In the present study, using stream-dwelling brown trout (Salmo trutta) as a model species, movement through the summer and autumn in two large Norwegian rivers, River Glomma and River Gudbrandsdalslågen, was observed. In addition fish from each river were sampled for age and growth analysis. The aim of the study was to test for which individual characteristics (sex, body mass, body condition factor, tagging site and cohort) that influenced movement and to test for correlations between growth rates (both immature and mature) and movement (movement during the growth season and spawning migration) on a large spatiotemporal scale. Model selection showed that body condition was negatively related to movement during the growth season and that there was a difference in movement activity between the two rivers. Female body size had a positive effect on the activity level shown for movement during the growth season and spawning period; however no such relationship was found for males. As this relationship has not been shown before in salmonids, the reason for this pattern remains unknown. However, one might speculate that it is related to differences between the two sexes in size-specific energy requirements associated with spawning. Neither movement during the growth season nor spawning migration could be predicted from growth rates experienced as juveniles. This indicates that variation in movement among individuals is not temporally consistent throughout life in brown trout.

Acoustic telemetry was used to study the movements and habitat use of sea trout (Salmo trutta L.) and Arctic char (Salvelinus alpinus (L.)) in Repparfjord in Northern Norway during July until October 2010. In total, 18 trout and 8 char was internally tagged with acoustic depth temperature-tags (ADTT), and 6 trout and 3 char with identification-tags. Detected fish ranged in size with an average (mean±SE) of 27.8±1.6 cm for trout and 29.1±1.8 cm for char. All fish was monitored by 32 stationary hydrophones placed in zones over the fjord system during the whole time period in addition to manual tracking. Concerning temporal aspects results indicated that trout ascend earlier than char, contradicting other findings in areas close to the study area. However, no statistical analysis were carried out due to all fish were captured at sea so no descend time was recorded. Concerning spatial usage data showed results on distance to land and temperature preferences with fish length. However, species had a trend on distance to land and temperature, where char was observed closer to shore and in colder waters. Concerning zone there was a significant difference in spatial habitat usage on interaction between fish length and species as well as on species. There was a trend with a negative relationship on fish length and zone usage for char indicating that smaller fish seek further out in the system in addition to differences between species where trout occupied inner areas and char was detected more often in the outer areas of the system. This is in accordance with earlier studies that states species will exploit different areas of the system. Data collected from the ADTT-tags showed that trout on average preferred slightly warmer (0.7°C warmer) and shallower water (0.59 m. vs. 0.75 m.) than char. However, the only significant here was on temperature with a positive relationship over fish length.

Summary1. Migration is present in all animal taxa and is defined as a periodic movement pattern between given ranges. Migratory individuals generally move more directional and with higher speed than stationary individuals during the migration seasons. It is suggested that migratory individuals in these periods encounter more risk factors, and therefore experience a higher mortality.2. I studied the variation in the speed of movement and the number of times migratory and stationary moose were crossing elements associated with mortality risk, i.e. water bodies, roads and railroads, in Central Norway. This was done by examining the movement pattern of 121 GPS-collared moose. I also examined whether realized mortality differed between the two movement strategies. 3. The results only partly supported my hypothesis that migratory moose experience higher costs of movement and are confronted with more risk elements than stationary moose. As predicted, migratory moose moved faster than stationary moose, particularly during the migratory season. However, stationary moose had higher densities of risk elements within their home ranges, and crossed risk elements more frequently than migratory moose. For a given density of risk elements, migratory moose crossed more frequently, supporting the hypothesis that migratory moose are less risk adverse. This pattern was present throughout the year, suggesting that the behavior is not only related to higher movement during the migratory period. 4. I found no effect of movement strategy on the mortality rates, but the sample size was low. However, the trend of realized mortality was opposite of what I expected, with migratory moose having a lower mortality rate than stationary moose.5. My results suggest that migratory moose experience a higher risk of mortality by their movement strategy compared to stationary moose. However, this varies between individuals. By considering individual differences in costs of migration, it is possible to increase our understanding of partial migration. Increased human induced risks such as roads, will most likely increase the number of road crossings. The differences between the two movement strategies in number of crossings will most likely decrease as risk density increase, resulting in a high crossing frequency of risk factors performed by moose.

Summary1. Recruitment failure may represent an important demographic response to changes in the environment or in population size. In this study, I examined whether there was a positive relationship between recruitment rates and ovulation rates in year t-1 in eight Norwegian moose populations. Further, I examined how body condition and climate affected the spatiotemporal variation in recruitment rates and ovulation rates. 2. Both recruitment rates and ovulation rates exhibited spatial and temporal variation. The ovulation and twin ovulation rate in yearlings showed more temporal variation than in prime-aged adults. Furthermore, twinning rates varied more than ovulation and calving rates.3. The number of calves per female recruited to the population was positively related to number of eggs per female the previous year. More calves per female were recorded in years with a high June temperature, smaller snow depths and larger yearling body mass, indicating that more egg cells are realised into a calf in years with good living conditions.,4. Additionally, more calves per female were found in regions with higher number of eggs per female, cool June temperatures and low snow depths. The level of recruitment failure varied among regions, and was highest in Vestfold which is associated with low ovulation rates and body masses. This shows that prenatal or neonatal losses of offspring are likely to be an important demographic response in moose to changes in population size or in the environment.

