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Ecosystem Engineering: Sediment entrainment and flocculation mediated by microbial produced extracellular polymeric substances (EPS)

Sediment erosion and transport is critical to the ecological and commercial health of aquatic habitats from watershed to sea. There is now a consensus that microorganisms inhabiting the system mediate the erosive response of natural sediments ('ecosystem engineers') along with physicochemical properties. The biological mechanism is through secretion of a microbial organic glue (EPS: extracellular polymeric substances) that enhances binding forces between sediment grains to impact sediment stability and post-entrainment flocculation. The proposed work will elucidate the functional capability of heterotrophic bacteria, cyanobacteria and eukaryotic microalgae for mediating freshwater sediments to influence sediment erosion and transport. The potential and relevance of natural biofilms to provide this important 'ecosystem service' will be investigated for different niches in a freshwater habitat. Thereby, variations of the EPS 'quality' and 'quantity' to influence cohesion within sediments and flocs will be related to shifts in biofilm composition, sediment characteristics (e.g. organic background) and varying abiotic conditions (e.g. light, hydrodynamic regime) in the water body. Thus, the proposed interdisciplinary work will contribute to a conceptual understanding of microbial sediment engineering that represents an important ecosystem function in freshwater habitats. The research has wide implications for the water framework directive and sediment management strategies.

Spatial heterogeneity and substrate availability as limiting factors for subsoil C-turnover

In subsoils, organic matter (SOM) concentrations and microbial densities are much lower than in topsoils and most likely highly heterogeneously distributed. We therefore hypothesize, that the spatial separation between consumers (microorganisms) and their substrates (SOM) is an important limiting factor for carbon turnover in subsoils. Further, we expect microbial activity to occur mainly in few hot spots, such as the rhizosphere or flow paths where fresh substrate inputs are rapidly mineralized. In a first step, the spatial distribution of enzyme and microbial activities in top- and subsoils will be determined in order to identify hot spots and relate this to apparent 14C age, SOM composition, microbial community composition and soil properties, as determined by the other projects within the research unit. In a further step it will be determined, if microbial activity and SOM turnover is limited by substrate availability in spatially distinct soil microsites. By relating this data to root distribution and preferential flow paths we will contribute to the understanding of stabilizing and destabilizing processes of subsoil organic matter. As it is unclear, at which spatial scale these differentiating processes are effective, the analysis of spatial variability will cover the dm to the mm scale. As spatial segregation between consumers and substrates will depend on the pore and aggregate architecture of the soil, the role of the physical integrity of these structures on SOM turnover will also be investigated in laboratory experiments.

Schwerpunktprogramm (SPP) 1158: Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas; Bereich Infrastruktur - Antarktisforschung mit vergleichenden Untersuchungen in arktischen Eisgebieten, Biological soil crust algae in the polar regions - biodiversity, genetic diversity and ecosystem resilience under global change scenarios

Terrestrial green algae and cyanobacteria are typical and abundant components of biological soil crusts in the Polar Regions. These communities form water-stable aggregates that have important ecological roles in primary production, nitrogen fixation, nutrient cycling, water retention and stabilization of soils. Although available data on green algae and cyanobacteria are generally very limited for the Arctic and Antarctica, their functional importance as ecosystem developers in nutrient poor environments is regarded as high. Therefore, the main goal of the interdisciplinary project is, for the first time, a precise evaluation of their 1.) Biodiversity as well as of 2.) The infra-specific genetic diversity, 3.) ecophysiological performance and 4.) transcriptomics of the most abundant taxa in biological soil crusts isolated from the Antarctic Peninsula and Arctic Svalbard. Biodiversity will be investigated using a classical culture approach in combination with molecular-taxonomical methods as well as with metagenomics. The infra-specific genetic diversity of the most abundant green algae and cyanobacteria will be studied using fingerprinting techniques, and a range of selected populations characterized in relation to their physiological plasticity. Temperature and water availability, two key environmental factors for terrestrial organisms, are currently changing in Polar Regions due to global warming, and hence their effect on growth and photosynthesis response patterns will be comparatively investigated. The data will indicate whether and how global change influence population structure and ecological performance of key organisms in polar soil crusts, and help to make predictions on the future significance of the ecological functions of these pioneer communities. Such a multiphasic approach has never been applied before to soil algae and cyanobacteria in both Polar Regions, and hence represents one of the key innovations of this proposal.

