Fischer J.-T.,Austrian Research Center for Forests |
Kofler A.,Austrian Research Center for Forests |
Fellin W.,University of Innsbruck |
Granig M.,Snow and Avalanche Center |
Kleemayr K.,Austrian Research Center for Forests
Journal of Glaciology | Year: 2015
Snow avalanche simulation software is a commonly used tool for hazard estimation and mitigation planning. In this study a depth-averaged flow model, combining a simple entrainment and friction relation, is implemented in the software SamosAT. Computational results strongly depend on the simulation input, in particular on the employed model parameters. A long-standing problem is to quantify the influence of these parameters on the simulation results. We present a new multivariate optimization approach for avalanche simulation in three-dimensional terrain. The method takes into account the entire physically relevant range of the two friction parameters (Coulomb friction, turbulent drag) and one entrainment parameter. These three flow model parameters are scrutinized with respect to six optimization variables (runout, matched and exceeded affected area, maximum velocity, average deposition depth and mass growth). The approach is applied to a documented extreme avalanche event, recorded in St Anton, Austria. The final results provide adjusted parameter distributions optimizing the simulation-observation correspondence. At the same time, the degree of parameter-variable correspondence is determined. We show that the specification of optimal values for certain model parameters is near-impossible, if corresponding optimization variables are neglected or unavailable.
Paule J.,Senckenberg Institute |
Kolar F.,University of Oslo |
Kolar F.,Charles University |
Kolar F.,Academy of Sciences of the Czech Republic |
And 2 more authors.
Preslia | Year: 2015
The link between polyploidy and the disjunct arctic-alpine European distribution of Potentilla crantzii was studied with particular reference to the role of serpentine habitats. Flow cytometry, AFLPs and cpDNA sequencing provided insights into ploidy level variation and the genetic structure of European populations. We recorded a ploidy differentiated arctic-alpine disjunction with tetraploids limited to the central- and southern-European mountain chains and hexaploids dominating in the Subarctic. Two lowland serpentine populations in the Czech Republic and Austria exhibited contrasting genetic patterns suggesting different evolutionary histories, with the tetraploid Czech population showing a conspicuously high genetic diversity. Finally, our genetic and cytological data did not support a distinct taxonomic status for the serpentine populations that were traditionally differentiated as P. crantzii subsp. serpentini.
Amon B.,Leibniz Institute for Agricultural Engineering |
Winiwarter W.,International Institute For Applied Systems Analysis |
Anderl M.,Environment Agency Austria |
Baumgarten A.,Austrian Agency for Health and Food Safety AGES |
And 14 more authors.
GAIA | Year: 2014
FarmClim aims at contributing to a more considerate use of nitrogen in Austrian agriculture. The transdisciplinary research project attempts to tackle the "science-policy gap" by using a participatory approach, that is, stakeholders influence the research process as much as the scientists strive for the implementation of their ideas. This paper describes the project design and communication processes. Full integration of practice partners adds to the complexity of the project's structure, but brings consider able benefits right from the outset. Taking advantage of the existing institutional setting of FarmClim partners, we expect to maintain expert consultancy beyond the lifetime of the project, helping agriculture to meet the challenges of environmental and economic performance of a producing agriculture.
Stolting K.N.,University of Fribourg |
Paris M.,University of Fribourg |
Meier C.,University of Fribourg |
Heinze B.,Austrian Research Center for Forests |
And 3 more authors.
New Phytologist | Year: 2015
Studying the divergence continuum in plants is relevant to fundamental and applied biology because of the potential to reveal functionally important genetic variation. In this context, whole-genome sequencing (WGS) provides the necessary rigour for uncovering footprints of selection. We resequenced populations of two divergent phylogeographic lineages of Populus alba (n = 48), thoroughly characterized by microsatellites (n = 317), and scanned their genomes for regions of unusually high allelic differentiation and reduced diversity using > 1.7 million single nucleotide polymorphisms (SNPs) from WGS. Results were confirmed by Sanger sequencing. On average, 9134 high-differentiation (≥ 4 standard deviations) outlier SNPs were uncovered between populations, 848 of which were shared by ≥ three replicate comparisons. Annotation revealed that 545 of these were located in 437 predicted genes. Twelve percent of differentiation outlier genome regions exhibited significantly reduced genetic diversity. Gene ontology (GO) searches were successful for 327 high-differentiation genes, and these were enriched for 63 GO terms. Our results provide a snapshot of the roles of 'hard selective sweeps' vs divergent selection of standing genetic variation in distinct postglacial recolonization lineages of P. alba. Thus, this study adds to our understanding of the mechanisms responsible for the origin of functionally relevant variation in temperate trees. © 2015 New Phytologist Trust.
