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Found 93 results.

Forest management in the Earth system

Das Projekt "Forest management in the Earth system" wird vom Umweltbundesamt gefördert und von Max-Planck-Institut für Meteorologie durchgeführt. The majority of the worlds forests has undergone some form of management, such as clear-cut or thinning. This management has direct relevance for global climate: Studies estimate that forest management emissions add a third to those from deforestation, while enhanced productivity in managed forests increases the capacity of the terrestrial biosphere to act as a sink for carbon dioxide emissions. However, uncertainties in the assessment of these fluxes are large. Moreover, forests influence climate also by altering the energy and water balance of the land surface. In many regions of historical deforestation, such biogeophysical effects have substantially counteracted warming due to carbon dioxide emissions. However, the effect of management on biogeophysical effects is largely unknown beyond local case studies. While the effects of climate on forest productivity is well established in forestry models, the effects of forest management on climate is less understood. Closing this feedback cycle is crucial to understand the driving forces behind past climate changes to be able to predict future climate responses and thus the required effort to adapt to it or avert it. To investigate the role of forest management in the climate system I propose to integrate a forest management module into a comprehensive Earth system model. The resulting model will be able to simultaneously address both directions of the interactions between climate and the managed land surface. My proposed work includes model development and implementation for key forest management processes, determining the growth and stock of living biomass, soil carbon cycle, and biophysical land surface properties. With this unique tool I will be able to improve estimates of terrestrial carbon source and sink terms and to assess the susceptibility of past and future climate to combined carbon cycle and biophysical effects of forest management. Furthermore, representing feedbacks between forest management and climate in a global climate model could advance efforts to combat climate change. Changes in forest management are inevitable to adapt to future climate change. In this process, is it possible to identify win-win strategies for which local management changes do not only help adaptation, but at the same time mitigate global warming by presenting favorable effects on climate? The proposed work opens a range of long-term research paths, with the aim of strengthening the climate perspective in the economic considerations of forest management and helping to improve local decisionmaking with respect to adaptation and mitigation.

Upwelling in the Atlantic sector of the Southern Ocean

Das Projekt "Upwelling in the Atlantic sector of the Southern Ocean" wird vom Umweltbundesamt gefördert und von Universität Bremen, Institut für Umweltphysik, Abteilung Ozeanographie durchgeführt. Upwelling is an important process in setting the characteristic of the mixed layer. Upwelling also provides a pathway for gases, nutrients, and other compounds from the ocean's interior into the mixed layer and ultimately into the atmosphere. Since the upwelling velocities are small, they cannot be measured directly. Recently, Rhein et al. (2010) exploited the helium isotope disequilibria found in the equatorial eastern Atlantic to infer upwelling speeds, upwelling rates, and vertical heat fluxes between the mixed layer and the ocean's interior. The disequilibrium in the mixed layer is caused by upwelling of 3He-enriched water from the interior. The surplus 3He is introduced into the deep ocean by hydrothermal activities.A first survey of historical Helium isotope data in the Antarctic Circumpolar Current (ACC) and the Weddell Sea showed, that the mixed layer is also enriched with 3He, which in summer months is supplied by upwelling of water from below the mixed layer. Although the first estimates of upwelling velocities from the historical data set look promising, the present Helium data lack a sufficient resolution in the upper 200-300m to determine the horizontal and vertical He gradients, necessary for the compilation of the upwelling velocity and of the contribution of diapycnal mixing. Here we propose to take the historical He data, and a new dedicated He data sets to be taken in November 2010 - February 2011 during the POLARSTERN cruise ANT 27/2 and January- February 2012 during POLARSTERN cruise ANT28/3 to calculate upwelling speeds and -rates in the Weddell Sea and the ACC, as well as heat fluxes between the interior and the mixed layer.This proposal is part of the Cluster ' Eddies and Upwelling: Major Factors in the Carbon Budget ofthe Southern Ocean'

