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.
2018
Forfattere
Per-Erik Mellander Philip Jordan Marianne Bechmann Ophélie Fovet Mairead M. Shore Noeleen T. McDonald Chantal Gascuel-OdouxSammendrag
Det er ikke registrert sammendrag
Forfattere
Jian Liu Peter J. A. Kleinman Helena Aronsson Don Flaten Richard W. McDowell Marianne Bechmann Douglas B. Beegle Timothy P. Robinson Ray B. Bryant Hongbin Liu Andrew N. Sharpley Tamie L. VeithSammendrag
Winter manure application elevates nutrient losses and impairment of water quality as compared to manure applications in other seasons. In conjunction with reviewing global distribution of animal densities, we reviewed worldwide mandatory regulations and voluntary guidelines on efforts to reduce off-site nutrient losses associated with winter manure applications. Most of the developed countries implement regulations or guidelines to restrict winter manure application, which range from a regulative ban to guidelines based upon weather and field management conditions. In contrast, developing countries lack such official directives, despite an increasing animal production industry and concern over water quality. An analysis of five case studies reveals that directives are derived from a common rationale to reduce off-site manure nutrient losses, but they are also affected by local socioeconomic and biophysical considerations. Successful programs combine site-specific management strategies along with expansion of manure storage to offer farmers greater flexibility in winter manure management.
Forfattere
Magdalena Z. Bieroza A. Louise Heathwaite Marianne Bechmann Katarina Kyllmar Philip JordanSammendrag
Recent technological breakthroughs of optical sensors and analysers have enabled matching the water quality measurement interval to the time scales of stream flow changes and led to an improved understanding of spatially and temporally heterogeneous sources and delivery pathways for many solutes and particulates. This new ability to match the chemograph with the hydrograph has promoted renewed interest in the concentration-discharge (c-q) relationship and its value in characterizing catchment storage, time lags and legacy effects for both weathering products and anthropogenic pollutants. In this paper we evaluated the stream c-q relationships for a number of water quality determinands (phosphorus, suspended sediments, nitrogen) in intensively managed agricultural catchments based on both high-frequency (sub-hourly) and long-term low-frequency (fortnightly-monthly) routine monitoring data. We used resampled high-frequency data to test the uncertainty in water quality parameters (e.g. mean, 95th percentile and load) derived from low-frequency sub-datasets. We showed that the uncertainty in water quality parameters increases with reduced sampling frequency as a function of the c-q slope. We also showed that different sources and delivery pathways control c-q relationship for different solutes and particulates. Secondly, we evaluated the variation in c-q slopes derived from the long-term low-frequency data for different determinands and catchments and showed strong chemostatic behaviour for phosphorus and nitrogen due to saturation and agricultural legacy effects. The c-q slope analysis can provide an effective tool to evaluate the current monitoring networks and the effectiveness of water management interventions. This research highlights how improved understanding of solute and particulate dynamics obtained with optical sensors and analysers can be used to understand patterns in long-term water quality time series, reduce the uncertainty in the monitoring data and to manage eutrophication in agricultural catchments.
Forfattere
Rachel Cassidy Philip Jordan Marianne Bechmann Brian Kronvang Katarina Kyllmar Mairead ShoreSammendrag
Achieving an operational compromise between spatial coverage and temporal resolution in national scale river water quality monitoring is a major challenge for regulatory authorities, particularly where chemical concentrations are hydrologically dependent. The efficacy of flow-weighted composite sampling (FWCS) approaches for total phosphorus (TP) sampling (n = 26–52 analysed samples per year), previously applied in monitoring programmes in Norway, Sweden and Denmark, and which account for low to high flow discharges, was assessed by repeated simulated sampling on high resolution TP data. These data were collected in three research catchments in Ireland over the period 2010–13 covering a base-flow index range of 0.38 to 0.69. Comparisons of load estimates were also made with discrete (set time interval) daily and sub-daily sampling approaches (n = 365 to >1200 analysed samples per year). For all years and all sites a proxy of the Norwegian sampling approach, which is based on re-forecasting discharge for each 2-week deployment, proved most stable (median TP load estimates of 87–98%). Danish and Swedish approaches, using long-term flow records to set a flow constant, were only slightly less effective (median load estimates of 64–102% and 80–96%, respectively). Though TP load estimates over repeated iterations were more accurate using the discrete approaches, particularly the 24/7 approach (one sample every 7 h in a 24 bottle sampler - median % load estimates of 93–100%), composite load estimates were more stable, due to the integration of multiple small samples (n = 100–588) over a deployment.
