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751 Uppsatser om Threatened species - Sida 11 av 51
Examination of mycorrhizal associations of Allanblackia stuhlmannii : a tree under current domestication
Allanblackia is a tree genus native to humid forests in West, Central and East Africa. Its fruits contain large seeds from which edible high-quality fat can be extracted. In order to create a sustainable supply chain of Allanblackia seeds, a domestication program has been initiated with the purpose to enable smallholder farmers to grow the tree as an agroforestry component and cash crop. More knowledge is required to understand the tree?s biology and possible symbioses involving soil microorganisms with plant growth enhancing poten-tial.
Vandring av vårlekande fisk och jämförelse av fångst mellan ryssja och strömöversiktsnät i Hammerstaån, Stockholms län
During the last two hundred years many wetlands and streams in Sweden have been lowered to provide land for agriculture and forestry. Some of the coastal wetlands and streams probably served as spawning sites for certain species of fish in the Baltic Sea, but the present situation is not well known. As standardized methods to monitor fish in running waters are carried out during late summer or autumn, there is a need for methods to sample spring-spawning fish in these streams.The aim of this study was to survey the lower kilometer stretch of Hammerstaån in Stockholm, to investigate the extent to which the stream is used by spring-spawning fish. Furthermore, the study aims to evaluate a new type of survey fishing gill net calledströmöversiktsnät (SÖN). This was done by comparing the catch of fish by SÖN with that of fyke nets.
Klibbalens gödslingseffekt på volymproduktionen i ett blandbestånd av gran och klibbal : en simulering i Heureka
A secondary and a pioneer tree species can with advantage be included in a mixed stand to increase the use of sunlight. Nitrogen-fixing plants have been shown to increase the supply of nitrogen in the soil by, for example, litter fall. This deposition acts as a biological fertilization, which may be used by non-fixing plants. Alder is a nitrogen-fixing, pioneer tree species that loses its nitrogen-rich leaves late in the autumn. The aim of this study was to examine the effect on the total volume of production, when different proportions of nitrogen-fixing Alder were part of spruce stands.
På jakt efter dalanavellaven Umbilicaria subglabra samt klättringens påverkan på lav- och mossvegetationen på Ålandsklipporna utanför Uppsala :
In search of Umbilicaria subglabra
In Sweden Umbilicaria subglabra has its only known occurrence in Lybergsgnupens nature reserve in the county of Dalarna where it has been found only once in 1936. It was found on the east-facing rock spur, approximately 650 meters above sea-level. The lichen is now red-listed as Regionally Extinct (RE) in Sweden. The aim of this study was find U. subglabra.
Rekreationsanpassad skötselplan för Skedalaskogen :
In this master thesis we suggest a recreational directed forest management plan for the
Skedalaskogen. The forest is situated 10 kilometres east of the city of Halmstad and is owned by the municipality.
We have in literature and in research investigated what people like and want in the forest, how to manage the forest for recreation according to for example tree species, mixtures and density. We tried to adapt the forestry methods more to recreational thinking. We have also looked at issues like what is rare and not rare in this part of the country according to nature and forest, where people live and which connection they have to the Skedalaskogen.
The Skedalaskogen is a quite big area, totally 830 hectares. The area have about 100 000
visitors a year.
Risk för spridning av ogräsfrö med rötrester : en litteraturstudie
With an increasing production of biogas follows an increased amount of digestate. This could potentially be a valuable source of fertiliser with the destruction of weed seeds as a possible advantage. However, there have been some concerns regarding the product still containing viable seeds of weed.
In this Bsc thesis the results of previous research on the fate of weed seeds in biogas production is summarized. It is also a comparison of research on the effect of similar processes such as silage, compost or animal passage on seeds. The purpose of this is to evaluate risks of spreading viable seeds, potentially problematic species and perhaps to find out how to eliminate the risks.
The literature review revealed that previous research mainly indicates low risks regarding many of the tested weed species, but not all studies show the same result, therefore extended research on the subject is desirable.
Suitability analysis of a reintroduction of the great bustard (Otis tarda) to Sweden
The great bustard (Otis tarda) became extinct in Sweden during the mid-19th century. Globally, populations have suffered dramatic declines during the past two centuries. Recently, local populations have stabilized or increased after hunting bans and conservation efforts. Despite positive trends the species is still classified by IUCN as vulnerable (VU), mainly due to withdrawals in the distribution. The limited distribution emphasizes the need for finding ?new? areas suitable for a translocation or reintroduction.
Naturreservat : en bra naturvårdsåtgärd för att bevara enskilda arter och/eller bevara den biologiska mångfalden?
The examination of the adequate nature conservation methods in a natural reserve, to conserve a specific species and / or increase biological diversity is the subject of this study. This work is based on four species, that can be found during the Spring season, liverleaf, wood anemone, brimstone and woodpecker. The incidence and availability is studied and closely observed for these species in twenty forests, i.e. ten forests which are nature reserves and ten forests with the similar characteristics as the nature reserves habitat, but are not nature reserves in Gnesta mucipality, Södermanland. Measurements of the tree crown and the diameter of the tree trunks where noted to study how these factors could affect the outcome of the abundance and incidence of the four species.