The Lake Naivasha Coring Project

Das Projekt "The Lake Naivasha Coring Project" wird vom Umweltbundesamt gefördert und von Universität Potsdam, Institut für Geowissenschaften durchgeführt. High-quality chronologies of late Pleistocene tropical climate have become increasingly important in discussions concerning tropical forcing of deglaciation, i.e., the transition from a glacial to an interglacial. The key argument of this hypothesis is that tropical climate leads high-latitude ice volumes by several thousand years. A tropical forcing of deglaciation would also help to explain why ice ages occur in both hemispheres simultaneously, although the changes in solar irradiance from orbital variations have opposite effects in the two hemispheres. Lake Naivasha provides a unique opportunity to study a continuous record of tropical climate changes during the last two glacial-interglacial cycles (approximately 175 kyr) through sedimentologic and paleoecologic changes reflected in the sediments. We propose a two-step strategy to reconstruct the lake history during this period: (A) a high-resolution seismic survey to characterize the depositional setting, lake-level fluctuations and neotectonics in the Naivasha basin. This survey will also guide up to the best sites for (B) two 50- and 40-m-long sediment cores from the present lake area. These sediment records are expected to fill the gap between a well-studied section exposed south of the present lake (175 to 60 kyr before present) and two sediment cores studied in the 1960's (25 kyr to present).

Integrating Cloud Observations from Ground and Space - a Way to Combine Time and Space Information (ICOS)

Das Projekt "Integrating Cloud Observations from Ground and Space - a Way to Combine Time and Space Information (ICOS)" wird vom Umweltbundesamt gefördert und von Universität Köln, Institut für Geophysik und Meteorologie, Bereich Meteorologie, Arbeitsgruppe Integrierte Fernerkundung durchgeführt. Cloud processes remain one of the largest challenges in atmospheric research partly due to a gap in statistically significant observations of cloud macro- and microphysical properties. The most detailed and continuous observations available today come from the combination of state-of-the-art ground-based sensors at a few 'super sites' worldwide. The integrated profiling technique (IPT) developed by the proposers has been established to provide cloud liquid water (LWC) profiles with their error and the associated environmental conditions (temperature, humidity) from a combination of microwave radiometer, cloud radar and ceilometer. Here we propose to extend this method by incorporating satellite observations by Meteosat SEVIRI into the IPT optimal estimation framework for the additional retrieval of cloud microphysics (effective radius, optical thickness) and cloud radiation budget. In addition SEVIRI measurements will be exploited to provide auxiliary information on a) the history of the cloud observed at the super site (lifetime, microphysical development, environment) and b) the representativeness of the cloud for the cloud field around the site. The method will be developed on the basis of existing data sets from observation sites at Cabauw, Lindenberg and AMF/Murg Valley.

Sub project: Spherule layers in the 2011 ICDP drilling in the Barberton Mountain Land: Early impact record on Earth

Das Projekt "Sub project: Spherule layers in the 2011 ICDP drilling in the Barberton Mountain Land: Early impact record on Earth" wird vom Umweltbundesamt gefördert und von Museum für Naturkunde - Leibniz-Institut für Evolutions- und Biodiversitätsforschung durchgeführt. The 2011 ICDP drilling 'Barberton Mountain Land' drilled relatively unweathered rare late Archean volcanic and sedimentary rocks including the oldest known impact ejecta layers on Earth. The chemical signature (high Iridium concentrations, Chromium isotopic ratios) of some of these up to tens of cm thick Archean spherule layers advocate that these ejecta deposits formed dominantly from extraterrestrial material. The ejecta layers contain millimeter sized spherules that are larger and form thicker layers compared to any impact ejecta layer known from Phanerozoic sediments, including the global ejecta layer of the Chicxulub impact catering event that terminated the Mesozoic era of Earths history. We propose to conduct 1) bulk chemical analyses of major and trace elements, 2) petrographic, micro-chemical and mineralogical characterization of the impact ejecta layers, and 3) LA-ICP-MS elemental mapping of platinum group element (PGE) distributions. This aims at 1) characterization of the ejecta layers, 2) identification of the phases hosting the extraterrestrial PGE signature, 3) discrimination of the primary geological evidence of the impact event from those characteristics that resulted from syn- and post-sedimentary alteration. We want to exploit the geological evidence for extracting key information regarding size, type and frequency of projectiles impacting the Archean Earth.

