Dissolved organic matter (DOM) is one major source of subsoil organic matter (OM). P5 aims at quantifying the impact of DOM input, transport, and transformation to the OC storage in the subsoil environment. The central hypotheses of this proposal are that in matric soil the increasing 14C age of organic carbon (OC) with soil depth is due to a cascade effect, thus, leading to old OC in young subsoil, whereas within preferential flowpaths sorptive stabilization is weak, and young and bioa-vailable DOM is translocated to the subsoil at high quantities. These hypotheses will be tested by a combination of DOC flux measurements with the comparative analysis of the composition and the turnover of DOM and mineral-associated OM. The work programme utilizes a DOM monitoring at the Grinderwald subsoil observatory, supplemented by defined experiments under field and labora-tory conditions, and laboratory DOM leaching experiments on soils of regional variability. A central aspect of the experiments is the link of a 13C-leaf litter labelling experiment to the 14C age of DOM and OM. With that P5 contributes to the grand goal of the research unit and addresses the general hypotheses that subsoil OM largely consists of displaced and old OM from overlying horizons, the sorption capacity of DOM and the pool size of mineral-associated OM are controlled by interaction with minerals, and that preferential flowpaths represent 'hot spots' of high substrate availability.
Flowering time (FTi) genes play a key role as regulators of complex gene expression networks, and the influence of these networks on other complex systems means that FTi gene expression triggers a cascade of regulatory effects with a broad global effect on plant development. Hence, allelic and expression differences in FTi genes can play a central role in phenotypic variation throughput the plant lifecycle. A prime example for this is found in Brassica napus, a phenotypically and genetically diverse species with enormous variation in vernalisation requirement and flowering traits. The species includes oilseed rape (canola), one of the most important oilseed crops worldwide. Previously we have identified QTL clusters related to plant development, seed yield and heterosis in winter oilseed rape that seem to be conserved in diverse genetic backgrounds. We suspect that these QTL are controlled by global regulatory genes that influence numerous traits at different developmental stages. Interestingly, many of the QTL clusters for yield and biomass heterosis appear to correspond to the positions of meta-QTL for FTi in spring-type and/or winter-type B. napus. Based on the hypothesis that diversity in FTi genes has a key influence on plant development and yield, the aim of this study is a detailed analysis of DNA sequence variation in regulatory FTi genes in B. napus, combined with an investigation of associations between FTi gene haplotypes, developmental traits, yield components and seed yield.
In diesem Forschungsvorhaben sollen die Effekte von Habitatfragmentierung auf Nahrungsnetze untersucht werden. Als Modellsystem dient die trophische Kaskade 'Pflanze - Pilz/Blattschneiderameise - Prädator/Parasit' im Atlantischen Regenwald Brasiliens, eines der weltweit am stärksten gefährdeten Waldökosysteme. Seit langem wird eine Zunahme der Dichte und Diversität von Blattschneiderameisen (BSA) in gestörten Habitaten beobachtet. Die Gründe hierfür sind jedoch weitgehend ungeklärt. Die diesem Projekt zugrunde liegenden Arbeitshypothesen basieren auf der Annahme, dass sowohl die Kontrolle durch Resourcenqualität als auch durch Prädation und Parasitismus in fragmentierten Wäldern weniger effizient sind als in geschlossenen Waldsystemen. Zur Beurteilung der bottom-up-Kontrolle wird daher untersucht, ob (1) pflanzliche Abwehr, (2) BSA Nahrungsbreite, (3) -Aktionsradius und (4) -Herbivorierate in Waldfragmenten zunehmen. Die Effizienz der top-down Kontrolle wird darüber bestimmt ob (1) Prädationsrate sowie (2) Ameisen- und Pilzparasitierung in kontinuierlichen Wäldern zunehmen und (3) der Koloniegründungserfolg abnimmt. Die Evaluierung der einzelnen Parameter und ihrer relativen Bedeutung soll das Verständnis der funktionellen Rolle trophischer Interaktionen am Beispiel dieser Schlüsselarten neotropischer Ökosysteme verbessern
Submerged macrophytes stabilize the clear water regime in shallow lakes, but were often completely lost during eutrophication resulting in a shift to the turbid, phytoplankton-dominated regime. Re-colonization of submerged macrophytes often failed after reoligotrophication of shallow lakes despite an increased light availability in spring. Shading by periphyton is supposed to be one of the reasons. Periphyton biomass in eutrophic lakes has been suggested to be potentially controlled by a cascading effect of fish predation on periphyton-grazing invertebrates. Direct experimental evidence of this top-down control of periphyton and its relevance for submerged macrophyte re-colonization, however, is still lacking. We plan a combination of field and laboratory experiments and modeling to unravel the role of periphyton shading for the development of submerged macrophytes as a base for sustainable management of shallow eutrophic lakes. The focus is on in situ evidence of topdown control of periphyton by a fish-invertebrates-cascade, the shading impact during early stages of macrophyte development and the impact of timing of the clear water phase and tuber sprouting in spring for a mismatch between periphyton and macrophyte growth.
