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.
2011
Abstract
1. Surrogate species measures of biodiversity (SSB) are used worldwide in conservation prioritisations. We address the important question whether the ideas behind SSB are consistent with current knowledge on distribution patterns of species, as reflected in theories of community assembly. 2. We investigated whether assumptions necessary for successful functioning of SSB (nested species assemblages, cross-taxon congruence, spatio-temporal consistency) were supported by predictions from either niche or neutral community models. 3. We found a general mismatch between ideas behind SSB and ecological community theory, except that SSB based on complementarity may be consistent with niche-based theory when gradients in species composition are strong. 4. Synthesis and applications. The lack of a necessary scientific foundation may explain the disappointing results of empirical tests of SSB. We argue that site selection should be based on costs and opportunities within complementary environmental/land units, rather than expensive inventories of unfounded surrogate species.
Authors
Kari Bjørneraas Erling Johan Solberg Ivar Herfindal Bram Van Moorter Christer Moe Rolandsen Jean-Pierre Tremblay Christina Skarpe Bernt-Erik Sæther Rune Eriksen Rasmus AstrupAbstract
No abstract has been registered
Abstract
Vegetation height information is one of the most important variables for predicting forest attributes such as timber volume and biomass. Although airborne laser scanning (ALS) data are operationally used in forest planning inventories in Norway, a regularly repeated acquisition of ALS data for large regions has yet to be realized. Therefore, several research groups analyze the use of other data sources to retrieve vegetation height information. One very promising approach is the photogrammetric derivation of vegetation heights from overlapping digital aerial images. Aerial images are acquired over almost all European countries on a regular basis making image data readily available. The Norwegian Forest and Landscape Institute (Skog og Landskap) invited researchers and practitioners that produce and utilize photogrammetric data to share their experiences. More than 30 participants followed the invitation and contributed to a successful event with interesting presentations and discussions. We wish to thank the speakers for their contributions and hope that all participants found the seminar useful. These short proceedings of the seminar include summaries of the talks. The presentations, which provide more information, can be found at the end of this document.
Abstract
The Norwegian National Forest Inventory (NNFI) provides estimates of forest parameters on national and regional scales by means of a systematic network of permanent sample plots. One of the biggest challenges for the NNFI is the interest in forest attribute information for small subpopulations such as municipalities or protected areas. Frequently, too few sampled observations are available for those small areas to allow an estimate with acceptable precision. However, if an auxiliary variable exists that is correlated with the variable of interest, small area estimation (SAE) techniques may provide means to improve the precision of estimates.
Abstract
Top dieback and mortality of Norway spruce is a particular forest damage that has severe occurrences in scattered forest stands in southeast Norway. As a part of a project to study the extent and causes of the damage we are working on an algorithm for automatic detection dead and declining spruce trees for an entire county, - Vestfold. The data set is aerial imagery. The county was covered in 2007. Preliminary tests showed a considerable confusion between dead trees and bare ground. In order to avoid this confusion we have had the imagery automatically processed into a photogrammetric digital surface model (DSM) and true orthophotos. The data set derived from this processing was a 5 layer file, containing blue, green, red, and near-infrared, as well as the height above ground of the canopy height model (a DSM normalized by the terrain height, nDSM)
Abstract
No abstract has been registered
Abstract
This study is a part of a larger project designed to find out the causes of top dieback symptoms in Norway spruce in SE Norway. Because sapwood tracheids constitute a water transport system while parenchyma serves as a reserve tissue (Sellin, 1991), the separation and quantification of the sapwood and heartwood may contribute to understanding of the healthy tree functioning. As the extent of sapwood is related to tree vitality, it reflects the tree growth, health and effect of environmental factors (Sandberg & Sterley, 2009). Therefore, the sapwood cross-sectional area is widely used as a biometric parameter indicating the tree vitality, although its estimation and evaluation is prone to scaling errors....
Authors
Ishita Ahuja Birgit Hafeld Borgen Magnor Kåre Hansen Bjørn Ivar Honne Caroline Müller Jens Rohloff John Trevor Rossiter Atle M. BonesAbstract
No abstract has been registered
Authors
Eirik NordhagenAbstract
We studied drying of wood chips by surplus heat from two hydroelectric plants in the western part of Norway. The wood was chipped and loaded into the dryer; a tractor-trailer and a container were used. The dryers had perforated floors where warm air from the plants was funnelled into the dryer, using an electric fan of 4 kW. Four separate trials were conducted in September and October 2009. The drying capacity of the trailer and the container was roughly 11.5 m3 and 29 m3 loose respectively. The effective height at which drying took place was 1.2 m and 1.9 m. The average temperatures of the air channelled into the dryers was 15–18 °C in the trailer and 24–26 °C in the container. The fan was operated for 139 hours (twice) for the trailer and 121.5 and 67.5 hour periods for the container. The fan used 556 kWh (twice), 486 kWh and 270 kWh of electricity respectively. The chips located at the bottom dried first, and chips located above dried later. The water content in the chip was measured to 66.1 to 52.1% (wet base) before and 9.6 to 6.9% (wet base) after drying. The amount of water removed from the container was approximately 28 kg per hour and 22 kg per hour from the trailer. For the container, drying cost roughly 9 Euro per MWh; the cost of the trailer was nearly twice as much. This indicates that the drying volume should be as high as possible. Drying determines net calorific value and hence market value of wood chip.
Authors
Aparna Tiwari Adam Vivian-Smith Roeland E. Voorrips Myckel E.J. Habets Lin B. Xue Remko Offringa Ep HeuvelinkAbstract
Background Parthenocarpy is a desirable trait in Capsicum annuum production because it improves fruit quality and results in a more regular fruit set. Previously, we identified several C. annuum genotypes that already show a certain level of parthenocarpy, and the seedless fruits obtained from these genotypes often contain carpel-like structures. In the Arabidopsis bel1 mutant ovule integuments are transformed into carpels, and we therefore carefully studied ovule development in C. annuum and correlated aberrant ovule development and carpelloid transformation with parthenocarpic fruit set. Results We identified several additional C. annuum genotypes with a certain level of parthenocarpy, and confirmed a positive correlation between parthenocarpic potential and the development of carpelloid structures. Investigations into the source of these carpel-like structures showed that while the majority of the ovules in C. annuum gynoecia are unitegmic and anatropous, several abnormal ovules were observed, abundant at the top and base of the placenta, with altered integument growth. Abnormal ovule primordia arose from the placenta and most likely transformed into carpelloid structures in analogy to the Arabidopsis bel1 mutant. When pollination was present fruit weight was positively correlated with seed number, but in the absence of seeds, fruit weight proportionally increased with the carpelloid mass and number. Capsicum genotypes with high parthenocarpic potential always showed stronger carpelloid development. The parthenocarpic potential appeared to be controlled by a single recessive gene, but no variation in coding sequence was observed in a candidate gene CaARF8. Conclusions Our results suggest that in the absence of fertilization most C. annuum genotypes, have parthenocarpic potential and carpelloid growth, which can substitute developing seeds in promoting fruit development.