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.
2019
Authors
Line JohansenAbstract
No abstract has been registered
Abstract
Understanding how drivers of change affect ecosystem services (ES) is of great importance. Indicators of ES can be developed based on biophysical measures and be used to investigate the service flow from ecosystems to socio-ecological systems. However, the ES concept is multivariate and the use of normalized composite indicators reduces complexity and facilitates communication between science and policy. The aim of this study is to analyze how land use change affects ES and species richness and how the effects are modified by environmental factors by using composite indicators based on biophysical indicators. Using multivariate and regression analyses, we analyze the effect of grazing management abandonment in semi-natural grasslands in Norway on six ES: nutrient cycling, pollination, forage quality, aesthetics and global and regional climate regulation in addition to species richness along soil and climate gradients. Nutrient cycling, forage quality, regional climate regulation, aesthetics and species richness are larger in managed compared to abandoned grasslands. There are trade-offs among ES as different management strategies provide various ES and these trade-offs vary along environmental gradients. Management policies that aim to conserve ES need to have conservation goals that are context dependent, should recognize ES trade-offs and be adapted to local conditions.
Authors
Sølvi Wehn Anna Westin Line Johansen Anamaria Iuga Cosmin Marius Ivascu Eveliina Kallioniemi Tommy LennartssonAbstract
Semi-natural grasslands are hotspots of biodiversity in Europe and provide amounts of flower resources for pollinators. We present data on composition and spatial turnover of herb species and flower resources in and between semi-natural grasslands in Romania mown at different times during the growth season (early, intermediate, late). The data include herb species occurrences, their phenological stage, flower resources, and measures of spatial turnover of the species occurrences and flower resources based on Detrended Correspondence Analyses (DCA), in the start of August. The dataset is provided as supplementary material and associated with the research article “Traditional semi-natural grassland management with heterogeneous mowing times enhances flower resources for pollinators in agricultural landscapes” [1] Johansen et al.. See Johansen et al. for data interpretation.
Abstract
No abstract has been registered
Authors
Line Johansen Anna Westin Sølvi Wehn Anamaria Iuga Cosmin Marius Ivascu Eveliina Kallioniemi Tommy LennartssonAbstract
For a diverse pollinator fauna it is important that pollen and nectar are available over the entire summer at spatially relevant scales. Semi-natural hay meadows are among the most important sources of flower resources for pollinators, but the resources are strongly affected by the timing of mowing. Management recommendations for hay meadows often prescribe late mowing on order to allow undisturbed flowering during most of the summer. Traditional practices, however, often include also earlier mowing. We investigate the link between the temporal variation of flower resources and traditional mowing practices of semi-natural hay meadows in a low-intensity agricultural landscape in Romania. In early August, we botanically surveyed meadows that were cut early, intermediately, or late in the season. We recorded all herb species, their phenological stage, and the number of reproductive units of each species. Data were analysed using DCA, LM and GLM. Plant species richness and composition are not affected by the time of mowing, but different sets of species flower in semi-natural grasslands with different mowing regimes. In August the proportion of species flowering and flower density are highest in the early-mown meadows due to re-flowering after mowing. Analyses of phenological stages indicate that late-mown meadows are the main pollen and nectar sources in July, whereas meadows mown early are the main resource from August to the end of the season. The results demonstrate that for pollinator conservation, heterogeneous mowing times within a landscape need to be encouraged when possible, and that strict focus on late mowing may lead to shortage of flower resources late in the summer. Studies of low-intensity agriculture has a great potential for learning about management methods that can be used in other parts of the world where traditional practices have been lost. Such studies can thereby contribute with important knowledge to manage global pollinator loss.
Authors
Audun KorsæthAbstract
No abstract has been registered
Authors
Audun KorsæthAbstract
No abstract has been registered
Authors
Audun KorsæthAbstract
No abstract has been registered
Abstract
In this paper, we present a novel method for obstacle avoidance designed for a nonholonomic mobile robot. The method relies on light detection and ranging (LiDAR) readings, which are mapped into a polar coordinate system. Obstacles are taken into consideration when they are within a predefined radius from the robot. A central part of the approach is a new Heading Weight Function (HWF), in which the beams within the aperture angle of the LiDAR are virtually weighted in order to generate the best trajectory candidate for the robot. The HWF is designed to find a solution also in the case of a local-minima situation. The function is coupled with the robot’s controller in order to provide both linear and angular velocities. We tested the method both by simulations in a digital environment with a range of different static obstacles, and in a real, experimental environment including static and dynamic obstacles. The results showed that when utilizing the novel HWF, the robot was able to navigate safely toward the target while avoiding all obstacles included in the tests. Our findings thus show that it is possible for a robot to navigate safely in a populated environment using this method, and that sufficient efficiency in navigation may be obtained without basing the method on a global planner. This is particularly promising for navigation challenges occurring in unknown environments where models of the world cannot be obtained.
Authors
Audun KorsæthAbstract
No abstract has been registered