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.
2007
Sammendrag
Floral induction and development requirements of a range of latitudinal and altitudinal Norwegian populations of the wild strawberry Fragaria vesca L. have been studied in controlled environments. Rooted runner plants were exposed to a range of photoperiods and temperatures for 5 weeks for floral induction and then transferred to long day (LD) at 20 degrees C for flower development. A pronounced interaction of temperature and photoperiod was shown in the control of flowering. At 9 degrees C, flowers were initiated in both short day (SD) and LD conditions, at 15 and 18 degrees C in SD only, whereas no initiation took place at 21 degrees C regardless of daylength conditions. The critical photoperiod for SD floral induction was about 16 h and 14 h at 15 and 18 degrees C, respectively, the induction being incomplete at 18 degrees C. The optimal condition for floral induction was SD at 15 degrees C. A minimum of 4 weeks of exposure to such optimal conditions was required. Although the populations varied significantly in their flowering performance, no clinal relationship was present between latitude of origin and critical photoperiod. Flower development of SD-induced plants was only marginally advanced by LD conditions, while inflorescence elongation and runnering were strongly enhanced by LD at this stage. The main shift in these responses took place at photoperiods between 16 and 17 h. Unlike all other populations studied, a high-latitude population from 70 degrees N ('Alta') had an obligatory vernalization requirement. Although flowering and fruiting in its native Subarctic environment and after overwintering in the field in south Norway, this population did not flower in the laboratory in the absence of vernalization, even with 10 or 15 weeks of exposure to SD at 9 degrees C. Flowering performance in the field likewise indicated a vernalization requirement of this high-latitude population.
Forfattere
Svein Solberg Erik NæssetSammendrag
The aim of this article is to present a concept of using airborne laser scanning (LIDAR), with one scan only, to map defoliation as a forest health variable. The idea is to apply two independent algorithms on the LIDAR data set, to produce both actual and expected leaf area index (LAI) values for every cell in a grid over the area. LAI is estimated based on laser pulse penetration through the canopy layer, and expected LAI values are derived from stand density based on position and height of single trees as obtained from a single-tree segmentation algorithm. The results are preliminary findings from four ongoing and related studies. In the first study repeated laser scans had close to equal extinction coefficients for LAI estimation although the instruments and flight specifications were different. In the second study, based on the findings in the first we derived normal LAI values from extisting and large scale data sets with LIDAR and field data. The main independent variable was stand density, defined as the ratio between mean tree height and mean distance between the trees. The ratio between LAI and stand density was around 0.5, and this is a preliminary standard for a healthy pine forest. In a third study the woody area fraction of LAI was estimated from 14 total harvested trees, and turned out to be slightly below 50% for a healthy pine tree, which means that a totally defoliated pine forest would have an LAI/stand density ratio around 0.2. In the fourth study, these LAI standard values were confirmed with LIDAR data from a severe insect defoliation event in Norway 2005. In conclusion, the present preliminary results demonstrate a potential for application of airborne laser scanning for monitoring or mapping of defoliation as a forest health variable.
Sammendrag
Capercaillie Tetrao urogallus leks have repeatedly been reported to be located in old forest. However, two conditions may have biased this widely held view. First, leks are known to be continuously used over several decades, and therefore might have been established when forest stands were younger. Second, stand -replacement logging (clearcutting) was not widely applied until the 1950s, leaving even-aged regenerating stands too young for leks to have been established in the latter part of the 20th century. Here we report eight cases of lek formation in young plantations from south-central Norway. Stand age ranged within 2646 years when display activity started. At six of the sites, we confirmed that females were regularly feeding on pine trees in winter prior to lek establishment, and at four of these sites displaying males were observed courting the females in late winter. These findings support the hotspot model of lek formation put forward by Gjerde et al. (2000), and it offers promising options for managing capercaillie leks in commercially utilised forests.
