• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 130
  • 30
  • 10
  • 5
  • 4
  • 4
  • 1
  • 1
  • 1
  • Tagged with
  • 191
  • 191
  • 54
  • 44
  • 41
  • 28
  • 27
  • 25
  • 24
  • 24
  • 22
  • 21
  • 20
  • 15
  • 11
  • 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

Incidence of root and butt rot in consecutive rotations, with emphasis on Heterobasidion annosum in Norway spruce /

Rönnberg, Jonas, January 1900 (has links) (PDF)
Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniv. / Härtill 5 uppsatser.
32

Adaptive evolution and demographic history of Norway spruce (Picea abies) /

Källman, Thomas, January 2009 (has links)
Diss. (sammanfattning) Uppsala : Uppsala universitet, 2009. / Härtill 5 uppsatser.
33

Mapování chromozomů smrku (Picea abies (L.) Karst.) pomocí chromozomově specifických sond

Überall, Ivo January 2004 (has links)
No description available.
34

Vliv klimatických stresorů na kmenoviny smrku ztepilého v oblasti severovýchodní Moravy

Stanovský, Jiří January 2003 (has links)
Angl. resumé
35

Strategie hospodaření v horských polohách Hrubého Jeseníku

Pňáček, Jiří January 2006 (has links)
No description available.
36

Populace smrku ztepilého při horní hranici lesa v Hrubém Jeseníku

Šenfeldr, Martin January 2014 (has links)
This dissertation presents research results of Norway spruce (Picea abies L. Karst) populations in timberline ecotone of the Hrubý Jeseník Mts. The work is presented in the form of five scientific articles, 3 of which are accepted for publication, or already printed. Two articles are in the form of submitted manuscripts. The first article describes the biometric and age structure of spruce populations, including the assessment of the possibility of their vegetative as well as seed-based reproduction and compares these characteristics between two vertically connected sections of timberline ecotone. The second article analyzes the influence of dwarf pine stands of different cover on the ability of vegetative reproduction of spruce and their height growth. The third article deals with the historical dynamic of spruce trees establishment within timberline ecotone. This are correlated with both temperature characteristics and agricultural land abandonment during the last 100 years. The fourth article deals with measurements of the quantity and directions of sap flow in layering branches as well as parent and daughter trees in Norway spruce clonal groups. The article evaluates the importance of sap flow quantity in layering branch to the total amount of water use by parent and daughter trees. The fifth article substantially extends the fourth article of measurements on more interconnected tree pairs within a longer time series. Additionally, this article includes the drought stress experiment in the daughter tree and subsequent monitoring of changes in sap flow in layering branch.
37

Photosynthesis response to temperatures – A study of fertilized and unfertilized Picea abies : Fotosyntes i respons till temperatur – En studie av gödslad och ogödslad Picea abies / Fotosyntes i respons till temperatur – En studie av gödslad och ogödslad Picea abies

Schyman, Anna January 2018 (has links)
The effect climate change has on forest trees is a large scaled topic. It is to believe that one of the largest threat to the environment today is global warming (IPPC, 2007). The use of fossil fuels seems to be the big threat with its greenhouse gas (GHG) emission and therefore forest is of interest. Forest contributes in several ways. Forest trees work as a renewable source of numerus materials and as it takes up CO 2 from the greenhouse gasses it gives us oxygen (O2). The important process of photosynthesis, to able production of more trees and creation of more forests, tells us the vitality of understanding the tree physiology to the fullest. The response of photosynthesis to temperature is a central facet of trees’ response to climate change. With its photosynthesis plants play a large role in the carbon cycle as they store the hazardous carbon dioxide helping us humans to deal with problems directly linked to climatic change and in the same time they build up biomass that can be used as a renewable source. To understand, and to find the key, how plants can achieve optimum potential of photosynthesis several observations were made using plant material from fertilized and unfertilized Picea abies. Well acknowledged leaf gas exchange measurements were used to see the limitations of photosynthesis, observing the net CO2 uptake rate (Anet), the maximum Rubisco carboxylation (Vcmax), maximum rate of electron transport for regeneration of RuBP (Jmax) and their unique response to temperatures. For three days observations were conducted at the Slu Asa field research station in Lammhult, Sweden. In addition to gas exchange measurements, nitrogen (N), phosphorus (P) and chlorophyll content was measured in needles of the fertilized and unfertilized P. abies to see if the content somehow made an impact on photosynthetic parameters and the influence nutrients might have on the specific leaf area (SLA). Results from the observations showed that optimum temperature for photosynthesis varies to be by fertilized 22°C and unfertilized 19°C. The net photosynthetic rate responded to the influence by added fertilizers to almost a double, 9.10 μmol m−2 sec−1 than of the unfertilized, 5.36 μmol m−2 sec−1. These results indicate that a fertilized P. abies has a greater potency to capture carbon than of an unfertilized P. abies. The result also reveals the future prospect of adding fertilizer to a P. abies as a potential of growth in biomass as well as a carbon sink when atmospheric CO2 levels rise. There were no great differences in the behaviour between Vcmax and Jmax to the added or non-added fertilized P. abies. Perhaps the fact that given fertilizer contained both nitrogen and phosphorous could have in their combinations influenced the sensitivity of the relationship between them two and therefore also the result. The presence of N and P in the fertilized P. abies affected the concentration of chlorophyll positively, paving the way for photosynthesis, accumulated biomass and possibly for trees defence against abiotic stress factors.
38

