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.
2023
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Authors
Melanie Furrer Sara A. Meier Maxime Jan Paul Franken Monica Alterskjær Sundset Steven A. Brown Gabriela Wagner Reto HuberAbstract
Timing and quantity of sleep depend on a circadian (ca 24-h) rhythm and a specific sleep requirement. Sleep curtailment results in a homeostatic rebound of more and deeper sleep, the latter reflected in increased electroencephalographic (EEG) slow-wave activity (SWA) during non-rapid eye movement (NREM) sleep. Circadian rhythms are synchronized by the light-dark cycle but persist under constant conditions. Strikingly, arctic reindeer behavior is arrhythmic during the solstices. Moreover, the Arctic’s extreme seasonal environmental changes cause large variations in overall activity and food intake. We hypothesized that the maintenance of optimal functioning under these extremely fluctuating conditions would require adaptations not only in daily activity patterns but also in the homeostatic regulation of sleep. We studied sleep using non-invasive EEG in four Eurasian tundra reindeer (Rangifer tarandus tarandus) in Tromsø, Norway (69degreesN) during the fall equinox and both solstices. As expected, sleep-wake rhythms paralleled daily activity distribution, and sleep deprivation resulted in a homeostatic rebound in all seasons. Yet, these sleep rebounds were smaller in sum- mer and fall than in winter. Surprisingly, SWA decreased not only during NREM sleep but also during rumination. Quantitative modeling revealed that sleep pressure decayed at similar rates during the two behavioral states. Finally, reindeer spent less time in NREM sleep the more they ruminated. These results suggest that they can sleep during rumination. The ability to reduce sleep need during rumination—undisturbed phases for both sleep recovery and digestion—might allow for near-constant feeding in the arctic summer.
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Gabriela WagnerAbstract
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Gabriela WagnerAbstract
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Jo Jorem AarsethAbstract
In northern Norway, an increasing population of Greylag Geese (Anser anser) forages considerably on dairy grassland and can eat up to 60% of the grass (dry matter mass) on a field if allowed to eat undisturbed throughout the growing season. In this study, the seasonal foraging behavior of Greylag Geese on diary grassland was continuously monitored with game cameras from late April to the end of August to be able to pinpoint effective preventive measures to manage, control, and prevent this crop damage. Limited, but regular, lethal scaring was conducted on some fields to reveal the preventive effect of this measure. Foraging from Greylag Geese in a rangeland area was also monitored, and a complete dataset of seasonal foraging behavior of this species is presented here. Greylag Geese foraging on the fields reaches a top between 04:00 and 08:00 h am, all season. Energy and digestibility of the field grass (timothy) did not reveal any correlation with grazing patterns. Greylag Geese do not visit the fields during molting; however, they may visit fields with their chicks to forage. Lethal scaring completely removes visits from Greylag Geese on the fields where this is conducted, while foraging continues if geese are given undisturbed access. In the rangeland area foraging seems to be even and continuous throughout the season, but significantly lower. In the end of June and late July/early August, there is a peak in visits and number of geese per visit on the fields. Preventive and effective measures against crop damage from Greylag Geese must therefore at least be initiated during late June and early August, and between 04:00 and 08:00 am.
Authors
Unni Støbet LandeAbstract
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Authors
Henriikka Salminen Helena Tukiainen Janne Alahuhta Jan Hjort Karoliina Huusko John Arvid Grytnes Laura Camila Pacheco Riano Jutta Kapfer Risto Virtanen Tuija MaliniemiAbstract
Context Recent studies show that geodiversity—the diversity of Earth's landforms, materials, and processes—has a positive relationship with biodiversity at a landscape scale. However, there is a substantial lack of evidence from finer scales, although this knowledge could improve the understanding of biodiversity patterns. Objectives We investigate whether plot-scale geodiversity and plant species richness (vascular plants, bryophytes, lichens, and total richness) are positively linked in different tundra landscapes. Methods We collected geodiversity (presence of different geofeatures) and plant species richness data from 165 sites in three distinct regions: isolated low-lying mountain heaths, and in sporadic and continuous mountain heaths and tundra. We used non-metric multidimensional scaling (NMDS) ordination to explore the correlations between the composition of geofeatures and species richness, followed by univariate and multivariate generalized linear models (GLM), to assess whether georichness is important for species richness. Results Geofeature composition was linked to species richness in all regions, as indicated by NMDS ordination. Both univariate and multivariate GLM models showed statistically significant relationship between species richness and georichness in all studied species richness groups in continuous Arctic-alpine tundra. Additionally, there was a positive link between georichness and lichen richness in isolated boreal mountain tops. Main conclusions We showed that plot-scale geodiversity has a positive relationship with species richness, yet the effect varies regionally and between species groups. Our study provides strong empirical evidence that geodiversity supports species richness in continuous Arctic-alpine tundra. This information can be used in species richness models but also be applied in biodiversity management and conservation.