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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.
1

Srovnání vybraných vlastností dřeva jasanu ze dvou odlišných vegetačních stupňů

Štěpán, Ondřej January 2009 (has links)
No description available.
2

Monitoring výskytu a bionomie Chalara fraxinea na polesí Bílovice nad Svitavou

Novosadová, Kateřina January 2012 (has links)
No description available.
3

Occurrence of putative dsRNA mycoviruses in Ash Dieback Causal Agent

Čermáková, Vendula January 2014 (has links)
Thanks to environmental changes, globalization, long distance trade and plant transport, invasive organisms have become a major threat for world biodiversity and ecosystem services. Over the last 20 years, common European ash trees (Fraxinus excelsior L., Fraxinus angustifolia Vahl. etc.) have been subjected to heavy dieback and mortality because of the introduction and spread of the ascomycetous fungal pathogen Hymenoscyphus pseudoalbidus Queloz (syn. Chalara fraxinea Kowalski). Once the disease is established, its management is hardly possible. Therefore, one of the main objectives of European researchers is to find effective and respectful control methods, such as biological control. The discovery of viruses which reduce the virulence of the chestnut blight fungus Cryphonecria parasitica (Murr.) Barr., has intensively stimulated the research of fungal viruses as potential biological control agents (BCA). The occurrence of putative dsRNA particles in the decaying fungus H. pseudoalbidus was investigated as an important indicator of the mycoviruses' presence. In total, 106 samples of this pathogen were obtained from eight different European countries. According to the results, dsRNA segments were confirmed in 32.1 % of examined samples (two similarly sized at 2--2.5 kb and a third one of approximately 5 kb). Statistical results have revealed no significant relation between the presence of dsRNA and growth rate, colour or any other characteristic of the mycelium.
4

Infekční biologie Chalara fraxinea a faktory ovlivňující fruktifikaci teleomorfy Hymenoscyphus pseudoalbidus jako zdroje infekce nekrózy jasanu

Rozsypálek, Jiří January 2015 (has links)
The diploma thesis deals with ash dieback caused by pathogenic agent Hymenoscyphus pseudoalbidus. This pathogenic fungus has spread across the whole Europe during the last twenty years and became a serious threat for European ash populations (Fraxinus sp.). This work is mainly focused on H. fraxineus symptomatology in relation to phenology of Fraxinus excelsior L. in situ. Artificial infectious experiments were carried out and several control measures were tested. The methodology of inoculation with ascospores and methodology of evaluation of ash stands infected by H. fraxineus were designed. Outside the terms of assignment of this thesis, the speed of infection spread and mortality rate in stands of different ages were observed. One of the most interesting results is a finding that severe infection causes significant slowdown of phenological phases of F. excelsior. Infectious experiments showed high susceptibility of F. excelsior to the infection. The infection broke out in 83.7% of tested individuals. The susceptibility of F. pensylvanica and F. americana was proved to be considerably lower.
5

Srovnání vybraných vlastností dřeva dubu a jasanu z oblasti lužního lesa

Brauner, Tomáš January 2010 (has links)
No description available.
6

Monitoring výskytu a bionomie Chalara fraxinea na polesí Městské lesy Hostinné

Meňházová, Jitka January 2012 (has links)
No description available.
7

Gene flow from planted common ash (Fraxinus excelsior L.) stands to old-growth forests – implications for conservation and use of genetic resources affected by ash dieback

Semizer Cuming, Devrim 02 February 2018 (has links)
No description available.
8

Les accrus de frêne (Fraxinus excelsior L.) à l'interface environnement/sylviculture dans les Pyrénées Centrales : distribution spatiale et croissance / Spatial distribution and growth of Fraxinus excelsior (L.) in Pyrenean agricultural landscapes : role of environmental factors and management practices

Mdawar, Ola 13 November 2009 (has links)
Le changement des pratiques agricoles et surtout pastorales dans les Pyrénées Centrales a entraîné une colonisation des terres par le frêne (Fraxinus excelsior L.) en constituant des peuplements denses et fréquents dans le paysage pyrénéen. Ce travail est centré sur l'étude de la répartition actuelle et future de ces peuplements qu'on appelle "des accrus" et sur leur potentialité de croissance en relation avec les facteurs qui peuvent être limitants dans la perspective d'une valorisation économique de ces accrus. L'étude de la croissance a été réalisée à trois niveaux : la croissance en hauteur en fonction de la fertilité, et la croissance en diamètre en fonction du climat et de la compétition. Pour ce dernier facteur, la croissance a été étudiée sur des peuplements en place (sans intervention) et suites à deux modalités d'éclaircie. La détection des accrus de frêne au stade perchis avec les outils de télédétection n'est pas réalisable et nécessiterait d'importants investissements et adaptations pour devenir utilisables. La présence des accrus de frêne est surtout modulée par la topographie et l'utilisation du sol. En ce qui concerne la croissance en diamètre de ces accrus, elle est modulée par la vigueur des arbres, la compétition et le climat. Ce sont surtout les températures maximales d'avril et les températures minimales de septembre ou d'août qui influencent la croissance en surface de cerne. Le frêne réagit dès la première année à l'éclaircie, d'autant plus fortement et durablement que le peuplement est plus jeune. L'effet de la nutrition minérale sur la classification des accrus étudiés, selon leur croissance en hauteur, n'est pas évident. L'ensemble des résultats obtenus dans ce travail constitue un outil pour aider à gérer les accrus de frêne dans la zone étudiée surtout dans un objectif économique. / The changes of pastoral management practices in the Central Pyrenees are at the origin of the colonization process of grasslands by the ash (Fraxinus excelsior L.). This colonization process leads to the establishment of very dense and frequent patches of ashes in the Pyrenean landscape. The research is focused on the study of the current and future distribution of these forest patches resulting of the extension of ash trees by natural seeding called "the accrues" and on their potentiality of growth in relation to the nutritional factors which can be limiting from the point of view of an economic valorization of these new forest patches. The study of the tree growth was carried out on different levels: growth in height according to the fertility, and growth in diameter according to the climate and the competition. For this last factor, the growth was studied on in situ tree settlements without intervention and with two levels of thinning. The recognition of ash patches patterns within the mountain landscape was not possible using the traditional tools of remote sensing (SPOT) and should have require new technologies such as LIDAR or multispectral aero data which were out of reach during the PhD work. Exploratory field work has shown that at the landscape level, the presence of ash patches is a function of the topography and the land use history. With regard to the diameter growth of these increased, it is modulated by the strength of the trees, the level of competition and the climate. The maximum temperatures of April and the minimal temperatures of September or August influence the growth on the surface of tree ring. The ash reacts to the first year to thinning, especially for recent settlements and young trees. The effect of the mineral nutrition on the tree growth in height is not significant. The results on spatial pattern dynamics and the references on ash growth in a wide range of soil conditions obtained during this work constitutes a tool to help to manage ash patches within the studied area mainly with an economic point of view.
9

Functional diversity of mycorrhizal fungi with regard to nutrient transfer

Valtanen, Kerttu 18 December 2012 (has links)
No description available.
10

Effects of earthworms and tree species (Fagus sylvatica L., Fraxinus excelsior L.) on greenhouse trace gas fluxes in mixed deciduous broad-leaved forests

Schützenmeister, Klaus 09 April 2014 (has links)
No description available.

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