream farmers which rounds off the picture of structural change in the German dairy sector.
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.
Die Relevanz von Unsicherheitsanalysen in der Hydrogeology ist vergleichsweise groß aufgrund der Tatsache, dass Aquifereigenschaften oft sehr heterogen sind und meist nur wenige in-situ Daten zu deren Charakterisierung zu Verfügung stehen. Die Bayes'sche Statistik ist hervorragend geeignet, um solche Analysen durch zu führen. Verglichen mit klassicher, frequentistischer Statistik lassen sich Unsicherheiten deutlich einfacher modellieren, können Wahrscheinlichkeitsaussagen auch für Einzelfälle getroffen werden und Hintergrundwissen von ex-situ Messungen konsistent mittels der A-priori-Verteilung repräsentiert werden. In der Praxis werden allerdings sowohl Unsicherheitsanalyse wie auch Aquifercharakterisierung nur selten mit Bayes'schen Methoden durchgeführt. Der wahrscheinlich wichtigste Hinderungsgrund ist dabei die Schwierigkeit die A-priori-Verteilung zu bestimmen, welche die (Un)sicherheit bzgl. der Aquifereigenschaften ausdrückt bevor in-situ Daten berücksichtigt wurden. In diesem Projekt werde ich dieses Problem angehen, in dem ich (i) einen Arbeitsablauf zur Bestimmung der A-priori-Verteilung ausarbeite und (ii) den Einfluss solch einer Verteilung untersuche. Im ersten Teil werde ich Gebrauch machen von dem hierarchischem Bayes'schen Modell zur Bestimmung von A-priori-Verteilungen, welches in einer Zusammenarbeit zwischen der Arbeitsgruppe von Prof. Yoram Rubin und mir entwickelt wurde. Um dieses Modell mit einem umfangreichen und repräsentativen Datensatz zu versorgen, werde ich es mit einer etablierten Datenbank hydrogeologischer Messungen koppeln. Dadurch wird es möglich informative A-priori-Verteilungen zu bestimmen, welche das Hintergrundwissen von ex-situ Messungen repräsentieren. Im zweiten Teil werde ich den Einfluss dieser informativen A-priori-Verteilungen auf Fragen der Unsicherheitsreduktion und des resultierenden Datenwertes untersuchen. Dazu werde ich eine Reihe von klassischen Meß- und Interpretationsverfahren mit einem Bayes'schen Aquivalent vergleichen. Dabei wird vor allem die Frage des relativen Datenwertes im Mittelpunkt stehen. Relativ bezieht sich hierbei auf den Einfluss von in-situ Daten verglichen mit den ex-situ Daten, welche in der A-priori-Verteilung enthalten sind. Die Ergebnisse dieses Projektes werden demnach helfen einen konsistenten und reproduzierbaren Arbeitsablauf zur Ableitung hydrogeologischer A-priori-Verteilungen zu etablieren sowie deren Einfluss auf Fragen der Unsicherheitsreduktion und des relativen Datenwertes von in-situ Messungen zu bestimmen. Des Weiteren werden die Ergebnisse dazu dienen die Vorteile sowie mögliche Nachteile Bayes'scher Methoden für die hydrogeologische Unsicherheitsanalyse zu verstehen. Dadurch werden die Herausforderungen klar, die zu überwinden sind, um Bayes'sche Statistik zu einem allgemein genutztem Standard für hydrogeologische Unsicherheitsanalysen werden zu lassen.
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