@misc{SmithBookhagenCannon2015,
  author    = {Smith, Taylor and Bookhagen, Bodo and Cannon, Forest},
  title     = {Improving semi-automated glacier mapping with a multi-method approach},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {510},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-40847},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408471},
  pages     = {13},
  year      = {2015},
  abstract  = {Studies of glaciers generally require precise glacier outlines. Where these are not available, extensive manual digitization in a geographic information system (GIS) must be performed, as current algorithms struggle to delineate glacier areas with debris cover or other irregular spectral profiles. Although several approaches have improved upon spectral band ratio delineation of glacier areas, none have entered wide use due to complexity or computational intensity. In this study, we present and apply a glacier mapping algorithm in Central Asia which delineates both clean glacier ice and debris-covered glacier tongues. The algorithm is built around the unique velocity and topographic characteristics of glaciers and further leverages spectral and spatial relationship data. We found that the algorithm misclassifies between 2 and 10\% of glacier areas, as compared to a similar to 750 glacier control data set, and can reliably classify a given Landsat scene in 3-5 min. The algorithm does not completely solve the difficulties inherent in classifying glacier areas from remotely sensed imagery but does represent a significant improvement over purely spectral-based classification schemes, such as the band ratio of Landsat 7 bands three and five or the normalized difference snow index. The main caveats of the algorithm are (1) classification errors at an individual glacier level, (2) reliance on manual intervention to separate connected glacier areas, and (3) dependence on fidelity of the input Landsat data.},
  language  = {en}
}
@misc{FrindteAllgaierGrossartetal.2015,
  author    = {Frindte, Katharina and Allgaier, Martin and Grossart, Hans-Peter and Eckert, Werner},
  title     = {Microbial response to experimentally controlled redox transitions at the sediment water interface},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {509},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-40846},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408464},
  pages     = {17},
  year      = {2015},
  abstract  = {The sediment-water interface of freshwater lakes is characterized by sharp chemical gradients, shaped by the interplay between physical, chemical and microbial processes. As dissolved oxygen is depleted in the uppermost sediment, the availability of alternative electron acceptors, e.g. nitrate and sulfate, becomes the limiting factor. We performed a time series experiment in a mesocosm to simulate the transition from aerobic to anaerobic conditions at the sediment-water interface. Our goal was to identify changes in the microbial activity due to redox transitions induced by successive depletion of available electron acceptors. Monitoring critical hydrochemical parameters in the overlying water in conjunction with a new sampling strategy for sediment bacteria enabled us to correlate redox changes in the water to shifts in the active microbial community and the expression of functional genes representing specific redox-dependent microbial processes. Our results show that during several transitions from oxic-heterotrophic condition to sulfate-reducing condition, nitrate-availability and the on-set of sulfate reduction strongly affected the corresponding functional gene expression. There was evidence of anaerobic methane oxidation with NOx. DGGE analysis revealed redox-related changes in microbial activity and expression of functional genes involved in sulfate and nitrite reduction, whereas methanogenesis and methanotrophy showed only minor changes during redox transitions. The combination of high-frequency chemical measurements and molecular methods provide new insights into the temporal dynamics of the interplay between microbial activity and specific redox transitions at the sediment-water interface.},
  language  = {en}
}
@misc{MarcusBochDurkaetal.2015,
  author    = {Marcus, Tamar and Boch, Steffen and Durka, Walter and Gossner, Martin M. and M{\"u}ller, J{\"o}rg and Sch{\"o}ning, Ingo and Weisser, Wolfgang W. and Drees, Claudia and Assmann, Thorsten},
  title     = {Living in heterogeneous woodlands},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {508},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-40845},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408451},
  pages     = {18},
  year      = {2015},
