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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.
31

NEO 2 / NEO 2

Molišová, Kateřina Unknown Date (has links)
Diploma thesis is an environmentally and process oriented project which is based on the issue of the so-called bark beetle calamity. It deals with the personification of non-human life. It uses experience with materials, their handling and processing.
32

Efficacy of Chemical and Biological Stump Treatments for the Control of Heterobasidion occidentale Infection of California Abies concolor

Poloni, Adrian Luis 01 June 2022 (has links) (PDF)
We conducted an experimental evaluation of treatments to limit Heterobasidion occidentale infection of white fir (Abies concolor) stumps and wounds in California mixed conifer forests. We tested the efficacy of urea, borate, and a mixture of two locally collected Phlebiopsis gigantea strains in preventing pathogen colonization of fir stumps and separately, urea and borate as infection controls on experimental stem wounds. These were paired with a laboratory test on ~100 g wood blocks with and without a one-week delay between inoculation and treatment. Urea, borates, and Phlebiopsis treatments all significantly reduced the stump surface area that was colonized by H. occidentale at 84%, 91%, and 68%, respectively, relative to the controls. However, only the borate treatments significantly lowered the number of stumps that were infected by the pathogen. The laboratory study matched the patterns that were found in the stump experiment with a reduced area of colonization for urea, borates, or P. gigantea treatments relative to the controls; delaying the treatment did not affect efficacy. The field wound experiment did not result in any Heterobasidion colonization, even in positive control treatments, rendering the experiment uninformative. Our study suggests treatments that are known to limit Heterobasidion establishment on pine or spruce stumps elsewhere in the world may also be effective on true firs in California.
33

An assessment of loblolly pine (Pinus taeda L.) mortality and the impact of habitat fragmentation on southern pine beetle (Dendroctonus frontalis Zimmerman) infestation in Mississippi, USA

Taiwo, Damilola M 08 December 2023 (has links) (PDF)
This thesis has two data chapters that consider factors affecting loblolly pine health in localized regions of Mississippi. The first data chapter investigated the abiotic and biotic factors contributing to loblolly pine (Pinus taeda) mortality on private timberland in Mississippi. This assessment considered temperature and precipitation variations, bark beetle populations, foliar and root pathogen tests, and drone survey. The results revealed that the loblolly pine mortality resulted from combination of factors. The second data chapter examined the impact of habitat fragmentation on southern pine beetle (SPB; Dendroctonus frontalis) infestation in Homochitto National Forest (HNF). This was assessed through remote sensing and categorization of SPB spots in HNF over nine years. Results indicated that increased total pine patch area, decreased distance between pine patches, and low patch diversity are important drivers of SPB outbreak in HNF. These results can help improve loblolly pine health and management in the southeastern United States.
34

Formování postojů žáků v hodinách zeměpisu na příkladu problematiky kůrovcových kalamit / Shaping of Students' Attitudes in Geographical Education - The Issue of Ips Typographus Outbreaks

Faflák, Jiří January 2013 (has links)
Shaping of students' attitudes in geographical education - the issue of Ips typographus outbreaks Abstract The diploma thesis deals with shaping the students' attitudes by utilising various texts during the geography classes. This experiment is shown on particular problem of Spruce Bark Beetle in the National Park of Šumava. There are two main streams towards this issue of Spruce Bark Beetle-one of them promotes the idea of incorporating the human intervention, while reducing the disaster, the other follows the opposite attitude towards the outbreak of the Spruce Bark Beetle, and that is not to intervene at all and to leave the destructed vegetation to regenerate. The backbone of the thesis is represented by a survey that aims at finding attitudes towards the problem mentioned above. Moreover, the survey also questions the way the attitudes change depending on critical reading of distinctive texts. Two main questions are posed in this research. The results are graphically depicted and commented upon in the thesis. The research shows the extent to which it is possible to influence the students' opinion utilising quality study texts. Key words: Spruce Bark Beetle (Ips typographus), National park Šumava, Spruce Bark Beetle outbreak, geographical education, critical thinking, active reading, shaping of attitudes
35

Bioinspired smell sensor to trace pheromone released by the European spruce bark beetle

Cederquist, Isac January 2020 (has links)
Forests have as a of late become increasingly plagued with bark beetle infestations as a result of climate change. The damage caused by tree killing bark beetles has within recent years seen a substantial increase. Detecting and removing infested trees at an early stage is an essential part of mitigating the spread of and the damage caused by the beetle. Today, the most common way of early detection is visual detection by forestry personnel. However, this is time consuming with highly variable results. In this thesis a novel approach to tracing the European spruce bark beetle through pheromone detection is investigated. With this approach, the antennae of the beetle were paired with an epitaxial graphene chip in order to create a bioinspired smell sensor. Tests were conducted on the sensor in order to investigate how the resistance changed over the chip as a result of the sensor being exposed to the pheromone 2-methyl-3-buten-2-ol. As a result of the tests, a corelation between exposing the sensor to pheromone and an increase of the resistance over the graphene chip was noted. However, more tests need to be conducted in order to draw any definite conclusions about the efficacy of the sensor in its current form. Additionally there are opportunities to investigate further optimization alternatives regarding the design of the sensor.
36

HODNOCENÍ POŠKOZENÍ LESNÍCH POROSTŮ S VYUŽITÍM DRUŽICOVÝCH A LIDAROVÝCH DAT / Assessments of forest damage using satellite and LIDAR data

