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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.
111

Biogeography of Norway spruce (Picea abies (L.) Karst.) : Insights from a genome-wide study

Fagernäs, Zandra January 2017 (has links)
Norway spruce (Picea abies (L.) Karst.) together with the sister species Siberian spruce (P. obovata Ledeb.) form a vast continuous distribution over Eurasia. The present distribution of P. abies in Europe was formed recently, after the last glacial maximum. Theories about the colonization routes and history of this species differ depending on the datasets examined to date. This thesis aims to investigate the genetic structure and diversity of P. abies and establish its glacial refugia and postglacial migration. A range-wide sampling was performed of both P. abies and P. obovata, and a genotyping-by-sequencing approach was used to obtain whole-genome single nucleotide polymorphism (SNP) data. Two major genetic lineages of P. abies were found; northern and central Europe. The northern lineage was further divided into a Scandinavian and a north-east European cluster; the Scandinavian cluster being more closely related to P. obovata and the north-east European cluster to the central European lineage. Introgression from P. obovata was detected far into northern Fennoscandia. The central European lineage was divided into an Alpine and a Carpathian cluster, originating from different glacial refugia. Genetic diversity was higher in the northern part of the range, which can be attributed to the relatively large refugium that recolonized this area, as well as introgression from P. obovata. Genetic diversity was also somewhat elevated where the two central European clusters meet, as is expected in areas where two previously isolated lineages admix. This study is the first range-wide investigation of P. abies using whole-genome SNP information, and shows how the genetic structure of the species has been shaped by the last glacial maximum and postglacial recolonization.
112

Stanovení těkavých izoprenoidů jako markerů vlivu vodního stresu na rezistenci smrku vůči kůrovcům / Determination of volatile isoprenoids as water stress markers of spruce resistance against bark beetle

Slušná, Michaela January 2012 (has links)
Isoprenoids are important components of conifer resin and represent an important part of constituted defence system against herbivores and pathogens. Drought is one of the most important factors that influences the tree physiology and resitance. Due to decreased turgor of resin canal cells, the water insufficiency affects the pressure of the resin and thereby the ability of trees to physically prevent pathogen or herbivore invasion by effective outpouring of the resin. In addition, drought can also change the resin composition and thus can influence the quality of volatiles emitted by the tree. The Norway spruce, Picea abies, is the predominant species of production forests in moderate climate zone. Bark beetles, Ips typographus, represent the most important pest species of spruce. In general, pioneer bark beetles use host volatiles to orient themselves toward the tree suitable for colonization and in many species host volatiles synergize bark beetle aggregation pheromones. Thus the host volatile composition could affect significantly host colonization. This diploma thesis studied the influence of drought on the production and composition of isoprenoid volatile organic compounds in 80 - 100 years old spruce trees. Using I. typographus antennae as biological detectors, we also studied which resin...
113

Dendrokronologisk undersökning av granbeståndet i Siggaboda naturreservat / Dendrochronologic study of Norway spruce stand in Siggaboda nature reserve, Sweden

Regnér, Alexander January 2013 (has links)
Med hjälp av såg- och borrprover studerades åldern på 41 granar och en tall i Siggaboda naturreservat i sydligaste Småland, med syfte att undersöka granens etablering och döende på lokalen. Vidare har reservatet delats in i tre områden för att undersöka om några geografiska skillnader i granarnas etablerings- och dödsår förekommer. Analysarbetet utfördes på Nationella laboratoriet för vedanatomi och dendrokronologi vid Lunds universitet. På lokalen har tidigare bland annat en pollenanalys utförts (Björkman & Bradshaw 1996) samt en kombinerad pollenanalytisk och dendrokronologisk studie (Hannon et al. 2010). Enligt dessa har granen etablerats i Siggaboda under sista halvan av 1700-talet. Någon undersökning med sågprover som material har tidigare inte genomförts på lokalen. Resultaten visar att det äldsta trädet grodde runt 1771 och att en kraftig expansion skedde under mitten av 1800-talet. De visar även att merparten av granarna har dött mellan åren 2005 och 2008, vilket indikerar att granbarkborre etablerade sig till följd av januaristormen 2005 och därefter spred sig även till stående träd - något som har fått omfattande konsekvenser för granarna i reservatet.
114

