Boreal peatlands are important ecosystems from a carbon balance perspective because they are natural carbon sinks as a result of millennia of peat formation. However, due to climate change, these ecosystems are susceptible to changes in hydrology and temperature. To predict future changes in boreal peatland carbon balance, I need to understand their future role as carbon sinks and their potential to mitigate climate change effects. One way to model and predict these future changes is using plant community traits and environmental variables. In this study, I assessed which environmental variables and plant community characteristics are the best predictors of CO2 and CH4 fluxes in a boreal bog. The importance of variables was studied within a peatland and across time (mid-August to the beginning of November) to capture variation in plant communities and microclimate, and abiotic conditions that change over the seasons. In addition, I investigated if CH4 flux measured under dark conditions is underestimated compared to light conditions due to possible transportation through open stomata. To carry out these research questions, I used 16 permanent collars that were distributed over different microsites in Harbo peatland (ca. 40 km northwest of Uppsala). CO2 and CH4 fluxes were measured using the closed chamber technique. Plant community characteristics included shrub cover, sedge shoot density, moss capitula density (i.e. shoots per unit area), moss biomass. Environmental variables measured were soil and air temperature, Photosynthetic Active Radiation (PAR), and water table depth. For CO2 fluxes, I found that PAR, peat moss biomass, and peat moss capitula density are important predictor variables, and the bog was a carbon source at most measuring points. For CH4 fluxes, the seasonality (difference in the gas emission from the summer to autumn periods) effect was rather small. I found that all of the studied predictor variables had a significant, but generally small effect on CH4 fluxes, except for sedge shoot density, which was the most important variable affecting CH4 emission. Finally, I concluded that CH4 emissions were not generally underestimated when measured in dark compared to light conditions.  ­

Vegetation in and along aquatic systems has important regulatory and ecological functions. Aquatic vegetation is also frequently used as an indicator of environmental conditions. To enhance our knowledge of the complex natural processes in the littoral zone, i.e., the zone from the high water mark to the lower limit of aquatic vegetation, it is critical to assess plant occurrence and abundance at the species level. This assessment is traditionally performed with labour-intensive field methods. Recently developed remote sensing systems with unmanned aircrafts that take aerial images at low flying height, offer new possibilities for surveying aquatic and riparian vegetation. Unmanned aerial systems (UASs) produce aerial images with sub-decimetre spatial resolution and high spatial accuracy at low cost and are highly flexible in time and space. The goal of this thesis was to evaluate the potential of an UAS for surveying non-submerged aquatic and riparian vegetation, including the identification of plants at the species level and vegetation mapping. Based on produced vegetation maps and field sampling, we also assessed the total biomass of entire riparian zones (320-m river stretches) and the biomass and trace metal content of dominant species along a pollution gradient. In total, the UAS was tested in four aquatic systems, two lakes and two rivers, in boreal northern Sweden. Generated orthoimages were interpreted visually. The spatial resolution varied from 5–5.6 cm. At two test sites we identified plant species with high accuracy (94.6 and 80.4% for aquatic and riparian vegetation, respectively). Prior knowledge on locally occurring species was necessary for correct species identification. The time needed for manual vegetation mapping increased with increasing vegetation complexity. At the test site for biomass assessment, biomass and trace element (Cu, Cd, and Zn) contents varied considerably between species. Salix sp. (willows) comprised only 3% of the total dominant-species biomass but contained 73% of all Cd and 24% of all Zn. In contrast, Carex rostrata/vesicaria (bottle and blister sedge) comprised 80% of the total biomass and contained 85% of all Cu and 66% of all Zn. This result emphasizes the need for species-specific assessment, for example, in planning of phytoremediation measures. The tested UAS facilitates species-level surveying and mapping of non-submerged aquatic and riparian vegetation and can be used in combination with field sampling to accurately assess biomass and the amount of accumulated contaminants at the scale of entire riparian zones. The main future challenge will be to identify/develop automated methods for vegetation mapping which successfully cope with the inherent complexity of the orthoimages generated with the presented UAS.

