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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.

2025

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Abstract

The spatio-temporal evolution of woody plant lineages in the Holarctic is still understudied, limiting our understanding of evolutionary processes that promote higher diversity at higher latitudes in some lineages, which contradicts the latitudinal gradient hypothesis which predicts higher species richness in the tropics. Shrub willows (Salix subgenus Vetrix) comprise about 350 species of which many are adapted to arctic-alpine ecosystems and thus form an important element across the Holarctic region. In this study, we utilized RAD sequencing to estimate the spatio-temporal evolution of the Vetrix clade based on about 140 species covering most of its morphological and geographical diversity. The resolved phylogeny revealed four lineages: the Pan-Himalayan clade, the North American clade and two clades containing species from Eurasia. Widespread circumpolar species form a hybridogenetic grade between the Eurasian and North American clades. Our results confirm that shrub willows originated in the Tertiary, probably in Asia, and that diversification coincided with the climatic cooling in the Pleistocene. At least two radiations were observed, in the Pan Himalayas and in North America. Speciation was further shaped by migration and dispersal in Eurasia, likely accelerated by the uplift of mountain chains, the closure of the Turgai Strait and expansion of suitable habitats. The dated phylogeny revealed that speciation of arctic lineages predates adaptation to high latitudes, as also evident from the fossil record. Small wind-dispersed seeds enabled shrub willows to colonize the expanding arctic tundra regions in the Miocene and their recolonization after the LGM. Given the high observed number of polyploid species equally distributed in all clades and indications of genetic admixture, we assume that species diversity in shrub willows was additionally increased by hybridization and polyploidization.

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Calibration is essential to ensure hydrological models’ reliability. While performance metrics for simulated variables are often used as the primary indicators of model adequacy, it is equally important to verify that the underlying hydrological processes are realistically represented. This consideration becomes even more critical in complex basins characterized by heterogeneous climatic or geological conditions, where processes variability may necessitate the use of zonal calibration approaches. This study presents a multi-spatial and multi-criteria calibration of a SWAT+ model for the Upper Tagus River basin, a large and geologically diverse catchment. This approach, which includes a sensitivity analysis, has been designed to ensure a realistic simulation of hydrological processes in geologically diverse areas. The daily streamflow simulation performance and its components have been evaluated at 22 gauged areas, as inflows to 12 reservoirs, collectively covering 44 % of the modelled area (all under natural flow regimes). The optimization of the model required a detailed zonation based on geological properties, and a comprehensive validation process, including a fine-tuning, was necessary to obtain a set of parameters resulting in an accurate (considering performance metrics) and realistic (considering the streamflow components) simulation in most of the areas evaluated. The global performance (evaluated aggregating streamflow of the different areas considered) demonstrated a very good daily streamflow simulation performance (NSE > 0.8, PBIAS < 5 %) and an accurate simulation of the daily streamflow components. The developed calibration approach, coded in R, can be effectively applied to other hydrologically complex regions.

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Abstract

Many studies that use an automated sorption balance to determine a water vapor sorption isotherm for wood collect data until the moisture content change is less than or equal to 0.002% min −1 (20 µg g −1 min −1 ). This stop criterion has been claimed to give errors in equilibrium moisture content (EMC) predictions of less than 0.001 g g −1 but over the past 10 years, studies have shown that the actual errors can be greater than 0.01 g g −1 because the measurements are stopped well before equilibrium is reached. Despite the large errors associated with this stop criterion, it remains popular due to the speed at which isotherms can be measured. This paper utilizes data from a worldwide interlaboratory study on automated sorption balances to develop a correction method for estimating EMC of western larch ( Larix occidentalis Nutt.) from the moisture content corresponding to the 20 µg g −1 min −1 criterion. The study uses data from 72 relative humidity absorption steps with hold times of 7–10 days from 21 different laboratories and eight different instrument models. EMC is defined based on the inherent mass stability of automated sorption balances determined in the first part of this interlaboratory study. On average the sorption process is less than 80% complete when the 20 µg g −1 min −1 criterion is reached, resulting in a mean absolute error (MAE) of 0.006 g g −1 . The correction equation for estimating EMC reduces the MAE to 0.001 g g −1 . The analysis presented in this paper, along with the correction equation, can be considered for certain use cases to reduce systematic errors and shorten measurement times.

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No abstract has been registered

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We studied the drivers of population-genetic structuring and genetic diversity in specialist parasites based on whole-genome resequencing data from 82 Echinophthirius horridus seal louse individuals sampled from 12 ecologically and behaviourally different phocine seal species, subspecies and populations across the Holarctic. We found that the main genetic disjunctions in E. horridus lice occur across seal host species and subspecies, with a further level of population subdivision emerging among host individuals within some populations. Endemic and relict landlocked seal (sub)species host the genetically most distinct louse populations, while lice associated with sympatric marine seals show signatures of occasional gene flow across hosts. Within the latter, the most extreme case is seen in the near-panmictic lice associated with northern European grey and harbour seals, which aggregate in shared rookeries and colonies. Although the louse and seal phylogenies were overall statistically significantly congruent, evidence for similar host shifts in the past is reflected in several conflicts in the phylogenetic trees of the lice and their hosts. Population-level mean heterozygosity and theta in seal lice varied considerably, and both measures of genetic variation were statistically significantly related to host population size. Taken together, our results support a non-adaptive model of parasite diversification, in which geographic and behavioural isolation among hosts drives parasite genetic differentiation, and genetic erosion in bottlenecked hosts cascades up to their specialist parasites. Our results provide new insights into processes that generate parasite diversity and trigger parallel losses of genetic diversity in endangered host–parasite systems.

