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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

The use of highway crossings to maintain landscape connectivity for moose and roe deer

Olsson, Mattias January 2007 (has links)
Increasingly wildlife managers and land managers are challenged to maintain the viability and connectivity among large mammal populations. Thus, it is important that effective highway crossings are identified and optimized with respect to construction cost, facilitation of ungulate movements, and ability to reduce wildlife-vehicle collisions. The use of exclusion fencing to reduce ungulate-vehicle collisions is commonly installed along Swedish highways. However, exclusion fences may pose a threat to the viability of wildlife populations because they serve as barriers to individual movements and may limit accessibility to resources. Various types of wildlife crossings intended to reduce road-kills and increase habitat connectivity across fenced highways have been constructed throughout the world. Previous studies have evaluated the importance of structure design and size for many ungulate species, but few studies involved moose (Alces alces) which is the target species for most large ungulate mitigations in Sweden. The results of the studies are intended to facilitate the development of wildlife crossings and conventional road passages to meet ungulate demands. We monitored moose fitted with GPS radio collars and characterized their space and habitat use patterns in southwestern Sweden. Moose had seasonal differences in habitat selection within their home range, and generally preferred clear-cuts and early successional forest, boreal forest, and glades, but avoided agricultural areas and open water. We used infrared remote cameras, track surveys, and GPS telemetry to monitor the use of wildlife crossings and conventional road passages by moose and roe deer (Capreolus capreolus). The upgrading of a non-fenced road to a fenced highway with three wildlife crossings decreased the moose movements across the highway by 67-89 %. Overpass use by moose and roe deer declined with increased traffic volume on the highway and both species walked during periods of low highway traffic volumes and shifted to trotting as traffic intensity increased. Low rates of human disturbances and proximity to forest edges increased use of highway underpasses by roe deer. Moose used large underpasses to a higher degree than small.
72

Habitat selection by moose (Alces alces) in southwestern Sweden / Älgars habitatval i sydvästra Sverige

Olovsson, Anders January 2007 (has links)
The moose (Alces alces) is very important both economically and ecologically, therefore all knowledge of moose is vital for future management of the moose population. Little is known about moose habitat selection in Sweden. In coastal southwestern Sweden growing human population and new infrastructure projects continuously threaten to fragment and isolate local moose populations. The habitat selection of 22 moose, 8 males and 14 females, in southwestern Sweden was studied from February 2002 until December 2005. The moose were captured and fitted with GPS-collars and positions were collected at 2-hour intervals. The number of moose positions totaled 71103 during the study period of 46 months. Data for individual animals were divided into four seasons: spring, summer, fall and winter based on climate and moose biology. A total of 125 moose seasonal home ranges were generated and habitat use within each of the generated home ranges was studied using Euclidean distance-based analysis. A reclassified digital landcover map was divided into the land use classes agriculture, clear-cut, coniferous forest, deciduous forest, mire and mountain. The results showed that there was a difference in habitat selection between males and females. Males were significantly closer to forest and clear-cuts compared to females. Both males and females selected clear-cuts and avoided agriculture within their home ranges. / Älgen är en viktig art, både ekonomiskt och ekologiskt, och all kunskap är viktig för att även i framtiden kunna sköta en sund älgstam. Trots flertalet studier finns det många frågetecken om älgens habitatval i Sverige. En ökad exploateringstakt och nya infrastrukturprojekt hotar att fragmentera och isolera populationer av älg. Habitatvalet hos 22 älgar, 8 tjurar och 14 kor, i sydvästra Sverige studerades mellan februari 2002 och december 2005. Älgarna sövdes och utrustades med GPS-sändare, deras positioner registrerades varannan timma och det totala antalet positioner under den 46 månader långa studietiden var 71103 stycken. Data från varje älg delades in i 4 säsonger; vår, sommar, höst och vinter, baserat på klimat och älgens biologi. Totalt genererades 125 hemområden baserade på säsong, och valet av habitat inom varje hemområde studerades med hjälp av Euclidean distance-based analysis. En omklassificerad digital marktäckedata användes som var indelad i 6 olika klasser; odlad mark, hygge, barrskog, lövskog, myrmark och berg i dagen. Resultaten visade att det var skillnad mellan könen i hur de väljer habitat. Tjurarna var signifikant närmare barrskog och hyggen än korna, men både tjurar och kor selekterade för hyggen och undvek odlad mark inom deras hemområden.
73

Diet reconstruction of wolves following a decline in Manitoba moose populations

Mocker, Danielle 14 September 2015 (has links)
Moose populations in southern Manitoba have declined. Although the primary cause of this decline is unclear, wolf predation is considered a main contributor because wolves have limited moose populations elsewhere. To help understand the role of wolf predation in limiting moose populations we reconstructed the proportional diet of wolves using stable isotope analysis and a Bayesian stable isotope mixing model (MixSIAR). We tested the assumptions of MixSIAR by running sensitivity analyses on trophic discrimination and prior information. We observed differences in wolf diet in areas where moose and deer coexist and are spatially separated, with changes both seasonally and annually. Our results suggest white-tailed deer were preyed on during winter, even in areas where deer are locally rare, suggesting prey catchability is more important than local prey density. Seasonal changes in prey accessibility strongly affect wolf predation rates, and manipulating alternative prey populations could mitigate predation impacts on moose. / October 2015
74

