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.
2012
Forfattere
Kjell Andreassen Bernt-Håvard ØyenSammendrag
Growth conditions in Fennoscandia are characterized by relatively short growth seasons and cold winters, from 130 growth days (T 5C) in the far north high mountains to more than 200 in south Sweden and Norway. Growth models from different regions predict different forest growth.In this study, we compare some models commonly applied in forest growth prognosis in pure even aged stands of Norway spruce, Scots pine and birch in Finland, Sweden and Norway. The objectives is to identify behavioural properties, accuracy and bias in selected Nordic growth models using a wide-ranging test data set from permanent research plots in Norway.Present tentative conclusions about the accuracy of growth outside the geographical range of the original base materials. With four different response variables in the tested models we emphasized relative deviations rather than absolute values as most suitable for comparisons. The models were compared by statistical tests, a visual inspection of the smoothed curve of the relative deviations in different stand properties and ranked due to their performance.We observed site index, stand density and mean tree size as the three main components in the models. For Norway spruce a basal area increment model from Sweden had the lowest standard deviation with 23 %. The mean R2 between residuals and stand characteristics from this model was also low (1.3 %), which indicates that variables are well included in the model. For Scots pine and birch, Finnish percent volume growth models showed the best fit to the Norwegian test data, with a R2 between residuals and stand characteristics of 2.8 and 6.7 %, respectively. Several of the models from Sweden and Finland predict the growth as well as stand models frequently in use in Norway.
Forfattere
Jane Uhd Jepsen Erik Martin Biuw Rolf Anker Ims Lauri Teemu Kapari Tino Schott Ole Petter Laksforsmo Vindstad Snorre HagenSammendrag
Insect outbreaks in northern-boreal forests are expected to intensify owing to climate warming, but our understanding of direct and cascading impacts of insect outbreaks on forest ecosystem functioning is deficient. The duration and severity of outbreaks by geometrid moths in northern Fennoscandian mountain birch forests have been shown to be accentuated by a recent climatemediated range expansion, in particular of winter moth (Operophtera brumata). Here, we assess the effect of moth outbreak severity, quantified from satellite-based defoliation maps, on the state of understory vegetation and the abundance of key vertebrate herbivores in mountain birch forest in northern Norway. We show that the most recent moth outbreak caused a regional-scale state change to the understory vegetation, mainly due to a shift in dominance from the allelopathic and unpalatable dwarf-shrub Empetrum nigrum to the productive and palatable grass Avenella flexuosa. Both these central understory plant species responded significantly and nonlinearly to increasing outbreak severity. We further provide evidence that the effects of the outbreak on understory vegetation cascaded to cause strong but opposite impacts on the abundance of the two most common herbivore groups. Rodents increased with defoliation, largely mirroring the increase in A. flexuosa, whereas ungulate abundance instead showed a decreasing trend. Our analyses also suggest that the response of understory vegetation to defoliation may depend on the initial state of the forest, with poorer forest types potentially allowing stronger responses to defoliation
Forfattere
Roman Gebauer Daniel Volařík Josef Urban Isabella Børja Nina Elisabeth Nagy Toril Eldhuset Paal KrokeneSammendrag
Conifer needles are extraordinarily variable and much of this diversity is linked to the water transport capacity of the xylem and to xylem conduit properties. However, we still know little about how anatomical characteristics influence the hydraulic efficiency of needle xylem in different parts of the crown. In this study we evaluated needle function and anatomy in Norway spruce families exposed to different light conditions. We measured tracheid and needle characteristics of sun-exposed and shaded current-year needles in two experimental plots: a control plot and a thinned plot with 50% reduction in stand density. Sun-exposed needles had a larger tracheid lumen area than shaded needles, and this was caused by a larger maximum tracheid lumen diameter, while the minimum lumen diameter was less plastic. Sun-exposed needles had also higher theoretical hydraulic conductivity than shaded needles. Thinning leads to increased radiation to the lower branches, and presumably exposes the upper branches to stronger water stress than before thinning. Thinning affected several needle parameters both in sun-exposed and shaded needles; tracheid lumens were more circular and minimum tracheid lumen diameter was larger in the thinned plot, whereas maximum tracheid lumen diameter was less plastic on both plots. This study demonstrates that needle xylem structure in Norway spruce is clearly influenced by the light gradient within the tree crown.
