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.
2014
Authors
Nicholas Clarke Toril Drabløs Eldhuset Kjersti Holt Hanssen Ari Hietala O. Janne Kjønaas Holger Lange Jørn-Frode Nordbakken Tonje Økland Ingvald RøsbergAbstract
No abstract has been registered
2013
Abstract
Three methods for extracting DNA were tested on otoliths, scales, fins, and gill tissue from European whitefish [Coregonus lavaratus (L.)]. The aim was to find time-efficient and affordable ways to simultaneously extract DNA suitable for conservation genetic studies from a large number of samples and different tissues. A rapid low-cost method led to 97 % success of microsatellite amplification in otoliths and 100 % in scales. High amplification success was achieved with fin (97 %) and gill (99 %) tissue using a salt lysis-based protocol. A commercial extraction kit delivered good results with all tissues. The findings are useful for conservation genetic studies using both contemporary and archived samples.
Abstract
Over the past 40 years, a new multidisciplinary field of study has emerged which is characterised by at least two major changes in the way some scientists treat systems. First, it is increasingly accepted that we cannot fully understand the laws that govern a system simply by studying its parts, nor can we fully understand the behaviour of the parts without placing them in the context of the larger system in which they are embedded. This realization, which has arisen as we face the limits of reductionist science, has given rise to the development of new models and methods that facilitate the study of systems across multiple scales of organization. Second, the notions of equilibrium and predictability in natural systems, developed in the 19th Century and continuously pursued until far into the 20th Century, are being rejected in favour of models that embrace variability, diversity, continual change and adaptation as the status quo. Traditional analytical models that assume a stable equilibrium are being replaced by new approaches that facilitate the exploration of a system’s natural range of variation and its possible emergent responses to changing external conditions. The implications of this new field, now known as complexity science, are manifest across disciplines, fundamentally changing the way we study, analyze and perceive natural systems. We provide an overview of complexity science in the context of forest management.
Authors
Ryan Bright Rasmus Astrup Anders Hammer Strømman Clara Antón-Fernández Maria Malene Kvalevåg Francesco CherubiniAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Tonje Økland Jørn Frode Nordbakken Holger Lange Ingvald Røsberg Janne O. Kjønaas Kjersti Holt Hanssen Toril Drabløs Eldhuset Nicholas ClarkeAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Solberg, Svein; Astrup, Rasmus Andreas; Weydahl, Dan Johan. Detection of forest clear-cuts with shuttle radar topography mission (SRTM) and tandem-X InSAR data. Remote Sensing 2013 ;Volum 5.(11) s. 5449-5462
Abstract
There is a need for monitoring methods for forest volume, biomass and carbon based on satellite remote sensing. In the present study we tested interferometric X-band SAR (InSAR) from the Tandem-X mission. The aim of the study was to describe how accurate volume and biomass could be estimated from InSAR height and test whether the relationships were curvilinear or not. The study area was a spruce dominated forest in southeast Norway. We selected 28 stands in which we established 192 circular sample plots of 250 m2, accurately positioned by a Differential Global Positioning System (dGPS). Plot level data on stem volume and aboveground biomass were derived from field inventory. Stem volume ranged fromzero to 596 m3/ha, and aboveground biomass up to 338 t/ha.We generated 2 Digital Surface Models (DSMs) fromInSAR processing of two co-registered, HH-polarized TanDEM-X image pairs – one ascending and one descending pair.We used a Digital TerrainModel (DTM) from airborne laser scanning (ALS) as a reference and derived a 10 m × 10 m Canopy Height Model (CHM), or InSAR height model. We assigned each plot to the nearest 10 m × 10 m InSAR height pixel. We applied a nonlinear, mixed model for the volume and biomass modeling, and from a full model we removed effects with a backward stepwise approach. InSAR heightwas proportional to volume and aboveground biomass, where a 1 m increase in InSAR height corresponded to a volume increase of 23 m3/ha and a biomass increase of 14 t/ha. Root Mean Square Error (RMSE) values were 43–44% at the plot level and 19–20% at the stand level.
Abstract
We provide a demonstration of the new tomographic profiling (TP) technique, here applied to forestry for the first time. The portable ground-based synthetic aperture radar (GB-SAR) system was used to capture profiles of the vertical polarimetric backscattering patterns through a 7 m tall stand of Norway spruce trees. The TP scheme collects data as for normal SAR imaging, but with the antennae aligned in the along-track direction. Adaptive post-processing meant that each TP scan simultaneously captured along-track image transects over the incidence angle range 0°–60°. An important feature of the derived image products is that incidence angle is constant at every point within an image. The measured HH–VV height backscatter profiles were very similar, whilst the cross-/co-polarization ratio showed very little variation with height through the stand. Backscattering profiles showed closest agreement with the branch biomass distribution through the canopy, rather than with trunk or branch + trunk biomasses. Equivalent interferometric tree heights were estimated from the centre of mass of the backscatter-height distribution, which displayed increasing height with increasing incidence angle. There was no significant vertical separation between the cross- and co-polarization returns.