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.
2014
Forfattere
Maria Handeland Nils Grude Torfinn Torp Rune SlimestadSammendrag
Det er ikke registrert sammendrag
Forfattere
James David Mervyn Speed Gunnar Austrheim Alison J. Hester Erling Meisingset Atle Mysterud Jean-Pierre Tremblay Dag-Inge Øien Erling Johan SolbergSammendrag
Understanding the responses of ecological communities to perturbation is a key challenge within contemporary ecology research. In this study we seek to separate specifi c community responses from general community responses of plant communities to exclusion of large cervid herbivores. Cervid herbivory and forestry are the main drivers of vegetation structure and diversity in boreal forests. While many studies focus on the impact of cervids on trees, a high proportion of the biodiversity and ecosystem services in boreal forests is found in the fi eld layer. However, experimental approaches investigating the infl uence of herbivory on understory vegetation are highly localised. In this study we use a regionalscale design with 51 sites in four boreal forest regions of Norway, to investigate the infl uence of cervid herbivory on the physical and ecological structure of fi eld layer vegetation. Our study sites cover a range of forest types diff ering in productivity, management and dominant cervid species, allowing us to identify generic responses and those that are specifi c to particular conditions. We found that the height of the fi eld layer and the abundances of individual species were most susceptible to change following short-term cervid exclusion across diff erent forest types and cervid species. Total vegetation density and vascular plant diversity did not respond to cervid exclusion on the same time scale. We also found that the fi eld-layer vegetation in clear-cut forests used by moose was more susceptible to change following cervid exclusion than mature forests used by red deer, but no strong evidence that the response of vegetation to herbivore exclusion varied with productivity. Our study suggests that the parameters that respond to cervid exclusion are consistent across forest types, but that the responsiveness of diff erent forest types is idiosyncratic and hard to predict.
Sammendrag
Usnea longissima Ach. is a circumboreal epiphytic lichen draping tree canopies in moist coastal and mountainous forests. It is extinct from many European and North-American localities, presumably due to industrial forestry and air pollution, but still has a stronghold in parts of Scandinavia and U.S. and Canadian Pacific Northwest. In 2005/06 we used a comparative and retrospective approach to evaluate how present and historic tree and stand characteristics influenced the occurrence and abundance of the lichen (Storaunet et al. 2008). In 2012, we re-inventoried ten Norway spruce forest stands with 401 U. longissima-bearing trees and recorded changes in the number of U. longissima thalli. Seven of the stands had been experimentally, selectively logged 5–8 years before, where the lichen-bearing trees had been marked in the field and were avoided during the logging operation. Total number of lichen-bearing trees decreased slightly (2.9%), whereas the number of thalli had increased with 34%. Number of thalli increased more where the forest was open (low basal area, m2ha-1) whether or not the low tree density was caused by the logging events. At high tree densities the change in number of thalli was negligible. We suggest that selective logging, securing lichen-bearing trees, may be a viable management option to keep tree density from becoming too dense, thereby enhancing growth and establishment of U. longissima.
Forfattere
Eric Hansen Erlend Nybakk Rajat PanwarSammendrag
Det er ikke registrert sammendrag
Sammendrag
Increasing inter-continental trade with wood chips represents a challenge for phytosanitary authorities, as such trade may lead to pest introductions and invasions with huge impacts on forest ecosystems and economy. Predicting species invasions and their impacts in advance may be difficult, but improved information about potential invasive species ahead of any interceptions is an important precautionary step to reduce the probability of invasions. Here we identify bark- and wood-boring insects that have a potential to become invasive in northern Europe, and that may be introduced by import of deciduous wood chips from North America. The potentially most damaging species belong to the beetle genus Agrilus (Buprestidae), which includes the highly damaging emerald ash borer A. planipennis. We give a brief presentation of this and seven other Agrilus species or subspecies, and review factors of importance for the risk of establishment and potential economic and ecological impacts of these species. We also discuss one Scolytinae, Hylurgopinus rufipes. There are strong indications in the literature that some north European trees are highly susceptible to attack from the selected beetle species. We therefore conclude that because north European trees have not coevolved with these herbivores and thus may lack adequate defenses, most of the identified beetle species are likely to spread in “defense- and enemy-free space” if they are introduced to northern Europe, with considerable economic and ecological consequences.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Johannes Breidenbach Clara Antón-Fernández Hans Petersson Ronald E. McRoberts Rasmus AstrupSammendrag
National Forest Inventories (NFIs) provide estimates of forest parameters for national and regional scales. Many key variables of interest, such as biomass and timber volume, cannot be measured directly in the field. Instead, models are used to predict those variables from measurements of other field variables. Therefore, the uncertainty or variability of NFI estimates results not only from selecting a sample of the population but also from uncertainties in the models used to predict the variables of interest. The aim of this study was to quantify the model-related variability of Norway spruce (Picea abies [L.] Karst) biomass stock and change estimates for the Norwegian NFI. The model-related variability of the estimates stems from uncertainty in parameter estimates of biomass models as well as residual variability and was quantified using a Monte Carlo simulation technique. Uncertainties in model parameter estimates, which are often not available for published biomass models, had considerable influence on the model-related variability of biomass stock and change estimates. The assumption that the residual variability is larger than documented for the models and the correlation of within-plot model residuals influenced the model-related variability of biomass stock change estimates much more than estimates of the biomass stock. The larger influence on the stock change resulted from the large influence of harvests on the stock change, although harvests were observed rarely on the NFI sample plots in the 5-year period that was considered. In addition, the temporal correlation between model residuals due to changes in the allometry had considerable influence on the model-related variability of the biomass stock change estimate. The allometry may, however, be assumed to be rather stable over a 5-year period. Because the effects of model-related variability of the biomass stock and change estimates were much smaller than those of the sampling-related variability, efforts to increase the precision of estimates should focus on reducing the sampling variability. If the model-related variability is to be decreased, the focus should be on the tree fractions of living branches as well as stump and roots.
