Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2018
Forfattere
Torbjørn Ekrem Roberto Guidetti K. Ingemar Jönsson Łukasz Kaczmarek Terje Meier Elisabeth Stur Tommy Prestø Kristian Hassel Karstein Hårsaker Lasse Topstad Ivar GjerdeSammendrag
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.
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Unmanned aerial vehicles (UAVs) are increasingly used as tools to perform a detailed assessment of post-harvest sites. One of the potential use of UAV photogrammetric data is to obtain tree-stump information that can then be used to support more precise decisions. This study developed and tested a methodology to automatically detect, segment, classify, and measure tree-stumps. Among the potential applications for single stump data, this study assessed the possibility (1) to detect and map root- and butt-rot on the stumps using a machine learning approach, and (2) directly measure or model tree stump diameter from the UAV data. The results revealed that the tree-stumps were detected with an overall accuracy of 68–80%, and once the stump was detected, the presence of root- and butt-rot was detected with an accuracy of 82.1%. Furthermore, the root mean square error of the UAV-derived measurements or model predictions for the stump diameter was 7.5 cm and 6.4 cm, respectively, and with the former systematically under predicting the diameter by 3.3 cm. The results of this study are promising and can lead to the development of more cost-effective and comprehensive UAV post-harvest surveys.
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The effectiveness of generating virtual transects on unmanned aerial vehicle-derived orthomosaics was evaluated in estimating the extent of soil disturbance by severity class. Combinations of 4 transect lengths (5–50 m) and five sampling intensities (1–20 transects per ha) were used in assessing traffic intensity and the severity of soil disturbance on six post-harvest, cut-to-length (CTL) clearfell sites. In total, 15% of the 33 ha studied showed some trace of vehicle traffic. Of this, 63% of was categorized as light (no visible surface disturbance). Traffic intensity varied from 787 to 1256 m ha−1, with a weighted mean of 956 m ha−1, approximately twice the geometrical minimum achievable with CTL technology under perfect conditions. An overall weighted mean of 4.7% of the total site area was compromised by severe rutting. A high sampling intensity, increasing with decreasing incidence of soil disturbance, is required if mean estimation error is to be kept below 20%. The paper presents a methodology that can be generally applied in forest management or in similar land-use evaluations.
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Background and aims Layered profiles of designed soils may provide long-term benefits for green roofs, provided the vegetation can exploit resources in the different layers. We aimed to quantify Sedum root foraging for water and nutrients in designed soils of different texture and layering. Methods In a controlled pot experiment we quantified the root foraging ability of the species Sedum album (L.) and S. rupestre (L.) in response to substrate structure (fine, coarse, layered or mixed), vertical fertiliser placement (top or bottom half of pot) and watering (5, 10 or 20 mm week−1 ). Results Water availability was the main driver of plant growth, followed by substrate structure, while fertiliser placement only had marginal effects on plant growth. Root foraging ability was low to moderate, as also reflected in the low proportion of biomass allocated to roots (5–13%). Increased watering reduced the proportion of root length and root biomass in deeper layers. Conclusions Both S. album and S. rupestre had a low ability to exploit water and nutrients by precise root foraging in substrates of different texture and layering. Allocation of biomass to roots was low and showed limited flexibility even under water-deficient conditions.
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Olfaction is the most important sensory mechanism by which many insects interact with their environment and a wind tunnel is an excellent tool to study insect chemical ecology. Insects can locate point sources in a three-dimensional environment through the sensory interaction and sophisticated behavior. The quantification of this behavior is a key element in the development of new tools for pest control and decision support. A wind tunnel with a suitable flight section with laminar air flow, visual cues for in-flight feedback and a variety of options for the application of odors can be used to measure complex behaviour which subsequently may allow the identification of attractive or repellent odors, insect flight characteristics, visual-odor interactions and interactions between attractants and odors lingering as background odors in the environment. A wind tunnel holds the advantage of studying the odor mediated behavioural repertoire of an insect in a laboratory setting. Behavioural measures in a controlled setting provide the link between the insect physiology and field application. A wind tunnel must be a flexible tool and should easily support the changes to setup and hardware to fit different research questions. The major disadvantage to the wind tunnel setup described here, is the clean odor background which necessitates special attention when developing a synthetic volatile blend for field application.
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Carbonic anhydrase (CA) plays an important physiological role in all biological systems by accelerating the interconversion of CO2 and HCO3 −. In algae, CA is essential for photosynthesis: external CA (CAext) dehydrates HCO3 −, enhancing the supply of CO2 to the cell surface, and internal CA (CAint) interconverts HCO3 − and CO2 to maintain the inorganic carbon (Ci) pool and supply CO2 to RuBisCO. We frst conducted a literature review comparing the conditions in which CA extraction and measurement have been carried out, using the commonly used Wilbur–Anderson method. We found that the assay has been widely modifed since its introduction in 1948, mostly without being optimized for the species tested. Based on the review, an optimized protocol for measuring CA in Macrocystis pyrifera was developed, which showed that the assay conditions can strongly afect CA activity. Tris–HCl bufer gave the highest levels of CA activity, but phosphate bufer reduced activity signifcantly. Bufers containing polyvinylpyrrolidone (PVP) and dithiothreitol (DTT) stabilized CA. Using the optimized assay, CAext and CAint activities were readily measured in Macrocystis with higher precision compared to the non-optimized method. The CAint activity was 2×higher than CAext, which is attributed to the Ci uptake mechanisms of Macrocystis. This study suggests that the CA assay needs to be optimized for each species prior to experimental work to obtain both accurate and precise results.