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.
2021
Abstract
No abstract has been registered
Authors
Fabian Sauter Harald Albrecht Johannes Kollmann Marion LangAbstract
Competition is ubiquitous in plant communities with various effects on plant fitness and community structure. A long-standing debate about different approaches to explain competition is the controversy between David Tilman and Philip Grime. Grime stated that the importance of competition relative to the impact of the environment increases along a productivity gradient, while Tilman argued that the intensity of competition is independent of productivity. To revisit this controversy, we assumed that the effects of plant–plant interactions are additive and applied the new competition indices by Díaz-Sierra et al. (2017) in a field experiment along a productivity gradient in S-Germany, using the rare arable plant Arnoseris minima as a study species. The ‘target technique' was applied, to separate the effects of root and shoot competition. The study plants were exposed to five competition treatments with three replicates in 18 sites, respectively. We investigated the expectation that root competition is more intense in unproductive sites than shoot competition. Additionally, we predicted survival to be less affected by competition than growth-related plant parameters. Using the biomass of individuals without competition as a proxy for site productivity there was a positive relationship with competition importance but no relationship with competition intensity when plants experienced full competition. Survival of the target plants was unaffected by competition. Root competition was the main mechanism determining the performance of the target plants, whereas the effect of shoot competition was relatively low albeit increasing with productivity. We conclude that when considering plant–plant interactions additive both Grime's and Tilman's theories can be supported.
Authors
Sandra Rojas-Botero Johannes Kollmann Leonardo H. TeixeiraAbstract
Invasive non-native plants challenge ecosystems restoration, and understanding the factors that determine the establishment of invasive plants is crucial to improve restoration outcomes. However, the drivers of invasibility of plant communities are not sufficiently clear, and combined effects are not understood. Therefore, we investigated the contribution of the main drivers of invasion success during early phases of restoration, i.e., biotic resistance, invasive propagule pressure, and environmental fluctuations. We compared the contribution of these drivers in a series of mesocosms experiments using designed grasslands as a model system, and Solidago gigantea as invasive model species. Two grassland communities were designed according to competitive trait hierarchies with different sowing patterns, reflecting variation in biotic resistance. We then manipulated invader propagule pressure and applied different scenarios of environmental fluctuation, i.e., flood, heat, and N fertilization. Invasive biomass was considered as proxy for invasion success, while native biomass represented restoration success. There were consistent effects of biotic resistance to S. gigantea invasion via competitive trait hierarchies in the three experiments. Communities dominated by species with high-competition traits were more resistant regardless of environmental fluctuation. Clumped seeding of the native community reduced invasibility, whereas high non-native propagule density increased invasion. The effects of environmental fluctuation were less consistent and context-dependent, thus playing a secondary role when compared to biotic drivers of invasion. Restoration initiatives on grasslands impacted by invasive plants should consider biotic resistance of the restored community as a key driver and the importance of controlling further arrivals of invasive species during community assembly.
Abstract
No abstract has been registered
Abstract
There are neither volume nor velocity thresholds that define big data. Any data ranging from just beyond the capacity of a single personal computer to tera- and petabytes of data can be considered big data. Although it is common to use High Performance Computers (HPCs) and cloud facilities to compute big data, migrating to such facilities is not always practical due to various reasons, especially for medium/small analysis. Personal computers at public institutions and business companies are often idle during parts of the day and the entire night. Exploiting such computational resources can partly alleviate the need for HPC and cloud services for analysis of big data where HPC and cloud facilities are not immediate options. This is particularly relevant also during testing and pilot application before implementation on HPC or cloud computing. In this paper, we show a real case of using a local network of personal computers using open-source software packages configured for distributed processing to process remotely sensed big data. Sentinel-2 image time series are used for the testing of the distributed system. The normalized difference vegetation index (NDVI) and the monthly median band values are the variables computed to test and evaluate the practicality and efficiency of the distributed cluster. Computational efficiencies of the cluster in relation to different cluster setup, different data sources and different data distribution are tested and evaluated. The results demonstrate that the proposed cluster of local computers is efficient and practical to process remotely sensed data where single personal computers cannot perform the computation. Careful configurations of the computers, the distributed framework and the data are important aspects to be considered in optimizing the efficiency of such a system. If correctly implemented, the solution leads to an efficient use of the computer facilities and allows the processing of big, remote, sensing data without the need to migrate it to larger facilities such as HPC and cloud computing systems, except when going to production and large applications.
