The impact of in vitro ozone and sulfur dioxide fumigation on pollen from two Fraser fir populations was examined. Populations were located at Mt. Rogers, Va, and Mt. Mitchell, S.C.. Two age groups "young" (less then 30 years old) and "old" (more then 40 years old) were examined within each population. No statistically significant age group differences in pollen germination percentage or pollen tube length were found. Mt. Mitchell pollen had a higher germination percentage than Mt. Rogers population. The statistically significant differences in pollen germination between populations were most probably due to the confounding effect of collection practices, and environmental conditions during 1986 pollen collection, rather than actual differences between populations. In vitro pollen fumigation with sulfur dioxide had no impact on pollen germination while fumigation with ozone decreased pollen germination percentage but did not change pollen tube length. Most of the variation in pollen germination percentage, and pollen tube length was due to genotype of the pollen parent tree. The phenotypic expression of six isozymes (previously correlated with resistance to air pollutants) in pollen was studied using polyacrylamide gel electrophoresis. The pattern of isozyme distribution among pollen phenotypes confirmed results from pollen germination studies. There was a difference between locations but no difference between age groups. None of isozyme phenotypes was correlated with a "resistance" to pollen fumigation with ozone or sulfur dioxide. / Master of Science

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.

Les écosystèmes forestiers méditerranéens présentent des espèces d'arbres vivant en limite sud de leur aire de répartition sensibles aux stress climatiques et des espèces vivant au coeur de leur aire de répartition et a priori adaptées à ces mêmes stress. Ces contrastes interrogent sur la diversité potentielle des mécanismes régulant la dynamique des populations de leurs parasites, et en retour l'impact des parasites sur la dynamique de leurs hôtes. Les scolytes constituent un bon modèle pour l'étude de ces interactions hôte-parasite car ils alternent des phases endémiques et épidémiques. Nous avons développé une approche pluridisciplinaire couplant la caractérisation de traits écophysiologiques et dendrométriques impliqués dans la résistance des populations d'arbres aux attaques de scolytes avec la caractérisation de facteurs écologiques clés pour la démographie des scolytes. Chez le pin d'Alep, T. destruens est présent à un niveau endémique mais des attaques subsistent dans des patchs d'arbres formés par des arbres attaqués et morts suite aux attaques, des arbres attaqués qui ont résisté et des arbres non attaqués. Des stratégies de dispersion locale différentes selon les deux grandes phases du cycle de T . destruens semblent favoriser l'exploitation d'une ressource peu abondante. Chez le sapin pectiné, nous avons montré qu'une communauté abondante de scolytes s'attaque à des arbres déjà affaiblis par des sécheresses répétées et présentant un mauvais état sanitaire et une croissance en baisse. Ces deux écosystèmes forestiers permettent de mieux appréhender les mécanismes impliqués dans les interactions plantes-insectes dans un contexte de changement global. / Mediterranean forest ecosystems have both trees living in their southern range and being sensitive to climatic stress and tree species living in the core of their range and being non sensitive to the same stress. These contrasts in tree populations questioned about potential contrasts in their interrelationships with their parasites and on the impact of that parasites have on their host in turn. Bark beetles are a relevant model to study such host-parasite interactions because they alternate endemic and epidemic phases. We developed a multidisciplinary approach combining the characterization of ecophysiological and dendrometrical traits involved in resistance of tree populations to bark beetle attacks with this assessment of key ecological factors involved in bark beetles demography. We focused on the two following contrasted Mediterranean ecosystems in South-Eastern France: a healthy Aleppo pine interacting with a bark beetle population at an endemic state and a declining population of the Silver fir interacting with a bark beetle community at an epidemic state. Our results suggested that this Aleppo pine population, the pine shoot beetle T. destruens showed low abundance levels. All attacks remained in patches formed by dead trees following the attacks. T. destruens dispersal strategies seem to favor the exploitation of a scarce resource. On silver fir, we showed a bark beetle community attacking trees already weakened by repeated droughts and with poor health status and low growth. The study of these two contrasted forest ecosystems allowed us to shed some critical light on the mechanisms involved in plant-insect interactions in the context of global change.

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.

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.

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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...