Jag trivs bäst när havet svallar, och måsarna ger skri : En textanalytisk studie av biologisk mångfald i läroböcker
Biological diversity is one out of four dimensions, characterizing the subject of Biology ac-cording to the school curriculum. As a concept, biological diversity had its break through at the UN environmental conference in Rio de Janeiro in 1992, where the convention about bio-logical diversity, named CBD, was signed. According to the convention, almost all the na-tions of the world have engaged themselves to preserve the national diversity of species, in-cluding the diversity of genetics and ecological systems.This thesis focuses the biological diversity from the perspective of school books. The aim is to find out how the biological diversity is presented in biology books for students aged 12-15 years.In 1994, the current Swedish secondary and high school curriculum called LPO-94 was pre-sented. The biology books used in this study were published between 1994 and 2007, all of them exist in many editions and are published by three different publishers.The conclusion of the study is that all the biology books that were examined have reached different levels of the development in the field of biological diversity..
Utveckling av gran, Douglasgran, bok och tall under skärm av hybridlärk :
?Development of Norway spruce, Douglas fir beech and Scots pine with a larch
shelter wood? is a report written by Per-Olof Magnusson. The thesis is a
compulsory part of forest engineer program at ?Skogsmästarskolan?, SLU,
Skinnskatteberg, Sweden.
The purpose of this report is to describe and evaluate an experiment with hybrid
larch (Larix x eurolepis) as shelter wood, and different tree species growth and
survival depending on the density of the shelter wood. The experiment is
conducted by southern Swedish forest research centre, faculty of forestry, SLU in
Alnarp.
The hybrid larch ought to be an interesting alternative to birch (Betula sp.) as
shelterwood on suitable sites in southern Sweden.
Hästars behov av socialt umgänge- En studie om hur hästhållare i Laholms kommun uppfyller hästars behov av social kontakt
The problem with keeping horses with to little social contact has come to attention in a new regulation that comes into effect august 1st 2009. It states that horses? need of social contact has to be accommodated. That?s why it feels important to try to survey the horse owners? awareness about the regulation and its present fulfillment.
Förekomst av Chlamydia/Chlamydophila spp hos gris med och utan konjunktivit.
ABSTRACTChlamydia and Chlamydophila are species of a family of bacteria (Chlamydiaceae) that cause a range of diseases, including conjunctivitis, in a variety of animals including pigs and humans. Some species cause zoonotic disease. This study examined the occurrence of Chlamydiaceae in samples taken from the lower eyelid conjunctiva in pigs with and without conjunctivitis. The study was initiated based on a herd investigation aimed to examine the experienced increase of conjunctivitis in some finisher herds. This study was conducted as a case-control study, by collecting samples from 62 case pigs (16-26 weeks old) and an equal number of controls, from three herds in Uppland, Sweden.
Vad styr förekomsten av sälg och asp? : en studie av olika beståndstyper inom Hamra kronopark, Dalarna
Aspen (Populus tremula L.) and goat willow (Salix caprea L.) are two important tree species in the aspect of nature conservation. Due to the elimination of forest fires, a former negative attitude towards deciduous trees in forestry and a strong herbivore pressure, these tree species have been negatively affected during the last fifty years. The aim of this study was to investigate whether the occurrence of aspen and goat willow could be related to either human impact or to site properties, such as ground moisture and vegetation type. A side study included an inventory of a number of cyanobacterial tree lichens on aspen and goat willow in order to try to relate the occurrence of these lichens species to stand history and stand properties.
The study was performed in Hamra State Forest in northern Dalarna. Nature reserves were compared with stands in managed areas.
En jämförelse av sitkagranens (Picea sitchensis) och den vanliga granens (P. abies) produktion :
Sitka spruce (Picea sitchensis) is a tree species that have its natural distribution along the
West Coast of North America, from Alaska in the north to northern California in the south.
Sitka spruce is a typical coastal tree species that can reach heights up to 85 meters and occurs
in single pure as well as in mixed stands.
The main purposes of this study were to describe the Sitka spruce growing characteristics and
the volume production in comparison to spruce (Picea abies). The possibility to predict future
volume production by using prognosis tools designed to be used on spruce were also studied.
The material that has been used in this study are permanent sitka trials established by the
Faculty of Forestry fixed Sitka trials and also material gathered in this study.
A literature study was also carried out in order to determine the Sitka spruce growing
characteristics.
Sitka spruce has a high adaptation and a high volume production on a broad scale of soil
types. The tree species is a pioneer species that has a fast early growth and in combination
with sharp needles it is less susceptible to animal browsing than spruce. The factor that is the
single most limiting factor for where the Sitka spruce can be planted is frost. This factor can
be limited by using plant material with a well-suited provenance.
According to the literature, the Sitka spruce has an average total volume production that is
between 20-40% higher than spruce.
Svampsamhällen och svampsjukdomar på åkerböna samt svamparnas inverkan på grobarheten
Broad beans are becoming a larger crop in Sweden. This is probably due to the current discussion about the cultivation of soya beans that are imported to be used as protein fodder. Broad beans are a good break crop in a small grain intensive crop rotation and works as a protein source for animals together with for example ley. At present little research has been done on broad beans and more knowledge is needed. This study is about fungal communities and diseases on broad beans and the impact of these fungi on seed germination.