Možnosti využití hnojení při zalesňování nelesních půd v PLO 31 Českomoravské mezihoří

Dujka, Petr January 2017 (has links)
An afforestation of agricultural lands in the Czech Republic has a long tradition. In the future, a few thousands of hectares of agricultural lands is considered to be afforested. The aim of this thesis is to research possibilities of fertilisation usage in process of agricultural lands afforestation within Natural forest area (NFA) 31 Českomoravské mezihoří. The research part of the thesis contains results of soil and nutrition analyses applied in Letovice-Kochov research area. The main goal of analyses was to find the impact of fertilisation on chemical soil characteristics, on nutrition of Norway spruce's needles (Picea abies (L.) Karsten), on the development of morphological quantity, and on the health of specimen. All of the characteristics are assessed in the context of climate in 2016. The positive effects of fertilisers were researched despite a low-humid year. The best effects were spotted at fertiliser SilvamixR30. To the results, SilvamixR30 fertilizer could be used in praxis, especially for agricultural lands afforested in named NFA.
115

Förekomst och spridning av hänglavar från äldre skogar till unga tidigare avverkade områden i Västerbottens inland

Maksimova, Emma January 2023 (has links)
The Swedish forestry and the use of clearcutting models has resulted in great losses of older forests in Sweden, resulting in several species being affected negatively. Hair lichens are important organisms that are providing several ecological functions in forest ecosystems and are declining due to being associated with older forests with high continuity. This study investigates the occurrence and dispersal ability of the genus Alectoria, Bryoria and Usnea between older forests and young secondary forests in three different areas in Storuman municipality, Västerbotten county. Bryoria were found on all trees in all forest patches, both in the old and young forest patches, while Alectoria had much lower occurrence in the young secondary forest. Usnea had no observed pattern in occurrence between the different areas. The average length of the lichens, here used as a proxy for lichen biomass, showed a statistical difference in biomass between areas for genera Bryoria and Usnea. The genera Alectoria showed a difference in biomass between areas, distance to closest older forest and the interaction between these two. Therefore, this study suggests that Alectoria is limited in dispersal in these areas. Some of the results could be explained by distribution and dispersal ability of the studied genera. To further evaluate the differences seen in occurrence and biomass between the genera and the different areas more studies are needed. This could provide important information for sustainable forestry that favors lichens and benefits reindeer husbandry.
116

How does debarking of bark-beetle-colonised spruces affect the saproxylic beetle species richness and composition?

Janiec, Karolina January 2024 (has links)
In many natural forests, forest managers fell and debark spruces (Picea abies) colonised by theEuropean spruce bark beetle (Ips typographus) to prevent the beetle from spreading to other tree stands. The aim of this study was to examine how this method affects the biodiversity of other saproxylic beetle species. Eclector traps were installed on debarked and non-debarked dead spruces of four different ages in four nature reserves to compare the richness and composition of saproxylic beetles. The results indicated that a significantly higher number of species and individuals emerged from standing dead trees with bark compared to debarked logs. The highest emergence of species and individuals occurred in one-year-old standing trees with bark. There was a significant interaction between the type and the age of wood, suggesting thatthe richness declined with the aging of wood with bark, while it remained constantly low in debarked logs. The species composition varied greatly between standing trees with bark and debarked logs, as well as between standing trees with bark of different ages. This study demonstrated that debarking spruces as a pest control method reduces the diversity of nontarget saproxylic beetle species. Potential reasons behind that could be the hardening and drying of consumable parts of the wood, rendering it inhabitable for many saproxylic organisms, as well as the presence of the European spruce bark beetle itself, which is associated with many other species.
117

Olika markberedningsmetoders effekt på granens (Picea abies) utveckling 16 år efter plantering med och utan snytbaggeskydd / The effect of different soil scarification methods on the development of Norway spruce (Picea abies) 16 years after planting with and without pine weevil protection

