Das Projekt "Root distribution and dynamics and their contribution to subsoil C-fluxes" wird vom Umweltbundesamt gefördert und von Universität Göttingen, Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Abteilung Pflanzenökologie und Ökosystemforschung durchgeführt. It has been suggested that dying and decaying fine roots and root exudation represent important, if not the most important, sources of soil organic carbon (SOC) in forest soils. This may be especially true for deep-reaching roots in the subsoil, but precise data to prove this assumption are lacking. This subproject (1) examines the distribution and abundance of fine roots (greater than 2 mm diameter) and coarse roots (greater than 2 mm) in the subsoil to 240 cm depth of the three subsoil observatories in a mature European beech (Fagus sylvatica) stand, (2) quantifies the turnover of beech fine roots by direct observation (mini-rhizotron approach), (3) measures the decomposition of dead fine root mass in different soil depths, and (4) quantifies root exudation and the N-uptake potential with novel techniques under in situ conditions with the aim (i) to quantify the C flux to the SOC pool upon root death in the subsoil, (ii) to obtain a quantitative estimate of root exudation in the subsoil, and (iii) to assess the uptake activity of fine roots in the subsoil as compared to roots in the topsoil. Key methods applied are (a) the microscopic distinction between live and dead fine root mass, (b) the estimation of fine and coarse root age by the 14C bomb approach and annual ring counting in roots, (c) the direct observation of the formation and disappearance of fine roots in rhizotron tubes by sequential root imaging (CI-600 system, CID) and the calculation of root turnover, (d) the measurement of root litter decomposition using litter bags under field and controlled laboratory conditions, (e) the estimation of root N-uptake capacity by exposing intact fine roots to 15NH4+ and 15NO3- solutions, and (f) the measurement of root exudation by exposing intact fine root branches to trap solutions in cuvettes in the field and analysing for carbohydrates and amino acids by HPLC and Py-FIMS (cooperation with Prof. A. Fischer, University of Trier). The obtained data will be analysed for differences in root abundance and activity between subsoil (100-200 cm) and topsoil (0-20 cm) and will be related to soil chemical and soil biological data collected by the partner projects that may control root turnover and exudation in the subsoil. In a supplementary study, fine root biomass distribution and root turnover will also be studied at the four additional beech sites for examining root-borne C fluxes in the subsoil of beech forests under contrasting soil conditions of different geological substrates (Triassic limestone and sandstone, Quaternary sand and loess deposits).
Das Projekt "Sub project: Dynamics of Mid-latitude/ Mediterranean climate during the last 150 ka: Black Sea /Northern Anatolian Paleoenvironmental Reconstructions (DynNAP)" wird vom Umweltbundesamt gefördert und von Universität Göttingen, Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Abteilung für Palynologie und Klimadynamik durchgeführt. As an isolated marginal sea, the Black Sea reacted particularly sensitive to paleoclimatic and paleoenvironmental changes and on both global and regional scales. In spite of its unique potential for high resolution paleoclimate reconstructions, late Quaternary sediment sequences of the Black Sea have only subordinately been studied with respect to paleoclimatic questions. This is somewhat surprising considering the key-geographic location of the Black Sea, where climate is strongly affected by two major climate systems; the North Atlantic/Siberian pressure system in winter and the Indian monsoon in summer. Highly-resolved and precisely dated paleoclimate records are crucial for reconstructing past regional climate variability, which can then be compared to paleoclimate records from the North Atlantic, Europe and the Indian monsoon domain. Several core sites in the Black Sea along the North-Anatolian rim can provide records of vegetation dynamics and changing precipitation regimes in the Anatolian hinterland as well as paleoceanographic/ paleolimnologic data of environmental changes in the marine/limnic Black Sea system itself. Uranium-series dated stalagmites from Sofular Cave located at the Black Sea coast in north-western Turkey will provide, as terrestrial counterpart, long complementary paleorecords of changes in vegetation and precipitation. When combined, such records will allow us to better quantify the far-field effects of North Atlantic climate and Indian monsoon during the Holocene, Eemian and the last two glacial/interglacial transitions (T1 and T2).
