• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 298
  • 43
  • 21
  • 13
  • 10
  • 10
  • 5
  • 4
  • 4
  • 4
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 527
  • 106
  • 90
  • 55
  • 54
  • 49
  • 49
  • 46
  • 44
  • 38
  • 36
  • 34
  • 34
  • 32
  • 32
  • 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.
331

Variabilité phénotypique et génétique des traits de reproduction de deux espèces de chêne blanc européen (Quercus petraea et Q. robur) / Phenotypic and genetic variability of reproduction-related traits in two European white oak species (Quercus petraea and Q. robur)

Caignard, Thomas 02 May 2018 (has links)
La dynamique et le fonctionnement des écosystèmes forestiers dépendent fortement de la reproduction des arbres. Ainsi de nombreux travaux se sont intéressés aux fortes fluctuations interannuelles à la fois synchrones et non prévisibles des productions de graines, mais très peu d’études ont pu caractériser la sensibilité aux variables climatiques et le déterminisme des traits de reproduction. Dans le cadre de cette thèse nous avons étudié la reproduction de deux espèces de chênes tempérés européens (Quercus petraea et Quercus robur) avec pour objectifs (i) d’évaluer l’évolution des traits de reproduction au cours des deux dernières décennies, notamment vis-à-vis des changements de température, (ii) d’estimer la contribution des facteurs génétiques et environnementaux à la variation de ces traits le long de gradients environnementaux et enfin (iii) d’estimer l’héritabilité des traits de reproduction ainsi que d’identifier les régions du génome qui leurs sont associées. A partir de suivis long-termes de l’effort de reproduction « in situ » sur tout le territoire de France métropolitaine, nous avons pu mettre en évidence une augmentation significative de la production fruitière des chênes au cours des 14 dernières années. Ces accroissements du nombre et de la taille des glands sont fortement corrélés à l’augmentation des températures printanières. Cette sensibilité à la température a par ailleurs pu être confirmée grâce à un dispositif indépendant installé le long de gradients altitudinaux dans les Pyrénées. Nos résultats montrent également une différenciation génétique entre les populations provenant du gradient altitudinal et une opposition de signes entre les clines génétique et phénotypique « contre-gradient » pour les deux traits de reproduction étudiés. Contrairement aux traits de croissance pour lesquels nous observons un « co-gradient », le « contre gradient » observé pour la reproduction suggère que les variations génétiques contrecarrent en partie la forte plasticité environnementale, minimisant ainsi la tendance (ou patron) de l’effort de reproduction avec la température. Enfin, nous avons observé une forte héritabilité pour chacun des traits de reproduction chez le chêne pédonculé dans une famille de pleins frères, confirmant l’existence d’un déterminisme génétique évoqué précédemment. De plus, nous avons identifié pour la première fois chez les arbres forestiers, des locus à caractère quantitatif (QTLs) associés à la reproduction du chêne. Ces résultats suggèrent qu’en réponse à des changements environnementaux, les traits de reproduction ont la capacité de répondre à la sélection et de faciliter l'adaptation locale, et ainsi apportent de nouvelles perspectives dans l’étude de la réponse des arbres forestiers aux changements climatiques. / Forest ecosystem dynamics closely depend on tree reproduction. Many studies have investigated the synchronous and non-predictable year-to-year variability of seed production, characteristic of masting species. However, little is known about the sensitivity of tree reproduction to climate variables and to which extent this phenotypic variability is genetically and/or environmentally driven. We intensively studied the reproduction of two European temperate oaks and our aims were (i) to characterize the change in reproductive traits over the last two decades, (ii) to assess the determinism of their variations along environmental gradients and (iii) to estimate the heritability of reproductive traits and identify the regions of their genome related to reproduction. We were able to show a dramatic increase in seed production over the last 14 years. This increase in seed production and size was significantly correlated with increasing spring temperatures. We then confirmed this sensitivity to temperature by studying the reproduction of oak populations growing along the elevation gradient of the Pyrenees. Based on a common garden approach, we then showed significant genetic differentiation between oak provenances and demonstrated that the genetic and phenotypic clines for the reproductive traits observed along the environmental gradient have opposite signs (counter-gradient). Contrary to growth traits, for which genetic variation parallels phenotypic variation, the counter-gradient observed for reproduction-related traits suggested that genetic variation partly counteracts the phenotypic effect of temperature, moderating the change in reproductive effort according to temperature. Finally, using a full-sib family where reproduction was monitored during four consecutive years, we found a high heritability of reproductive traits and showed high genetic differentiation between trees of a same population, which confirms the significant genetic determinism observed earlier. Furthermore, we were able to identify for the first time in forest trees quantitative trait loci (QTLs) associated with seed production and size. Our findings show that reproduction-related traits may undergo evolutionary changes under selective pressure and may be determinant for tree adaptation in response to environmental changes.
332