Sammendrag
The winter hardiness of strawberry cultivars used in perennial production systems varies greatly, although a strong linkage exists between transcriptional and metabolic changes during cold acclimation. Still, little information is available on how plant metabolism adapts to cold and freezing temperatures under natural temperature and light conditions. In order to examine the hardening process of overwintering meristematic tissue in Fragaria x ananassa, crown samples of field-grown cvs. ‘Polka’ and ‘Honeoye’ were consecutively collected over a period of 15 weeks, i.e. from the end of the season (week 35/ end August) until midwinter (week 50/ December). Samples were subjected to qGC MS metabolite profiling to assess the reconfiguration of central metabolism, and characterize the regulation of selected compatible solutes (amino acids, Krebs metabolites, sugars, polyols). Besides changes in amino acid patterns (glutamic acid, aspartic acid, and asparagine), monosaccharide levels (fructose) were strongly enhanced until the end of the acclimation period in cv. ‘Honeoye’ (180-fold compared to start control). In contrast, ‘Polka’ showed a concentration peak (36-fold) in week 47 and a decline towards week 50. Also sucrose levels were steadily enhanced throughout the cold hardening period with averagely 6-fold higher levels in ‘Honeoye’ compared to ‘Polka’, thus underscoring cultivar differences. However, both cultivars showed a clear decline in sucrose levels after week 47. Particularly, the raffinose pathway was affected leading to strongly and transiently increased levels of the precursor galactinol (week 42/ mid October) and the trisaccharide raffinose (weeks 43 to 47/ end October to mid November). While galactinol biosynthesis was obviously earlier induced in cv. ‘Polka’ (week 38) compared to ‘Honeoye’ (week 39), subsequent raffinose production and concentration peaks were clearly delayed in ‘Polka’ (week 47) in contrast to ‘Honeoye’ (week 45). Major metabolic changes in both cultivars coincided with a decrease in daylength below 14 h after week 37 (mid September), and a consistent drop below 10°C average day temperature in week 39 (end September). The effect of temperature and light conditions on metabolic cold acclimation in field-grown strawberry is discussed. Keywords: Winter hardiness, metabolite profiling, quadrupole gas chromatography-mass spectrometry (qGC-MS), temperature, light
Sammendrag
Abstract: This paper reviews several studies of earthworms in agricultural soils in Norway. Crops and management significantly influence the earthworm fauna. Beneficial impacts of earthworms on plant growth are likely, but challenging to prove. Earthworm casts contain high amounts of extractable plant nutrients, which probably contribute to plant nutrient uptake. Geophagous (soil-eating) species such as Aporrectodea caliginosa and A.rosea dominate the earthworm fauna in our arable soils1. Lumbricus terrestris is also present and was found also in all-arable crop rotations with annual ploughing2. In southern Norway, L. rubellus and A. longa are also common. Earthworm populations, recorded in autumn, vary between 30 and 350 individuals m-2, with the lowest values found in all-arable systems2. The inclusion of leys in the crop rotation increases the abundance of channels, earthworm numbers and their biomass2. Since most earthworms prefer living in the upper soil layer, shallow ploughing (15 cm depth) might be expected to be detrimental. However we found that the number and biomass of earthworms was not lower with shallow than with deep ploughing (25 cm)1. In a study, green manure management affected the biomass, species and number of earthworms3. More worms were found in plots where the green manure was left on the field, compared with where it was removed. L. rubellus responded positively and rapidly to mulching, and so did A.caliginosa in clay soil. The use of biogas slurry from green manure in one season gave no effect on number and biomass of earthworms3. Long-term use of solid animal manure positively influenced some earthworm parameters, even three years after the last application1, compared to mineral fertilizer. Utilizing animal manure to produce biogas may reduce fossil fuel usage and emissions of greenhouse gases. However, there is limited information on how the recycling of digested manure as a fertilizer affects soil fertility in the long run. Reduced recycling of carbon to the soil, may harm soil fauna, including earthworms. In a newly started project on the organic research farm at Tingvoll, Norway, anaerobically digested manure is compared with undigested slurry in perennial ley and arable crops. Effects on crop yields, soil fauna, microbial communities, soil structure, organic matter and nutrient concentrations are being measured. Initial studies showed that several earthworm species were present (A.caliginosa, A.rosea, L.terrestris, L.rubellus, Octolasion cyaneum). Earthworm casts (excrements) from the detritivorous species L. terrestris (that feeds on plant residues) have been shown to be richer in nutrients than bulk soil, but little was known previously about the casts of geophagous species (that ingest mostly soil). Casts from two soil depths (13 and 25 cm) were collected by means of litter bags, to study whether such casts also contained more plant available nutrients than the bulk soil. A.caliginosa and A.rosea were the dominant species in these fields. The casts had considerably higher concentrations of plant nutrients than the bulk soil. The content of total-N was 28 % higher in casts, total-C was 37% higher, the contents of available P and K were 40-60%, whilst those of Ca and Mg were 10-20 % higher. On average for the two sites, these differences corresponded to the following amounts (kg ha-1 y-1): 5.6 for P, 8.9 for K, 5.3 for Mg, 144 for N and 2542 for C. With earthworm densities such as those found in farming systems incl. ley and animal manure (ca. 230 individuals m-2), about 220 tonnes of topsoil per hectare passes through the earthworm digestive tract each year. Our study indicated that earthworm casts are valuable sources of plant nutrients even in soils where the fauna is dominated by geophagous species.