  abstract  = {Abstract Although genetic diversity is one of the key components of biodiversity, its drivers are still not fully understood. While it is known that genetic diversity is affected both by environmental parameters as well as habitat history, these factors are not often tested together. Therefore, we analyzed 14 microsatellite loci in Abax parallelepipedus, a flightless, forest dwelling ground beetle, from 88 plots in two study regions in Germany. We modeled the effects of historical and environmental variables on allelic richness, and found for one of the regions, the Schorfheide-Chorin, a significant effect of the depth of the litter layer, which is a main component of habitat quality, and of the sampling effort, which serves as an inverse proxy for local population size. For the other region, the Schwabische Alb, none of the potential drivers showed a significant effect on allelic richness. We conclude that the genetic diversity in our study species is being driven by current local population sizes via environmental variables and not by historical processes in the studied regions. This is also supported by lack of genetic differentiation between local populations sampled from ancient and from recent woodlands. We suggest that the potential effects of former fragmentation and recolonization processes have been mitigated by the large and stable local populations of Abax parallelepipedus in combination with the proximity of the ancient and recent woodlands in the studied landscapes.},
  language  = {en}
}
@misc{AichnerFeakinsLeeetal.2015,
  author    = {Aichner, Bernhard and Feakins, Sarah J. and Lee, J. E. and Herzschuh, Ulrike and Liu, X.},
  title     = {High-resolution leaf wax carbon and hydrogen isotopic record of the late Holocene paleoclimate in arid Central Asia},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {506},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-40844},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408442},
  pages     = {15},
  year      = {2015},
  abstract  = {Central Asia is located at the confluence of large-scale atmospheric circulation systems. It is thus likely to be highly susceptible to changes in the dynamics of those systems; however, little is still known about the regional paleoclimate history. Here we present carbon and hydrogen isotopic compositions of n-alkanoic acids from a late Holocene sediment core from Lake Karakuli (eastern Pamir, Xinjiang Province, China). Instrumental evidence and isotopeenabled climate model experiments with the Laboratoire de Meteorologie Dynamique Zoom model version 4 (LMDZ4) demonstrate that delta D values of precipitation in the region are influenced by both temperature and precipitation amount. We find that these parameters are inversely correlated on an annual scale, i.e., the climate has varied between relatively cool and wet and more warm and dry over the last 50 years. Since the isotopic signals of these changes are in the same direction and therefore additive, isotopes in precipitation are sensitive recorders of climatic changes in the region. Additionally, we infer that plants use year-round precipitation (including snowmelt), and thus leaf wax delta D values must also respond to shifts in the proportion of moisture derived from westerly storms during late winter and early spring. Downcore results give evidence for a gradual shift to cooler and wetter climates between 3.5 and 2.5 cal kyr BP, interrupted by a warm and dry episode between 3.0 and 2.7 kyr BP. Further cool and wet episodes occur between 1.9 and 1.5 and between 0.6 and 0.1 kyr BP, the latter coeval with the Little Ice Age. Warm and dry episodes from 2.5 to 1.9 and 1.5 to 0.6 kyr BP coincide with the Roman Warm Period and Medieval Climate Anomaly, respectively. Finally, we find a drying tend in recent decades. Regional comparisons lead us to infer that the strength and position of the westerlies, and wider northern hemispheric climate dynamics, control climatic shifts in arid Central Asia, leading to complex local responses. Our new archive from Lake Karakuli provides a detailed record of the local signatures of these climate transitions in the eastern Pamir.},
  language  = {en}
}
@misc{KellermannSchoebelKundelaetal.2015,
  author    = {Kellermann, Patric and Sch{\"o}bel, A. and Kundela, G. and Thieken, Annegret},
  title     = {Estimating flood damage to railway infrastructure},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {504},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-40842},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408429},
  pages     = {12},
  year      = {2015},
  abstract  = {Models for estimating flood losses to infrastructure are rare and their reliability is seldom investigated although infrastructure losses might contribute considerably to the overall flood losses. In this paper, an empirical modelling approach for estimating direct structural flood damage to railway infrastructure and associated financial losses is presented. Via a combination of event data, i.e. photo-documented damage on the Northern Railway in Lower Austria caused by the March River flood in 2006, and simulated flood characteristics, i.e. water levels, flow velocities and combinations thereof, the correlations between physical flood impact parameters and damage occurred to the railway track were investigated and subsequently rendered into a damage model. After calibrating the loss estimation using recorded repair costs of the Austrian Federal Railways, the model was applied to three synthetic scenarios with return periods of 30, 100 and 300 years of March River flooding. Finally, the model results are compared to depth-damage-curve-based approaches for the infrastructure sector obtained from the Rhine Atlas damage model and the Damage Scanner model. The results of this case study indicate a good performance of our two-stage model approach. However, due to a lack of independent event and damage data, the model could not yet be validated. Future research in natural risk should focus on the development of event and damage documentation procedures to overcome this significant hurdle in flood damage modelling.},
