<div>Native and invasive bark and ambrosia beetles threaten the health and productivity of natural and planted forests worldwide. Management of these pests relies on semiochemical-based tactics, but these are often ineffective at monitoring for incipient populations or decreasing pest populations. The role of fungal and non-host volatiles in colonization behavior remains unknown for many important bark and ambrosia beetle species, thereby hindering their control. In this dissertation, I tested the hypothesis that fungal and tree-associated volatiles influence the host colonization behavior of bark and ambrosia beetles that affect hardwood trees. This work describes the identification of novel fungal and host-associated semiochemicals that may aid in future management of these important pests.</div><div><br></div><div>In Chapter 1, I review the current literature describing the volatile chemical ecology of bark and ambrosia beetles that inhabit hardwood trees. A review of groups with numerous identified semiochemicals, as well as considerations for future research is included.</div><div><br></div><div>In Chapter 2, I test the hypothesis that host colonization by the peach bark beetle (Phloeotribus liminaris) is chemically mediated by compounds associated with infested hosts. I found that benzaldehyde mediates colonization by the peach bark beetle, and that that benzaldehyde lures are effective attractants in field-trapping studies.</div><div><br></div><div>In Chapter 3, I test the hypothesis that ambrosia beetle attraction to host stress compounds can be modified by symbiotic fungal volatiles. I found that for three species of invasive ambrosia beetles individual fungal volatiles act as repellents, with species-specific differences in response to different compounds.</div><div><br></div><div>In Chapter 4, I test the hypothesis that attraction of the walnut twig beetle (Pityophthorus juglandis) to its pheromone lure can be enhanced by symbiotic fungal volatiles. I found that symbiotic fungal volatiles consistently enhance attraction of the beetles to their fungus, while one symbiotic fungal volatile of ambrosia beetle species repelled the walnut twig beetle.</div><div><br></div><div>In Chapter 5, I summarize results from each of the chapters and discuss patterns observed in the response to fungal and host-associated volatiles among the focal bark and ambrosia beetle species. I also discuss future research needs and directions to continue development of the knowledge surrounding scolytine chemical ecology and management of these pest beetle species.</div>

This doctoral thesis investigates the potential of classification methods based on spatial context to infer specific forms of land use from remote sensing data. The problem is that some types of land use are characterized by a complex configuration of land covers that traditional per-pixel based methods have problems classifying due to spectral heterogeneity. The problem of spectral heterogeneity is also present in classification of high resolution imagery. Two novel methods based on contextual information are evaluated, Spatial Relational Post-Classification (SRPC) and Window Independent Context Segmentation (WICS). The thesis includes six case studies in rural and urban areas focusing on the classification of: agricultural systems, urban characteristics, and dead wood areas. In the rural case studies specific types of agricultural systems associated with different household strategies are mapped by inferring the physical expression of land use using the SRPC method. The urban remote sensing studies demonstrate how the WICS method is able to extract information corresponding to different phases of development. Additionally, different urban classes are shown to correspond to different socioeconomic profiles, demonstrating how urban remote sensing can be used to make a connection between the physical environment and the social lives of residents. Finally, in one study the WICS method is used to successfully classify dead trees from high resolution imagery. Taken together these studies demonstrate how approaches based on spatial context can be used to extract information on land use in rural and urban environments where land use manifests itself in the form of complex spectral class and land cover patterns. The thesis, thus, contributes to the research field by showing that contextual methods can capture multifaceted patterns that can be linked to land use. This, in turn, enables an increased use of remote sensing data, particularly in the social sciences. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript. Paper 5: Manuscript. Paper 6: Manuscript.</p>

