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SLU Sveriges lantbruksuniversitet
Recent Submissions
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Adapting Scots pine Regeneration to the Changing Climate: An investigation of the effects of seed coating, arginine addition, and planting position
(Swedish University of Agricultural Sciences, 2022) Domevscik, Matej
In Sweden, new forest stands have long been artificially regenerated using conifer seedlings. While standardized and widely adopted, this approach may need to be further adapted to the predicted increases in variations in the weather, such as extended periods of drought. In light of this, coated seeds of Scots pine, as well as adding arginine phosphate to the coating, were tested across 12 sites in Sweden. The coatings should facilitate germination and establishment of seedlings, while the addition of arginine phosphate would enhance growth. In another study across 11 sites in Sweden, the effects of arginine phosphate addition on survival and growth of nursery grown seedlings planted into mineral soil or in capped mounds were tested. Seedlings planted in mineral soil may be better adapted to dry conditions but may suffer from lower availability of nutrients compared to the capped mounds. The results showed no difference in survival between seedlings from coated seeds with or without arginine (following three growing seasons), whereas survival of nursery grown seedlings increased as a result of arginine addition (following two growing seasons). Arginine phosphate addition increased growth, both for coated seeds and for nursery grown seedlings planted in mineral soil as well as in capped mounds. The importance of precipitation was demonstrated in both studies, with positive relationships between survival and precipitation in the month following deployment. Hence, of the methods tested here, planting nursery grown seedlings in mineral soil with an amendment of arginine phosphate appears to be the most valuable to enhance both survival and growth of seedlings subjected to dry weather conditions.
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Salmonids and grey seals (Halichoerus grypus): mitigation in pontoon traps
(Department of Aquatic Resources, Swedish University of Agricultural Sciences, 2018) Calamnius, Linda
In the 1970’s, the seal populations of the Baltic Sea Area were at historically low levels. They have recovered and increased since then. The increase of the seal populations is a success for the management of the Baltic Sea Area environment. It has also meant an increase in number of interactions with coastal fisheries. Seals take fish and damage fishing gear. Three studies were carried out with the purpose of contributing to a sustainable fishery and fewer interactions between seals and fishers.
The first study compared the effect two different Seal Exclusion Devices (SEDs) had on the catch and on seal visits. The SEDs used were a diamond mesh SED and a square mesh SED, with the frame rotated 45°. They were compared with a control, an open frame. The expectation was that using SEDs would reduce the number of seal visits, increase the catch and deter larger fish from entering. Larger salmons (Salmo salar) were caught in the traps with selection panels. For brown trout (Salmo trutta), there was no difference in size of fish between the SEDs. Neither of the SEDs had any effect on total catch or catch per unit effort. The number of seal visits were too low to be able to draw any conclusions regarding presence of seals.
The second study examined the efficiency of selection panels in a pontoon trap for salmon and whitefish. One control and two experimental traps were used. The mesh in the control trap had 35 mm bar length. The selection panel was square mesh with 50 mm bar length. In one of the experimental traps, the selection panel covered 30 % of the inner netting. In the other, it covered 100 %. The results showed that proportionally more fish of commercial size were caught in traps with selection panels. Using selection panels contributes to a sustainable fishery.
