Lake Vättern contains Swedens most valuable population of arctic charr (Salvelinus umbla). The stock of this Salmonidae fish showed a negative trend for several decades but has now turned to a more positive one. Too minimize the risk of a new backlash it is important to obtain knowledge about the arctic charr and its interaction with other species. The purpose of this paper is to investigate the interspecific competition between arctic charr and two other valuable species i.e. whitefish (Coregonus maraena) and burbot (Lota lota). Data of stomach contents from two periods (1964-1978 & 2006-2011) were analyzed. The consumers were divided into different groups with respect to size and season. The measure of the competition was then answered quantitatively with two indexes (Pianka & Laubmeier). The results support the conclusion that small charr (<30 cm) was exposed of remarkably tough competition from whitefish regarding the older period. This derives from the fact that these two species show a very similar diet including Opossum shrimp (Mysis relicta) and Monoporeia affinis. With increasing size charr turns to a more piscivore diet and begins to compete with burbot. The piscivorous charr consumes mostly smelt (Osmerus eperlanus) while burbot shows a more diverse behavior of  its selection of fish species as a resource. The fact that these three species can coexist despite tough competition likely derives from the fact that Vätterns food web contains a lot of actors at the lower trophic levels.

The ongoing shrubification of the Arctic tundra may in the future have serious consequences for the ecosystem. More trees and shrubs will lead to changes in species composition and may alter diversity, carbon and nutrient balance, and result in a lower albedo. Reindeer can reduce the spread of shrubs, but plants have developed chemical defenses against herbivores made up of secondary metabolites. The concentration of these can be affected by several factors, including damages from herbivory and the availability of nutrients. In this study samples of the shrub B. nana ssp. nana (dwarf birch) and soil samples were collected from outside and inside herbivore exclosures in Fennoscandia. Then, concentrations of phenols and terpenes, the major defense component in birches, and soil nutrient availability were analyzed. A proxy was created for measuring the density of reindeer at each location. The aim was to evaluate this data and see if the exclusion of herbivores or the nutrient availability had any effect on the concentration of the defense components. Few differences between the exclosures and control plots could be found and only two out of 18 t-tests showed any difference that was deemed statistically significant. The density of herbivores was found to have no effect and the nutrient availability showed no clear results. This study concludes there are many factors influencing the concentration of defense components in dwarf birches, including the rising temperatures, that need to be considered in future studies. A better understanding of this subject would be essential in visualizing the future of the Arctic tundra.

Today, old growth forests are continuously decreasing, due to deforestation, threatening species to extinction. Species dependent on dead wood, different stages of decaying wood, large trees, and forest cover continuity have a particularly high risk of extinction, such as saproxylic beetle species. The aim of this study was to explore effects of forest management and some ecological factors on saproxylic beetles in spruce dominated forests, in County of Östergötland in Sweden. Sampling was done by mounting 175 window traps in 35 study sites of different age, around the county. Results showed that nature reserves had the highest number of species, individuals, and threatened species, while production forest, 15-25 years old, had the lowest. Production forests, 65-85 years old, had similarities in species composition with nature reserves, probably due to historical reasons. To some extent, these kinds of forests provide habitat for threatened species at a landscape level and could provide habitat for more threatened species in the future, with the right management. Quantity and quality of dead wood, basal area/ha, and vegetation cover increased species richness and number of individuals. Suggestions to generate a successful long-term conservation is to increase total amount of dead wood, improve diversity of dead wood, leave more large-sized trees during retention and a mixture of tree species in production forests. This will probably aid species dependent on later successional stages, increase vegetation complexity, habitat heterogeneity, and probably increase both number of individuals- and saproxylic beetle species in production forests in the future.

Saving the white-backed woodpecker (Dendrocopos leucotos) from extinction in Sweden has been an ongoing struggle for decades. Despite this, there have been remarkably few studies on the species ecology in Sweden, especially in the north. The aim of this study was to investigate if the white-backed woodpeckers living in the Umeå region show a preference regarding what kind of trees they use for foraging, based on the factors tree species, tree condition (dead/alive), and tree size. Data were gathered at three sites in the vicinity of the lower Umeå River region and was made up of holes left by the woodpeckers from excavating trees for food. By comparing the trees carrying these traces with a representative sample of remaining trees at the sites, a test for preference could be performed. The results from this study indicate that the local white-backed woodpeckers strongly favour trees of the Salix genus when deep-boring, and that they also have a preference for dead trees independent of species. No significant effect of tree size on foraging choice could be found, although this would ideally require further studies. These findings provide knowledge on the local behaviour of the white-backed woodpecker that could potentially be of importance for implementing precise conservation efforts for this area-demanding species.

Simultaneous biomass production and wastewater treatment through algal cultivation holds great potential in ameliorating nutrient pollution and eutrophication. However, it is not widely feasible in higher latitudes due to low light and temperature conditions affecting productivity and removal efficiency. These issues could potentially be offset by the mixotrophic growth of algae, as it reduces dependency on light availability. This could allow year-round operation for nutrient removal as well as biomass production, which can be used as biofuels or feedstock. The present study compares the use of local agal consortia under mixotrophic and phototrophic growth in open systems in terms of algal biomass production and nutrient removal from landfill leachate. It also explored the bacterial and algal species present in the suspended culture and associated biofilm under both modes of growth. The mixotrophic and photoautotrophic systems had similar nutrient removal rates and were highly efficient at ammonium removal (over 75% in all systems with a maximum of 99.6%). The biomass produced by the mixotrophic system was significantly higher (p<0.05) than the photoautotrophic system. The dominating algal species identified was Desmodesmus armatus in both treatments. The dominating bacteria phyla were Myxococcota, Proteobacteria and Actinobacteriota in both systems. The results indicate that mixotrophic growth produces higher biomass than photoautotrophic growth.  This implies that in the combined biomass production and wastewater treatment system utilization of mixotrophic algal growth can potentially facilitate better algal biomass production in higher latitudes than photoautotrophic growth, without loss in nutrient removal efficiency.

