Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2001
Authors
Karen Refsgaard Arild VatnAbstract
Over the last years many new methods have become available for treating wastewater. The purpose of this paper is to demonstrate the potential for cost reductions by a transition from a household strategy (HS) to a recipient strategy (RS). We will further discuss reasons for why municipalities still base their policies on the former strategy. Results from a case study show that an RS is clearly better than an HS from a standard allocative efficiency point of view. In addition, it is more flexible. However, such an assessment underestimates important factors. First, transaction costs following a transition from HS to RS may reduce profits substantially. Secondly, in most cases there will be both gainers and losers following a transition. Who they are, will, however, depend on the chosen rules for distribution costs under the RS. Thus, this ex ante uncertainty constitutes an impedement for change since action must be expected first of all from the potential gainers. Finally, since changes in the rights structure are involved, the economic gain obtained may not be great enough to compensate the losers, if this is a necessary prerequisite. The perceived loss may be much higher than the monetary loss as calculated in the standard analysis. This argument is based on the observed deviations between WTP and WTA in the literature. Most probably the existing municipal organizations have to initiate the process if a change is to come about. However lack of knowledge and professonal traditions concerning the planning of wastewater systems may delay or obstruct such a change.
Authors
Per Otto Flæte Bohumil Kucera Erlend Ystrøm HaartveitAbstract
No abstract has been registered
Abstract
Epiphytic lichens (and some non-lichenized fungi) on 34 coppices (204 stems) of Corylus avellana were investigated in a 140 ha study area in south-western Norway. A total of 65 species were recorded on a total bark area of 63 m2. Corylus in broad-leaved deciduous forest supported more species of macrolichens, and fewer species of icrolichens, than Corylus in pine forest. The macrolichen flora of the deciduous forest differed from that of the pine forest by having a rich flora of species belonging to the Lobarion alliance. Old Corylus coppices with tall stems (>8 m), large girth (>8 cm diameter at breast height) and a noticeable cover of macrolichens (>10% of bark area) supported the highest number of rare species, and overall, species of mcrolichens. More than 50% cover of icrolichens indicated richness and rarity of microlichens on Corylus
Authors
Isabella BørjaAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Two zone sites, i.e. two circular areas with 50 km radius, were established in southern Norway. The zone sites were centred in Tofte (the location of a major pulp mill) and in Drammen (the site of a major timber yard). From June to October 2000, 66 forest blocks were visited, 65 of which were situated within the zone site areas. Samples were collected from 40 forest blocks, especially from wood attacked by wood boring insects. At 34 forest blocks, trees of Scots pine, Pinus sylvestris, or Norway spruce Picea abies were provided as trap-logs for Monochamus spp. This material will be sampled in the survey of 2001. Some samples were also taken from a wood chip pile and from imported wood material. The total number of wood samples analysed for nematodes were 275. Out of these, 214 samples were collected from forest trees, stumps, timber and logging wastes of P. sylvestris and P. abies. Three samples contained nematodes belonging to the genus Bursaphelenchus, but the Pine Wood Nematode (PWN), B. xylophilus, was not detected. Similarly, this nematode was not detected in the 10 samples of wood chips, or in the 25 samples of imported lumber or in the 26 samples of imported solid wood packing material. In order reach the minimal number of 3000 samples within reasonable time, the number of samples for the next survey season of 2001 needs to be increased drastically. To achieve this, the sampling will continue within the existing zone sites, and be extended into new zone sites to be established in 2001.
Authors
Oddvar SkreAbstract
Småplanter av tre bjørkepopulasjonar (Betula pubescens) blei dyrka i veksttorv ved to ulike gjødselnivå, tilsvarande 1 og 10 g N m-2 yr-1 ved 50 og 450 m høgd i det sørlege Noreg. Det var ei sterk opphoping av karbohydrat i røter frå det høgaste feltet, samanlikna med det lågaste. Normal og alternativ (cyanid-resistent) respirasjon blei målt i stengel- og rotsegment og på avskorne bladskiver frå dei tre bjørkepopulasjonane. Den totale og alternative mørkerespirasjonen minka med aukande temperatur i bladskiver og stengelsegment. I rotsegment frå dei same plantene auka derimot totalrespirasjonen med temperaturen. Ved lågt gjødselnivå var det ein viss reduksjon av respirasjonen i skot ved høg temperatur, og det meste av denne var cyanid-resistent, i.e. ikkje kopla til veksten. Den økologiske tydinga av dette er at ved låg temperatur kan auka alternativ respirasjon i blad og stengel føra til redusert vekst. Ved høg temperatur derimot, tyder auka totalrespirasjon i røter på auka absorbsjon av nitrogen i røter, som igjen fører til auka fotosyntesekapasitet, som kan kompensera for karbohydratmangel ved sterk vekst. Den alternative respirasjonen ved lågt næringsnivå og temperatur kan vera ein mekanisme for å unngå vekst ved ugunstige forhold.
Authors
Steen Koekebakker Gudbrand LienAbstract
Empirical evidence suggests that agricultural futures price movements have fat-tailed distributions and exhibit sudden and un xpected price jumps. There is also evidence that the volatility of futures prices contains a term structure depending on both calendar-time and time to maturity. This paper extends Bates (1991) jump-diffusion option pricing model by including both seas nal and maturity effects in volatility. An in-sample fit to market option prices on wheat futures show that our model outperforms previous models considered in the literature. A numerical example illustrates the economic significance of our results for option valuation.
Authors
Steen Koekebakker Gudbrand LienAbstract
No abstract has been registered