Hoyer-Tomiczek U.,Austrian Research Center for Forests |
Sauseng G.,Sonnenweg 1 |
Hoch G.,Austrian Research Center for Forests
EPPO Bulletin | Year: 2016
Surveillance for the Asian longhorn beetle, Anoplophora glabripennis, currently depends on visual inspection. As one complementary method, dogs have been trained and employed for the detection of A. glabripennis since 2009. In this study, two sets of experiments in double-blind trials were carried out to quantify the sensitivity of the dog detection method using 10 dogs in the first set and 14 dogs in the second. All experiments used the same basic set-up of 2 positive and 6 negative samples presented in random order. In the first series, A. glabripennis scent material (frass, a living larva or infested wood plus a living larva) was placed in hollow building blocks invisible to dogs and handlers. The experiments had an overall sensitivity of 85-93% (correct positives of all positives) and specificity of 79-94% (correct negatives of all negatives). The second series tested more realistic but also standardized situations: A. glabripennis frass and wood shavings were hidden in ground vegetation at the base of young poplar trees in a plantation, in tubes at a height of 1.8 m on these poplar trees and in crevices on old trees in an orchard at a height of about 1.8 m, respectively. These experiments had an overall sensitivity of 75-88% and a specificity of 85-96%. © 2016 The Authors.
Krenn J.,University of Natural Resources and Life Sciences, Vienna |
Mergili M.,University of Natural Resources and Life Sciences, Vienna |
Mergili M.,University of Vienna |
Fischer J.T.,Austrian Research Center for Forests |
And 2 more authors.
Landslides and Engineered Slopes. Experience, Theory and Practice | Year: 2016
The parameter set up of mass flow models decides on the quality of the results. We present a novel parameter optimization procedure, building on the comparison of model results and observed deposition areas. As it is evident that natural conditions cannot be represented by one constant value for larger areas we suggest using input value ranges rather than discrete values. The proposed procedure consists in a stepwise optimization of the input parameter values and ranges by using the precedent results as input for the next step. The procedure is applicable to any type of single-value input parameter and any type of mass flow propagation model. We use two GIS-based open source modelling tools: (i) the conceptual r.randomwalk and (ii) the complex physically-based r.avaflow. Both tools are capable to process value ranges of input parameters. The still ongoing study aims to derive reliable guiding values for various process types to be used for forward calculations. We demonstrate the procedure using two rock avalanche events (Acheron and Black Rapids). The first outcomes are promising, but more work is necessary to confirm and extend the validity of the results. © 2016 Associazione Geotecnica Italiana, Rome, Italy.
Jansen S.,Austrian Research Center for Forests |
Geburek T.,Austrian Research Center for Forests
Forest Ecology and Management | Year: 2016
For the first time we have reviewed historic data throughout Europe to assess how European larch has been artificially distributed from the 17th until the mid-20th century. Over this period, larch genetic resources have been translocated with varying intensity. Especially Alpine plant material was transferred outside the native range across Europe, while genetic resources originating from the Sudetes were mainly spread to northeastern Germany, northwestern Poland, and to the Sudetes outside of the species’ native range. Polish larch was mainly translocated within Poland. Genetic resources from the Carpathian Mountains (Tatras, eastern and southern Carpathians) were not used for long-distance transfer. While native larch populations in the Alps and in Poland were not significantly affected by allochthonous plant material, the native gene pool of larch in the Sudetes and Carpathians Mountains was strongly altered by Alpine plant material. We provide several maps illustrating these translocations over time and space. These findings are of special importance, as genetic data tracking the original seed source are presently not available. © 2016 Elsevier B.V.