Authors
Magdalena Broda Callum Aidan Stephen HillAbstract
This paper reviews the degradation, preservation and conservation of waterlogged archaeological wood. Degradation due to bacteria in anoxic and soft-rot fungi and bacteria in oxic waterlogged conditions is discussed with consideration of the effect on the chemical composition of wood, as well as the deposition of sulphur and iron within the structure. The effects on physical properties are also considered. The paper then discusses the role of consolidants in preserving waterlogged archaeological wood after it is excavated as well as issues to be considered when reburial is used as a means of preservation. The use of alum and polyethylene glycol (PEG) as consolidants is presented along with various case studies with particular emphasis on marine artefacts. The properties of consolidated wood are examined, especially with respect to the degradation of the wood post-conservation. Different consolidants are reviewed along with their use and properties. The merits and risks of reburial and in situ preservation are considered as an alternative to conservation.
Authors
Živa Fišer Giovanna Aronne Tsipe Aavik Meleksen Akin Paraskevi Alizoti Filippos Aravanopoulos Gianluigi Bacchetta Manica Balant Dalibor Ballian Oz Barazani Andrea Francesca Bellia Nadine Bernhardt Magda Bou Dagher Kharrat Adrian Bugeja Douglas Michael Burkart Dušica Ćalić André Carapeto Tor Carlsen Silvia Castro Guy Colling Joana Cursach Sara Cvetanoska Cvetanka Cvetkoska Renata Ćušterevska Laura Daco Kalina Danova Aida Dervishi Gordana Djukanović Snežana Dragićević Andreas Ensslin Marianne Evju Giuseppe Fenu Ana Francisco Pedro Pablo Gallego Marta Galloni Anatolie Ganea Birgit Gemeinholzer Peter Glasnović Sandrine Godefroid Mette Thomsen Melinda Halassy Aveliina Helm Marko Hyvärinen Jasmin Joshi Amra Kazić Michael Kiehn Marcin Klisz Anneleen Kool Olav Skarpaas Goran Zdunic Elke ZippelAbstract
Even though plants represent an essential part of our lives offering exploitational, supporting and cultural services, we know very little about the biology of the rarest and most threatened plant species, and even less about their conservation status. Rapid changes in the environment and climate, today more pronounced than ever, affect their fitness and distribution causing rapid species declines, sometimes even before they had been discovered. Despite the high goals set by conservationists to protect native plants from further degradation and extinction, the initiatives for the conservation of threatened species in Europe are scattered and have not yielded the desired results. The main aim of this Action is to improve plant conservation in Europe through the establishment of a network of scientists and other stakeholders who deal with different aspects of plant conservation, from plant taxonomy, ecology, conservation genetics, conservation physiology and reproductive biology to protected area's managers, not forgetting social scientists, who are crucial when dealing with the general public. in situ plant conservation, ex situ plant conservation, conservation genetics, red lists of threatened plant species, citizen science
Abstract
Water consumption along value chains of goods and services has increased globally and led to increased attention on water footprinting. Most global water consumption is accounted for by evaporation (E), which is connected via bridges of atmospheric moisture transport to other regions on Earth. However, the resultant source–receptor relationships between different drainage basins have not yet been considered in water footprinting. Based on a previously developed data set on the fate of land evaporation, we aim to close this gap by using comprehensive information on evaporation recycling in water footprinting for the first time. By considering both basin internal evaporation recycling (BIER; >5% in 2% of the world’s basins) and basin external evaporation recycling (BEER; >50% in 37% of the world’s basins), we were able to use three types of water inventories (basin internal, basin external, and transboundary inventories), which imply different evaluation perspectives in water footprinting. Drawing on recently developed impact assessment methods, we produced characterization models for assessing the impacts of blue and green water evaporation on blue water availability for all evaluation perspectives. The results show that the negative effects of evaporation in the originating basins are counteracted (and partly overcompensated) by the positive effects of reprecipitation in receiving basins. By aggregating them, combined net impacts can be determined. While we argue that these offset results should not be used as a standalone evaluation, the water footprint community should consider atmospheric moisture recycling in future standards and guidelines.