Elninių žvėrių gausos ir žiemos ganyklų būklės dinamika Padauguvos miško biosferos poligone / Dynamics of Deer (Cervidea) abundance in Padauguva forest biosphere polygon

Ceslevičius, Dainius 21 June 2010 (has links)
Tyrimai buvo atliekami 2008 ir 2010 m. pavasarį Padauguvos miško biosferos poligone, kurio plotas yra 5782 ha. Kiekvienais metais tyrimų metu buvo išskirta apie 500 apskaitos aikštelių, kuriose įvertinta žiemos ganyklų būklė. Nustatyta, kad elninių žvėrių žiemos ganyklų būklė yra gera. Taip pat tyrimų metu nustatyta trako ir pomiškio medelių gausa, skabymo intensyvumas ir jų dinamika per 2008 – 2010 metus. Stirnų populiacijos būklė yra gera, gyvenanti intensyvaus trikdymo teritorijoje. Taurjiųjų elnių populiacija šioje teritorijoje yra vertinama kaip perspektyvi. Briedžių tankis Padauguvos miško biosferos poligono teritorijoje yra permažas. Padauguvos miško biosferos poligono teritorijoje vyrauja Gryni lapuočių ir mišrūs lapuočių su spygliuočiais medynai, kurie sudaro 78,0 % nuo viso medyno medyno ploto. / Research performed in spring of 2008 and 2010 in Padauguva forest biosphere plygon, which covers 5782 ha. Each year around 500 sampling plots were intercepted to evaluate condition of winter pastures. It was estimated, that winter pastures are in good condition. It was estimated intensity and dynamics of deer browsing on undergrowth and understorey tree and shrub species during the 2008-2010 period. Condition of Roe deer population, living in high disturbance zone, is good. Population of Red deer, living in same territory, considered as perspective. Density of Moose Padauguva forest biosphere polygon is too low. Broadleaves and mixed broadleaved with coniferous stands dominates in Padauguva forest biosphere polygon. They compose 78,0% of total area of forest stand.
75

Wolf responses to spatial variation in moose density in northern Ontario

Anderson, Morgan 02 May 2012 (has links)
Forty-four wolves in 3 boreal forest sites in Ontario were monitored via GPS radiotelemetry during 2010 and 2011 to examine spatial responses to variation in prey density. Home ranges were defined using a Brownian bridge utilization distribution, and a resource utilization function was calculated for each pack in winter and summer, based on habitat, topography, and prey density. Wolf territories were smaller where moose density was higher. Third order selection (within home range) varied by pack and season. Wolves generally selected for sloping areas, areas near water, and stands with deciduous or regenerating forest, but selected against areas with dense conifer cover. Roads were most important in summer, especially in those territories with large road networks. Habitat use in a mild winter was similar to habitat use in summer. Variable resource selection among packs emphasizes the adaptable, generalist nature of wolves even in the relatively homogenous the boreal shield. / National Science and Engineering Research Council, Ontario Graduate Scholarships, Ontario Ministry of Natural Resources - Wildlife Research and Development Section, Center for Northern Forest Ecosystem Research, Ontario Ministry of Natural Resources, Canadian Forest Service, Forest Ecosystem Science Cooperative
76

Snowmobile, motorcycle and moose-car accidents : aspects on injury control

Björnstig, Ulf January 1985 (has links)
Injuries related to snowmobiles, motorcycles and moose-car collisions have increased. The aim of the present thesis was to analyse mechanisms and consequences in fatal and non-fatal accidents of these types, and to penetrate possible preventive measures. Snowmobiles The median age of the injured was 30 and of the killed 32, males pre­dominating. A majority of the accidents occurred during weekends, and especially the fatal accidents occurred after dark. The extremities were the most commonly injured parts of the body, however, drowning, crushed chest and cranial injuries caused most of the fatalities. Among the fatalities, four out of five were under the influence of alcohol. The present Swedish laws regarding snowmobiles seem well motivated. "Built-in" safety measures in the construction of the snowmobiles, pro­perly designed snowmobile tracks and functional search and rescue sys­tems could reduce the injuries. Motorcycles The median age was 19 years for both the traffic injured and the kil­led. Half of the traffic accidents were collisions with other motor ve­hicles. In the fatally injured group, also collisions with fixed road­side objects were common. Of the fatally injured, more than every fifth person died in an accident where alcohol was an influential factor. In the injured group, lower extremity injuries (especially in off-road riding) were common and among the fatalities most riders died from injuries to the head or chest. Out of one thousand motorcycle riders interviewed, 45% reported wobbling experiences (8% reported severe wobbling). Possible injury reducing measures include increasing the licensing age, more discriminating driving test, "built-in" restriction of the motorcycle's top speed, elimination of motorcycles prone to wobbling, and a more intensive traffic supervision (speeding, alco­hol). Moose-car collisitions The median age of the drivers was 38 years. Most collisions happened at dusk or when dark (3/4). The median collision speed was 70 km/h. The damage to the car was typical, the roof and the windshield pillars were deformed downwards and backwards. The broken windshield was often pressed into the passenger compartment. Most of the injured car occu­pants suffered cuts predominantly to the head and upper extremities. Nearly all the fatally injured died of head and neck injuries. The injuries may be reduced by strengthening the roof and the windshield pillars, and by introducing anti 1 acerati ve windshields. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1985</p> / digitalisering@umu
77