Fungi have a key role in the decomposition of coniferous litter and affect nutrient cycling in forest ecosystems. Therefore, great emphasis is placed on exploring the diversity of these organisms. The aim of this thesis was to describe fungal diversity in spruce litter and revealed temporal development of this community in a forest regenerating after bark beetle outbreak. Another objective was to compare sites with different length of bark beetle damage. The study area was located in the Bohemian Forest mountain range. Litter bags with spruce needles were placed on the forest soil and several samplings were performed in the course of three years. Diversity of fungi and changes in the fungal community were assessed by two methods: cultivation of needles on 2ř MEA and fingerprinting method T-RFLP. In total 71 fungal species were obtained from needles during a three-year succession by cultivation approach. Using T-RFLP 122 different fragments were generally recorded. The dominant species were Scleroconidioma sphagnicola, Thysanophora penicillioides, Hormonema dematiodes, Ceuthospora pinastri, species of genus Chalara, Trichoderma polysporum, Mycena galopus and unknown species Helotiales sp. 1. Primary saprotrophs occured in the community mainly in first 8 months and then were replaced by basidiomycetes....

The diploma thesis deals with the issues of the spruce monocultures in the relation to the incidence of the bark beetle (Ips typographus) in the Šumava National park. The aim of the thesis is not only to unify and arrange the information, but also find out the level of knowledge about this topic among the pupils of the ninth grade of the basic school. The work also shows the level of knowledge of the pupils about the related problems and what are their opinions and suggested solutions. The thesis is divided into the theoretical and practical part. The theoretical part consists of eight chapters, that are devoted to the history of the Šumava forests, pine tree monocultures with the closer focus on the Norway spruce (Picea abies), the differences among the "natural" and "economical" forest and to the uniqueness of the Boubín primeval forest. In one of the chapters we get information about the huriccane Kyrill and its effects on the Šumava forests and followed by the information about the bark beetle calamities and about the bark beetle on its own. The last two chapters are devoted the solution of the current situation in the Šumava forests and their future perspectives. The practical part of the thesis contains mainly of the questionnaire survey proceeded among the pupils of the ninth grade of the...

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The aim of this study was to compare and contrast mineral and microbial nitrogen concentrations in soils of semi-natural and natural mountain spruce forests in the Březník area, the Bohemian Forest National Park, under dead wood and four plant dominants with respect to different forest management after windstorm and bark beetle events applied in 1997.

Spruce forest is an important production ecosystem for our civilization. Its development can be affected by three main types of disturbances: forest fire, windstorms and spruce bark beetle attack. Experiences with a massive and long-term attack of spruce bark beetle in the Šumava mountains and a strong windstorm in 2004 in the spruce forest in the High Tatra provoke questions, how natural are such severe disturbances. To understand the current development of forest ecosystems, it is necessary to study past structure of these forests and frequency of forest disturbances. This work is about locality Tatranská Lomnice located in the High Tatra mountains, in the belt of mountain spruce forest. In my work, I used mainly pollen and plant macro-fossils analyses. I compared my data with disturbance information originating from dendroecology for windstorms and from charcoal analysis for fires. My research found that according to the pollen assemblages, most of the disturbances did not have strong influence on the forest composition, and most likely they only caused the forest thinning. The most significant fire occurred around 1420. The most significant wind disturbance probably occurred in 1890. The was not found any effect of spruce bark beetle. In the past millennium disturbances affected spruce forest...