Svanfeldt Ohlsén, Anna January 2019 (has links)
Vid föryngring ger markberedning en bra förutsättning för plantan att överleva och växa, och med mindre risk för snytbaggeangrepp. Syftet med denna studie var att undersöka hur snytbaggeskydd och olika markberedningsmetoder långsiktigt påverkar stamantal, medelhöjd och volymproduktion hos gran (Picea abies). Markberedningsmetoderna som jämfördes var högläggning, fläckmarkberedning och inversmarkberedning. De jämfördes med att inte markbereda alls. Hälften av plantorna var behandlade mot snytbagge med permetrin, dessa var jämt fördelade i försöket. Studien genomfördes i en försöksyta 9284, vid SLU:s försökspark i Siljansfors, Mora kommun. Beståndet var 17 år när det mättes (16 år efter plantering) hösten 2018. Då mättes trädens höjd, diameter samt grönkronans höjd. Volym beräknades med volymfunktioner. Högläggning, inversmarkberedning, och fläckmarkberedning (i nu nämnd ordning) och snytbaggeskydd gynnade granplantornas volymtillväxt, gav flest stammar samt högst höjd. Att högläggning och inversmarkberedning var så framgångsrika i detta försök beror troligen på att marken i Siljansfors är näringsfattig och fuktig. Hög planteringspunkt ökar risken för en planta att torka. Permetrinbehandling hade en positiv effekt på volymen och stamantalet, dock var det ingen signifikant skillnad vad gäller höjden. Markberedning samt permetrinbehandling ger bestående långsiktiga resultat för produktionen. / In regenerations, soil preparation provides good conditions for plants to survive and grow, and reduces the risk of damage by pine weevil (Hylobius abietis). The aim of this study was to investigate the long-term effect of protection against pine weevil damage and the long-term effect of different soil scarification methods on the number of trees, tree height and the volume production of spruce (Picea abies). The soil preparation methods that were compared were mounding, patch scarification and the inverse method. These were compared as well as to, no soil preparation at all. Half of the plants were treated against pine weevil with permethrin. These were evenly distributed in the experiment. The study was conducted in the trial area 9284, at SLU's experimental park in Siljansfors, Mora municipality. The trees were 17 years old when measured (16 years after planting) in the autumn 2018. Then tree height, diameter and the height of the green crown was measured. Volume was calculated with volume functions. Mounding, the inverse method and patch scarification (in the order mentioned) and pine weevil protection benefited the volume production of the spruce trees, the numbers of trees and tree height. The fact that mounding and the inverse method was so successful in this experiment is probably due to that the soil in Siljansfors is nutrient-poor and moist. High planting points increases the risk of drought. Permethrin treatment had a positive effect on volume production and the number of plants, however, there was no significant difference regarding tree height. Soil preparation and permethrin treatment provide lasting long-term effects on production.
118

Analyse von Schälschadensinventuren in Harz und Solling / Unter Berücksichtigung ausgewählter Umweltparameter in ihrer Rolle als potentielle Einflussfaktoren / Examination of bark stripping damage in the Harz and Solling mountains / Considering environmental parametres in their role as potential factors of influence

