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.
Rain-cracking limits the production of many soft and fleshy fruit including sweet cherries world wide. Cracking is thought to result from increased water uptake through surface and pedicel. Water uptake increases fruit volume, and hence, turgor of cells (Pcell) and the pressure inside the fruit (Pfruit) and subjects the skin to tangential stress and hence, strain. When the strain exceeds the limits of extensibility the fruit cracks. This hypothesis is referred to as the Pfruit driven strain cracking. Based on this hypothesis cracking is related to two independent groups of factors: (1) water transport characteristics and (2) the intrinsic cracking susceptibility of the fruit defined as the amount of cracking per unit water uptake. The intrinsic cracking susceptibility thus reflects the mechanical constitution of the fruit. Most studies focussed on water transport through the fruit surface (factors 1), but only little information is available on the mechanical constitution (i.e., Pfruit and Pcell, tensile properties such as fracture strain, fracture pressure and modulus of elasticity of the exocarp; factors 2). The few published estimates of Pfruit in sweet cherry are all obtained indirectly (calculated from fruit water potential and osmotic potentials of juice extracts) and unrealistically high. They exceed those measured by pressure probe techniques in mature grape berry by several orders of magnitude. The objective of the proposed project is to test the hypothesis of the Pfruit driven strain cracking. Initially we will focus on establishing systems of widely differing intrinsic cracking susceptibility by varying species (sweet and sour cherry, Ribes and Vaccinium berries, plum, tomato), genotype (within sweet cherry), stage of development and temperature. These systems will then be used for testing the hypothesis of Pfruit driven strain cracking. We will quantify Pfruit und Pcell by pressure probe techniques and compression tests and the mechanical properties of the exocarp using biaxial tensile tests. When the presence of high Pfruit and Pcell is confirmed by direct measurements, subsequent studies will focus on the mode of failure of the exocarp (fracture along vs. across cell walls) and the relationship between failure thresholds and morphometric characteristics of the exocarp. However, when Pfruit und Pcell are low, the hypothesis of Pfruit driven strain cracking must be rejected and the mechanistic basis for low pressures (presence of apoplastic solutes) clarified on a temporal (in the course of development) and a spatial scale (exocarp vs. mesocarp). We focus on sweet cherry, because detailed information on this species and experience in extending the short harvest period is available. Where appropriate, other cracking susceptible species (sour cherry, plum, Vaccinium, Ribes, tomato) will be included to further extend the experimental period and to maximize the range in intrinsic cracking susceptibility.
Prehistoric pits are filled with ancient topsoil material, which has been preserved there over millennia. A characteristic of these pit fillings is that their colour is different depending on the time the soil material was relocated. Soil colour is the result of soil forming processes and soil properties, and it could therefore indicate the soil characteristics present during that specific period. To the best of our knowledge, no investigation analysed and explained the reasons for these soil colour changes over time. The proposed project will investigate soil parameters from pit fillings of different archaeological periods in the loess area of the Lower Rhine Basin (NW-Germany). It aims to implement the measurement of colour spectra as a novel analytical tool for the rapid analyses of a high number of soil samples: the main goal is to relate highresolution colour data measured by a spectrophotometer to soil parameters that were analysed by conventional pedogenic methods and by mid infrared spectroscopy (MIRS), with a main focus on charred organic matter (BPCAs). This tool would enable us to quantify the variation of soil properties over a timescale of several millennia, during different prehistoric periods at regional scale and for loess soils in general. Detailed information concerning changing soil properties on a regional scale is necessary to determine past soil quality and it helps to increase our understanding of prehistoric soil cultivation practices. Furthermore, these information could also help to increase our understanding about agricultural systems in different archaeological periods.