Nos recherches abordent, par une approche multidisciplinaire, l’écologie spatiale et la dynamique d’invasion du ravageur de l’épicéa Ips typographus (Coleoptera :Scolytinae) en Belgique. Bien que cette espèce ne puisse pas être considérée au sens strict comme invasive en Belgique où elle est implantée depuis le milieu du 19ème siècle, de très vraisemblables introductions de souches exotiques en provenance de Russie et des Pays baltes, en font un modèle exceptionnel pour l’étude de ces processus.<p><p>Une analyse en milieu urbain, suivant des transects centre-périphérie, a d’une part suggéré l’introduction probable de ces souches exotiques et d’autre part permis d’étudier ce ravageur forestier dans un milieu qui lui est a priori défavorable. Il en résulte que, malgré un effet de la structure urbaine sur l’abondance du scolyte, sa présence a été observée partout, y compris dans les zones densément bâties du centre de Bruxelles. Cela suggère, en terme de dispersion, que cette espèce est capable d’atteindre des arbres isolés, et en terme d’infestation, que tout épicéa constitue un hôte potentiel tant en milieu forestier qu’en milieu ouvert ou urbain.<p><p>Une étape préliminaire dans l’estimation des risques liés aux invasions biologiques est d’effectuer une analyse de filière, afin d’analyser les différentes voies d’introduction et les risques liés aux pays d’origine des marchandises importées. Sur base de l’analyse de l’ensemble des sources de données statistiques disponibles, nous avons déterminé l’ampleur du commerce de grumes d’épicéa entre l’est de l’Europe et la Belgique, les modes de transport utilisés, les origines et destinations des grumes, ainsi que la variabilité de la localisation et du nombre des différents points d’entrée de ces marchandises sur le territoire belge d’une année à l’autre, depuis le début des importations en 1996. Notre analyse illustre les difficultés inhérentes à ce genre d’étude, particulièrement au niveau de la disponibilité des données à une échelle appropriée.<p> <p>Par une approche de modélisation, nous avons envisagé différents scénarios de dispersion de souches introduites d’Ips typographus afin d’estimer l’expansion de celles-ci en Belgique.<p>Notre modèle a permis de mettre en évidence l’importance de la bonne connaissance de certains paramètres biologiques caractétistiques de l’espèce étudiée (phénologie, capacité de dispersion, taux de croissance). Par ailleurs, les volumes d’importation et la localisation des points d’entrée des marchandises semblent jouer un rôle secondaire.<p><p>Enfin, nous avons utilisé des marqueurs génétiques afin d’essayer de prouver l’introduction de souches russes et baltes du scolyte de l’épicéa en Belgique. Des échantillons ont été collectés dans neuf pays européens ainsi que sur l’ensemble du territoire wallon. La structure génétique observée n’a pas permis de mettre en évidence une différenciation entre les populations de l’est et de l’ouest de l’Europe. La présence d’haplotypes communs à l’est et à l’ouest rejoint l’hypothèse d’une homogénéisation des populations en relation avec le large pouvoir de dispersion du typographe. Cependant, un grand nombre de mutations a été observé entre 2 haplotypes. Des introductions d’origines lointaines telles que la Sibérie ne sont donc pas improbables.<p><p>Les résultats détaillés de chacune de ces études sont développés dans les différents articles constituant cette thèse. La discussion générale met ceux-ci en relation et aborde les perspectives découlant de nos recherches. / Doctorat en sciences, Spécialisation géographie / info:eu-repo/semantics/nonPublished

En stor skadegörare på de svenska granskogarna är den åttatandade granbarkborren Ips typographus (L.). Torkstress, vattentillgång och landskapets topografi är faktorer som påverkar granens vitalitet. Om granen har en låg vitalitet riskerar den i högre utsträckning att bli angripen av granbarkborren. Syftet med studien var att analysera topografi och markfuktighet för granbarkborreskadad skog. Områden med skadade träd och oskadade träd jämfördes i GIS-programmet QGIS för att se om det fanns en skillnad med avseende på markfuktighet, lutning, lutningsriktning och höjd över havet. Resultatet visade att granbarkborren angriper främst gran i syd till sydvästlig och östlig riktning. Även områden på torrare marker har en ökad risk för angrepp samt områden där terrängen inte sluttar. Troligtvis löper områden där ovan nämnda variabler sammanfaller större risk att bli angripna av granbarkborren.

Nitrogen availability and transformation in acidified and N saturated soils of Czech (The Bohemian Forest, Ore Mountains) and Ukraine (Pop Ivan massif) mountain forest ecosystems were investigated. The study was primarily focused on the role of microbial immobilization in soil N retention. The study was based on field measurements (ion exchange resins), analyses of selected soil biochemical and microbial characteristics, and on laboratory experiments (15N labelling).