International audienceContext Evaluations of forest inventories usually end when accuracy and precision have been quantified. Aims We aim to value the accuracy of information derived from different remote sensing sensors (airborne laser scanning, aerial multispectral and hyperspectral imagery) and four alternative forest inventory approaches. Methods The approaches were (1) mean values or (2) diameter distributions both obtained by the area-based approach (ABA), (3) individual tree crown (ITC) segmentation and (4) an approach called semi-individual tree crown (SITC) segmentation. The estimated tree information was assessed and used to evaluate how erroneous inventory data affect economic value and loss due to suboptimal harvesting decisions. Field measured data used as reference come from 23 field plots collected in a study area in south-eastern Norway typical of managed boreal forests in Norway. Results The accuracy of the forest inventory was generally in line with previous studies. Our results show that using mean values from the area-based approach may yield large economic losses, while adding a diameter distribution to the area-based approach yielded less loss than the individual tree crown methods. Adding information from imagery had little effect on the results. Conclusions Taking inventory costs into account, diameter distributions from the area-based approach without additional information seems favourable

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Production ef ciency in the Norwegian sawmilling sector was investigated by means of data envelopment analysis, using individual mill observations from the period 1974 -91. The resulting ef ciency scores were evaluated with respect to size using censored regression analysis and non-parametric comparison tests. Average ef ciency estimates indicated that the smallest mills (5 5000 m 3 yr ¼ 1 ) were less ef cient than large mills (lumber output \ 25 000 m 3 yr ¼ 1 ). During most of the period studied, average ef ciency estimates for the smallest mills were signi cantly lower than for larger mills.

Protection of biodiversity on private forest land often yields conflict. In standard economic theory, disputes about compensation and compensation level are held forward as the main reason for conflict. We discuss the reasons for conflict in protection of biodiversity in forests also including institutional explanations and use survey data on Nordic forest owners to empirically explore different hypotheses for why conflict appears. Type of process and level of communication stand out as important elements when explaining forest owners' attitudes towards forest protection. If one wants to lessen or avoid conflict, offering forest owners extended possibilities to participate in the protection process is important.

New and ambitious targets for renewable energy production put attention to increased supply of biomass. Harvest residues are only to a limited extent demanded by the traditional forest industries and represent an unutilized resource for increased production of renewable energy in Norway. The overall objective of this paper is to study how GIS and forest modelling can be combined to improve estimates of the supply of harvest residues, taking different environmental and economic constraints into consideration. The analyses are based on a case study of a forest area of more than 40 000 ha in Southern Norway divided into about 500 private forest properties. The study was carried out by computations of timber harvest using the forestry scenario model SGIS based on extensive forest inventory data at stand level. In the studied area energy utilization of harvest residues is not profitable below an energy price of about €3.2/GJ (NOK 0.10 /kWh) when the distance from roadside to industry is 20 km. Above this level supply increases rapidly over a rather narrow price range and is nearly inelastic above €4.1/GJ (NOK 0.12/kWh). We did not find significant negative shifts in the residues supply caused by changes in location of roundwood harvest over time. Exclusion of collection from stands with a site index (H 40) below 14 reduced the potential supply of residues by 16-27%. The optimisation method combined selection of exogenous variables in order to map observed harvesting level and is probably the best approach to map future harvest.