  language  = {en}
}
@misc{ParkLuehrStolleetal.2015,
  author    = {Park, J. and L{\"u}hr, H. and Stolle, Claudia and Malhotra, G. and Baker, J. B. H. and Buchert, Stephan and Gill, R.},
  title     = {Estimating along-track plasma drift speed from electron density measurements by the three Swarm satellites},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {503},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-40841},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408417},
  pages     = {7},
  year      = {2015},
  abstract  = {Plasma convection in the high-latitude ionosphere provides important information about magnetosphere-ionosphere-thermosphere coupling. In this study we estimate the along-track component of plasma convection within and around the polar cap, using electron density profiles measured by the three Swarm satellites. The velocity values estimated from the two different satellite pairs agree with each other. In both hemispheres the estimated velocity is generally anti-sunward, especially for higher speeds. The obtained velocity is in qualitative agreement with Super Dual Auroral Radar Network data. Our method can supplement currently available instruments for ionospheric plasma velocity measurements, especially in cases where these traditional instruments suffer from their inherent limitations. Also, the method can be generalized to other satellite constellations carrying electron density probes.},
  language  = {en}
}
@misc{TedderCarleialGołębiewskaetal.2015,
  author    = {Tedder, Andrew and Carleial, Samuel and Gołębiewska, Martyna and Kappel, Christian and Shimizu, Kentaro K. and Stift, Marc},
  title     = {Evolution of the selfing syndrome in Arabis alpina (Brassicaceae)},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {502},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-40840},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408401},
  pages     = {17},
  year      = {2015},
  abstract  = {Introduction The transition from cross-fertilisation (outcrossing) to self-fertilisation (selfing) frequently coincides with changes towards a floral morphology that optimises self-pollination, the selfing syndrome. Population genetic studies have reported the existence of both outcrossing and selfing populations in Arabis alpina (Brassicaceae), which is an emerging model species for studying the molecular basis of perenniality and local adaptation. It is unknown whether its selfing populations have evolved a selfing syndrome. Methods Using macro-photography, microscopy and automated cell counting, we compared floral syndromes (size, herkogamy, pollen and ovule numbers) between three outcrossing populations from the Apuan Alps and three selfing populations from the Western and Central Alps (Maritime Alps and Dolomites). In addition, we genotyped the plants for 12 microsatellite loci to confirm previous measures of diversity and inbreeding coefficients based on allozymes, and performed Bayesian clustering. Results and Discussion Plants from the three selfing populations had markedly smaller flowers, less herkogamy and lower pollen production than plants from the three outcrossing populations, whereas pistil length and ovule number have remained constant. Compared to allozymes, microsatellite variation was higher, but revealed similar patterns of low diversity and high Fis in selfing populations. Bayesian clustering revealed two clusters. The first cluster contained the three outcrossing populations from the Apuan Alps, the second contained the three selfing populations from the Maritime Alps and Dolomites. Conclusion We conclude that in comparison to three outcrossing populations, three populations with high selfing rates are characterised by a flower morphology that is closer to the selfing syndrome. The presence of outcrossing and selfing floral syndromes within a single species will facilitate unravelling the genetic basis of the selfing syndrome, and addressing which selective forces drive its evolution.},
  language  = {en}
}
@misc{DubovskayaTangGladyshevetal.2015,
  author    = {Dubovskaya, Olga P. and Tang, Kam W. and Gladyshev, Michail I. and Kirillin, Georgiy and Buseva, Zhanna and Kasprzak, Peter and Tolomeev, Aleksandr P. and Grossart, Hans-Peter},
  title     = {Estimating in situ zooplankton non-predation mortality in an oligo-mesotrophic lake from sediment trap data},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {501},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-40839},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408392},
  pages     = {17},
  year      = {2015},