The overarching goal of our proposal is to understand the regulation of organic carbon (OC) transfor-mation across terrestrial-aquatic interfaces from soil, to lotic and lentic waters, with emphasis on ephemeral streams. These systems considerably expand the terrestrial-aquatic interface and are thus potential sites for intensive OC-transformation. Despite the different environmental conditions of ter-restrial, semi-aquatic and aquatic sites, likely major factors for the transformation of OC at all sites are the quality of the organic matter, the supply with oxygen and nutrients and the water regime. We will target the effects of (1) OC quality and priming, (2) stream sediment properties that control the advective supply of hyporheic sediments with oxygen and nutrients, and (3) the water regime. The responses of sediment associated metabolic activities, C turn-over, C-flow in the microbial food web, and the combined transformations of terrestrial and aquatic OC will be quantified and characterized in complementary laboratory and field experiments. Analogous mesocosm experiments in terrestrial soil, ephemeral and perennial streams and pond shore will be conducted in the experimental Chicken Creek catchment. This research site is ideal due to a wide but well-defined terrestrial-aquatic transition zone and due to low background concentrations of labile organic carbon. The studies will benefit from new methodologies and techniques, including development of hyporheic flow path tubes and comparative assessment of soil and stream sediment respiration with methods from soil and aquatic sciences. We will combine tracer techniques to assess advective supply of sediments, respiration measurements, greenhouse gas flux measurements, isotope labeling, and isotope natural abundance studies. Our studies will contribute to the understanding of OC mineralization and thus CO2 emissions across terrestrial and aquatic systems. A deeper knowledge of OC-transformation in the terrestrial-aquatic interface is of high relevance for the modelling of carbon flow through landscapes and for the understanding of the global C cycle.
In this project we experimentally explore the transport of engineered inorganic nanoparticles (EINP) through soils. This is done for original EINPs and some pre-aged form. Transport of NPs in soil is expected to be different from that of reactive solutes, in that hydrodynamic drag, inertial and shear forces as well as the affinity to water-gas interfaces are expected to be more relevant. Hence, the mobility of EINPs in soil is highly sensitive to the morphology of the porous structure and the dynamics of water saturation.This project provides the pore network structure for natural soils using X-ray micro-tomography to allow for an up-scaling of pore-scale interactions explored by project partners to the scale of soil horizons. The pore structure is represented by a network model suitable for pore scale simulations including the dynamics of water-gas interfaces.Pore network simulations will be compared to column experiments for conservative tracers as well as for unaltered and pre-aged EINPs (obtained from INTERFACE). This includes steady state flow scenarios for saturated (ponding) and unsaturated conditions as well as for transient flow to explore the impact of moving water-gas interfaces. The final goal is to arrive at a consistent interpretation of experimental findings and numerical simulations to develop a module for modelling EINP transfer through soil as a function of particle properties, soil structural characteristics and external forcing in terms of flux boundary conditions.