Authors
Line Nybakken Inger Sundheim Fløistad Melissa Magerøy Maren Lomsdal Solveig Strålberg Paal Krokene Johan AsplundAbstract
Nursery-grown Norway spruce Picea abies seedlings are often heavily attacked by the pine weevil Hylobius abietis on clear-cuts the first years after planting. Because the seedlings are not resource-limited during the growing phase in the nursery they are expected to invest less in defence than naturally regenerated seedlings already present on the clear-cuts. The latter have had to cope with various environmental stressors that could make them invest more in defence. We tested if naturally regenerated plants have stronger chemical defences than nursery-grown plants. Nursery-grown plants were planted in-between naturally regenerated plants on fresh clear cuts, and phenolic and terpene compounds in the stem bark were measured after one growing season. To test both constitutive and inducible defences, plants were either wounded, painted with methyl jasmonate (MeJA) to induce defences, or given a combination of both treatments. Growth and pine weevil attacks of the plants were registered. Nursery-grown plants had higher total concentrations of phenolic compounds and lower concentrations of terpenes than naturally regenerated plants. These opposite responses were reflected in very different compound profiles in the two plant types. We suggest the differences between plant types to be results of differences in plant age, stress level, genetic origin or possibly a combination of these factors. Most compounds showed no response to wounding, MeJA-treatment or wounding and MeJA-treatment combined, but the terpenes 3-carene, eucalyptol, limonene and para-cymene had higher concentrations in MeJA-treated nursery-grown plants than in control plants. These compounds are known to be effective in conifer resistance against weevils and bark beetles. Overall, 27% of our 400 study plants had signs of pine weevil damage after 3 ½ months in the field. However, treatment or plant type had no significant effect on whether plants were attacked or not and this might have been a result of the relatively low overall level of attacks in this study. Further studies are needed to disentangle the importance of plant age, stress level, genetic origin and resource availability for chemical defence mechanisms of young Norway spruce plants, as strengthening the natural resistance of nursery plants may be increasingly important in a future with less pesticide use.
Authors
Helene Birkelund Erlandsen Stein Beldring Stephanie Eisner Hege Hisdal Shaochun Huang Lena Merete TallaksenAbstract
Robust projections of changes in the hydrological cycle in a non-stationary climate rely on trustworthy estimates of the water balance elements. Additional drivers than precipitation and temperature, namely wind, radiation, and humidity are known to have a significant influence on processes such as evaporation, snow accumulation, and snow-melt. A gridded version of the rainfall-runoff HBV model is run at a 1 × 1 km scale for mainland Norway for the period 1980–2014, with the following alterations: (i) the implementation of a physically based evaporation scheme; (ii) a net radiation-restricted degree-day factor for snow-melt, and (iii) a diagnostic precipitation phase threshold based on temperature and humidity. The combination of improved forcing data and model alterations allowed for a regional calibration with fewer calibrated parameters. Concurrently, modeled discharge showed equally good or better validation results than previous gridded model versions constructed for the same domain; and discharge trend patterns, snow water equivalent, and potential evaporation compared fairly to observations. Compared with previous studies, lower precipitation and evaporation values for mainland Norway were found. The results suggest that a more robust and more physically based model for climate change studies has been obtained, although additional studies will be needed to further constrain evaporation estimates.