No description available.

No description available.

Skiing tourism is a growing activity in the world and in Norway. This study has investigated the effect of a commercial skiing system on wildlife activity by comparing areas within the skiing system with nearby reference areas outside of the system. The study was performed by counting the number of animal tracks in predefined transects with different levels of human activity on multiple occasions. The results showed that there were fewer tracks from wildlife in the transects located in the area used for skiing than in reference areas without any tourists. Due to covid-19, comparisons were also made in the skiing areas before and after the skiing resort was closed down. The number of wildlife tracks increased significantly after three weeks of closure. All in all, the study showed that wildlife is impacted by the presence of tourists. / Skidturism är en växande aktivitet i världen och i Norge. Denna studie har undersökt effekten av ett kommersiellt skidsystem på djurlivet genom att jämföra områden inom skidsystemet med närliggande referensområden utanför systemet. Studien utfördes genom att beräkna mängden djurspår i fördefinierade transekter med olika nivå av mänsklig aktivitet vid olika tillfällen. Resultatet visade att det fanns mindre spår från djur i transekterna i samband med skidorten jämfört med referensområden utan några turister. På grund av covid-19, jämfördes också skidområdena före och efter det att skidanläggningen stängdes. Spår från djurlivet ökade betydligt efter tre veckor stängning. Sammanfattningsvis, visar studien att djurlivet påverkas av turister.

The continuing increase in urbanization is changing the natural habitats of wild animals. Some wildlife have colonized urban areas and are exposed to new stimuli to which they respond differently: some species adapt whereas others thrive. Living in such an environment can lead to increased stress and elevated aggression. The purpose of this study was to examine the intraspecific aggression among mallards (Anas platyrhynchos) in two habitats with different degree of urbanization. Field observations were performed on groups of mallards in urban and rural environments. I predicted that there would be more aggressive behavior among mallards in urban than in rural habitats, based on the hypothesis that increased stress in an urban environment results in elevated aggression. Aggression was defined as the number of attacks, which was classified as chases, nips, and threats. I observed on average more than three times as many attacks (chases, nips and threats) in urban as in rural habitats. In addition, more females relative to males in the groups resulted in more attacks. Wild birds are important to flora, fauna, and man. Because high aggression can affect the fitness of wild urban animals negatively through, for example, physical injuries and increased disease transmission during fights, it is important that humans intervene to prevent this. / Den fortsatta ökande urbaniseringen förändrar vilda djurs naturliga habitat. Vissa vilda djur har koloniserat urbana områden och utsätts för nya stimuli som de responderar olika på: somliga arter anpassar sig medan andra frodas. Att leva i en sådan miljö kan leda till ökad stress och förhöjd aggression. Syftet med denna studie var att undersöka den intraspecifika aggressionen mellan gräsänder (Anas platyrhynchos) i två habitat med olika nivå av urbanisering. Fältobservationer genomfördes på grupper av gräsänder i urbana och rurala miljöer. Jag förväntade mig att det skulle förekomma fler utdelade attacker bland gräsänder i urbana än i rurala habitat, baserat på hypotesen att ökad stress i en urban miljö resulterar i förhöjd aggressivitet. Aggression definierades som antalet utdelade attacker, vilket klassificerades till jagningar, nyp och hot. Jag observerade i medel mer än tre gånger så många attacker (jagningar, nyp och hot) i urbana som i rurala habitat. Utöver detta resulterade fler honor relativt hanar i grupperna i fler attacker. Vilda fåglar är viktiga för flora, fauna och människa. Eftersom hög aggression kan påverka vilda urbana djurs fitness negativt genom till exempel fysiska skador och ökad sjukdomsöverföring vid strid, är det viktigt att människan ingriper för att förhindra detta.

Habitat loss and fragmentation are believed to be two of the main reasons for high extinction rates of species, resulting in decreased biodiversity. According to the island biogeography theory, the species richness in a patch, here a semi-natural grassland, is dependent on the landscape composition, and therefore changes in the landscape composition will result in changes in the species richness of the grassland. However, this change in species richness may be delayed for several years, causing an extinction debt. The aim of this study was to examine the change of species richness of vascular plants in Swedish semi-natural grasslands between 2007 and 2020 and investigate if there is evidence of an extinction debt and evaluate what factors causes changes in the plant community. Data of species richness and occurrence for 40 semi-natural grasslands, as well as data of landscape changes in area and connectivity between the 1950:s and the 2000:s for these grasslands, were analysed. This study found that changes in species richness in semi-natural grasslands were affected by the changes in connectivity of the landscape. However, the effect depended on the degree of specialisation of the species to semi-natural grassland. Between 2007 and 2020, the species richness of semi- natural grasslands specialist decreased, while the species richness of non-specialist species increased. This resulted in a mean increase of overall species richness between 2007 and 2020. Observed immigration of new non-specialist species appears to suggest that, not only the connectivity, but also the habitat types in the matrix surrounding the semi-natural grasslands may substantially influence the species composition in the grassland; this is in contrast to what is predicted by the original theory of island biogeography. Species that were classified as specialist were more vulnerable to ceased management, such as grazing, than to area and connectivity decrease. This was likely because the ceased management increased the competition for light. The results also indicated that re-established management of abandoned grasslands may increase specialist species richness, highlighting the need for management actions taken in order to reverse extinction debt.