Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2017
Forfattere
Holger LangeSammendrag
Long time series of environmental variables are reflecting the dynamics of ecosystems. Data on climate, water, carbon, nutrients and other observables provide the key to understand terrestrial systems and to detect trends, systemic changes and responses, e.g. to changing climate, disturbances, or management. We present a number of diagnostic measures, based on symbolic dynamics or order statistics, which quantify the information content and the complexity of environmental time series. Three examples for the application of complexity measures in environmental sciences will be provided: Earth System Models and their ability to reproduce observations of Gross Primary Productivity, the dynamics of river runoff, and long-term behavior of ion concentrations in stream water from a monitoring site in Germany. Diagnostic measures of this kind provide data-analytical tools that distinguish different types of natural processes based solely on their dynamics, and are thus highly suitable for environmental science applications such as model structural diagnostics.
Sammendrag
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Sammendrag
Volatiles emitted by plants convey an array of information through different trophic levels. Animals such as host-seeking herbivores encounter plumes with filaments from both host and non-host plants. While studies showed a behavioral effect of non-host plants on herbivore host location, less information is available on how a searching insect herbivore perceives and flies upwind to a host-plant odor plume within a background of non-host volatiles. We hypothesized here that herbivorous insects in search of a host-plant can discriminate plumes of host and non-host plants and that the taxonomic relatedness of the non-host have an effect on finding the host. We also predicted that the ratio between certain plant volatiles is cognized as host-plant recognition cue by a receiver herbivorous insect. To verify these hypotheses we measured the wind tunnel response of the moth Argyresthia conjugella to the host plant rowan, to non-host plants taxonomically related (Rosaceae, apple and pear) or unrelated to the host (Pinaceae, spruce) and to binary combination of host and non-host plants. Volatiles were collected from all plant combinations and delivered to the test insect via an ultrasonic sprayer as an artificial plume. While the response to the rowan as a plant was not affected by the addition of any of the non-host plants, the attraction to the corresponding sprayed headspace decreased when pear or apple but not spruce were added to rowan. A similar result was measured toward the odor exiting a jar where freshly cut plant material of apple or pear or spruce was intermixed with rowan. Dose-response gas-chromatography coupled to electroantennography revealed the presence of seven field attractive and seven background non-attractive antennally active compounds. Although the abundance of field attractive and of some background volatiles decreased in all dual combinations in comparison with rowan alone, an increased amount of the background compounds (3E)-4,8-Dimethyl-1,3,7-nonatriene ((E)-DMNT) and (Z)-3-hexenyl acetate was found in the rowan-apple and rowan-pear but not in the rowan-spruce headspace. A higher ratio between the abundance of each field attractive component and that of (E)-DMNT and (Z)-3-hexenyl acetate was measured for rowan and rowan-spruce in contrast to rowan-pear and rowan-apple headspaces. Our result suggests that the ratio between field attractive and background antennaly active volatiles encodes host-plant recognition in our study system.
Forfattere
Klaus Mittenzwei Stefan MannSammendrag
Purpose Outside farming, pluriactivity is generally considered as undesirable, whereas agricultural economists tend to recommend part-time farming. This contradiction is to be solved. The paper aims to discuss this issue. Design/methodology/approach Linking tax-payer and statistical farm-level data from Norway, the authors tested how profitable part-time farming is for Norwegian farm households. Findings The analysis showed that concentrating on either working on-farm or off-farm generates a higher household income than combining the two. Practical implications Part-time farming may be a lifestyle decision, but apparently is not economically optimal for most farms. Originality/value The contribution solves an apparent contradiction between the discourses inside and outside agriculture.
Forfattere
Arne Henningsen Tomasz Gerard Czekaj Björn Forkman Mogens Lund Aske Schou NielsenSammendrag
We propose a theoretical framework for the relationship between animal welfare and the economic performance of livestock farms. We empirically analyse this relationship based on a unique dataset of randomly sampled Danish pig herds that includes information from unannounced inspections of the compliance with the animal welfare legislation. We find large variations in economic performance and animal welfare. The relationship between these two indicators is rather weak, but tends to be slightly positive. A possible explanation for our results is that management has a major influence on both economic performance and animal welfare so that good farm managers are able to meet all animal welfare regulations, while achieving a high economic performance.
Sammendrag
Area-efficient constructed systems for stormwater management and bioretention may involve large fluc-tuations in subsurface water levels. Such fluctuations challenge vegetation by forcing roots to exploredeeper layers to access water during dry periods. In a controlled experiment, we studied growth pat-terns and the ability of Phragmites australis roots to track subsurface water level fluctuations of differingamplitude and frequency in substrates with contrasting water-holding capacity. We found that P. aus-tralis was able to adjust its rooting pattern to considerable subsurface water level fluctuations (to wellbelow 120 cm), but that substrate characteristics can restrict its ability to adjust to larger fluctuations.Fluctuation amplitude was the driving factor for plant growth and biomass allocation responses, whilesubstrate characteristics and fluctuation frequency were less important. When not exposed to large waterlevel fluctuations, P. australis grew larger shoots and only explored intermediate rooting depths. Therewas a negative relationship between root and rhizome biomass, showing a resource-based trade-off andshort-term costs of adjusting rooting patterns to large water level fluctuations. These results indicatethat P. australis is suited for systems with considerable subsurface water fluctuations, but constraints onits flexibility need to be investigated.
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Sammendrag
Large herbivores gain nutritional benefits from following the sequential flush of newly emergent, high- quality forage along environmental gradients in the landscape, termed green wave surfing. Which landscape characteristics underlie the environmental gradi-ent causing the green wave and to what extent landscape characteristics alone explain individual variation in nutritional benefits remain unresolved questions. Here, we com-bine GPS data from 346 red deer (Cervus elaphus) from four partially migratory popula-tions in Norway with the satellite- derived normalized difference vegetation index (NDVI), an index of plant phenology. We quantify whether migratory deer had access to higher quality forage than resident deer, how landscape characteristics within sum-mer home ranges affected nutritional benefits, and whether differences in landscape characteristics could explain differences in nutritional gain between migratory and resident deer. We found that migratory red deer gained access to higher quality forage than resident deer but that this difference persisted even after controlling for land-scape characteristics within the summer home ranges. There was a positive effect of elevation on access to high- quality forage, but only for migratory deer. We discuss how the landscape an ungulate inhabits may determine its responses to plant phenol-ogy and also highlight how individual behavior may influence nutritional gain beyond the effect of landscape.
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Forfattere
Anja Karine Ruud Susanne Skinnehaugen Windju Andrea Ficke Jon Arne Dieseth Timothy L. Friesen Morten LillemoSammendrag
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