Sub project: Long- and short-term effects of climate variability and physical forcing on the diversity of aquatic organisms

Das Projekt "Sub project: Long- and short-term effects of climate variability and physical forcing on the diversity of aquatic organisms" wird vom Umweltbundesamt gefördert und von Universität Oldenburg, Institut für Chemie und Biologie des Meeres (ICBM), Arbeitsgruppe Planktologie durchgeführt. Climate variations over the Northern Hemisphere are to a substantial proportion associated with atmospheric circulations, e.g. the North Atlantic Oscillation (NAO). Recently, many studies have revealed the impact of the NAO on the dynamics of organisms in different ecosystems, especially on the timing of life history events, on the biomass of organisms, and on the biomass of different trophic levels. However, no study has developed a consistent picture on how the NAO affects biodiversity. Here we propose a unique study aiming at analysing long-term data on the diversity of aquatic communities in combination with the prediction of trends in aquatic biodiversity while disentangling long-term and short-term effects of climate variability. To achieve this goal, we will combine databases from different marine and freshwater ecosystems in North-Central Europe. These databases provide long-term time series of species abundance and community composition from lakes, streams and 2 marine sites, comprising a spatial extent from Germany to Northern Sweden. We will use these data to test: 1)Whether there are decadal or yearly trends in the diversity of aquatic communities related to climate variability. 2) Whether asynchrony of species-specific responses leads to shifting community patterns related to climate variability, including information on shifts in seasonal co-occurrence of interacting organisms (match-mismatch), and 3) Whether the short-term variability of climate has an effect on diversity in the ecological time frame of disturbances. We will use this information to predict changes in future biodiversity under changed climate scenarios. This study will result in modelling and experimental approaches to the role of climate forcing for aquatic biodiversity.

Adaptations and counter-adaptations in the coevolutionary arms race of a baculovirus and its insect host

Das Projekt "Adaptations and counter-adaptations in the coevolutionary arms race of a baculovirus and its insect host" wird vom Umweltbundesamt gefördert und von Julius Kühn-Institut, Bundesforschungsinstitut für Kulturpflanzen, Institut für Biologischen Pflanzenschutz durchgeführt. Cydia pomonella granulovirus (CpGV, Baculoviridae) is one of the most important agents for the control of codling moth (CM, Cydia pomonella, L.) in both biological and integrated pest management. The rapid emergence of resistance against CpGV-M, which was observed in about 40 European CM field populations from 2003 on, could be traced back to a single, dominant, sex-linked gene. Since then, resistance management has been based on mixtures of new CpGV isolates (CpGV-I12, -S), which are able to overcome this resistance. Recently, resistance even to these novel isolates was observed in CM field populations. This resistance does not follow the described dominant, sex-linked inheritance trait. At the same time, another isolate CpGV-V15 was identified showing high virulence against these resistant populations. To elucidate this novel resistance mechanism and to identify the resistance gene(s) involved, we propose a comprehensive analysis of this resistance on the cellular and genomic level of codling moth. Because of the lack of previous knowledge of the molecular mechanisms of virus resistance in insects, several different and complementary approaches will be pursued. This study will not only give an in-depth insight into the genetic possibilities for development of baculovirus resistance in CM field populations and how the virus overcomes it, but can also serve as an important model for other baculovirus-host interaction systems.

U-Th-Ra disequilibria in basalts from the Mid-Atlantic Ridge 6-11 S: Constraints on melting, mixing and time-scales of magmatic processes

Das Projekt "U-Th-Ra disequilibria in basalts from the Mid-Atlantic Ridge 6-11 S: Constraints on melting, mixing and time-scales of magmatic processes" wird vom Umweltbundesamt gefördert und von Universität Erlangen-Nürnberg, Geowissenschaftliches Zentrum Nordbayern, Lehrstuhl für Endogene Geodynamik durchgeführt. We propose to study the U, Th, and Ra isotopic compositions of zero-age MORB samples from the slow-spreading Mid-Atlantic Ridge between 6 and 11 degree S. This part of the spreading axis shows large variations in axial depth, crustal thickness and samples melts with significant variations in major and trace element geochemistry as well as Sr, Nd, and Pb isotopic composition. The existing data indicates a complex interplay of variations in mantle sources, binary mixing and degree of magma differentiation during melt ascent. In the first year wie suggest to determine U, Th and Ra isotope compositions of fresh young samples along the axis and from young ( 200.000 years) near- axis seamounts to evalute the depth and extent of melting, the mantle composition, porosity and upwelling rate and the mixing processes along a propagating ridge segment. In the second year wie propose to investigate the timing of magma evolution and eruption processes on this spreading axis on the basis of U series isotope data and stratigraphic mapping and sampling of selected volcanic structures of the working area.