  abstract  = {Background Mortality is a main driver in zooplankton population biology but it is poorly constrained in models that describe zooplankton population dynamics, food web interactions and nutrient dynamics. Mortality due to non-predation factors is often ignored even though anecdotal evidence of non-predation mass mortality of zooplankton has been reported repeatedly. One way to estimate non-predation mortality rate is to measure the removal rate of carcasses, for which sinking is the primary removal mechanism especially in quiescent shallow water bodies. Objectives and Results We used sediment traps to quantify in situ carcass sinking velocity and non-predation mortality rate on eight consecutive days in 2013 for the cladoceran Bosmina longirostris in the oligo-mesotrophic Lake Stechlin; the outcomes were compared against estimates derived from in vitro carcass sinking velocity measurements and an empirical model correcting in vitro sinking velocity for turbulence resuspension and microbial decomposition of carcasses. Our results show that the latter two approaches produced unrealistically high mortality rates of 0.58-1.04 d(-1), whereas the sediment trap approach, when used properly, yielded a mortality rate estimate of 0.015 d(-1), which is more consistent with concurrent population abundance data and comparable to physiological death rate from the literature. Ecological implications Zooplankton carcasses may be exposed to water column microbes for days before entering the benthos; therefore, non-predation mortality affects not only zooplankton population dynamics but also microbial and benthic food webs. This would be particularly important for carbon and nitrogen cycles in systems where recurring mid-summer decline of zooplankton population due to non-predation mortality is observed.},
  language  = {en}
}
@misc{MuenchKipfstuhlFreitagetal.2016,
  author    = {M{\"u}nch, Thomas and Kipfstuhl, Sepp and Freitag, Johannes and Meyer, Hanno and Laepple, Thomas},
  title     = {Regional climate signal vs. local noise},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {500},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-40838},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408385},
  pages     = {17},
  year      = {2016},
  abstract  = {In low-accumulation regions, the reliability of delta O-18-derived temperature signals from ice cores within the Holocene is unclear, primarily due to the small climate changes relative to the intrinsic noise of the isotopic signal. In order to learn about the representativity of single ice cores and to optimise future ice-core-based climate reconstructions, we studied the stable-water isotope composition of firn at Kohnen Station, Dronning Maud Land, Antarctica. Analysing delta O-18 in two 50m long snow trenches allowed us to create an unprecedented, two-dimensional image characterising the isotopic variations from the centimetre to the 100-metre scale. Our results show seasonal layering of the isotopic composition but also high horizontal isotopic variability caused by local stratigraphic noise. Based on the horizontal and vertical structure of the isotopic variations, we derive a statistical noise model which successfully explains the trench data. The model further allows one to determine an upper bound for the reliability of climate reconstructions conducted in our study region at seasonal to annual resolution, depending on the number and the spacing of the cores taken.},
  language  = {en}
}
@misc{WilskeEccardZistlSchlingmannetal.2015,
  author    = {Wilske, Burkhard and Eccard, Jana and Zistl-Schlingmann, Marcus and Hohmann, Maximilian and Methler, Annabel and Herde, Antje and Liesenjohann, Thilo and Dannenmann, Michael and Butterbach-Bahl, Klaus and Breuer, Lutz},
  title     = {Effects of short term bioturbation by common voles on biogeochemical soil variables},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {499},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-40837},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408375},
  pages     = {19},
  year      = {2015},
  abstract  = {Bioturbation contributes to soil formation and ecosystem functioning. With respect to the active transport of matter by voles, bioturbation may be considered as a very dynamic process among those shaping soil formation and biogeochemistry. The present study aimed at characterizing and quantifying the effects of bioturbation by voles on soil water relations and carbon and nitrogen stocks. Bioturbation effects were examined based on a field set up in a luvic arenosol comprising of eight 50 x 50 m enclosures with greatly different numbers of common vole (Microtus arvalis L., ca. 35-150 individuals ha(-1) mth(-1)). Eleven key soil variables were analyzed: bulk density, infiltration rate, saturated hydraulic conductivity, water holding capacity, contents of soil organic carbon (SOC) and total nitrogen (N), CO2 emission potential, C/N ratio, the stable isotopic signatures of C-13 and N-15, and pH. The highest vole densities were hypothesized to cause significant changes in some variables within 21 months. Results showed that land history had still a major influence, as eight key variables displayed an additional or sole influence of topography. However, the delta N-15 at depths of 10-20 and 20-30 cm decreased and increased with increasing vole numbers, respectively. Also the CO2 emission potential from soil collected at a depth of 15-30 cm decreased and the C/N ratio at 5-10 cm depth narrowed with increasing vole numbers. These variables indicated the first influence of voles on the respective mineralization processes in some soil layers. Tendencies of vole activity homogenizing SOC and N contents across layers were not significant. The results of the other seven key variables did not confirm significant effects of voles. Thus overall, we found mainly a first response of variables that are indicative for changes in biogeochemical dynamics but not yet of those representing changes in pools.},
  language  = {en}
}