The third study analysed a series of visits by seals in the middle chamber of a herring pontoon trap. Visiting seals were filmed in the middle chamber. Roughly, 1 400 visits by 12 seals were recorded. Of all visits, 3.5 % were overlapping visits, i.e. two seals inside the middle chamber at the same time. Forty simulations of random visits were performed resulting in an average of 7.1 % overlapping visits. There was a significant difference between the actual overlapping visits and the simulated. This suggests that the seals avoided swimming in when another seal was present
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Planning at the edge - aspects on inter-municipal and border related spatial planning in a new Swedish geography
(Department of Landscape Architecture, Planning and Management, Swedish University of Agricultural Sciences, 2021) Lexén, Thomas
This licentiate thesis investigates how municipal division and local borders may affect spatial planning and the possibilities for coordination of inter-municipal and cross-border planning issues, which has become increasingly important in recent decades as a result of, amongst other things, regional enlargement and an emerging need for increased environmental consideration and climate change adaptation. The overall question, which derives from the author's many years of professional experience as a planning architect, is examined through two studies, presented in two different papers: The first paper explores the problem from a municipal perspective through a case study of two municipalities, Hallsberg and Kumla, with a long history of border related conflicts and collaborations, while the second paper examines the question primarily from a state perspective by investigating the Swedish planning system and municipal division in relation to certain recent geographical changes. Generally, the findings indicate that municipal borders are increasingly suboptimal due to the discrepancy between the emerging new geography and the “old” geography that has formed the basis of both municipal division and the planning legislation. Local geography and territorial conditions are thereby being increasingly influential to the process and outcome of spatial planning. On a theoretical note, the thesis contributes to a fuller understanding of the complex local border geography and helps to bring the discussion on planning back to a geographical, and territorial context.
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Contaminants of Emerging Concern in Swedish Freshwater Environments: Sources, Occurrence, and Impacts
(Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, 2023) Malnes, Daniel
Contaminants of emerging concern (CECs) is one of several reasons for the deterioration of surface water quality globally, even though the CECs occur in trace concentrations. This thesis produced new CEC data through a oneyear field study for substances which occur in Sweden’s three largest lakes and their associated rivers. The purpose was to investigate mass flows and seasonal variations of CECs, as well as estimate the potential ecotoxicological hazard posed by the CECs’ occurrence. It was found that numerous CECs occurred in all examined rivers, and that a continuous influx of CECs with suspected hazardous properties into the lakes occurred. Total mass loads of the investigated CECs were estimated from 0.51 to 5.6 kg/day in the influx to the lakes, and from 0.12 to 4.3 kg/day in the outflux from the lakes. Seasonal variations were observed in the aquatic environment for both individual and groups of CECs. This could be due to variations in consumption and environmental conditions. Some of the seasonal variations were being reported for the first time in the academic literature. Many of the CECs were suspected to have the combination of the hazardous properties of persistency, mobility, and toxicity (PMT). Of the 71 CECs detected far from any suspected input into the lakes, 20 had previously been suspected of having PMT properties. Within the remaining 51 CECs, multiple others also had suspected PMT properties. The thesis suggests that CECs with suspected PMT properties should be analysed closer with respect to these properties.
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Impact of litter size on sow health and welfare
(Department of Animal Environment and Health, Swedish University of Agricultural Sciences, 2018) Andersson, Emma
Genetic improvement of litter size has been the main breeding goal in piglet production during the last decades, resulting in a steady increase in total number of born piglets in each litter both in Sweden and in other European countries. It has been suggested that large litters pose a major welfare problem for sows and piglets. However, there is a lack of recent studies investigating the impact of litter size on the health and welfare of sows. Therefore the objective of this thesis was to investigate the association between litter sizes and sow health and welfare. The two studies included in this thesis were performed as observational studies and investigated by retrospective analysis of available pig production data. The first study investigated the association between litter sizes and sow stayability, and the second study the association between litter size and medical treatment of sows during farrowing and lactation. The final dataset used in the first study included a study population of 38 878 sows in 24 herds and the final dataset in the second study included observations from 1 947 litters from 655 sows.
Associations between litter size and sow health and welfare was found. There was an association between litter size and stayability of the sow, as well as association between litter size and medical treatment of the sow. The results from both studies imply that sows with medium sized litters have a better lifetime production than sows with very small or large litters. Piglet producers should therefore pay even more attention to prophylactic management of sows during gestation and lactation. In planning of breeding strategies and annual removal of sows, piglet producers should also aim for keeping sows giving birth to a medium-sized litter, with approximately 12 to 14 piglets born in total in their breeding program, as this seems to improve sows’ stayability and decreasing the risk of unplanned removal which would favour health and welfare of both sow and piglets.