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Den sällsynta nordiska drakblomman (Dracocephalum ruyschiana) är en hotad och fridlyst art som växer framförallt på stäppartade torrängar belägna i Västra Götaland, Ulricehamn och Falköpings kommuner. Länsstyrelsen i Västra Götaland har som ambition att bevara och gynna drakblomman för att främja det svenska miljömålet om ett rikt växt-och djurliv samt en biologisk mångfald för att nå hållbar utveckling. Studien är tänkt att fungera som ett underlag eller ett hjälpmedel i bevarandearbetet med drakblomman. Studien syftar till att undersöka vad som påverkar artens förekomst i de stäppartade torrängarna genom att analysera flera miljö- och klimatfaktorer. Faktorer som undersökts är förekomsten av humlor, blomrikedom och avstånd till andra drakblommelokaler. En litteratursammanfattning har även genomförts som sammanställer tidigare forskning i ämnet. Analyserna har utförts i kartprogrammet QGIS 3.20.3 Odense och statistiskt testats i statistikprogrammet Rstudio version 1.4.1717 för Mac OS. Studiens resultat visar att antalet drakblommor är högre i områden där humlor observerats, vilket indikerar på att det kan finnas ett samband. Det finns ett statistiskt signifikant samband mellan drakblommans förekomst och graden blomrikedom som visar att drakblomman i högre utsträckning finns på lokaler med övrigt örtrik torrängsflora. Resultatet kan inte fastslå att det finns ett samband mellan artens förekomst och avstånd till andra drakblommelokaler, däremot konstateras det att lokalerna överlag ligger nära varandra. Studiens resultat indikerar på att det är viktigt att gynna humlors förekomst genom att inkludera gynnsam skötsel för övrig örtrik flora i drakblommans skötselåtgärder för att långsiktigt gynna artens överlevnad. / The rare flower species Dracocephalum ruyschiana is a threatened and protected species in Sweden. Its main occupancy is in semi-natural dry meadows in the municipalities of Ulricehamn and Falköping in the province of Västra Götaland. The County Adminstrative Board of Västra Götaland have the ambition to conserve and protect the populations of D. ruyschiana to improve the work with biodiversity and sustainable development. This study was constructed to work as a support tool in the conservation work of the species. The purpose of this study is to investigate what affects D. ruyschiana’s presence in semi-natural dry meadows by analyzing environmental factors. These factors are: bumblebee frequency, flower abundance and distance to other locations with D. ruyschiana. Several analysis have been conducted and examined through the statistical program Rstudio version 1.4.1717 for Mac OS and the software program QGIS 3.20.3 Odense. A literature review of previous research in the area has also been conducted. Test results demonstrate higher frequency of D. ruyschiana in localities where bumblebees had been observed, which indicates a relationship between the variables. Flower abundance seems to positively affect the distribution and a statistical significant relationship was detected between the variables; D. ruyschiana was mostly found on locations with high flower richness. No connections between location distance and D. ruyschiana’s frequency were found, however the locations seem to be near each other in general. The results from this study indicates and highlights the importance to improve bumblebee presence in areas with D. ruyschiana. Flower richness is known to attract bumblebees and therefore must D. ruyschiana’s maintenance work also favor flower abundance in general. This measurement is important for the long-term survival of the species.

Scots Pine (P. sylvestris L.) has one of the largest distributions among trees in Eurasia. It is important both economically and ecologically, with a dominant role in forests ecosystems. Its distribution and survival may be affected by climate change as well as by abiotic and biotic factors. Therefore, it is important to conserve genetic diversity that can be of major importance for the species adaptation to future conditions. Relictual populations are of particular importance since they could display very rare traits. The aim of this study is to investigate if there are relictual populations in the Massif Central region of France, by determining if there are phenotypic differences between populations. This area has been highly planted with trees from “Germany” or “Riga” in the second half of the 19th century since the local trees had the reputation of not growing straight enough. We compared 100 Scots pines from 10 populations using five phenotypic traits (diameter of the trunk, shape of the trunk, crown, and branches along with the colour of the trunk and foliage). We detected phenotypic differences between populations that were independent from the diameter and elevation of the trees for three out of the five phenotypes (bark colour, shape of the stem and crown). However, the outstanding populations were never the same. It was therefore not possible to determine if a population was relictual or not based only on these phenotypic traits. In future studies, genetic data could give more information about the possible origins of each tree.

