At the end of April 1986 reactor number 4 of the nuclear power plant at Chernobyl explod-ed and large amounts of radioactive particles were then released into the atmosphere due to both the explosion as well as the consecutive fire of the graphite core. A cloud of radioac-tivity was spread over the northern hemisphere, including Sweden, due to the prevailing wind directions. The radioactive particles were washed out from the cloud by rain and snowfall in some areas of Sweden and deposited on the ground. The deposited radionu-clides, primarily cesium and iodine isotopes, were later absorbed into the soil and taken up by the roots of the plants. Some of these radionuclides, like 137Cs, still persist in some of the terrestrial ecosystems at relatively high concentrations which lead to contamination of the meat of moose, roe deer and wild boar even today.The two municipalities Heby and Uppsala, in the eastern part of central Sweden, experi-enced a relatively large deposition of 137Cs which resulted in high levels of 137Cs in moose and other game.

During 2006 SNVDB (the national road data base for forestry) is being introduced to Holmen Skog. This data base contains all information about Holmen Skogs road systems. The information will then be used in different kinds of optimisation models which only produce correct and reliable results if the input data are of the adequate quality. Today there are reasons to believe that road data is of various qualities. The forest roads are often in a bad condition and have to be improved before a planned harvest. The cost of maintenance and construction of new roads is a large part of the total harvesting cost.

The eutrophication of lakes and seas with the algal bloom and deficiency inoxygen that follow, has been given priority by the Swedish government as oneof 16 environmental objectives. The purpose of this project was to develop a toolbased on a simple model, limited amount of data and geographic informationsystem (GIS) to identify areas with risk for phosphorus losses due to surfacerunoff. This tool can act as a decision support to decide where appropriatemeasures should be applied with the aim of reducing phosphorus losses and bythat the eutrophication.The method that has been used is a combination of two models, one calculatingthe potential erosion while the other one identifies areas of erosion (net erosion)or deposition. This ability is of great importance because potential erosionshould be calculated on areas with net erosion. Areas with high potential erosionhave an increased risk for phosphorus losses due to surface runoff.The potential erosion was calculated based on factors which describe how topography(LS), land use (C), soil type (K) and precipitation (R) effect the erosion.All of them have been modified to a greater or lesser extent.

It has been observed by both onion producers and a plant protection advisor on Öland (an island off the east coast of Sweden) that basal rot is the largest contributory factor to reduced onion quality and yield. Basal rot is mainly caused by species of Fusarium fungi. The aim of this study was to: a) investigate which species of Fusarium that can be found in onion produced on Öland, b) describe the symptoms caused by the different Fusarium fungi found and c) explore, through interviews with the onion producers on Öland, the mechanisms that may be involved in the observed increase in basal rot.Onion bulbs (Allium cepa) were sampled on two occasions. In total 181 onions from 11 different fields were analysed. In addition, eight onion producers were interviewed.

When protection zones for wells are delineated, it is important to acquire good knowledge about possible travel time from different points in the catchment area to the well. Often, simple analytical methods are used for estimating travel times and the assumption is made that the hydraulic conductivity is relatively homogenous within the aquifer. Nevertheless, many aquifers are strongly heterogeneous which may lead to differences between estimates and actual travel times. As a part of the process to develop improved methods for delineating protection zones for groundwater supply wells, a tracer experiment was performed in a glaciofluvial esker formation in Järlåsa. On the basis of the experiment, a numerical flow model was created for the test site.The purpose of this master?s thesis was to apply the flow model to an aquifer where the hydraulic conductivity shows great variability and should be described by a stochastic distribution.

X-ray fluorescence (XRF) detection of heavy metals is a cost- and time-effective method for investigation of polluted areas. Compared to laboratory analysis, XRF analysis is limited by high detection limits and uncertainties in some situations. Preparation of samples is known to affect the results of measurements.The purpose of this thesis is to bring a deeper understanding of how different factors affect the results of XRF-analysis. A large number of measurements have been made with the instruments Niton XLt 700 and Niton Xli 700. Results from measurements of lead, zinc and copper have been analysed.This study has shown that a greater moisture content will give a lower measured concentration for the same sample.

After the last is age there was a long period when there was no shortage of forest for peoples needs. People living in Sweden could use the forest resources at their will. Around 4000 years BC the inhabitants of southern Sweden started to use the agricultural system and people become more stationary. The farms were located together in groups and together they formed a social association, the village. Successively the population grew and in some areas the forest started to become a finite resource.

BAE Systems Hägglunds has a long history of producing high performance terrain tracked vehicles (mostly for military applications), and they are now aiming at developing a tracked forwarder with similar techniques.The forwarder will be of series hybrid type where a diesel engine via a generator will power the motors (one for each drive wheel). Thanks to individually controlled motors and the gentle rubber tracks, this forwarder is calculated to have a considerably higher average speed in the terrain and to be more gentle to the soil. The forwarder with a weight of 11 metric tons and a load capacity of 15 metric tons is specified to have an average working speed of 7-10 km/h, a top speed in terrain of 15 km/h and a top speed on roads of 40 km/h.This master?s thesis aims at developing a conceptual design of the forwarder?s drive module which includes electric motor, gear unit, brake and drive wheel.To investigate if the requirements can be fulfilled a study of the dimensioning loading scenarios has been carried out. The resulting needs regarding the torque has been considered in order to determine the required gear ratios for different motor options.