Forfattere
Susanne Eich-Greatorex Trine A Sogn Anne Falk Øgaard Ivar AasenSammendrag
The objective of the present study was to investigate the influence of soil organic matter content and pH on plant availability of both inorganic and organic selenium (Se) fertilisers. Further, the risk of Se leaching after application of inorganic Se fertiliser was evaluated. A new interpretation of an older field study at different sites in Southern Norway showed that organic C was correlated with grain Se concentration in wheat, barley and oats, explaining up to 60% of the variation in Se concentration. Pot experiments with a peat soil, a loam soil and a peat/loam soil mixture were conducted for the present study at a range of pH values between pH 5 and 7. Below pH 6, Se uptake from added Se fertiliser was higher in the soil types with high organic matter content than in the loam. The opposite occurred at a soil pH above 6, where Se uptake was higher in the loam than in the peat soil. A simple leaching experiment after one growing season confirmed the findings of the pot experiments that Se availability in the loam soil with a relatively low organic matter content increased with increasing pH, whereas it decreased in the peat soil. Neither Se yeast, nor pure Se methionine, used as organic Se fertiliser, resulted in any significant uptake of Se when added at concentrations similar to the inorganic Se applications.
Sammendrag
High mortality among chicks, due to fragmentation and changes in habitat caused by commercial forestry, is considered one of the main reasons for the general decline in capercaillie Tetrao urogallus in boreal forests. Using GPS satellite telemetry, we studied the movement patterns of young capercaillie broods: 1) to test if this new technology could be applied to gain more detailed insight into behaviour and habitat selection at a small spatial scale, and if so, 2) to compare the broods' relative use of planted and older, naturally regenerated forests. Hens of four broods with chicks 2-7 days old were captured and fitted with 90-g backpacks containing GPS units and VHF transmitters. The GPS units were programmed to record positions every 15 minutes, the shortest interval possible. With a storage capacity of 450 positions, movements could be monitored for ca 4.5 days. In our study area (Varaldskogen) with moderate topography, the GPS technology performed quite well. A total of 1,277 positions were obtained (84% of potential maximum), of which 77% were within 20 in of the true position of the brood. The movement patterns of the four broods were quite similar, with a mean speed of 83.2 m +/- 9.9 (SE) per hour during the 4.5-day tracking period. Broods moved almost continuously during the 24-hour cycle, presumably foraging, although their speed was slower at night. The two oldest broods whose initial age was seven days moved faster than the two younger broods whose initial age was two and three days, respectively. Strong autocorrelation among successive positions made us examine habitat selection using a binominal choice method for each brood separately. When broods were inside old 'natural' forest, they remained there instead of moving into plantations. When inside plantations, they did not discriminate between remaining there and moving into nearby old forest, but they tended to move faster in plantations than in old forest. Clearly, the new, cost-effective GPS telemetry offers new and better opportunities for studying small-scale brood movement. Very frequent and accurate positions can be obtained without either disturbing the birds or leaving scent marks that may attract predators.
Sammendrag
Urbanization and an increasingly globalized food system cause growing physical and psychological distances between producers and customers. Alternative distribution initiatives with direct sale to local customers are emerging. This paper reports results of two surveys, one from producers and one from customers, in the newly introduced Norwegian farmers market system. The main aim of the research was to examine attitudes toward local foods and evaluate the potential of this new marketing channel to reduce the distances between farmers and consumers. Results show that producers were more concerned than customers regarding knowledge on how food was produced, and locally marketed, although customers were also interested in these issues. Both groups regarded as to how food was produced to be more important than where it was produced. Producers were more interested in giving customers information on agriculture than customers were in receiving this information. The attitudes toward food differed between respondents of larger urban cities and smaller cities in Norway. Producers traveled a longer distance (average 79 km) than customers (average 14 km) to come to the markets, but traveling distance differed substantially among the sites owing to market location, number of local farmers and small-scale local processors, and product diversity. Results suggest that the farmers markets have potential to reduce both physical and social distances between producers and consumers, and thereby contribute to the sustainability of local food production. Understanding farmer and consumer attitudes can contribute to organization and promotion of farmers markets in Norway and elsewhere. doi:10.1300/J064v30n04_06.