Schomaker, Philipp 25 February 2015 (has links)
Die vorliegende Arbeit stellt die Fortführung eines Projektes dar, in dem kausale Zusammenhänge zwischen Umweltfaktoren und dem Auftreten von Winterneuschälschäden an Fichte durch Rotwild im Harz und im Solling untersucht werden sollten. Ergänzt um die Analyse und detaillierte Darstellung der Datengrundlage der beiden Untersuchungsgebiete bedient sich diese Arbeit zunächst einfacher statistischer Tests zur Quantifizierung der während drei Inventurjahren mittels Klumpenstichprobe ermittelten Schälschäden. Hierbei werden die Werte mit Jagdstrecken- und Forsteinrichtungsdaten sowie Geländeparametern univariat assoziiert und die jeweiligen Chancenverhältnisse der Parameterklassen ausgewiesen. Im Anschluss werden die potentiellen Einflussfaktoren dann mittels binärer logistischer Regressionen sowie durch generalisierte lineare Modelle auf ihren Effektwert als erklärende Variable in multivariaten Modellen hin untersucht. Für die Durchführung dieser Untersuchung werden zu Beginn entsprechende Arbeitshypothesen aufgestellt. Die Berechnung der Chancenverhältnisse zeigt einen starken Zusammenhang zwischen vorangegangener Schäle und dem Auftreten neuer Winterschäle am Stichprobenpunkt. Ebenso lassen sich erhöhte Jagdstreckenergebnisse mit vermehrter Neuschäle assoziieren. Während junge Bestände häufiger Schälschäden aufweisen als ältere Bestände, lassen sich in Bezug auf die untersuchten Geländeausprägungen kaum eindeutige Aussagen treffen. Die Ergebnisse der Regressionsmodelle variieren in ihrem Niveau der Modellanpassung und des Erklärungspotentials und bleiben hinsichtlich ihrer Aussagekraft im Solling gegenüber dem Harz zurück. Je nach Inventurjahr und Gebiet werden unterschiedliche Variablen als Effektparameter ausgewiesenen. Zudem widersprechen sie einander zum Teil in ihrer Effektrichtung. Auch das Vorhandensein von Altschälvorkommen wird nicht in allen Modellen als erklärende Variable hinzugezogen. Die generalisierten linearen Modelle im Harz weisen für die reliefbasierten Parameter wiederkehrende Effekte. Ungeachtet der variierenden Effektstärke bleibt deren Ausprägung über die gesamte Untersuchungsreihe hinweg gleich. So lassen sich mit zunehmender Hangneigung eine Erhöhung und in Abhängigkeit von der Hangrichtung zumindest Unterschiede des Schälrisikos feststellen. Während das Schälrisiko mit zunehmender Exponiertheit des Stichprobenpunktes im Gelände sinkt, weisen Standorte mit einem höheren Strahlungspotential im Januar auch höhere Schälschädigungsraten auf. Die in dieser Arbeit erlangten Ergebnisse korrespondieren zum Teil mit den Erfahrungen anderer Autoren, zeigen jedoch auch Unterschiede zu deren Ergebnissen. Die widersprüchlichen Effektwerte der eigenen Untersuchungen lassen dabei grundsätzliche Zweifel an der Zuverlässigkeit der durch multivariate Modelle ausgewiesenen kausalen Zusammenhänge aufkommen. Neben einem geeigneten Stichprobendesign werden insbesondere auch eine zielgerichtete Parameterauswahl und -erhebung als entscheidende Faktoren für die spätere statistische Analyse hervorgehoben. Als Voraussetzung für die Schaffung eindeutig interpretierbarer Ergebnisse wird nachfolgenden Arbeiten von der Verschneidung ursprünglich nicht für die Untersuchung bestimmter Daten abgeraten und stattdessen eine studienabhängige Erhebung empfohlen.
119

Untersuchungen zur optimalen Steuerung der Waldentwicklung / Analysis of optimal forest development

Sánchez Orois, Sofia 27 June 2003 (has links)
No description available.
120

Stanovení obsahu ligninu v jehlicích smrku ztepilého (Picea abies L. Karst.) pomocí laboratorní a obrazové spektroskopie / Assessment of lignin content in needles of Norway Spruce (Picea abies L. Karst.) using laboratory and image spectroscopy

Suchá, Renáta January 2013 (has links)
The master thesis deals with determination of selected biochemicals (lignin, carotenoids, water) content in Norway spruce needles using laboratory and imaging spectroscopy. The first part of thesis summarizes literature dealing with methods of estimating lignin and other biochemicals content. Three types of data are used in this thesis: 1. spectra measured by contact probe and ASD FieldSpec 4 Wide Res spectroradiometer, 2. spectra measured by integrating sphere and spectroradiometer and 3. aerial hyperspectral image data acquired by APEX sensor. The most useful transformation methods - first derivative and continuum removal are applied to the spectrum. Further the linear relationship between measured spectrum and content of biochemicals is analysed. Stepwise multiple linear regression is applied to select suitable wavelengths for modeling of biochemicals content in spruce needles. The model is also calculated and applied on the level of image hyperspectral data. Maps of lignin content in Norway spruce are the final output of these part of this. Next part of the thesis compares spectra measured by contact probe and spectra measured by integrating sphere. Diffrerence between the studied areas based on biochemicals content in spruce needles and several chemical elements in the soil and based on...

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