Buhler Y.,Institute for Snow and Avalanche Research |
Adams M.S.,Austrian Research Center for Forests |
Bosch R.,Swiss Federal Institute of forest |
Stoffel A.,Institute for Snow and Avalanche Research
Cryosphere | Year: 2016
Detailed information on the spatiotemporal snow depth distribution is a crucial input for numerous applications in hydrology, climatology, ecology and avalanche research. Today, snow depth distribution is usually estimated by combining point measurements from weather stations or observers in the field with spatial interpolation algorithms. However, even a dense measurement network like the one in Switzerland, with more than one measurement station per 10 km2 on average, is not able to capture the large spatial variability of snow depth present in alpine terrain. Remote sensing methods, such as laser scanning or digital photogrammetry, have recently been successfully applied to map snow depth variability at local and regional scales. However, in most countries such data acquisition is costly if manned airplanes are involved. The effectiveness of ground-based measurements on the other hand is often hindered by occlusions, due to the complex terrain or acute viewing angles. In this paper, we investigate the application of unmanned aerial systems (UASs), in combination with structure-from-motion photogrammetry, to map snow depth distribution. Compared to manual measurements, such systems are relatively cost-effective and can be applied very flexibly to cover terrain not accessible from the ground. In this study, we map snow depth at two different locations: (a) a sheltered location at the bottom of the Fluëla valley (1900ma.s.l.) and (b) an exposed location on a peak (2500ma.s.l.) in the ski resort Jakobshorn, both in the vicinity of Davos, Switzerland. At the first test site, we monitor the ablation on three different dates. We validate the photogrammetric snow depth maps using simultaneously acquired manual snow depth measurements. The resulting snow depth values have a root mean square error (RMSE) of less than 0.07 to 0.15m on meadows and rocks and a RMSE of less than 0.30m on sections covered by bushes or tall grass, compared to manual probe measurements. This new measurement technology opens the door for efficient, flexible, repeatable and cost-effective snow depth monitoring over areas of several hectares for various applications, if the national and regional regulations permit the application of UASs. © 2016 Author(s).
Sovilla B.,WSL Institute for Snow and Avalanche Research SLF |
Faug T.,IRSTEA |
Kohler A.,WSL Institute for Snow and Avalanche Research SLF |
Baroudi D.,Aalto University |
And 2 more authors.
Cold Regions Science and Technology | Year: 2016
Low-speed wet avalanches exert hydrostatic forces on structures that are flow-depth dependent. However, the pressure amplification experienced by smaller structures has not been quantified previously. In particular, recent wet avalanche pressure measurements, performed with small cells at the "Vallée de la Sionne" test site, indicate significantly higher pressures than those considered by engineering guidelines and common practice rules based only on the contribution of inertial forces. In order to gain a deeper understanding and investigate the relevance of these measurements for structural design, we analyzed data measured on obstacles of different shapes and dimensions. The pressure measured on a 1 m2 pressure plate was, on average, 1.8 times smaller than the pressure measured on a 0.008 m2 piezoelectric cell installed on a 0.60 m wide pylon and 2.9 times smaller than the pressure measured on a 0.0125 m2 cantilever sensor extending freely into the avalanche flow. Further, avalanches characterized by a gravitational flow regime exerted pressures that increased linearly with avalanche depth. For Froude numbers larger than 1, an additional square-velocity dependent contribution could not be neglected. The pressure variations encountered by the different obstacles could be explained quantitatively with a granular force model, that assumes the formation of a mobilized volume of snow granules extending from the obstacle upstream whose dimensions depend on the incoming flow depth and the obstacle width. This mobilized volume is associated with the formation of a network of gravity-loaded grain-grain contacts, also called granular force chains, which densifies in front of the obstacle, producing force amplification. Our results underscore the fundamental influence of the dimensions of both the sensor and the obstacle on pressures in the gravitational flow regime and may help to improve rules for structural design. © 2016 The Authors.
PubMed | University of West Hungary, University of Salerno, Austrian Research Center for Forests and University of Fribourg
Type: Journal Article | Journal: The New phytologist | Year: 2015
Studying the divergence continuum in plants is relevant to fundamental and applied biology because of the potential to reveal functionally important genetic variation. In this context, whole-genome sequencing (WGS) provides the necessary rigour for uncovering footprints of selection. We resequenced populations of two divergent phylogeographic lineages of Populus alba (n = 48), thoroughly characterized by microsatellites (n = 317), and scanned their genomes for regions of unusually high allelic differentiation and reduced diversity using > 1.7 million single nucleotide polymorphisms (SNPs) from WGS. Results were confirmed by Sanger sequencing. On average, 9134 high-differentiation ( 4 standard deviations) outlier SNPs were uncovered between populations, 848 of which were shared by three replicate comparisons. Annotation revealed that 545 of these were located in 437 predicted genes. Twelve percent of differentiation outlier genome regions exhibited significantly reduced genetic diversity. Gene ontology (GO) searches were successful for 327 high-differentiation genes, and these were enriched for 63 GO terms. Our results provide a snapshot of the roles of hard selective sweeps vs divergent selection of standing genetic variation in distinct postglacial recolonization lineages of P. alba. Thus, this study adds to our understanding of the mechanisms responsible for the origin of functionally relevant variation in temperate trees.