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.
2010
Authors
Jari Vauhkonen Liviu Ene Svein Solberg Marius Hauglin Vegard Lien Petteri Packalén Terje Gobakken Erik Næsset Timo Tokola Matti MaltamoAbstract
The aim of this study was to validate and compare single-tree detection algorithms under different forest conditions. Field data and corresponding airborne laser scanning (ALS) data were acquired from boreal forests in Norway and Sweden, coniferous and broadleaved forests in Germany, and pulpwood plantations in Brazil. The data represented a variety of forest types from pure Eucalyptus stands with known ages and planting densities to conifer-dominated Scandinavian forests and more complex deciduous canopies in Central Europe. ALS data were acquired using different sensors with pulse densities varying between the data sets. Field data in varying extent were associated with each ALS data set for training purposes. Treetop positions were extracted using altogether six different algorithms developed in Finland, Germany, Norway and Sweden, and the accuracy of tree detection and height estimation was assessed. Furthermore, the weaknesses and strengths of the methods under different forest conditions were analyzed. The results showed that forest structure and density strongly affected the performance of all algorithms. The differences in performance between methods were more pronounced for tree detection than for height estimation. The algorithms showed a slightly better performance in the conditions for which they were developed, while some could be adapted by different parameterization according to training with local data. The results of this study may help guiding the choice of method under different conditions and may be of great value for future refinement of the single-tree detection algorithms.
Abstract
No abstract has been registered
Authors
E Lapied Deborah H. Oughton Erik JonerAbstract
In terrestrial ecotoxicology there is a serious lack of data for potential hazards posed by engineered nanoparticles (ENPs). This is partly due to complex interactions between ENPs and the soil matrix, but also to the lack of suitable toxicological endpoints in organisms that are exposed to ENPs in a relevant manner. Earthworms are recognized as key organisms in terrestrial ecosystems, but so far only physiological endpoints of low sensitivity have been used in ecotoxicity studies with ENPs. We exposed the earthworm Lumbricus terrestris to different concentrations (1-100 ppm) silver nanoparticles of two contrasting sizes under three different conditions; in water, in food and in soil. After exposure, we measured the impact on apoptosis in different tissues using two staining techniques to determine apoptosis; TUNEL and Apostain. A dose-dependent response was detected with respect to apoptotic activity in a range of tissues both at acute and sub-lethal concentrations (down to 4 mg kg soil-1). Comparing exposure in water and soil showed that reduced bioavailability in soil is reflected in the apoptotic response. Apoptosis thus seems to be a sensitive endpoint for detection of adverse effects of silver nanoparticles, and potentially a powerful tool for quantifying environmental hazards posed by ENPs.
Authors
Lise GrøvaAbstract
No abstract has been registered
Authors
Adam ParuchAbstract
No abstract has been registered
Authors
Adam ParuchAbstract
No abstract has been registered
Authors
Leif Sundheim Trond Hofsvang Christer Magnusson Trond Rafoss Arild Sletten Halvor Solheim Arne Stensvand Brita Toppe Anne Marte Tronsmo Bjørn ØklandAbstract
No abstract has been registered
Authors
Leif Sundheim Trond Hofsvang Christer Magnusson Trond Rafoss Arild Sletten Halvor Solheim Brita Toppe Anne Marte Tronsmo Bjørn ØklandAbstract
No abstract has been registered
Authors
Rebekka ØvstegårdAbstract
No abstract has been registered
Authors
Rebekka ØvstegårdAbstract
No abstract has been registered