Das Projekt "10Be Surface Exposure Dating in the Central Andes" wird vom Umweltbundesamt gefördert und von Universität Bern, Geographisches Institut durchgeführt. Surface exposure dating has become an important tool for glacial and climate reconstructions in recent years. Especially in arid mountain areas, where organic material for radiocarbon dating is scarce, it is now possible to establish precise glacial chronologies from moraine deposits. In previous and ongoing SNF-projects, we have mapped moraines in many parts of the Central Andes. Only recently we started to apply surface exposure dating using in-situ 10Be in the Cordillera Real and Cochabamba, Bolivia (ca.15 S), and in the Andes of Central Chile/Argentina (30-40 S). We expect to get important insights into past changes of the tropical and the ek-tropical atmospheric circulation, i.e. the westerlies in the south and the South American Summer Monsoon in the north. First results from northern Chile (ca.30 S) show that glaciers advanced ca.30 ka BP and again between ca.14 and 12 ka BP. Moisture advection during the temperature minimum of the global LGM (last glacial maximum: 18-20 ka BP) seems to have been insufficient to allow considerable glacial extents. Preliminary exposure ages indicate that glaciers in the Cordillera Real and Cochabamba did not only advance during the LGM, triggered by temperature reductions, but also during the Late Glacial and the Early Holocene - likely due to increased precipitation during the 'Tauca' and 'Coipasa' wet phases (18-14 and 13-11 ka BP). Although our preliminary results are promising and show the high potential of surface exposure dating for Late Quaternary glacier and climate reconstruction, three aspects are evident that currently limit the paleoclimatic interpretations: I.) our preliminary chronologies in Bolivia are based on too few exposure ages II.) there is a gap of glacial chronologies in NW-Argentina and South Bolivia III.) up to now there is a complete absence of calibration sites in the Central Andes In order to further assess the role of temperature and the tropical and ek-tropical moisture sources, respectively, on the glaciation history in the Central Andes, we intend to apply surface exposure dating in six selected research areas in NW-Argentina (4) and Bolivia (2). In combination with the glacier-climate model, which has previously been developed in our working group, the exposure age chronologies will allow the quantitative reconstruction of temperature and precipitation conditions for the dated glacial stages. An important focus of the proposed project is to carry out calibration studies. This implies the necessity to independently date glacial deposits using for example radiocarbon dating of lake sediments. This is the only way to minimize the systematic uncertainties of the exposure ages and thus to confirm the paleoclimatic interpretations.
Das Projekt "INQUA Project 1216 - RAISIN: Rates of soil forming processes obtained from soils and paleosols in well-defined settings" wird vom Umweltbundesamt gefördert und von Universität Zürich, Geographisches Institut durchgeführt. The project RAISIN represents a core project of the Focus Area Group PASTSOILS. One of the major goals of the Focus Area Group will be achieved through RAISIN: Rates of soil forming processes in different climates, obtained from soils and paleosols in settings where climatic conditions and duration of soil development are known, will be assessed and documented. Thus, the project will provide a solid base for future interpretation of paleosols in the frame of palaeo-environmental reconstructions. Numerous data on soil development with time, many of them based on soil chronosequence studies in various regions, have been published in the past decades. The main aim of the project is hence to bring together scientists working on rates of soil-forming processes in different regions of the world to share and discuss their results, review and compare published data and finally produce a document representing the current state of knowledge on soil formation rates in different climates. The outcome of the project will be published in a special issue of Quaternary International to make it available to the scientific public. Thus, a common standard for interpreting paleosols in soil-sediment successions in terms of duration and environmental conditions of soil development will be created. Moreover, gaps in our current knowledge will be identified in the process of reviewing existing data in the frame of the project. This will stimulate future research and possibly lead to collaborative projects aiming on closing the identified gaps step by step.