River ecosystems are some of the most complex ecosystems on Earth, characterized by a highly heterogenous environment which is able to sustain a disproportionally high level of biodiversity in relation to the area of which they occupy. However, anthropogenic activities are encroaching on the highly diverse riverine landscape, threatening freshwater biodiversity. Species with complex life cycles involving migrations between marine and freshwater environments are disproportionally threatened. One such species is the Atlantic salmon, which now is at historically low population levels. Restoration efforts are being made to restore degraded river ecosystems and strengthen salmonid populations. However, the response from salmonids and other organisms used as indicators for restoration success are inconclusive or lacking. Additionally, evaluation of restoration success lacks standardized procedures and tools for monitoring. Habitat variables have been shown to be robust indicators when assessing restoration success. This study attempts to asses restoration success using an accessible and user-friendly tool which can be used for measurements of both biotic and abiotic variables. Salmon eggs were planted in the riverbed at potential spawning grounds, from where hyporheic water was extracted to measure physicochemical habitat variables which are critical to salmon embryos. The results indicate that the functionality of available spawning habitats in the study area is adequate in both restored and non-restored sections. Habitat variables displayed spatial variation but were not more favorable at restored sites compared to non-restored sites. Similarly, egg hatching rate varied spatially but not between restored and non-restored sites. The apparent lack of response to the restoration efforts in the study area is likely due to a combination of factors such as biased site selection, limited sampling period and a lack of comparable pre-restoration values. This highlights the need of defined restoration goals, a robust monitoring plan and criteria for evaluation of restoration success. Nevertheless, the method used in this study can be applied to measure biotic and abiotic variables and may add to the toolbox for assessing restoration success. This will hopefully contribute to new insights for monitoring and evaluation of restoration success in other projects.

Performance of stream living juvenile brown trout (Salmo trutta) may be affected by both intra- and intercohort competition. In this study I examined if growth and density of cohorts of young-of the-year (0+) trout are dependent on temperature and density of older (>0+) trout and 0+ trout. Data on growth and densities were obtained using a long time series of quantitative electrofishing data from 1998 to - 2020 on size and densities of cohorts of trout from three sites in the stream Bastuån, Jämtland Sweden. The growth was defined as the length of 0+ in the end of august and densities were based on the three-removal method and area of the stream site. The growth of 0+ trout was not affected negatively by the density of >0+ trout or by the density of 0+ trout. On the other hand, increasing temperature had a positive effect on the growth of 0+ trout. The results suggest that temperature in the temperature range experienced by 0+ trout in this study is the main driver of growth of 0+ trout while density dependent growth is not a general pattern in this natural trout stream. Continuous sampling to expand the time series in Bastuån are recommended to allow for further studies of the factors behind growth and densities of juvenile trout especially when considering future expected climate change effects on water temperatures.

Most research on the biology of the western honey bee (Apis mellifera) focuses on the worker bees, but knowledge about drones is lacking despite their important role in mating with a virgin queen. Available information about their ecology and behavior are mainly based on direct observations in need of intensive experience and knowledge about honey bees. Only two recent studies conducted in France and Argentina have monitored drones continuously, but on the scale of a single observation hive or during a short time period only. Therefore, studies that have continuously monitored drone flight activity during the whole mating season are still lacking. Further, we are not aware of any studies that have compared the ecology and behavior of drones between different subspecies of Apis mellifera.  