Ecological use of wood resources in Switzerland In this project, researchers develop decision-making aids on environmental policy issues for actors in politics and industry. In so doing, they consider the entire life cycle of wood: from forestry via manufacturing and multiple use of wood products (cascade use) through to its use as a source of energy, or its disposal. Background Rising prices of resources and environmental problems call for an efficient use of renewable resources both for material and energetic applications. Thus future generations will not be able to afford to underuse the resource wood, as is still the case today. In order to make better use of wood, models are needed that not only incorporate mass fluxes, but also provide a comprehensive and spatially resolved assessment of the environment. Aim The aim of the project is to develop strategies that facilitate the sustainable and efficient use of wood resources in Switzerland. For this purpose, the researchers are studying existing and potential future value chains with the help of dynamic and spatially-resolved material flow and life-cycle analyses, improving methods for the assessment of ecological impacts of forestry and wood use as well as evaluating new technologies and giving feedback to their developers within the scope of NRP 66. The insights gained in the project will help the researchers to develop and assess different wood usage scenarios, from which they will derive strategies for decision-makers in politics, industry, forestry and research. Significance The project will result in a software tool which can be used to test nascent technologies in respect of their ecological consequences. First users of the new tool will be researchers developing new technologies and products in NRP 66 partner projects. Based on the knowledge gained through the research work, political strategies for an ecologically sound management of wood as a resource will be proposed.
The spatial and temporal distribution of reduced and oxidized carbon (e.g. CH4 and CO2), nitrogen, iron, manganese, and sulphur species is commonly used to analyse microbial mediated electron transfer reactions and to characterise the biogeochemical conditions in contaminated aquifers. However, the linkage of carbon, nitrogen, iron an sulphur cycles in aquifers with respect to electron flow mediated by chemolithoautotrophic communities is not thoroughly investigated yet. Reduced products from electron transfer reactions such as NH4+, Fe2+, S2-, and CH4 have the potential to support chemolithoautotrophic and heterotrophic microbial processes as electron donors, thus linking the nitrogen iron sulphur and carbon cycles in aquifers in various microbial mediated interactions. Once formed during organic carbon degradation, methane, ammonia or reduced sulphur species will be transported in the ground water, will leave the zone of formation and become potent electron donors for microbial processes in other geochemical zones of the aquifer. The microflora using these electron donors may compete for electron acceptors with organisms degrading contaminants. We will investigate the cascades of redox reactions coupling electron donor-acceptor interaction of heterotrophic and chemolithoautotrophic microbial processes at geochemical gradients. In particular, the transport of methane, ammonia and reduced sulphur species linking the metabolism of microbial communities over certain distance will be studied with respect to the regulation of carbon and electron lux in contaminated aquifers.
Ziel des Gesamtvorhabens ist es, eine modular aufgebaute Prozesskette zu entwickeln und zu realisieren, mit der die ausgewählten Hochtechnologiemetalle Gallium (Ga), Germanium (Ge), Neodym (Nd) und Tantal (Ta) dezentral zurückgewonnen werden können. Dies soll über eine Kaskade von Behandlungsschritten zur Aufkonzentration und Rückgewinnung dieser Metalle in industriell nutzbarer Form aus Elektro- und Elektronikaltgeräten (EAG) erfolgen. Als Inputstrom werden gemischte EAG der Sammelgruppen 3 und 5 adressiert. Zunächst werden im Projekt Fraktionen aus der mechanischen Aufbereitung dieser EAG identifiziert, welche die Zielmetalle in angereicherter Form enthalten. Die nachfolgende Prozesskette besteht aus den Kernkomponenten Vorbehandlung des Inputmaterials, thermo-chemische Stofftrennung, mechanische Aufbereitung des festen Pyrolyseprodukts und Metallfraktionierung durch Biosorption und -fällung sowie Elektrolyse. Durch die so gestaltete Kaskade werden die Zielmetalle mit jedem Prozessschritt sukzessive aufkonzentriert und schließlich gediegen in Reinmetallform, als Legierung oder, entsprechend der gewünschten Verwendung, als sonstige definierte chemische Verbindung zurückgewonnen. Durch Einbindung eines im Metallhandel tätigen Projektpartners wird dabei berücksichtigt, dass für die Produkte ein potentieller Markt besteht. Jeder Abschnitt der Prozesskette stellt mindestens einen neuartigen Ansatz dar. Durch die angestrebte dezentrale Rückgewinnung von Hochtechnologiemetallen können die End-of-Life-Recyclingraten signifikant erhöht werden, ohne bestehende Verwertungswege für Massen- und Edelmetalle zu beeinflussen. Im gesamten Projekt wird eine vollständige Verwertung aller Nebenprodukte angestrebt. So werden beispielsweise die bei der thermo-chemischen Stofftrennung generierten flüssigen und gasförmigen Produkte zur Versorgung der Prozesskette mit Strom und Wärme genutzt. Zur Sicherstellung einer nachhaltigen Entwicklung wird die gesamte Aufbereitungskette hinsichtlich ökonomischer, soziopolitischer und ökologischer Aspekte gegenüber der Primärgewinnung bewertet.
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