AZV Project West Greenland

The AZV (Altitudinal Zonation of Vegetation) Project was initiated in the year 2002. On the basis of a detailed regional study in continental West Greenland the knowledge about altitudinal vegetation zonation in the Arctic is aimed to be enhanced. The main objectives of the project are: a) considering the regional study: characterize mountain vegetation with regard to flora, vegetation types, vegetation pattern and habitat conditions, investigate the differentiation of these vegetation characteristics along the altitudinal gradient, develop concepts about altitudinal indicator values of species and plant communities, extract suitable characteristics for the distinction and delimitation of vegetation belts, assess altitudinal borderlines of vegetation belts in the study area. b) considering generalizations: test the validity of the altitudinal zonation hypothesis of the Circumpolar Arctic Vegetation Map ( CAVM Team 2003), find important determinants of altitudinal vegetation zonation in the Arctic, develop a first small scale vegetation map of entire continental West Greenland. Field work consists of vegetational surveys according to the Braun-Blanquet approach, transect studies, soil analyses, long-time-measurements of temperature on the soil surface and vegetation mapping in three different altitudinal vegetation belts (up to 1070 m a.s.l.).

Natural Forest Management in Caracarai, Roraima, Brazil

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.

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

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.

Unraveling the genetic architecture of winter hardiness and quality traits in durum by genome wide and canidate gene based association mapping

Durum wheat is mainly grown as a summer crop. An introduction of a winter form failed until now due to the difficulty to combine winter hardiness with required process quality. Winter hardiness is a complex trait, but in most regions the frost tolerance is decisive. Thereby a major QTL, which was found in T. monococcum, T.aestivum, H. vulgare and S.cereale on chromosome 5, seems especially important. With genotyping by sequencing it is now possible to make association mapping based on very high dense marker maps, which delivers new possibilities to detect main and epistatic effects. Furthermore, new sequencing techniques allow candidate gene based association mapping. The main aim of the project is to unravel the genetic architecture of frost tolerance and quality traits in durum. Thereby, the objectives are to (1) determine the genetic variance, heritability and correlations among frost tolerance and quality traits, (2) examine linkage disequilibrium and population structure, (3) investigate sequence polymorphism at candidate genes for frost tolerance, and (4) perform candidate gene based and genome wide association mapping.

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.

Ecological valuation of crop pollination in traditional Indonesian homegardens

Traditional Indonesian homegardens harbour often high crop diversity, which appears to be an important basis for a sustainable food-first strategy. Crop pollination by insects is a key ecosystem service but threatened by agricultural intensification and land conversion. Gaps in knowledge of actual benefits from pollination services limit effective management planning. Using an integrative and agronomic framework for the assessment of functional pollination services, we will conduct ecological experiments and surveys in Central Sulawesi, Indonesia. We propose to study pollination services and net revenues of the locally important crop species cucumber, carrot, and eggplant in traditional homegardens in a forest distance gradient, which is hypothesized to affect bee community structure and diversity. We will assess pollination services and interactions with environmental variables limiting fruit maturation, based on pollination experiments in a split-plot design of the following factors: drought, nutrient deficiency, weed pressure, and herbivory. The overall goal of this project is the development of 'biodiversity-friendly' land-use management, balancing human and ecological needs for local smallholders.

Barley dwarfs acting big in agronomy. Identification of genes and characterization of proteins involved in dwarfism, lodging resistance and crop yield

Barley (Hordeum vulgare) is an important cereal grain which serves as major animal fodder crop as well as basis for malt beverages or staple food. Currently barley is ranked fourth in terms of quantity of cereal crops produced worldwide. In times of a constantly growing world population in conjunction with an unforeseeable climate change and groundwater depletion, the accumulation of knowledge concerning cereal growth and rate of yield gain is important. The Nordic Genetic Resource Center holds a major collection of barley mutants produced by irradiation or chemical treatment. One phenotypic group of barley varieties are dwarf mutants (erectoides, brachytic, semidwarf, uzu). They are characterized by a compact spike and high rate of yield while the straw is short and stiff, enhancing the lodging resistance of the plant. Obviously they are of applied interest, but they are also of scientific interest as virtually nothing is known about the genes behind the development of plant dwarfism. The aim of this project is to identify and isolate the genes carrying the mutations by using state of the art techniques for gene cloning at the Carlsberg Laboratory. The identified genes will be connected with the mutant phenotype to reveal the gene function in general. One or two genes will be overexpressed and the resulting recombinant proteins will be biochemically and structurally characterized. The insights how the mutation effects the protein will display the protein function in particular. Identified genes and their mutant alleles will be tested in the barley breeding program of the Carlsberg brewery.

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