Austritt und Transport von Methan und Wasserstoff am mittelatlantischen Rücken

Das Projekt "Austritt und Transport von Methan und Wasserstoff am mittelatlantischen Rücken" wird vom Umweltbundesamt gefördert und von IFM-GEOMAR Leibniz-Institut für Meereswissenschaften durchgeführt. Unsere Zielsetzung in der dritten Antragsphase des SPPs besteht darin, den Transport von Methan, Wasserstoff und 3-Helium in den Plumes zu bestimmen, die den hydrothermalen Austrittstellen am Logatchev-Feld (Mittelatlantischer Rücken) zugeordnet werden. Wir (IFM-GEOMAR und IOW) beabsichtigen Tow-yo CTD Untersuchungen dieser gelösten Gase innerhalb einer Distanz von wenigen Kilometern zu diesen hydrothermalen Austrittstellen vorzunehmen. Die hierbei gewonnen Informationen werden mit Langzeit-Strömungsmessungen verknüpft, die von den Herren Fischer und Visbek (IFM-GEOMAR) durchgeführt werden. Die genannten Tow-yo CTD Untersuchungen werden zu Beginn und Ende der Langzeit-Strömungsmessungen erfolgen, d.h. auf der F/S MERIAN Fahrt 06/2 und 10/3. Diese Beprobungsstrategie ermöglicht es, die Ergebnisse der Kurzzeitaufnahmen aus der Ermittlung der Gasverteilung mit denen der Zeitreihenaufzeichnungen der Stömungsmessungen zu verknüpfen. Des Weiteren werden über eine Strecke von 100 km mit dem CTD-Rosettensystem Wasserproben entlang der Rückenachse genommen, welche an der Bruchzone bei 15 Grad 20N einsetzt. Durch diese Untersuchung soll das Inventar dieser Gase in diesem Rückensegment abgeschätzt werden. Methan und Wasserstoff werden bereits während der beiden Expeditionen an Bord gemessen. Die Heliumisotopen-Analysen werden jeweils nach den Expeditionen an der Universität Bremen durchgeführt. Ein weiteres in Beziehung stehendes Ziel besteht in der Konzentrationsbestimmung des gelösten Methans und Wasserstoffs in Fluiden, die an den hydrothermalen Austrittsstellen während der Expeditionen genommen werden. Über diese Ziele hinaus werden wir mit M. Perner an kinetischen Inkubationsexperimenten arbeiten, um die Raten der Wasserstoffzehrung in Fluiden zu bestimmen, die sich aus der mikrobiellen Aktivität in hydrothermalen Lösungen ableitet.

Bio-optische Eigenschaften als Echtzeittracer für die Transformation des organischem Materials in der SML (SP 1.3)

Das Projekt "Bio-optische Eigenschaften als Echtzeittracer für die Transformation des organischem Materials in der SML (SP 1.3)" wird vom Umweltbundesamt gefördert und von Helmholtz-Zentrum hereon GmbH durchgeführt. Die Sea-Surface Microlayer (SML) als dünne Grenzschicht trennt Hydrosphäre und Atmosphäre. Häufig sind die Konzentrationen bestimmter Verbindungen in der SML höher, entweder durch physikalische Konzentration aus dem darunter liegenden Wasser, durch Produktion in der SML oder durch atmosphärische Ablagerungen. Ein bekannter Aspekt ist die durchweg höhere Konzentration von chromophoren gelösten organischen Stoffen (CDOM) in der SML im Vergleich zum darunter liegenden Wasser. Kürzlich haben wir gezeigt, dass die inhärenten optischen Eigenschaften (IOP) â€Ì d.h. die Lichtstreu- und Absorptionseigenschaften von Wasser und seinen Bestandteilen â€Ì der SML genutzt werden können Komponenten in der SML zu charakterisieren und nützliche Informationen für den Strahlungstransfer und für Fernerkundungsstudien zu liefern. Darüber hinaus war unsere frühere Forschung zu optischen Eigenschaften in der SML unsere Motivation hier vorzuschlagen, IOPs und apparente optischen Eigenschaften (AOPs) â€Ì abgeleitet aus spektralradiometrischen Messungen des Lichtfeldes â€Ì sowie die Fluoreszenz zur Charakterisierung von organischen Stoffen (OM) und deren Transformation für die Echtzeitbewertung der SML als biologischen und chemischen Lebensraum zu nutzen. Hiermit können wir in außergewöhnlicher Weise die Kurzzeitdynamik relevanter biologischer und chemischer Treiber in der SML untersuchen.

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