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Found 378 results.

Native plants and mycorrhizal fungi in wind erosion control in the Kailash-Manasarovar region (Tibet, China)

We study the effects of plants and root-associated fungi on wind erosion within the alpine environment of Tibet. China is one of the countries most affected by desertification processes and Tibet, in particular, a key region in desertification combat. The presented project focuses on the Barkha Plain surrounded by Mount Kailash and the Lake of Manasarovar (Ngari Prefecture). This Western Tibet region experienced little scientific attention but, nowadays, faces rapidly increasing touristic activities and expanding local settlements associated with socio-economic changes that are serious threats to the delicate ecological balance and potential triggers of desertification. It exists almost unanimous agreement that revegetation is the most efficient and promising strategy to combat wind erosion and desertification in the long term. However, re-colonising success is often poor, mainly under extreme environmental conditions. Compared to conventional practices, the approach of the presented project attains better accordance with natural succession processes and promises acceleration of both plant and soil development and, conclusively, more efficient desertification control. The project assesses the potential of native plants and symbiotic fungi to control wind erosion and desertification processes. It aims to identify key plants and fungi that increase soil aggregate stability and efficiently drive succession into a natural and self-maintaining cycle of the ecosystem. Furthermore, it provides crucial information for implementing environmentally compatible and cost-effective measures to protect high-elevation ecosystems against desertification. Within three successional stages (early, intermediate, late), field investigations are performed on the basis of Modified-Whittaker plots. Classic methods of vegetation analysis and myco-sociology are combined with analysis of distribution patterns at different scales (patchiness, connectivity). Comprehensive soil analysis is performed comprising grain size distribution, aggregate stability, pH as well as water and nutrient contents. Additionally, important parameters of wind erosion are measured concurrently and continuously to assess their magnitude and variability with respect to vegetation and soil at different levels of development. The parameters addressed, include sediment transport, air temperature, radiation, precipitation, relative humidity as well as speed and direction of wind. Surface moisture is recorded periodically and roughness described. Species and environmental parameters are checked for spatial correlation. Cutting edge technologies are applied in laboratory work, comprising molecular methods for fungal species identification and micro-tomography to analyse soil structure. Furthermore, successfully cultivated fungi and plants are subject of synthesis experiments and industrial propagation in view of practical implementation in restoration measures.

Forschergruppe (FOR) 1740: Ein neuer Ansatz für verbesserte Abschätzungen des atlantischen Frischwasserhaushalts und von Frischwassertransporten als Teil des globalen Wasserkreislaufs, Variation of the fresh water in the western Nordic Seas

The goal of this project is to capture and analyse fluctuations of the fresh water in the western Nordic Seas and to understand the related processes. The East Greenland Current in the Nordic Seas constitutes an important conduit for fresh water exiting the Arctic Ocean towards the North Atlantic. The Arctic Ocean receives huge amounts of fresh water by continental runoff and by import from the Pacific Ocean. Within the Arctic Ocean fresh water is concentrated at the surface through sea ice formation. The East Greenland Current carries this fresh water in variable fractions as sea ice and in liquid form; part of it enters the central Nordic Seas, via branching of the current and through eddies. It controls the intensity of deep water formation and dilutes the water masses which result from convection. The last decades showed significant changes of the fresh water yield and distribution in the Nordic Seas and such anomalies were found to circulate through the North Atlantic. In this project the fresh water inventory, its spatial distribution and its pathways between the East Greenland Current and the interior Greenland and Icelandic seas shall be captured by autonomous glider missions. The new measurements and existing data will, in combination with the modeling work of the research group, serve as basis for understanding the causes of the fresh water variability and their consequences for the North Atlantic circulation and deep water formation.

AsFeP0 - A model concept for in situ investigation or arsenic and phosphate adsorption to predefined iron minerals and to characterize transformation processes of iron minerals