Forfattere
Inge Stupak Antti Asikainen M Jonsell E Karltun Anders Lunnan Nicholas ClarkeSammendrag
The substitution of fossil fuels by biomass in energy consumption is a measure to decrease the emission of greenhouse gases and thereby mitigate global warming. An increased use of wood-based biomass for energy can also, if well managed, enhance the socioeconomic benefits from forests, particularly for small forest owners substituting purchased energy resources with their own wood fuels. At both European and national levels, political plans exist for an increased use of forest biomass for energy. However, the potential negative impact on the forest ecosystem and the surrounding environment due to an increased utilisation of wood-based biomass for energy needs also to be considered. The increased use of wood-based biomass must be fully in accordance with the principles of sustainable forest management, for example as outlined by the pan-European Ministerial Conference on the Protection of Forests in Europe.
Sammendrag
The relationships between measures of forest structure as derived from airborne laser scanner data and the variation in quantity of young trees established by natural regeneration in a size-diverse spruce forest were analyzed. A regeneration success rate (RSR) was regressed against 27 different laser-derived explanatory variables. The 27 different models were ranked according to their Akaike information criterion score. Each laser variable was then associated with two categories. These were return and type. Within the return and type categories, the variables were grouped according to if they originated from first or last return echoes and if they were canopy height or canopy density metrics. The results show that the laser variables strongest correlated to the quantity of small trees could be attributed to last return and density metrics.
Forfattere
Anssi Niskanen Anders Lunnan Ikuo Ota Keith Blatner John Herbohn Lyndall Bull Ian Ferguson Gordon M HickeySammendrag
Many demand and supply-side policies impede or foster forestry entrepreneurship. A study was conducted to consolidate existing knowledge on policies influencing forestry entrepreneurship in Finland, Norway, Japan, Australia, the Philippines and the USA, and to draw conclusions on these impeding and fostering factors. From the country studies it was difficult to find common structures on policies affecting forestry entrepreneurship. This is understandable because most policies in forestry are aimed at supporting sustainable forest management, wood production and ecological services of the forests rather than entrepreneurship as such. Despite the high variety of policies applied in the study countries, it can be concluded that strict public control on forests? use and management potentially impedes forestry entrepreneurship. While these policies assist to correct market failure and to promote sustainability of forest management, they may also result into unnecessary and ineffective regulations that limit the opportunities for forestry entrepreneurship. A common feature promoting the demand for forestry entrepreneurship in some of the countries studied is the strong emphasis on forestry cooperatives, which were important institutions to support small-scale forestry entrepreneurship. In many study countries, different ad hoc programs are implemented to find new economic and entrepreneurial opportunities aside from the current use of wood and forests. Subsidies and tax incentives are commonly applied to reduce risks from making forestry investments or otherwise increase the economic return from timber production.
Forfattere
Gudbrand Lien Ståle Størdal Sjur BaardsenSammendrag
In Norway, as in many other European countries, income from forestry has become marginal to owners? household economies and most employment of forest-owner households is now undertaken off the property. Also, many forest owners have focused increasingly on other revenue-earning activities on their properties, such as providing recreational services. It is a challenge in all kinds of production to find the optimal way of converting inputs into outputs, i.e., to be technically efficient. Extent of financial dependency on income from forestry differs between part-time and full-time forest owners. Since the two groups have different livelihood strategies, it is plausible that full-time forest owners have more professional forest management practices. Data for a cross-section of 3,249 active (i.e., harvesting) forest owners were extracted from the 2004 Sample Survey of Agriculture and Forestry representing the year 2003. A stochastic production frontier analysis was applied to evaluate forest management efficiency impacts of important factors including property and owner characteristics, outfield-related and agricultural activities, off-property income and geographical location in central or remote areas. It was found that many forest owners are technically inefficient, and there exist opportunities for improved performance. Off-property income was found to have an estimated negative impact on technical efficiency, the inefficiency arising (weakly) with increasing share of household incomes from outfield activities, and properties in urban centred areas are less efficient than those in remote areas. One policy implication of the study is that a potentially substantial efficiency increase might be achieved from allowing small inefficient woodlots to merge into larger units of forestry production. Also, providing support for forest management plans may improve efficiency.