Magistro darbe tiriama kai kurių abiotinių veiksnių įtaka hibridinės drebulės adaptacijai ex vitro sąlygomis. Darbo objektas – Smulkiadantės tuopos x drebulės (Populus tremuloides x Populus tremula) hibridas. Darbo tikslas – Nustatyti temperatūros ir substrato pH įtaką hibridinės drebulės mikroūglių adaptacijai ex vitro sąlygomis. Darbo metodai – Temperatūros ir pH įtaka adaptacijai ex vitro sąlygoms. Darbo rezultatai: Mikroūglių be šaknų, paruoštų perkėlimui į daigintuves, poveikis skirtinga temperatūra parodė, kad geriausiai mikroūgliai adaptavosi prieš tai palaikyti 12 val. +4 ºC temperatūroje. Genotipų reakcija į skirtingas temperatūros sąlygas skyrėsi nežymiai. Adaptuojamus ex vitro sąlygose hibridinės drebulės mikroūglius rekomenduojama laistyti tirpalais, kurių pH (5,5–6) artimas arba šiek tiek didesnis už fiziologinį. Augimo reguliatoriai, PBZ ir ABR, gali būti naudojami hibridinės drebulės mikroūglių adaptacijos ex vitro sąlygose pagerinimui, ypač mažiau adaptacijai palankiomis sąlygomis (kai pH 5). / This master thesis researches some effects of abiotic factors on adaptation of the hybrid aspen under ex vitro conditions. Object of the research – Hybrid aspen (Populus tremuloides x Populus tremula). Purpose of the research – Defining the impact of temperature and pH substrate on adaptation of the hybrid aspen under ex vitro conditions. Research methods – The impact of temperature and pH substrate on adaptation under ex vitro conditions. Results of the research: The effect of different temperature on rootless micro plantlets prepared for planting shows that the best results of adaptation are achieved when micro plantlets are disposed to temperature of +4 ºC for 12 hours. The reaction of genotypes to different temperature conditions is of no significant importance. For better adaptation under ex vitro conditions, it is recommended to water micro plantlets with solutions that have the same pH (5,5 – 6) or minimally larger than physiological saline. Plant growth regulators, such as PBZ and ABR, can also be used for better adaptation results under ex vitro conditions, especially under less favourable conditions (when pH is 5).

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To understand the temporal dynamics of a forest, long-term direct observations are required. My study examined the long-term persistence of trembling aspen (Populus tremuloides Michx) and white spruce (Picea glauca (Moench) Voss) in the boreal mixed-wood forests of Riding Mountain National Park. A set of 266, disturbance-free, permanent sample plots were established in 1947 (stand age = 120 years) and followed through time for 55 years. My results indicate that although the density and basal areas of aspen do decline over the 55-year period, a successful regeneration and establishment occurs around 140 years. The long-term persistence of aspen is a result of clonal reproduction following the canopy breakup beginning around 130 years or earlier. This implies that the long-term persistence of both aspen and spruce occur and the expected succession to softwood dominance does not occur.

Regional variation in nitrogen (N) deposition increases plant productivity and decreases species diversity, but landscape- or local-scale influences on N deposition are less well-known. Using ion-exchange resin, we measured variation of N deposition and soil N availability within Elk Island National Park in the ecotone between grassland and boreal forest in western Canada. The park receives regionally high amounts of atmospheric N deposition (22 kg ha⁻¹ yr⁻¹). N deposition was on average higher ton clayrich luvisols than on brunisols, and areas burned 1 – 15 years previously received more atmospheric N than unburned sites. We suggest that the effects of previous fires and soil type on deposition rate act through differences in canopy structure. The magnitude of these effects varied with the presence of ungulate grazers (bison, moose, elk) and vegetation type (forest, shrubland, grassland). Available soil N (ammonium and nitrate) was higher in burned than unburned sites in the absence of grazing, suggesting an effect of deposition. On grazed sites, differences between fire treatments were small, presumably because the removal of biomass by grazers reduced the effect of fire. Aspen invades native grassland in this region, and our results suggest that fire without grazing might reinforce the expansion of forest into grassland facilitated by N deposition.

To understand the temporal dynamics of a forest, long-term direct observations are required. My study examined the long-term persistence of trembling aspen (Populus tremuloides Michx) and white spruce (Picea glauca (Moench) Voss) in the boreal mixed-wood forests of Riding Mountain National Park. A set of 266, disturbance-free, permanent sample plots were established in 1947 (stand age = 120 years) and followed through time for 55 years. My results indicate that although the density and basal areas of aspen do decline over the 55-year period, a successful regeneration and establishment occurs around 140 years. The long-term persistence of aspen is a result of clonal reproduction following the canopy breakup beginning around 130 years or earlier. This implies that the long-term persistence of both aspen and spruce occur and the expected succession to softwood dominance does not occur.