Unsere Motivation liegt in der Tatsache, dass die dynamische Verbindung zwischen dem marinen Oberflächenfilm (engl. sea-surface microlayer, SML) und der darunterliegenden oberflächennahen Wasserschicht über Konvektion zu heterogenen Eigenschaften der SML führt. Dies wiederum steuert das Ausmaß der bio-photochemischen Reaktionen und des Gasaustausches zwischen dem Ozean und der Atmosphäre. Die Konvektion wird durch Verdunstung angetrieben, die die SML abkühlt und es salzhaltiger macht. Infolgedessen wird die SML dichter, sinkt ab und wird durch das darunterliegende Wasser ersetzt. Die auftriebsgetriebene Konvektion wurde jedoch bei der Erforschung der SML und des Gasaustausches als dynamisches Bindeglied zwischen der Atmosphäre und dem Ozean vernachlässigt. Unser Hauptziel ist es, ein mechanistisches Verständnis der Dynamik zwischen der SML und der oberflächennahen Wasserschicht zu beschreiben. Ein mechanistisches Verständnis der Konvektion ist wichtig, da das Ausmaß der bio-photochemischen Reaktionen und Austauschprozessen von Spurengasen, Energie und Impuls letztlich durch Austauschprozesse zwischen der SML und der oberflächennahen Wasserschicht und schließlich mit tieferen Schichten bestimmt wird. Wir werden einen experimentellen Aufbau mit mehreren profilierenden Mikroelektroden und einem optischen Schlierensystem entwickeln, um die Konvektion unter verschiedenen externen Antrieben zu untersuchen. Wir werden den Effekt der horizontalen Strömung aufgrund von Gradienten der Oberflächenspannung (d.h. Marangoni-Effekt) untersuchen. Wir werden auch an dem gemeinsamen Mesokosmen-Experiment BASS teilnehmen, um den Einfluss biogener Tenside auf den konvektiven Transportmechanismus zwischen der SML und der oberflächennahen Wasserschicht zu untersuchen. Im gemeinsamen Feldexperiment BASS werden wir der Frage nachgehen, inwieweit Variationen der klein-skaligen Konvektion durch die Variabilität sub-mesoskaligen (1 km-10 km) und hydrodynamischen Prozessen nahe der Meeresoberfläche beeinflusst werden. Wir werden zwei Forschungskatamarane und eine Flotte von Treibbojen einsetzen, die mit Leitfähigkeits- und Temperatursensoren ausgestattet sind, um Dichteanomalien zwischen der SML und oberflächennahen Wasserschicht zu untersuchen. Wir werden externe ozeanische und atmosphärische Einflüsse beobachten, um die Dichteanomalien zu beschreiben. Schließlich werden wir die gewonnenen Erkenntnisse aus den Laborexperimenten, der Mesokosmos-Studie und der Feldstudie nutzen, um einen mathematischen Rahmen zur Beschreibung von Temperatur- und Salzgehaltsprofilen und deren Schwankungen unter dem Einfluss definierter ozeanischer und atmosphärischer Einflüsse zu entwickeln.
Objectives: Sustainable management of tropical moist forests through private forest owners will become increasingly important. Media report that in Brazil, particularly in Amazonia, approx. 80 percent of the timber harvested is from illegal sources. Private management of forests according to internationally acknowledged standards offers an opportunity to significantly lower the portion of illegally cut timber. Moreover, it contributes significantly to the conservation of the Amazon forest. Private forest owners show a clear long-term commitment towards the implementation of management standards according that is ecologically compatible, socially acceptable and economically viable. The project area, a pristine forest in legal Amazonia in the transition zone between moist tropical forests and savannas (cerrado), is extremely diverse in floristic and faunistic terms. The institute cooperates with the private forest owner. Main tasks are to document the faunistic and floristic diversity, to calculate the Annual Allowable Cut and to elaborate concepts for site-specific silviculture. Results: To date (Oct. 2006) the following activities were started: - a comprehensive inventory system for planning at the FMU-level has been successfully introduced; - the inventory system for the annual coupe area has been designed and data for the first coupe are being processed; - the annual allowable cut is currently calculated based on the results of the above described inventories; - two fauna surveys are completed; one focusing on large mammals and one on the avi-fauna. A long-term monitoring concept to assess the influence of forest management on the faunistic diversity is currently under development; - forest zoning is completed applying terrestrial surveys and interpreting high-resolution satellite images; - a study on the use of Bethollethia excelsa-fruits (Brazil nuts) is currently implemented; - a study on timber properties of lesser known species is currently implemented.
