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.
2018
Authors
Torbjørn Ekrem Roberto Guidetti K. Ingemar Jönsson Łukasz Kaczmarek Terje Meier Elisabeth Stur Tommy Prestø Kristian Hassel Karstein Hårsaker Lasse Topstad Ivar GjerdeAbstract
Background: The knowledge of Norwegian tardigrades is poor and their diversity, distribution and ecology in Norwegian forests is unknown. This project aims to investigate tardigrade diversity associated with different types of substrates in forests in Norway, evaluate the impact of forestry management practices on tardigrade biodiversity for future conservation policies, and expand the DNA barcode library of Norwegian tardigrades. It will also use environmental barcoding of substrates to test the effectiveness of this method in documenting tardigrade diversity and distribution. Results: We collected three hundred bryophyte-, lichen- and leaf litter samples from various protected deciduous and coniferous forests in Norway in 2017. The vegetation in each sample was identified, mostly to species-level. Tardigrades were extracted from most bryophyte- and lichen samples, and some litter samples. Preliminary analyses show that there are differences in abundance and community composition between both forest- and substrate types. Litter samples show lower abundances than bryophyte and lichen samples, but a higher diversity than expected. Conclusions: Remaining samples still need to be processed, but our preliminary conclusion is that different substrates and forest types host different tardigrade communities. DNA-barcoding will be performed on single specimens of as many of the sampled species as possible and added to the Barcode of Life Data Systems database (BOLD). We expect that DNA metabarcoding of environmental samples from selected localities will record the same diversity as traditional extraction of specimens, but also add information on the presence of species that were undetected.
Abstract
No abstract has been registered
Authors
Kjersti Holt HanssenAbstract
The production of ash from wood has greatly increased the last years, because biofuels are increasingly being used for heating and energy production. The ash may either be viewed as a waste problem, or as a resource. Wood ash has a liming effect and contains essential nutrients (P, K, Ca, Mg) which can be exploited for soil fertilisation. With enhanced knowledge about where and how wood ash addition may increase forest growth - without having negative effects on the environment - wood ash may become a renewable nutrient source. We studied the effect of fertilizing a Norway spruce (Picea abies) stand on relatively high site index in SE Norway with ash, nitrogen, or ash + nitrogen. After five years, both current annual increment and standing volume was best in the ASH + N treatment and least in the Control plots. The field trial should be followed for a longer period of time, as the ASH + N treatment still shows an increasing growth trend after five years.
Abstract
Several studies have shown the positive effect of nitrogen fertilization on conifer growth. In young Norway spruce (Picea abies) stands, an additional effect of including a mixture of other nutrients has often, but not always, been found. We studied effects of repeated fertilization in 28 stands with young Norway spruce in central Norway. The treatments consisted of plots without nutrient addition (Control), fertilization with 150 kg N ha−1 (150 N), and fertilization with 150 kg N plus addition of P, K, Mg, B, Mn and Cu (150 N + mix), repeated three times with approximately eight years interval. There was a clear positive effect on volume increment of the 150 N and 150 N + mix treatments compared to Control, and the effect was significantly higher for 150 N + mix than for 150 N. Fertilization had a stronger effect in the first fertilization period than in the second, while the third period was intermediate. The effect of 150 N + mix was strongest at plots > 300 m a.s.l. However, this correlation may be due to geological conditions rather than elevation. Further studies are needed to find out under which edaphic conditions a nutrient mixture will increase growth substantially in young spruce stands.
Abstract
No abstract has been registered
Authors
Kjersti Holt HanssenAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Enabling automated 3D mapping in forests is an important component of the future development of forest technology, and has been garnering interest in the scientific community, as can be seen from the many recent publications. Accordingly, the authors of the present paper propose the use of a Simultaneous Localisation and Mapping algorithm, called graph-SLAM, to generate local maps of forests. In their study, the 3D data required for the mapping process were collected using a custom-made, mobile platform equipped with a number of sensors, including Velodyne VLP-16 LiDAR, a stereo camera, an IMU, and a GPS. The 3D map was generated solely from laser scans, first by relying on laser odometry and then by improving it with robust graph optimisation after loop closures, which is the core of the graph-SLAM algorithm. The resulting map, in the form of a 3D point cloud, was then evaluated in terms of its accuracy and precision. Specifically, the accuracy of the fitted diameter at breast height (DBH) and the relative distance between the trees were evaluated. The results show that the DBH estimates using the Pratt circle fit method could enable a mean estimation error of approximately 2 cm (7–12%) and an RMSE of 2.38 cm (9%), whereas for tree positioning accuracy, the mean error was 0.0476 m. The authors conclude that robust SLAM algorithms can support the development of forestry by providing cost-effective and acceptable quality methods for forest mapping. Moreover, such maps open up the possibility for precision localisation for forestry vehicles.
Abstract
The forest understory is often associated with rapid rates of carbon and nutrient cycling, but cost-efficient quantification of its biomass remains challenging. We tested a new field technique for understory biomass assessment using an off-the-shelf handheld laser rangefinder. We conducted laser sampling in a pine forest with an understory dominated by invasive woody shrubs, especially Rhamnus frangula L. Laser sampling was conducted using a rangefinder, mounted on a monopod to provide a consistent reference height, and pointed vertically downward. Subsequently, the understory biomass was measured with destructive sampling. A series of metrics derived from the airborne LiDAR literature were evaluated alone and in combination for prediction of understory biomass using best-subsets regression. Resulting fits were good (r2 = 0.85 and 0.84 for the best single metric and best additive metric, respectively, and R2 = 0.93 for the best multivariate model). The results indicate that laser sampling could substantially reduce the need for costly destructive sampling within a double-sampling context.
Authors
Camilo Chiang Oda Toresdatter Aas Marianne Rindedal Jetmundsen YeonKyeong Lee Sissel Torre Inger Sundheim Fløistad Jorunn Elisabeth OlsenAbstract
Subalpine fir (Abies lasiocarpa (Hooker) Nuttall), which is native to western North America, is of considerable interest for Christmas tree production in northern Europe. Seedlings are usually grown from seeds under combined nursery greenhouse/outdoors conditions, but commonly show early growth cessation in the nursery, resulting in small plants for field transplanting. This increases the production time and makes the seedlings vulnerable to stressors at the planting site. Day extension with far-red (FR) light was shown to enhance elongation and delay bud set in seedlings of some woody species, but such information is limited for Abies. Here, we investigated the effects of day extension with FR, red (R), different R:FR-ratios or blue (B) light from light emitting diodes on subalpine fir seedlings grown at different temperatures. Day extension with FR or combined R-FR light, in contrast to R or B light, increased shoot elongation significantly as compared to short days without day extension, often with more growth at 18 ◦C than 24 ◦C. The FR treatments delayed terminal bud development, although bud set was not completely prevented. These results demonstrate that larger seedlings of subalpine fir seedlings for Christmas tree production can be obtained by employing day extension with FR or combined R:FR light, preferably under cool temperature.