This study presents mountain forest Norway spruce (Picea abies) injured by surface ozone and oxidative stress. Norway spruce is not a sensitive species but it is the most representative tree in our country and this is the reason to pay attention on its injury. Study was connected to the ozone measurement by CHMI in Jizerske mountains. Aim of our study was to find influence of surface ozone on the forest and show correlation between ozone concentrations, altitude and Norway spruce injury. Ozone concentrations are growing with the altitude. Increasing percentage of injury with growing concentrations and altitude was expected. Needles were collected at the altitude 750-1100 meters. Collected needle years were 2006, 2007 and 2009. The 2009 year was not evaluated because no symptoms were found. Injury was observed on the maroscopical, microscopical and biochemical level. Visual injury was assessed by percentage of injured needle surface by chlorosis and necrosis. Microscopical analysis studied injury on cross and longitudinal sections of needles. On the longitudinal sections were visible typically bone-cells. These cells have lost its shape by ozone stress and were narrowed in its width. Bone-cells were best visible near the stomata. Four symptoms were observed on the cross sections: tannin...

Tall och gran är de vanligaste trädarterna i svenska skogar. Förutom deras ekonomiska värde är de viktiga värdar för andra organismer och nyttjas oftast när de är döda. Säby Västerskog har skyddats i hundra år och är ett urskogsartat naturreservat där inga fördjupade analyser av dynamiken i trädskiktet har gjorts sedan 1930-talet. Denna studie gjordes med syfte av att uppdatera informationen om reservatets trädstatus samt att undersöka mortaliteten hos skogens barrträd. Det som undersöktes var om mortaliteten skiljde sig mellan trädslag, storleksklass och markslag. Förändringar i grundytan och balansen mellan arten undersöktes också. Träd identifierades med hjälp av data från en detaljerad karta från 1937, det togs mått på deras diameter och noterades vilken mark de stod på. Fler granar än tallar har dött i reservatet sedan 1937. Trädens storlek spelade ingen roll för tallars mortalitet, men väl för granar. Granens mortalitet skiljde sig inte mycket mellan olika markslag, men verkade spela roll för tall som hade högst mortalitet på våtmark och lägst på blockmark. Trots mortaliteten ökade trädens grundyta. Balansen mellan arterna förblev samma. / Scots pine and Norway spruce are the most common tree species in Swedish forests. They are important hosts to other organisms – mostly as dead wood. Säby Västerskog has been protected in hundred years but no in-depth analyses of dynamics in the tree layer have beendone since the 1930s. This study was done to update the information about the reserve’s tree status and examined mortality of conifers. I evaluated if mortality depended on tree species, size of the trees, or the type of ground they stood on. I also examined changes in trees’ basal area. The trees were identified with help of an old, detailed map from 1937. Their diameters were measured and the ground type they were standing on was noted. More spruces than pines had died in the reserve since 1937. Mortality varied with the tree size for spruce but not for pines. The mortality of pines varied among ground types (with the highest on wetlands and lowest on boulder deposits), but not for spruce. Despite high mortality basal area had increased. The balance between the species remained the same.

The Black Mountain range of western North Carolina supports some of the most extensive, but threatened high elevation forests in the southern Appalachians. Of particular note, the insect pathogen, balsam woolly adelgid (Adelges piceae Ratzeburg) has been present on Mt. Mitchell for over fifty years. In anticipation of potential changes in forest composition, vegetation surveys were first conducted in 1966 on nine one-acre plots near the summit of Mt. Mitchell. These plots were re-surveyed in 1978, 1985 and 2002. The purpose of this study was to re-census those plots and use those data to analyze long-term trends in forest composition for fir, spruce-fir, and spruce-fir-hardwood forest types. Since the 1960s and 1970s, all three forest types have experienced a transition away from an understory with a preponderance of Fraser fir (Abies fraseri (Pursh) Poir.) seedlings and saplings, to forests with higher densities of canopy and sub-canopy fir. Canopy red spruce (Picea rubens Sarg.) has similarly increased in density in the fir and spruce-fir types but declined in the spruce-fir-hardwood forest type. In all types, there has been a sharp decline in hardwood seedlings/saplings since a hardwood seedling explosion in 1978. The current analyses indicate that fir and spruce-fir forests have regenerated since the most severe die-offs and that each forest type will experience future impacts from balsam woolly adelgid but these will occur in a non-synchronous pattern.