Lihanová, Kristýna January 2013 (has links)
Assessment of forest damage using satellite and lidar data Abstract The main objective of this thesis is to create a methodical procedure used for the evaluation of forest damage in the chosen area of the National Park Sumava, Czech Republic. In this work were combined the multispectral satellite data and data of airborne laser scanning. The forests in this area are heavily damaged mainly due to bark beetle outbreak. You can find here as healthy so damaged forests. Based on this methodology will be differentiated greater number of classes than I found in the literature. In this work was used pansharpened multispectral image SPOT, multispectral image Landsat and airborne laser scanning data with low density points. Another task was to get height information from ALS data in the form of grid. Forest stands were classified using object-oriented classification, which included at first segmentation and then creation of classification base. In classification entered spectral information and height information obtained from the ALS data. Forests were classified into 5 classes and accuracy of both classifications was evaluated using the error matrix and kappa coefficient. SPOT image classification reached kappa coefficient of 68,5 % and Landsat image classification reached kappa coefficient of 72,3 %. From the...
37

Iniciální výzkum náchylnosti smrku ztepilého k napadení lýkožroutem smrkovým z hlediska dlouhodobého působení stresových faktorů / Initial study of predisposition of Norway spruce to bark beetle attack in relation to long term effects of multiple stress

KOTRC, Miroslav January 2014 (has links)
This thesis is a contribution to understanding of predisposition of solitary Norway spruce (Picea abies [L.] Karst.) to bark beetle (Ips typographus (L.)) attack. The predisposition is estimated from long term effects of multiple stress, which are determined by tree crown transformation. By virtue of created model, it was documented that some environmental variables could have considerable effect on tree crown transformation. Tree crown transformation is generally considered a mirror of spruce health status.
38

Společenstva pancířníků (Acari: Oribatida) přirozeně se vyvíjejících a asanovaných horských smrčin na Šumavě / Communities of oribatid mites (Acari: Oribatida) of naturally regenerating and salvage logged mountain spruce forests of Šumava Mts

KOKOŘOVÁ, Petra January 2015 (has links)
The main aim of this study was to describe and compare communities of oribatid mites of selected areas in mountain spruce forests near Březník in the Šumava National Park, where different types of management were used after the spruce dieback caused by bark beetle gradation more than 15 years ago. Naturally regenerating and salvage logged areas were compared. Significant differences were found in the oribatid mite community composition between the areas with different types of used management. The oribatid mite community in naturally regenerating areas was in better shape and its abundance and species composition was similar to the community of a control area in a fully grown healthy spruce forest.
39

Morfologie a vývoj střevních patogenů lýkožrouta smrkového / Morphology and development of the midgut pathogens in bark beetle

TONKA, Tomáš January 2013 (has links)
The bark beetle, Ips typographus is economically important pest of spruce standings across Europe. The knowledge of biology and ecology of bark beetles is important to protect spruce forests against beetles outbreaks. The research of pathogens of bark beetles is the main goal to use biological control of bark beetles and replace chemical or mechanical methods using today. During the bark beetle outbreak in Sumava mountains three main pathogens showed up very promising. Microsporidium Chytridiopsis typographi, the virus Ips typographus Entomopoxvirus and negregarine Menzbieria chalcographi were the most occured pathogens attacking beetles in Sumava outbreak area. Transmission of microspo ridium and virus have been introduced and propagated in living bark beetles in labo ratory. The reaserach of biology, transmission, morphogenesis and ultrastructure of these pathogens begun in living beetles in laboratory conditions. Results which were obtained can be divided to virological and microsporidian parts. In both cases the infection and routine passage have been successful in laboratory condition and now the infections of microsporidium Ch. typographi nad ITEV are routinely propagated to purchase infected material. Unlike the original description of ITEV in laboratory infected beetles the synthesis and origin of microspindles was described. In TEM the first steps of newly formed virions occluded into the spheroid were observed, including microspindles occlusion. ITEV develops in midgut epithelium of host. The successful infection of Ch. typographi has been managed in laboratory. Obtai ned results completed and revised findings which were published in first descriptions. Purchased results offer a possibility to compare old a new findings concernig this microsporidium. Budding as a unique process of multiplication has been described in microsporidia. This process is uncommon in microsporidia and has not never been observed. It acts as a tool to multiple vegetative stages in the life cycle. The ultrastructures and complete life cycle was described in Ch. typographi and the former description was revised.
40

Minskad årsringsbredd hos gran (Picea abies) : - en vitalitetsförlust efterföljande en torkperiod / Reduced annual ring width of spruce (Picea abies) : – a loss of vitality subsequent a drought period

Blomquist, Johan January 2020 (has links)
Effekten av torka på gran kan var stor. Sommaren 2018 var en av de torraste och varmaste somrarna på länge. En sådan period påverkar ofta granars vitalitet negativt och kan leda till en ökad risk för angrepp av granbarkborre. Denna studie har undersökt hur årsringsbredden på gran har förändrats till följd av torka genom att jämföra årsringsbredder före torkperioden med de efter. Mätningar genomfördes med en resistograf som genererade datafiler som sedan sammanställdes och analyserades, främst med hjälp av Excel. Vidare noterades markfuktighet, bonitet och angrepp av granbarkborre. Dessa faktorer jämfördes med varandra med syfte att finna eventuella samband. Studiens resultat visar att torkperioden 2018 haft en stor inverkan på granars vitalitet. Dessutom har samband mellan torrare bestånd och antal granar angripna av granbarkborre kunnat påvisas. Samband mellan minskad årsringsbredd och angrepp av granbarkborre har ej kunnat fastställas.

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