In recent years science has taken an increased interest in mineralization processes in tropical soils in particular under minimal tillage operations. Plant litter quality and management strongly affect mineralization-nitrification processes in soil and hence the fate of nitrogen in ecosystems and the environment. Plant secondary metabolites like lignin and polyphenols are poorly degradable and interact with proteins (protein binding capacity) and hence protect them from microbial attack. Nitrification, a microbiological process, directly and indirectly influences the efficiency of recovery of N in the vegetation as well as the loss of N (through denitrification and leaching) causing environmental pollution to water bodies and contributes to global warming (e.g. the greenhouse gas N2O is emitted as a by-product of nitrification and denitrification). Nitrifiers comprise a relatively narrow species diversity (at least as known to date) and are generally thought to be sensitive to low soil pH and stress. Despite these properties nitrification occurs in acid tropical soils with high levels of aluminium and manganese. Thus the main objective of the project will be the identification of micro-organisms and mechanisms responsible for mineralization-nitrification processes in acid tropical soils and the influence of long-term litter input of different chemical qualities and minimal tillage options. The project will include the use of stable isotopes (15N, 13C), mass spectrometry, gas chromatography (CO2, N2O), biochemical methods (PLFA) and molecular biology (16s rRNA., PCR, DGGE)
Teilprojekt C05 hat zum Ziel, den wichtigen Eintragsweg für Kunststoffe, in Form von Mikroplastik, in die Umwelt aus technischen Anlagen (MP) mechanistisch aufzuklären. Gleichzeitig sollen neue Ansätze verfolgt werden, die zur Vermeidung bzw. Reduktion von MP aus Standardkunststoffen maßgeblich beitragen sollen. Zu diesem Zweck sollen Polyethylen, Polypropylen, Polystyrol, Nylon, Polyethylenterephthalat, Polyisopren und Polyvinylchlorid durch Beschleuniger (in situ) in ihren Oberflächeneigenschaften für die Biofilmbildung modifiziert und dadurch unter Prozessbedingungen biologisch angreifbar und abbaubar gemacht werden. So können auch Standardkunststoffe umweltverträglicher bezüglich der MP-Partikel Bildung werden. Damit geht TP C05 weit über die bislang üblichen eher deskriptiven Studien zu MP in technischen Anlagen und der Umwelt hinaus. Folgende zentrale Fragen sollen in TP C05 in Hinblick MP-Partikel in technischen Anlagen der Abfall- und Abwasserwirtschaft beantwortet werden: 1. Kommt es in den Anlagen zu spezifischen (biologischen) Abbau- und Degradationsvorgängen? 2. Wie hängen die zu beobachtenden Prozesse von MP-Charakteristika (Materialsorte, Zusammensetzung, Größe, Morphologie, Beschichtung) ab, ? 3. Lassen sich die Vorgänge ('Bioabbaubarkeit') durch gezielte Modifikation der Partikeloberfläche vor oder in den Anlagen beschleunigen? 4. Welche ökologischen Konsequenzen einer Ausbringung der (modifizierten) Partikel in die Umwelt und hier vor allem in den Boden lassen sich postulieren?
Biogeochemical interfaces shape microbial community function in soil. On the other hand microbial communities influence the properties of biogeochemical interfaces. Despite the importance of this interplay, basic understanding of the role of biogeochemical interfaces for microbial performance is still missing. We postulate that biogeochemical interfaces in soil are important for the formation of functional consortia of microorganisms, which are able to shape their own microenvironment and therefore influence the properties of interfaces in soil. Furthermore biogeochemical interfaces act as genetic memory of soils, as they can store DNA from dead microbes and protect it from degradation. We propose that for the formation of functional biogeochemical interfaces microbial dispersal (e.g. along fungal networks) in response to quality and quantity of bioavailable carbon and/or water availability plays a major role, as the development of functional guilds of microbes requires energy and depends on the redox state of the habitat.To address these questions, hexadecane degradation will be studied in differently developed artificial and natural soils. To answer the question on the role of carbon quantity and quality, experiments will be performed with and without litter material at different water contents of the soil. Experiments will be performed with intact soil columns as well as soil samples where the developed interface structure has been artificially destroyed. Molecular analysis of hexadecane degrading microbial communties will be done in vitro as well as in situ. The corresponding toolbox has been successfully developed in the first phase of the priority program including methods for genome, transcriptome and proteome analysis.
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