The fallout from the Chernobyl nuclear accident resulted in large deposits of caesium, iodineand strontium as well as noble gases in various parts of Sweden. 137Cs has a radioactive halflifeof about 30 years and is therefore one of few radio-fission products remaining inmeasurable quantities in the Swedish soil. Radiocaesium behaves similarly to potassium insoil-plant systems and is easily absorbed by plants. It is important to understand how 137Csbehaves in different ecosystems in order to minimize the risk toward humans.The aim of this study was to determine how potassium fertilization influences radiocaesiumcontent in different forest plants and fungi. Potassium fertilizer was spread once in 1992 withapproximately 200 kg KCl per ha.

The estate of Rämningstorp in the region of Västergötland in southern Sweden is administered by the holding trust company Skogssällskapet i Skövde. In 1999 measures were taken by Skogssällskapet to drain the stream Fredstorpsbäcken as a means to increase the forest productivity of the surrounding lands, which are situated on the estate of Rämningstorp. Almost immediately after the drainage, the streamwater turned turbid and a landowner downstream reported the issue to the county administrative board of the region. The aim of this thesis was firstly to analyse the suspended matter that appeared during summer/autumn and secondly to explain why it came to be. Initial hypotheses for the explanation to the greyish turbid water were that it was either 1) a chemical/biochemical precipitate, or 2) an bacterial/algal blooming.

Around the world, forests are generally being fragmented and as plant populations decline in both sizeand number of individuals, the genetic variation will also decrease whitch in the end leads to totalextinction of the plant. In this paper, I wanted to investigate what specific species of trees and shrubsyou usually find in the edge and core habitats in some of the forests in the Baltic Sea region. I alsowanted to identify the edge effects and their sources and finally compare the results between thedifferent regions.The data sources used are derived from the ongoining research project Landscape structures, patterns ofbiodiversity and conservation strategies in the Baltic Sea region by Kari Lehtilä, Patrik Dinnétz ochTiina Vinter who have made a record of all herbaceous plant species in four randomly chosen forestregions situated around the Baltic Sea: Estonia, Skåne, Södermanland and Germany. I made statisticalanalyses, using the computer program R, concerning the distribution of species in the edge habitats ofthe forests as well as in the core habitats. I performed generalized linear models and then variationanalyses with the factors light and biomass in order to investigate wether edge effects might appear dueto these factors.

The limit for mercury in fish, set by health authorities, is exceeded in about half of the lakes in Sweden. Methyl mercury (MeHg) is the most toxic form of mercury and accumulates in fish. Therefore transformation of inorganic mercury (Hg) to methylmercury (MeHg) is an important process that we need to understand in order to possibly counteract the negative effects of mercury in the environment. The seasonal dynamics of mercury biogeochemistry is likely of great importance for the accumulation of MeHg in the aquatic food web. In thesis the chemical speciation and transformations of Hg and MeHg in bottom waters and sediments is followed in Ängessjön, a small lake located on the east coast in the middle of Sweden. The lake is not directly affected by any industrial pollution and concentrations of Hg in the sediment reflect the atmospheric deposition in this area, as well as processes taking place along the hydrological pathways from soil to lake. Samples from sediment, bottom- and streamwater were collected in average every second month during the period Feb.

The pathogenic fungus Rhizoctonia solani causes major economic losses for potato producers in Sweden. The producers, as well as advisors, have reported possible increases in severity of R. solani when free-living plant parasitic nematodes are present and active. There are several examples in the literature of interactions between pathogens where one, or both species, support or increase the damage made by the other organism. These complexes are important to investigate and to be able to forecast, since even low incidences of fungi or nematodes may result in an interaction of significance.

A geographical position and its social, cultural and political context as well as climate and specific physical characteristics define the scope for a landscape design project. This has become clearer for us in our master project where we have made a Design Program for the outdoor environment of Wollo University in Dessie, Ethiopia and analysed and reflected on the work and process. The aim for the project has been to design an attractive and functional outdoor environment for the Campus, based on the inventories and the needs and wishes of clients and users. But, the aim has also been for us as landscape architect students to gain a greater knowledge about landscape architecture and the design process by position ourselves outside our usual context. The method has been open and seeking where the site, literature studies, dialogues with people and our own experiences from the field study in Ethiopia has influenced the work. Wollo University is situated 400 kilometers north of Addis Ababa, in a mountainous landscape. It faces problems of heavy rainfall during the summer, soil erosion, a lack of essential facilities, and is still a construction site with empty spaces in-between buildings and infrastructure.

The moose is a keystone species in the boreal forest ecosystem, but the dense Swedish population do cause some serious problems. From a forestry perspective, their browsing on young Scot pine (Pinus sylvestris) causes extensive losses of revenue. Adjusting the cleaning along roadsides of low trafficked forest roads can favour the production of plant species preferred by the moose. This is thought to redirect the moose´s browsing to the roadsides and thereby decrease the damages on commercial forest.The aim of this study has been to present a first evaluation of the vegetation in roadsides, one year after wildlife-adapted roadside clearing has been undertaken. In the wildlifeadapted clearing operation, the roadside was widened by removal of some trees in the forest edge whereupon a complementary clearing with a conventional chain flail was conducted.