Forfattere
Liv Østrem Marcin Rapacz Arild Larsen Petter Marum Odd Arne RognliSammendrag
Det er ikke registrert sammendrag
Forfattere
Pauline Bristiel Lauren Gillespie Liv Østrem Jennifer Balachowski Cyrille Violle Florence VolaireSammendrag
1. A core tenet of functional ecology is that the vast phenotypic diversity observed in the plant kingdom could be partly generated by a trade-off between the ability of plants to grow quickly and acquire resources in rich environments vs. the ability to conserve resources and avoid mortality under stress. However, experimental demonstrations remain scarce and potentially blurred by phylogenetic constraints in cross-species analyses. Here, we experimentally decoupled growth potential and stress survival by applying an off-season stress on contrasting populations of the perennial grass Dactylis glomerata exhibiting a range of seasonal dormancy.2. Seventeen populations of D. glomerata, originating from a latitudinal gradient from Norway to Morocco, were subjected to three types of dehydration stress: winter frost in Norway, and summer drought and early spring (off-season) drought stress in the south of France. Growth rate and two leaf traits (leaf width and leaf dry matter content) suspected to be involved in the adaptation to dehydration stress were monitored under optimal conditions. We quantified plant dehydration survival as the amount of plant recovery after a severe stress.3. Nordic populations were found to be winter-dormant. Winter- and summer-dor-mant populations better survived frost and summer drought, respectively. However, no trade-off between growth potential and dehydration survival was detected in non-dormant plants in early spring when dehydration occurred unsea-sonably for all populations. Furthermore, Mediterranean populations better survived an early spring drought.4. Our results highlight the importance of assessing plant growth potential as a re-sponse to seasonal environmental cues. They suggest that growth potential and stress survival trade off when plants exhibit seasonal dormancy but can be func-tionally independent at other seasons. Consequently, the growth–stress survival relationship could be better described as a dynamic linkage rather than a constant and general trade-off. Moreover, leaf trait values, such as thinner and more ligni-fied leaves reflecting drought adaptation, may have contributed to the improved drought-stress survival without resulting in a cost to growth. 5. Further exploration of the growth–stress survival relationship should permit deci-phering the suite of plant traits and trait covariations involved in plants’ responses to increasing stress.
Sammendrag
Although pasture is low-cost feed, many farmers find it difficult to maintain high milk yield when using pasturefor high-yielding dairy cows in automatically milked herds. Therefore, a seven-week experiment with 40 cows inearly to mid-lactation was performed to evaluate a management model for including pasture in the diet withoutjeopardizing milk production. Within a part-time grazing system with morning and evening outdoor access, wecompared a group with ad libitum grass silage indoors combined with access to a small grass-covered permanentpaddock for exercise and recreation (group EX) with a group offered production pasture at a high allowance percow and day combined with restricted grass silage allowance at night (group PROD). Both groups had the sameoutdoor access times and the same concentrate allowance based on pre-experimental milk yield. Milk yield andmilking frequency were recorded daily in the automatic milking unit. Milk recordings and samplings for de-termination of milk composition took place weekly and outdoor behaviour of cows was recorded during pastureaccess hours on six observation days, evenly distributed over the experimental period. During the experiment,average metabolisable energy concentration was higher in the grass silage offered both groups than in pastureherbage. However, our results showed no significant difference in daily milk yield between treatments.Furthermore, no signifi cant differences between treatments were found in energy-corrected milk, milk fatproduction, or body weight change. Milk protein production was, however, significantly higher in group PROD.In early lactation, no difference in milking frequency was observed between treatments while for cows in mid- tolate lactation, milking frequency was significantly higher in group EX than group PROD. Over the entire ex-periment, group EX cows spent significantly less time outdoors than group PROD. In conclusion, offering highyielding dairy cows in automatic milking systems high-quality pasture at a high allowance for a few hours inmorning and afternoon appears to be an interesting alternative to exercise paddock with full indoor feeding, as itcan reduce costs for supplementary silage, facilitate natural behaviour, and encourage cows to spend more timeoutdoors, while maintaining milk production at a level comparable to that of full indoor feeding.
Forfattere
Grete H. M. JørgensenSammendrag
Det er ikke registrert sammendrag
Sammendrag
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Forfattere
Ola Stedje HanserudSammendrag
Det er ikke registrert sammendrag