The objective of this thesis was to determine how aspen (Populus tremuloides Michx.) root systems and suckering are affected by decking area (site of log processing and storage) disturbances and seasonal timing of these disturbances. In a field study, summer-built log decks reduced regeneration by half compared to fall-built decks, and if decks were built in the fall, 11 month and 1.5-3 month storage were similar in their impact. A growth-chamber study examined the timing of traffic-induced wounding of the root system and simulated log storage on aspen root systems and suckering. For both summer and winter treatments the combination of root wounding and log storage killed nearly the entire root system and prevented suckering. Root wounding and log storage alone caused a 35-40% reduction in living root mass, carbohydrate reserves, and sucker growth. Sucker numbers were reduced by one half for the winter but were unaffected for the summer.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-10-16T12:44:41Z No. of bitstreams: 1 THALITA CRISTINE RIBEIRO LUCAS FERNANDES - DISSERTAÇÃO (PPGEQ) 2017.pdf: 3155230 bytes, checksum: 29997db242a362fb2a65ffda6fcf8ba0 (MD5) / Made available in DSpace on 2018-10-16T12:44:41Z (GMT). No. of bitstreams: 1 THALITA CRISTINE RIBEIRO LUCAS FERNANDES - DISSERTAÇÃO (PPGEQ) 2017.pdf: 3155230 bytes, checksum: 29997db242a362fb2a65ffda6fcf8ba0 (MD5) Previous issue date: 2017-09-27 / CNPq / A hidrodesnitrogenação catalítica é um processo utilizado para remover impurezas de nitrogênio em produtos derivados de petróleo e ocorre mediante o tratamento da carga com hidrogênio a temperatura e pressão elevadas em um reator do tipo tricled-bed. Para otimizar as operações nestes reatores, é necessário que se tenha informações sobre a cinética das várias reações de hidrodesnitrogenação. Entretanto, as equações das taxas das reações não estão disponíveis na literatura. Assim, o objetivo deste trabalho consiste em obter as equações das taxas das reações e os parâmetros cinéticos para a rede reacional dos compostos nitrogenados utilizando o modelo rigoroso de hidrodesnitrogenação do Aspen Hysys como base numérica para as simulações. Experimentos numéricos foram realizados em um reator diferencial no software Aspen Hysys para obter dados de concentração de reagentes e produtos a diferentes alimentações. Diferentes métodos foram utilizados, um método de regressão linear multivariável para obtenção dos coeficientes de regressão, um método de metamodelagem interpoladora estocástica, o Kriging e a otimização do metamodelo Kriging utilizando o método dos mínimos quadrados. Para testar as metodologias propostas, todas as etapas foram aplicadas para um sistema de duas reações simples, uma reversível e outra irreversível, em um reator PFR. Os resultados referentes ao método de regressão linear mostraram que a metodologia pode ser utilizada para estimar parâmetros cinéticos desde que se conheça a equação da taxa correspondente. A comparação entre os dois métodos do tipo Kriging propostos (convencional e otimizado) foi feita a partir de técnicas de análise estatísticas, como o coeficiente de determinação R² e análise de variância (ANOVA). O kriging otimizado mostrou uma melhor aderência aos dados quando comparado com o kriging convencional. / Catalytic hydrodenitrogenation is one process used to remove nitrogen impurities from refinery streams, and it occurs by reacting a given charge with hydrogen at high temperature and pressure in a trickled-bed reactor. In order to optimize the operation of such reactors one needs information about the kinetics of the various hydrodenitrogenation reactions. However, reaction rate expressions are not available in the open literature. Therefore, this work aims at obtaining the reaction rate expressions and parameters for the reaction network of nitrogen compounds using the rigorous hydrodenitrogenation model in Aspen Hysys as the numerical basis for simulations. A differential reactor to simulate the process for different feed streams generated data to estimate of concentration of reagent and products at different feed loads. Three different methods were used, a multivariable linear regression model to obtain the regression coefficients, a stochastic interpolator metamodeling, Kriging and an optimized Kriging with least square method. In a first step, two simple reactions rates were used to test the methodologies in a reactor PFR in Hysys, a reversible and an irreversible. The results showed that linear regression might be use to estimate parameters satisfactory only if you know the reaction rate expression. By using statistical analysis as determination coefficient R² and analyze of variance, ANOVA, it was possible to compare both Krigings (conventional and optimized). Optimized Kriging showed a better adherence to the data when compared to conventional kriging.