Forfattere
Marta Camino-Serrano Bert Gielen Sebastiaan Luyssaert Philippe Ciais Sara Vicca Bertrand Guenet Bruno de Vos Nathalie Cools Bernhard Ahrens M. Altaf Arain Werner Borken Nicholas Clarke Beverley Clarkson Thomas Cummins Axel Don Elisabeth Graf Pannatier Hjalmar Laudon Tim Moore Tiina M. Nieminen Mats B. Nilsson Matthias Peichl Luitgard Schwendenmann Jan Siemens Ivan A. JanssensSammendrag
Det er ikke registrert sammendrag
Forfattere
Steffen Adler Stig Purup Jens Hansen-Møller Erling Thuen Anne-Maj Gustavsson Håvard SteinshamnSammendrag
Phyto-oestrogens are a group of secondary plant metabolites that may bind to oestrogen receptors and exert oestrogenic or anti-oestrogenic effects in humans and can protect against cancer diseases. When ingested by dairy cows, phyto-oestrogens can be metabolised and transferred to the milk. The objective of this study was to assess the effects of grazing a recently established pasture containing red clover (Trifolium pratense L.) and an older pasture containing a variety of sown and unsown plant species on milk concentrations of phyto-oestrogens. Sixteen Norwegian Red dairy cows [mean (standard deviation); body weight 599 (45.1) kg, stage of lactation 73 (15.0) d in milk, milk yield 29.9 (2.90) kg/d at the start of the experiment] were divided into two groups and grazed either a short-term pasture (SP) or a long-term pasture (LP). The SP was representative of organically managed leys in Norway, which are frequently, approximately every third year, renewed by soil tillage and seeding, whereas LP was representative of organically managed grasslands that are less frequently renewed. The SP contained meadow fescue (Festuca pratensis Huds.) (mean 34%), timothy (Phleum pratense L.) (mean 19%), red clover (mean 28%), shepherd׳s-purse (Capsella bursa-pastoris (L.) Medik.) (mean 6%), pineappleweed (Matricaria matricarioides Porter ex Britton) (mean 5%) and scentless mayweed (Tripleurospermum perforatum (Mérat) Laínz) (mean 4%), and LP contained mainly white clover (Trifolium repens L.) (mean 21%), smooth meadowgrass (Poa pratensis L.) (mean 19%), timothy (mean 17%), meadow fescue (mean 15%), perennial ryegrass (Lolium perenne L.) (mean 6%), tufted hairgrass (Deschampsia cespitosa (L.) P. Beauv.) (mean 5%), northern dock (Rumex longifolius DC.) (mean 4%), common couch (Elytrigia repens (L.) Desv. Ex Nevski) (mean 4%), red clover (mean 3%) and dandelion (Taraxacum spp.) (mean 3%). In addition to a daily pasture allowance of 20 kg dry matter per cow, supplements of 3.0 kg barley (Hordeum vulgare L.) concentrate were fed. Herbage, concentrates and milk was sampled during the last week of three experimental periods and analysed for phyto-oestrogens using LC-MS/MS technology. Herbage from SP had 19 times higher concentration of isoflavones than herbage from LP, whereas only small differences were found for lignans. Milk produced on SP had 14 times higher concentrations of the mammalian isoflavonoid equol, and the concentrations of equol were higher than found in most other studies. This study confirms that grazing pastures containing red clover increases concentrations of isoflavones and especially equol in bovine milk compared to grazing pastures with other botanical composition. The higher milk concentrations of the lignan metabolite enterodiol in milk from SP compared to LP could not be related to differences in intake of the analysed lignans and may therefore be related to unidentified lignans.