Besides the aim of analysing the ecology and behavior of drones in spring and summer in Sweden, where the climate poses challenging conditions for honey bees, the objective of this project was to compare the native, but threatened, subspecies Apis mellifera mellifera (Mel) with the hybrid ’Buckfast’ (Apis mellifera x, Buck). In Sweden, the latter is most commonly used in beekeeping today.  Activity data at the entrance of the hives was collected with the use of Radio Frequency Identification (RFID) technology at two different apiaries with 8 colonies each. RFID technology enables the continuous monitoring of bees tagged with a microchip on their thorax. Hereby, only newborn drones with a maximum age of 3 days were tagged. Further, drones’ activity and behavior at the entrance of the hive was studied from video recordings. Weather parameters were measured by weather stations installed within the apiaries, enabling a direct analysis of the activity in relation to weather conditions (temperature, wind speed, rain, humidity).  Drones survived at most 70 days (M = 22.67, SD = 17.9) with a shorter average lifespan in summer (M = 20.8, SD = 15.4) than in spring (M = 25.2, SD = 20.7). Mel drones showed longest survival at both locations and in both seasons. We discovered most first activity of drones five and six days after tagging (max. 11 days), but also registrations directly on the day of tagging were made with indications that these do not all display evictions from the hive. Compared to the spring trial, in the summer trial earlier first registrations were made (p = 0.022), with Mel drones becoming active significantly earlier than Buck drones (p = 0.027). Flight durations of more than 3 minutes, even longer than 10 minutes, were already performed right after tagging. This was especially the case in the summer trial. Further, RFID data and video records revealed that peak activity occurred in the afternoon, but differences between spring and summer were revealed with an earlier peak in spring. Buck’s peak preceded Mel’s peak of activity in both seasons. However, also registrations during the morning and evening occurred such that drones were mainly active during 7-8 hours of the day. Rain and wind speed negatively affected the activity, but increasing activity was present the higher the temperature and light intensity. Hereby, temperature had a significantly higher positive effect on Mel drones. Moreover, our registrations show that 40% of the drones drifted to other hives, whereby hives of the same subspecies were preferred. Mel drones drifted relatively more often than Buck drones. In addition, video records showed that upon departure, drones pay special attention to cleaning their antennae. This was especially observed at Mel hives. Also drifting drones showed this behavior.  To conclude, the present thesis confirms but also contradicts existing information, especially in terms of the age at first activity and lifespan. In addition, unknown aspects about drone ecology and behavior were revealed with differences between both seasons and subspecies. However, the applied method in the form of RFID technology to monitor the bees showed its limitations and needs further optimisation. / Die meisten Forschungen über die Biologie der Westlichen Honigbiene (Apis mellifera) konzentrieren sich auf die Arbeitsbienen, aber das Wissen über die Drohnen ist trotz ihrer wichtigen Rolle bei der Paarung mit einer jungfräulichen Königin unzureichend. Die verfügbaren Informationen über ihre Ökologie und ihr Verhalten beruhen hauptsächlich auf direkten Beobachtungen, die intensive Erfahrungen und Kenntnisse über Honigbienen voraussetzen. Nur zwei neuere Studien aus Frankreich und Argentinien haben Drohnen kontinuierlich beobachtet, allerdings nur von einem einzigen Bienenstock oder über einen kurzen Zeitraum. Daher gibt es keine Studien, die Daten über die Flugaktivität der Drohnen während der gesamten Paarungszeit gesammelt und analysiert haben. Außerdem sind uns keine Studien bekannt, welche die Ökologie und das Verhalten von Drohnen zwischen verschiedenen Unterarten von Apis mellifera verglichen haben. Neben dem Ziel die Ökologie und das Verhalten der Drohnen im Frühjahr und im Sommer in Schweden zu analysieren, wo der lange und dunkle Winter schwierige Bedingungen für Honigbienen bietet, bestand das Ziel dieses Projekts darin die einheimische, aber bedrohte, Unterart Apis mellifera mellifera (Mel) mit dem Hybriden ’Buckfast’ (Apis mellifera x, Buck) zu vergleichen. Letztere wird heute in Schweden am häufigsten in der Imkerei verwendet. Aktivitätsdaten am Eingang der Bienenstöcke wurden mit Hilfe der sogenannten RFID-Technologie (engl. Radio Frequency Identification) an zwei verschiedenen Bienengärten mit jeweils 8 Völkern erfasst. Diese Technologie ermöglicht die kontinuierliche Überwachung von Bienen, die mit einem Mikrochip auf dem Rücken gekennzeichnet sind. Dabei wurden nur neugeborene Drohnen mit einem Höchstalter von 3 Tagen markiert. Außerdem wurden die Aktivität und das Verhalten der Drohnen am Eingang des Bienenstocks anhand von Videoaufnahmen untersucht. Wetterparameter wurden von den in den Bienenstöcken installierten Wetterstationen gemessen, was eine direkte Analyse der Aktivität in Bezug auf die Wetterbedingungen ermöglichte (Temperatur, Regen, Windgeschwindigkeit, Luftfeuchtigkeit). Die Drohnen lebten höchstens 70 Tage (M = 22.67, SD = 17.9), wobei die durchschnittliche Lebensdauer im Sommer (M = 20.8, SD = 15.4) kürzer war als im Frühjahr (M = 25.2, SD = 20.7). Mel-Drohnen zeigten an beiden Standorten und in beiden Jahreszeiten die längste Überlebensdauer. Die meisten Erstaktivitäten von Drohnen wurden fünf und sechs Tage (max. 11 Tage) nach der Markierung erfasst, aber auch bereits direkt am Tag der Markierung. Im Vergleich zum Frühjahr wurden Drohnen im Sommer zeitiger das erste Mal registriert (p = 0.022), wobei Mel-Drohnen deutlich früher aktiv wurden als Buck-Drohnen (p = 0.027). Flugzeiten von mehr als 3 Minuten, sogar länger als 10 Minuten, wurden bereits unmittelbar nach der Markierung durchgeführt. Dies war insbesondere in der Sommerstudie der Fall. Außerdem zeigten die RFID-Daten und Videoaufzeichnungen, dass die Hauptaktivität am Nachmittag stattfand, aber es gab Unterschiede zwischen Frühjahr und Sommer mit einem früheren Höhepunkt im Frühjahr. Der Aktivitätshöhepunkt von Buck-Drohnen lag in beiden Jahreszeiten vor dem von Mel-Drohnen. Es gab jedoch auch Registrierungen am Morgen und am Abend, sodass die Drohnen hauptsächlich während 7-8 Stunden des Tages aktiv waren. Regen und Windgeschwindigkeit wirkten sich negativ auf die Aktivität aus und sie nahm zu je höher die Temperatur und die Lichtintensität waren. Dabei hatte die Temperatur eine stärkere positive Auswirkung auf Mel-Drohnen. Des Weiteren zeigen unsere Daten, dass 40% der Drohnen in fremde Bienenstöcke flogen, wobei Bienenstöcke der gleichen Unterart bevorzugt wurden. Hierbei flogen Mel-Drohnen relativ betrachtet häufiger in andere Bienenstöcke als Buck-Drohnen. Außerdem zeigten die Videoaufzeichnungen, dass die Drohnen beim Abflug besonderen Fokus auf die Reinigung ihrer Antennen richteten. Dies wurde verstärkt an Mel-Bienenstöcken beobachtet. Auch Drohnen an fremden Bienenstöcken zeigten dieses Verhalten. Zusammenfassend zeigt die vorliegende Arbeit, dass bestehende Literatur bestätigt wurde, aber ihr auch, insbesondere in Bezug auf das Alter bei der Erstaktivität und der Lebensdauer, widerspricht. Darüber hinaus wurden unbekannte Aspekte über die Ökologie und das Verhalten der Drohnen aufgedeckt. Mitunterkonnten Unterschiede zwischen den Jahreszeiten und den beiden Unterarten nachgewiesen werden. Die angewandte Methode in Form der RFID-Technologie zur Überwachung der Bienen zeigte jedoch ihre Grenzen auf und bedarf einer weiteren Optimierung für zukünftige Studien. / <p>Forskningsgrupp: Ekologisk modellering // Research group: Ecological modelling</p><p>Masteruppsatsen finansierades av projektet "BIstånd till nordiska bin – unik resurs för framtidens ekosystemtjänster" // The master thesis was financed by the research project "Supporting Nordic brown bees – a unique resource for our ecosystem services ".</p><p>För relaterade forskningsdata se databeskrivning i SND:s forskningsdatakatalog: Schaumann, F. (2023). Supplemental Material for: Comparison of drone ecology and behavior between Apis mellifera mellifera and the hybrid Buckfast in southwestern Sweden. (Version 1) [Dataset]. Högskolan i Skövde. Tillgänglig via: https://doi.org/10.5878/pyvm-re24 // For related research data see data description in SND's research data catalogue: Schaumann, F. (2023). Supplemental Material for: Comparison of drone ecology and behavior between Apis mellifera mellifera and the hybrid Buckfast in southwestern Sweden. (Version 1) [Data set]. University of Skövde. Available at: https://doi.org/10.5878/pyvm-re24</p>

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