Vliv lesa na migraci a sedimentaci rizikových prvků a vybrané environmentální problémy

Juřička, David January 2016 (has links)
The research of the dissertation thesis was focused on the ability of forests to activate and immobilize metals in the environment with their huge grants from deep mining of mineral resources. The research was be located in the area of Rožná with ongoing uranium mining, and area of Olší with ended uranium mining in the Czech Republic. During the years 2014 and 2015 was at the alluvial streams of Nedvědička (Rožná) and Hadůvka (Olší) recipients of pollution by radionuclides and metals from mining, taken in spring and autumn aspect of the overall 380 samples of leaves from trees, herb layer and river sediments. The samples were analyzed by the XFR and ICP-OES methods. In the organic matter were found such as elements Al, Cl, Cu, Cr, Fe, Mn, Mo, Ni, Rb, S, Sr, U, Zn and Zr, in many cases at high concentrations corresponding to polluted areas in the mining or industrial areas. A statistically significant difference in the concentrations of chemical elements in the fytomasss and river sediment between the upper, middle and lower stream areas of interest was not found. In the area of Nedvědička were found higher concentrations of a greater range of metals than in the area of Hadůvka. In the area of Hadůvka were by ICP-OES found significantly higher levels of uranium in the leaves than in the area of Nedvědička, reaching up to 34.86 mg.kg-1 in the dried material.The seasonal dynamics of the content of chemical elements in fytomass was confirmed. The species composition of the forest growth in the areas of interest with a predominance of Picea abies and the type of management has been evaluated as unfavorable for immobilization of metals in the environment. In the area of Nedvědička were suggested corrective actions - planting vegetation with a predominance of Fagus silvatica which should have a beneficial effect on soil and water pH by a suitable character of waste and contribute to the spread of inhibition of metals in the environment. In the area of Hadůvka are the suggested measures focused on the redevelopment of existing vegetation with a predominance of Picea abies on vegetation with a predominance of deciduous trees, especially Fagus silvatica, in order to adjust gradually the pH of the soil and thereby reduce the mobility of metals in the environment.
39

Dynamics of wood decay estaimated via acoustic tomography measurement

Klíč, Radek January 2019 (has links)
The aim of the study was to determine the dynamics of wood decay using acoustic tomography. Different devices are use to estimate range of internal damage of the tree caused by wood rot as is possible to find in literature. For purpose of these measurements were used devices ArborSonic Decay Detector 3D and Resistograph IML F400-S. Thesis was divided in two main sections. The first section was focused on practical testing of both devices, acquiring knowledge about research procedure and also learning about possible mistakes to be avoid during research. It was necessary to perform two measurements at a time interval of approximately one year. In first year, 70 samples of Norway spruce (Picea abies) were measured and evaluated their health and vitality status. Trees, that had symptoms of fungi wood decay, were measured in the second year once more. Subsequently, the ranges and changes of inner damages by wood fungi were determined and compared results from both devices. The second part was focused on comparison of the graphical results of the range of decay in the Fakopp 3D software with the actual state of the affected tree trunk. An obtained result showed the dynamics of wood decay in years 2018-2019 and therefore was possible to determine the dynamics of wood decay in Norway spruce wood, verify the influence of the basic parameters and also to compare the graphical image of the decay range with the real status in the trunk. The average change of decay range of evaluated Norway spruce trees was 3,32%. It was found out, that Acoustic tomograph overestimated cavity section in 21 cases, which was 84 % in comparison with Resistograph. This overestimation fact was was also proved by graphical result from Fakopp 3D software, which was compared with real status of trunk. The use of device methods for assessment of tree status and preparation for tree care plans were more described in Discussion chapter.
40

Vliv umělé mykorhizace na odrůstání kultur smrku ztepilého

Vlk, Jiří January 2017 (has links)
The diploma thesis deals with the effect of artificial mycorrhization on the growth and on the development of the root system of Picea abies (L.) Karst. cultures. The thesis was conducted at 2 sites under the administration of the Vojenské lesy a statky ČR, s.p., division Lipník nad Bečvou, that were afforested in 2012 and 2013. Every site was divided into 2 parts of the same area. One of the parts was afforested with the use of the mycorrhizal preparation Ectovit and the fertiliser Vápnitý dolomit. The effect of preparations on the above-ground part of trees was evaluated on 210 sample trees at every site. The effect of preparations on roots was evaluated on 10 sample trees. Following parameters were assessed for every sample: the height of the tree; the thickness of root collar; height increments; length of needles; the damage caused by biotic or abiotic factors; number, thickness and length of both horizontal and vertical roots; the number of fine roots; the weight of dry mass of both fine and coarse roots; branching index of fine roots and the specific length of fine roots. Unfortunately, one site had to be omitted from further evaluation of effects on the roots due to the high occurrence of root deformations. The measurement was carried out in June and July 2016. As regards the above-ground part, the research has not proved significant positive effect of preparations. The differences in height increments speak in some cases for, however in some cases against the application of preparations. The lengths of needles were in some years shorter at the sites with preparations and thus may indicate even negative effects of preparations. Regarding root system, a difference was found out only in the case of branching index. No difference was identified for other parameters of the trees on the check and on the test site. Some parameters (e.g. height increments), however, might be considerably influenced by the damage caused by wildlife or by other factors (e.g. heavily stony soil in some parts of the sites). Last but not least, the thesis formulates recommendations regarding the future use of preparations within the company VLS Lipník nad Bečvou.

Page generated in 0.0626 seconds