Das Projekt "The Swiss contribution to the ICDP Lake Van Drilling Project: Linking modern seismic and biogeochemical signatures to 500,000 years of environmental history" wird vom Umweltbundesamt gefördert und von Eidgenössische Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz, Abteilung Wasserressourcen und Trinkwasser durchgeführt. This SNF proposal seeks funding for the continuation of the Swiss contribution to the Lake Van Drilling Project executed by the International Continental Scientific Drilling Program (ICDP). Among other previous Swiss ICDP engagements, the Lake Van Drilling project was pivotal in triggering the newly established SNF-supported Swiss membership in ICDP. Further, the SNF Swiss contribution is a central building block of the entire ICDP PaleoVan initiative. Lake Van is the fourth-largest terminal lake in the world, extending 130 km WSW-ENE 1674 m above sea level on a high plateau in eastern Anatolia, Turkey. The lake is surrounded by active volcanoes within a tectonically active area and it is known to accumulate fluids emanating from the Earths mantle. The partly annually-laminated sedimentary record down to 220 m depth recovered from Lake Van during the ICDP PaleoVan drilling operations in 2010 has been shown to be an excellent palaeoclimate and palaeoenvironment archive. The continuous, high-resolution continental sequence, which covers several glacial-interglacial cycles (greater than 500 kyr), represents a unique possibility to investigate in detail the climatic, environmental, and volcanic changes that occurred in the Near East, the cradle of human civilization, during much of the Quaternary Period. Furthermore, the sediments contain an invaluable record of past earthquake activities, allowing the construction of a catalogue of prehistoric earthquakes and making it possible to study fluid transport in the continental crust that was triggered by seismic events. In this context, the societal vulnerability of the area to seismic hazards was dramatically documented by the occurrence of the devastating earthquake of magnitude 7.2 close to the city of Van on 23 October 2011 (hereafter referred to as the VE11 earthquake). This unfortunate and tragic event offers a unique opportunity to calibrate the past seismic events recorded in the sediments of Lake Van and the related emission of fluids from the solid earth to a modern seismic analogue. Sediment and fluid transport triggered by this major seismic event need to be quantified in order to calibrate the sedimentological record, which is targeted by the follow-up field campaign proposed within this project extension. The continuation of the Swiss initiative, embedded in the overarching ICDP drilling project on Lake Van, encompasses all the 5 initial research modules (A-E) of the ongoing SNF project (200021-124981). Within this proposal extension, the extended modules (A*-E*) will focus on key issues and new developments that expand the initial topics, with a special emphasis on the recent major earthquake VE11 and its biogeochemical and sedimentological implications. At the same time, this extension will also allow the results that have already been acquired to be further analysed and written up for publication by the project team. A large number of publications is foreseen. (...)
Das Projekt "Scanning in-situ reflectance spectroscopy as a novel tool for high-resolution climate reconstructions from lake sediments, southern Chile" wird vom Umweltbundesamt gefördert und von University of Bern, Oeschger Centre + NCCR Climate durchgeführt. Seasonal to annual quantitative reconstructions of spatially-explicit climate state variables for the last 1000 years are recognized as one of the primary targets for current climate research (IGBP-PAGES / WCRP-CLIWAR). The lack of adequate paleoclimate data series is strikingly evident for the southern hemisphere. This proposal will (i) explore systematically the potential of in-situ reflectance spectroscopy as a novel tool for quantitative high-resolution climate reconstructions in a variety of lakes in south-central Chile, and (ii) produce a number of temporally highly resolved temperature and/or precipitation reconstructions for the regional expression of climate variability during the past 1000 years. The project contributes to the international regional multi-proxy climate reconstruction in South America (IGBP-PAGES LOTRED-SA).
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