Forfattere
M Ashraful Islam Goutam Kuwar Jihong Liu Clarke Dag-Ragnar Blystad Hans Ragnar Gislerød Jorunn Elisabeth Olsen Sissel TorreSammendrag
Abstract Strict control of morphogenesis is essential in production of potted poinsettia. Commonly, this is obtained by the use of plant growth retardants (PGRs), often in combination with early morning temperature drops. Due to negative effects on human health and the environment, the use of PGRs is becoming restricted. Also, energy-saving growth regimes and periods of high temperatures limit effective use of temperature drops. In the present study the use of a high proportion of blue (B) light provided by light emitting diodes [LEDs, 20% blue (B), 80% red (R)] was compared with traditional high pressure sodium (HPS) lamps (5% B) providing similar phytochrome photostationary state to produce compact poinsettia plants. Both in the greenhouse and growth chamber, all cultivars were 20–34% shorter for LED compared to HPS grown plants. Also, leaf and bract area as well as chlorophyll content and total dry matter accumulation were lower under LED. The LED did not delay bract color formation, visible cyathia and flowering compared to HPS, and no difference in post production performance (cyathia/bract abscission or necrosis) between the two light treatments was found. The effect of end of day-red (EOD-R) lighting combination with LED and HPS supplemental lamps during the photoperiod in the greenhouse was also investigated. Reduced stem extension (13%) was observed under HPS only and for one of the two cultivars tested, whereas under the LED regime, there was no effect of EOD-R lighting.
Sammendrag
Plant parasitic nematodes associated with potato feed on roots and/or tubers. About 70 species, representing 24 genera, have been reported from potato. Since nematodes attack underground plant parts, there are no reliable foliar symptoms to show that nematodes may be the major cause of poor growth and reduced tuber yields. Potato roots damaged by nematodes may show lesions, abnormal proliferation of lateral roots, emerging white females and brown cysts. Nematode attacks may render plants vulnerable to other pathogens, so disease caused by microorganisms may have nematodes as an etiological component. Therefore, nematode damage may often have been attributed to other factors. In Scandinavia, potato cyst nematodes (Globodera rostochiensis and Globodera pallida) are by far the most important nematodes on potato. In Norway, the cost of compensations schemes due to imposed statutory regulations of potato cyst nematodes may some years exceed the compensation for any other pests or diseases organism in agriculture. Other important nematodes include root lesion nematodes (Pratylenchus spp.), stubby root nematodes (Trichodorus spp. and Paratrichodorus spp.), and potato rot and stem nematodes (Ditylenchus spp.). Root knot nematode Meloidogyne hapla is considered less important. Meloidogyne chitwoodi and Meloidogyne fallax are not known to be present in Nordic countries. In the control, crop rotations using non-host crops, alternating susceptible and resistant potato cultivars, are an important control measure. However, the use of resistant potato cultivars requires knowledge of the species and pathotypes present in the field.
Forfattere
Annika Höjer Steffen Adler Stig Purup Hansen-Møller Jens Martinsson Kjell Håvard Steinshamn Anne-Maj GustavssonSammendrag
Phytoestrogens are hormone-like substances in plants that can substantially influence human health (positively or negatively), and when fed to dairy cows are transferred to their milk. The aim of this study was to investigate effects of varying the botanical composition and regrowth interval of legume-grass silage on silage and phytoestrogen intake and milk phytoestrogen concentrations. In one experiment, 15 Swedish Red dairy cows were fed two- or three-cut red clover-grass silage (designated R2 and R3, respectively), or two-cut birdsfoot trefoil-grass silage (B2). In a second experiment, 16 Norwegian Red dairy cows were fed short-term ley silage with red clover (S3) or long-term ley silage with white clover (L3), and the effects of supplementation with α-tocopherol were also tested. There were high concentrations of formononetin and biochanin A in all silage mixtures with red clover (R2, R3, and S3). The milk concentration of equol was highest on diet R2 (1,494 μg/kg milk). Due to metabolism of biochanin A, genistein and prunetin, their concentrations in milk and the apparent recovery were low. Coumestrol was only detected in silage mixtures S3 and L3, and its milk concentration was low. Concentrations of secoisolariciresinol and matairesinol were higher in silage mixtures B2 and L3, those with legume species other than red clover and the highest grass proportions. B2 also resulted in higher enterolactone concentration than the other diets (226 μg/kg milk). Lengthening the regrowth interval increased the intake of secoisolariciresinol and decreased recovery of lignans. Feeding long-term ley silage resulted in higher lignan milk concentrations, but lower isoflavone milk concentrations than feeding short-term ley silage. The apparent recovery of all phytoestrogens except prunetin was highest on B2, indicating that condensed tannins (present in the birdsfoot trefoil) affect rumen metabolism. There was no effect of α-tocopherol supplementation on milk concentrations of any of the measured phytoestrogens. There were variations in milk concentrations of phytoestrogens, especially of equol, among cows, which could not be explained by variations in diet composition or phytoestrogen intake. The results show that milk phytoestrogen concentration is strongly influenced by silage botanical composition and management, but questions regarding phytoestrogen metabolism remain to be answered.
Forfattere
Jogeir N. StoklandSammendrag
Det er ikke registrert sammendrag
Forfattere
Jogeir N. StoklandSammendrag
Det er ikke registrert sammendrag