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Abstract

While social network analysis was originally developed for human sociology studies, it is also a valuable tool for characterizing behavioural aspects in many animal populations. For instance, social network analysis can be used for assessing the transmission of diseases or information within groups. Here, we describe co-occurrences and potential social associations of ringed seals, Pusa hispida saimensis, in Lake Saimaa, Finland, from 2016 to 2022, based on photoidentification data. Throughout seven successive moulting seasons (April to June), we identified 425 individuals, of which 178 had pairwise co-occurrences in altogether 185 dyads. These seals had a variable number of associates (up to 10), and co-occurrences were observed in 1–7 years. In general, observations of pairs or larger groups of seals (up to five individuals) were rare, and mainly occurred in the two most densely populated basins of the lake. Most of the group observations occurred on ice rather than on rocks. Overall, the fragmented nature of the lake system, site fidelity and moulting habitat availability are key factors that probably affect the observed co-occurrences. Most of the dyads were observed during only one year, which may indicate social tolerance while using the same moulting site. However, 21 dyads were observed during multiple moulting seasons, with some at different sites separated by up to 3 km in different years, suggesting the existence of actual long-lasting associations. Our study represents the first description of co-occurrences and potential social associations in the endangered Saimaa ringed seal. These results can be used for designing and implementing mitigation strategies in case of unforeseen and sudden changes in the environment, such as a disease outbreak.

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No abstract has been registered

Abstract

Recycling nutrients and organic matter available as waste in urban areas may close nutrient gaps and improve soil quality, but the concentrations of potentially toxic elements (PTEs) are commonly higher than in mineral fertilisers. How quickly may the limits for soil quality be exceeded, and for which elements, if such materials are applied intensively? For a rough answer to this question, we used soil data from ten case farms near Oslo and Bergen (Norway) to estimate how PTE concentrations increased when the demand for nitrogen (N), phosphorus (P) and potassium (K) in a theoretical carrot crop produced every year was covered by compost or digestate from source-separated food waste, or composted garden waste, compared with manure from horses and poultry which are often kept in peri-urban areas. With the intensive fertilisation assumed here, the Norwegian soil quality limits for PTEs were reached within 20–85 years, and faster for soil with more organic matter since regulatory limits set by weight discriminate soils with low bulk density. The limits were reached frst for Cu and Zn, which are both essential micronutrients for crop plants. The concentrations of macronutrients in the urban waste-based fertilisers were not well balanced. Rates covering the K demand would lead to high surpluses of P and N. In peri-urban vegetable growing, high applications of compost are not unusual, but more balanced fertilisation is required. The Norwegian regulations for PTEs in organic soil amendments and agricultural soil are stricter than in the EU, and do not support recycling of organic matter and nutrients from urban waste. Many materials which can only be applied with restricted amounts to Norwegian agricultural soil, may be applied according to crop demand in the EU. Growers utilising urban waste-based fertilisers intensively should monitor the soil regularly, including PTE analyses. Soil sampling should occur on fxed sampling points to reveal changes in concentrations over time. Norwegian authorities should consider a revision of the organic fertiliser regulation to support recycling of valuable organic materials. There is a need for more data on the PTE concentrations in agricultural soil and organic fertiliser materials

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Conservation practices like minimal disturbance, soil cover and crop diversification can enhance soil health, but evidence from Norway is limited due to challenging climatic conditions. This study examines long-term conservation (no-till, diverse crop rotation and cover crops) vs. conventional farming (annual ploughing and harrowing and cereal-based rotation) on loam soils in Southeast Norway, among the first at this latitude. Physical, chemical and biological soil indicators were measured on two neighbouring farms and compared to each other, to target values from sampling 29 fields within the same pedo-climatic zone and to literature benchmarks. Soil sampling followed a systematic approach, analysing aggregate stability, bulk density, cohesion, soil roughness, saturated hydraulic conductivity, total organic carbon, total nitrogen, carbon-to-nitrogen ratio, permanganate-oxidisable carbon (POXC), pH, earthworm count and plant coverage. Conservation farming significantly improved aggregate stability, earthworm count and POXC. Soil functions were visualised using radar charts based on soil indicators as proxies. Overall, conservation practices led to more sustained delivery of soil functions compared to the conventional field. These findings contribute to growing evidence that conservation agriculture can enhance soil health and ecosystem services, even in cold climates, though further field comparisons are needed.