Ny metod för behandling med viltskydd på skogsplantor / New method for treatment of forest plants with browsing-protection

Ljungar, Victor, Ottosson, Linnea January 2018 (has links)
A threat is that some of the tree species that are important for the biodiversity are under a lot of pressure because of the high browsing activity. The Swedish forestry agency has now together with the forest industry set an acceptable level of browsing on production forest that 70% must be non-browsed when the stands are 5 meters or higher. To protect the production forest from browsing the landowner can choose from several options, the conventional way is yet to point treat every production plant with a game repellent, but that way isn’t very time saving as to treat with this new method.This study is trying out a new method to treat the whole stand instead of point treating every production plant. The method was to use a petrol mistblower (Stihl SR200) and treat one hectare with 9 litres of water and 1 litre of the game repellent Trico viltskydd. Two inventories were made, one before treatment and one after treatment. In total 200 sample surfaces of 2,82m in radius where collected, 100 of them where control surfaces. Every tree species in the sample surfaces where record and if it was or wasn’t browsed. The result of this study shown that the increase of browsing on all tree species was reduced with the treatment method. The new method shows that it can have positive effects on preserving the bio diversity.
78

Verification of the fluid dynamics modules of the multiphysics simulation framework MOOSE : A work to test a candidate software for molten salt reactor analysis

Gustafsson, Erik January 2022 (has links)
This is a report of a verification study of the multiphysics simulation framework MOOSE which was preformed at the company Seaborg Technologies. In the process of designing molten salt reactors there is a special need of making credible multiphysics simulations since the fuel is in motion. In this study the incompressible version of Navier-Stokes equations of finite volumes available in the Navier-Stokes module of the MOOSE framework is verified by modelling and simulations of fluid flow and heat transfer in two different systems with available benchmarks. The first system, a thin buoyancy driven molten sodium hydroxide test loop which is verified by a similar model made with the high fidelity CFD software STAR-CCM+ as benchmark. The second system, forced convection of air through a straight pipe with heated walls which is verified by comparisons with an analytical solution. The resulting velocity profiles from simulations of the first system corresponds well with the benchmark but certain conclusions can not be drawn from it since the the transient simulations stops to converge before reaching equilibrium. The results from simulations of the second system corresponds well with the analytical solution and no convergence issues arise. The conclusion from the results is that the incompressible version of Navier-Stokes equations of finite volumes available in the Navier-Stokes module of the MOOSE framework has potential to be used in multiphysics simulations of molten salt reactors but seemingly not in cases of buoyancy driven flows in thin geometries. Two proposals for further work is recommended. The first is that this implementation is applied in a context with forced fluid flow or a context with thicker fluid domain. The second proposal is that the other available abilities of MOOSE such as finite element method and/or the compressible version of the Navier-Stokes equations should be tested.
79

Påverkas betesskador i unga tallbestånd av mängden risväxter i området? / Is browsing damage in young Scots pine stands affected by the amount of ericaceous shrubs in the area?

Åhsberg, Tove January 2021 (has links)
Flera markägare upplever att deras tallungskogar blir nedbetade av älgen. Syftet med denna studie var att undersöka och utvärdera om betesskador och betestryck i tallungskog var högre, i områden med liten andel risväxter. Studien var en pilotstudie där förhoppningen att ett verktyg på sikt, skulle kunna tas fram för inventering av fodermängd i fältskikt.  Någon signifikant relation mellan inventerade variabler och variationen av betesskador kunde inte förklaras i studien, troligtvis p.g.a. för liten datamängd. Signifikanta skillnader mellan fastigheter återfanns för två variabler - tallstammar och täckningsgrad. De fyra sätten att mäta risväxter visade sig vara starkt korrelerade med varandra.  Genom denna studie kan en potentiell vägledning ges gällande metoder som gör det lättare för markägaren att själv inventera andelen viltfoder i form av risväxter på fastigheten.
80

Effects of human disturbance on epiphyte assemblages in the Andes of Ecuador / Auswirkungen menschlicher Störung auf Epiphytengemeinschaften in den Anden Ecuadors

Werner, Florian A. 07 February 2008 (has links)
No description available.

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