Shallow groundwater of the huge deltaic systems of Asia like the Red River Delta in Vietnam is often enriched in inorganic arsenic (As), threatening the health of millions of residents. The massive abstraction of groundwater in these areas locally causes an irreversible mixing of arsenic-free groundwater resources with arsenic-rich groundwater. Increased concentrations of competitive anions, especially phosphate (PO43-), decrease the immobilization capacity of the sediments. During transport, the mobility of dissolved As in local aquifers is strongly influenced by adsorption to sedimentary and ubiquitously occurring iron(oxyhydr)oxides. Additionally, arsenic-rich groundwater is often enriched in reduced iron (Fe2+) as well, which is capable to react with iron(oxyhydr)oxides, thereby inducing mineral transformations. Such transformations permanently affect the arsenic adsorption and immobilization capacity of the sediments.Within the scope of this research project, the underlying mechanisms related to As transport and the resulting threat to arsenic-free groundwater resources will be characterized in cooperation with the Swiss Federal Institute of Aquatic Science and Technology (Eawag). The research concept aims at assessing the complex interactions within the arsenic-iron-phosphate-system under field conditions at a study site next to the Red River. First, filtration experiments using local groundwater enriched in As and PO43- will be used to determine the As adsorption capacity of different and previously geochemically characterized iron(oxyhydr)oxides. In a second step, sample carrier containing As loaded iron(oxyhydr)oxides will be introduced into surface near aquifer parts of the study site (via existing groundwater monitoring wells). These samples will be exposed to local groundwater characterized by increased As, Fe2+ and PO43- concentrations for the following nine months. Using the in situ exposition of predefined iron(oxyhydr)oxides, it will be possible to distinguish potential mineral transformations and their influences on the As immobilization capacity of the respective iron(oxyhydr)oxides. By combining the results and outcomes of the field experiments, new and important conclusions regarding the mobility of As can be drawn. The data can be used to create a hydrochemical transport model describing reactive As transport within the investigation area. In addition, the results of the in situ exposition experiments will allow to draw conclusions in respective to the long term As immobilization capacity of different iron(oxyhydr)oxides, which is an essential information regarding in situ decontamination techniques.

Development of a modelling system for prediction and regulation of livestock waste pollution in the humid tropics

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.

Dynamic (redox) interfaces in soil - Carbon turnover in microbial biomass and flux into soil organic matter

Existing models of soil organic matter (SOM) formation consider plant material as the main source of SOM. Recent results from nuclear magnetic resonance analyses of SOM and from own incubation studies, however, show that microbial residues also contribute to a large extent to SOM formation. Scanning electron microscopy showed that the soil mineral sur-faces are covered by numerous small patchy fragments (100 - 500 nm) deriving from microbial cell wall residues. We will study the formation and fate of these patchy fragments as continuously produced interfaces in artificial soil systems (quartz, montmorillonite, iron oxides, bacteria and carbon sources). We will quantify the relative contributions of different types of soil organisms to patchy fragment formation and elucidate the effect of redox con-ditions and iron mineralogy on the formation and turnover of patchy fragments. The develop-ment of patchy fragments during pedogenesis will be followed by studying soil samples from a chronosequence in the forefield of the retreating Damma glacier. We will characterize chemical and physical properties of the patchy fragments by nanothermal analysis and microscale condensation experiments in an environmental scanning electron microscope. The results will help understanding the processes at and characteristics of biogeochemical interfaces.

Can the resistance and resilience of trees to drought be increased through thinning to adapt forests to climate change?

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.

Technical Support for the revision of ecolabel and green public procurement GPP Criteria Lot 1

The project's objective is to support JRC IPTS in revising the existing Ecolabel and GPP criteria of personal computers and notebook computers. The priority in this revision process is to first analyse which of the existing criteria and the supporting evidence are still valid and to identify the additional research that should be carried out. Potential additional criteria can be developed, if identified as necessary in the course of the study. The study starts with a definition of the scope; the necessarity for new or revised Ecolabel and GPP criteria is based on a market analysis and a technical analysis with research on the most significant environmental impacts during the whole life cycle of the products. This also includes the application of a consistent methodological approach regarding the hazardous substances criteria. Based on these findings, the improvement potential will be derived resulting in a proposal for a revised Ecolabel and GPP criteria set for desktop and notebook computers which will be discussed in a European stakeholder process.

Uncertainty and the bioeconomics of near-natural silviculture

Research in 'silviculture' and 'forest economics' very often takes place largely independent from each other. While silviculture predominantly focuses on ecological aspects, forest eco-nomics is sometimes very theoretic. The applied bioeconomic models often lack biological realism. Investigating mixed forests this proposal tries to improve bioeconomic modelling and optimisation under uncertainty. The hypothesis is tested whether or not bioeconomic model-ling of interacting tree species and risk integration would implicitly lead to close-to-nature forestry. In a first part, economic consequences of interdependent tree species mixed at the stand level are modelled. This part is based on published literature, an improved model of timber quality and existing data on salvage harvests. A model of survival over age is then to be developed for mixed stands. A second section then builds upon data generated in part one and concentrates on the simultaneous optimisation of species proportions and harvest-ing ages. It starts with a mean-variance optimisation as a reference solution. The obtained results are compared with data from alternative approaches as stochastic dominance, down-side risk and information-gap robustness.