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As human induced disturbance in alpine ecosystems have increased, more knowledge is needed about the long-term effects of restoration efforts in such environments. There are benefits with using native species in restoration in alpine ecosystems, but the establishment success of native species compared to non-native species, and their effect on the establishment of native species has not been evaluated in detail. We examined ten disturbed alpine sites 21 years after seeding with a commercial seed mix, with regard to vegetation cover, species richness and soil conditions, and compared them with reference sites in close vicinity. After 21 years seeded sites had more vegetation cover, but native vegetation cover and species richness was larger in reference sites. Soil material did have a significant effect on vegetation cover, with less vegetation establishing as dominating soil particle size increased. However, native vegetation cover remained the same with increasing soil material. The effects of a native species, Festuca ovina, was compared with the effects of the main ingredient from the commercial seed mix used in 1989, Festuca rubra, on the establishment of the native Betula nana. Festuca rubra established slightly better than F. ovina on all soil types in the greenhouse experiment, but had larger plant size. B. nana experienced competition from both Festuca species, but less from F. ovina. The species F. ovina facilitated for B. nana on coarse soil. Even though these findings indicate that the native F. ovina is the best alternative with regard to establishment of a native species in the greenhouse, these patterns may not always be expected in nature due to other environmental factors, like wind. However the findings in this study indicate that using native species is the best alternative in alpine ecosystem restoration.

Effective population size (Ne) is a fundamental concept within biology and can be defined as the size of an ideal Wright-Fisher population in which the rate of genetic drift is the same as in the observed population. Natural populations are not ideal so that Ne is often < Nc. A low Ne can lead to inbreeding depression and less adaptability in a population, thus it is essential to know Ne for threatened populations. Ne can be estimated using genetic or demographic data. In this study four different genetic estimators (LDNE, ONeSAMP, MLNE and CoNe) and one demographic estimator were compared using data from a natural house sparrow metapopulation. How Ne related to Nc was also examined. All four genetic estimators seemed to be upwardly biased, however, LDNE often produced estimates in the expected range (Ne<N) and thus appeared to be less biased. To understand how characteristics of natural populations may affect the rate of genetic drift it is important to examine what influence the Ne/Nc-ratio. Thus, I investigated whether population characteristics such as population size, sex ratio, immigration rate, variance in population size and population growth rate explained the variation in the Ne/N ratio for the different genetic estimators. A general result was that the immigration rate had a positive effect on the Ne/Nc-ratio. The apparent upward bias of genetic Ne estimates and the positive effect of immigration rate on Ne/Nc-ratio suggest that gene flow between subpopulations within the study metapopulation was of significant importance for the rate of genetic drift. Genetic estimators of Ne seem like promising tools. However, if no knowledge of the ecology of the population in question exists, Ne should be interpreted cautiously. When assumptions underlying estimators are violated this can lead to erroneous conclusions about genetic processes in the population. 

Question: How does nutrient addition and seeding affect revegetation of seed plants, and are the effects differing among the stages of the regeneration pathway? Location: Two roads restored in 2002, located in Hjerkinn firing range, in lower alpine zone of Dovrefjell, Norway.Methods: Abundance of species and functional types (dwarf shrubs, forbs and graminoids) in four stages of the regeneration pathway (seed rain, seed bank, field seedlings and established vegetation) was recorded seven years after road reconstruction in treatment plots (with nutrient addition, nutrient + seed addition and no treatment). Results: The graminoid Deschampsia cespitosa dominated the vegetation and seed rain in fertilized plots, while the seeded Festuca rubra still dominated the seeded + fertilized plots. The germinable seed bank was lowest in the seeded + fertilized treatment, while the control plots had the highest number of seedlings germinating in the field. Dwarf shrubs had a high germination rate in the field, despite low rates in the seed rain and seed bank. The highest rate of dwarf shrub seedlings was in control plots, while the frequency of dwarf shrubs in the established vegetation increased with nutrient addition. Forbs had species specific responses.Conclusions: Both treatments that included nutrients were dominated by graminoids, with a higher vegetation cover and frequency of dwarf shrubs than the control plots. While graminoids are the most efficient seed producers, they are less able to germinate and survive as seedlings. Dwarf shrubs accounted for a high proportion of germinating seedlings in the field, but the low frequencies of dwarf shrubs in the established control plot vegetation suggest either low seedling survival or an ongoing successional change. It remains to be revealed if the high recruitment of dwarf shrubs in the control plots will speed up the establishment of the typical dwarf shrub cover similar to the surrounding vegetation and hereby indicate that unassisted recovery is the fastest way to restore alpine dwarf shrub heath.

Sik (Coregonus lavaretus) dominerte i littorale- og littorale habitater. Røyr hadde størst utbredelse i profundale habitater. Artene viste betydelig næringsoverlapp.

The ongoing global warming is especially pronounced in the arctic, and it is therefore important to investigate the effect of these changes on arctic ecosystems. In this study the Snow bunting (Plectrophenax nivalis) breeding in Spitsbergen, Svalbard was used as a model species to investigate how the climatic variations are affecting avian reproduction. Both big scale climatic parameters and local weather variables were included in an analysis of how these factors affected snow bunting breeding success. It turned out that both big scale and local variables were important. Locale temperature and wind was important for time off breeding. Temperature, precipitation, winter North Atlantic Oscillation (NAOw) and winter Arctic Oscillation (AOw) were important for number of fledged chicks, and wind and air pressure were important for growth rate.