Forschergruppe (FOR) 1525: INUIT - Ice Nuclei research UnIT, Die Bedeutung von Eisnukleationspartikeln und -moden für die Entstehung der Eisphase und Niederschlag: Modellsimulationen basierend auf Labormesssungen

In diesem Projekt sollen mit COSMO-SPECS, einem 3D-Wolkenmodell mit einer spektralen Beschreibung der wolken-mikrophysikalischen Prozesse von Hydrometeoren und Aerosolpartikeln, Modellsimulationen durchgeführt werden. Da dasselbe mikrophysikalische Schema in dem Luftpaketmodell enthalten ist, mit dem in INUIT-1 gearbeitet wurde, werden alle neuen Entwicklungen und Verbesserungen der Mikrophysik aus INUIT-1 direkt in COSMO-SPECS übertragen. Zunächst soll ein künstlicher Testfall simuliert werden, eine Wärmeblase über einem flachen Gelände. Sensitivitätsstudien sollen die Entwicklung der Eisphase und die Bildung von Niederschlag aufzeigen, wobei die Verteilung und die Typen der Eisnukleations-Partikel auf realistische Weise variiert werden. Ein anderer Schwerpunkt der Sensitivitätsstudien soll auf der Wirkung von sog. kleinen Triggern liegen, wie etwa Eisnukleations-Partikel oder Gefriermoden (z.B. biologische Partikel oder Kontaktgefrieren), die keine signifikanten Effekte hinsichtlich der Anzahl der entstehenden Eispartikel zeigen, aber doch die Dynamik der Wolke in einer Weise beeinflussen können, dass sich im Endeffekt die Eisbildung erhöht. Weiterhin ist in Zusammenarbeit mit INUIT RP5 eine Fallstudie geplant, die auf INUIT Feldexperimenten basiert. Hier sollen die Beiträge der verschiedenen eisbildenden Prozesse quantifiziert werden und dadurch die atmosphärische Relevanz der Eisbildungs-Regimes, wie sie in INUIT Labor- und Feldexperimenten untersucht werden, abgeschätzt werden. Gleichzeitig werden neue Parametrisierungen für Partikel, die während INUIT-2 untersucht werden, entwickelt und in das mikrophysikalische Schema eingebunden; vorhandene Parametrisierungen sollen weiter modifiziert und verbessert werden. Dieses Projekt schließt selbst auch Laborexperimente zum Kontakt- und Immersionsgefrieren ein, die am Mainzer vertikalen Windkanal und mit einer akustischen Tropfenfalle durchgeführt werden. Hier liegt der Schwerpunkt auf einer Verbesserung des Kontaktgefrierens. Die Experimente sollen am Mainzer vertikalen Windkanal durchgeführt werden, wobei unterkühlte Tropfen in einem Luftstrom, der die potentiellen Kontakteiskeime mit sich führt, frei ausgeschwebt werden. Auf diese Weise kann die Anzahl der Kollisionen zwischen Tropfen und Partikeln berechnet und die Gefriereffizienz, d.h. die Gefrierwahrscheinlichkeit für eine Tropfen-Partikel Kollision bestimmt werden.

Schwerpunktprogramm (SPP) 1315: Biogeochemische Grenzflächen in Böden; Biogeochemical Interfaces in Soil, Quantification of active interfaces with respect to dissolved chemicals in unsaturated structured soil

During the first project period we developed a general approach to quantify soil pore structure based on X-ray micro-tomography Vogel et al. (2010) which is applicable at various scales to cover soil pores larger that 0.05 mm in a representative way. Based on this method we generated equivalent network models to numerically simulate flow and transport of dissolved chemicals. The existing network model was extended to handle reactive transport and infiltration processes which are especially critical for matter flux in soil. The results were compared to experimental findings. The original research question 'what does a particle see on its way through soil' could be answered quantitatively for various boundary conditions including steady state flux and infiltration. However, we identified various critical aspects of the proposed modeling concept which will be in the focus of the second period. This includes 1) the spatial arrangement of interfaces having different quality which is crucial for chemical interactions and pore scale water dynamics, 2) the realistic multiphase dynamics at the pore scale which need to reflect the dynamic pressure and movement of trapped non-wetting phase and 3) the parametrization of structural complexity which need to be developed beyond the measurement of continuous Minkowski functions to allow the development of quantitative relations between structure and function. These aspects will be explored in a joint experiments in cooperation with partners within the SPP.

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