Effects of forest composition on trophic relationships among mast production and mammals in southern Illinois

Gillen, Carolyn Ann 01 May 2011 (has links)
Oak-dominated forest has declined in the eastern United States as shade-tolerant species (e.g., maple [Acer spp.]) replace oaks (Quercus spp.), sparking concern among ecologists regarding species that consume acorns. My goal was to describe how increasing mesophication of oak forests may affect consumers in higher trophic levels. I investigated relationships among forest composition, mast production, small-mammal density, and carnivore occurrence in 8 stands representing 4 forest types (upland oak, mixed-mesophytic, non-oak, and bottomland oak) in southern Illinois. I calculated tree-species richness, basal area, and other measures of forest composition using 3 0.04-ha plots/stand. In June-August 2009 and 2010, I live-trapped small mammals for 16,236 trap-nights with trapping webs to estimate population density of mice (Peromyscus spp.). I collected mast seeds during October-November 2009 and 2010 and calculated average dry biomass (g/m2) for each species and stand. During winter 2009-2011, I photographed carnivores using baited camera traps and combined these data with those from stands used in a concomitant large-scale carnivore survey. I regressed mast biomass, Peromyscus density, Peromyscus survival, and carnivore occurrence on measures of forest composition and hard-mast biomass. Peromyscus summer density was not related to % hard-mast basal area, nor to hard-mast biomass from the previous autumn. Survival of Peromyscus in 2010 displayed a significant positive relationship with hard-mast biomass in 2009 (F1,6 = 7.85, P = 0.04, r2 = 0.61). Logistic regressions of carnivore occurrence on Peromyscus density were not significant. Coyote (Canis latrans) occurrence at my sites and additional sites during January-April 2010 decreased with increasing % hard-mast basal area (x2 = 4.64, df = 1, P = 0.03). Bobcat (Lynx rufus) and gray fox (Urocyon cinereoargenteus) occurrence showed no relationship with % hard-mast basal area. Many other studies have demonstrated links of several species to oak forest, but the scale of this study may have been too small to detect effects of mesophication. Alternatively, small-mammal density may be influenced by invertebrate prey abundance or weather conditions. The landscape matrix of oak-hickory forest may also act to homogenize Peromyscus density across my study sites. Longer-term research could help clarify relationships among trophic levels. It is important for managers to consider techniques that may conserve oak forest.
333

Evaluating the success of oak afforestation on former agricultural lands in southern Illinois

Nickelson, Joshua Bradley 01 December 2014 (has links)
AN ABSTRACT OF THE THESIS OF Joshua B. Nickelson, for the Masters of Science degree in Forestry, at Southern Illinois University Carbondale TITLE: EVALUATING THE SUCCESS OF OAK AFFORESTATION ON FORMER AGRICULTURAL FIELDS IN SOUTHERN ILLINOIS Major Professor: Dr. Eric Holzmueller The establishment of oak (Quercus spp.) plantations has increased over the past two to three decades to reduce fragmentation and promote wildlife habitat throughout the Midwestern United States. However, influences such as competing vegetation, previous land cover, plantation size, and site preparation techniques may have varying outcomes on restorative successes. We established 219 plots (.02 ha) in 29 oak plantations located within Crab Orchard National Wildlife Refuge (Williamson County, Illinois) 15-18 years after mechanical planting. Sampling data for all trees over breast height included species, diameter, and lianas existence on the main bole of the tree. Additionally, free-to-grow status was recorded for all oak saplings and estimated cover of the exotic invasive shrub Elaeagnus umbellata and vine Lonicera japonica were documented. Results show significantly higher numbers of total oaks and free-to-grow oaks in plantings previously cropped in clover and soybeans when compared to the fallow sites host to brush species that received treatment (mowing and or herbicidal application). Significantly less oaks in the soybean and clover categories possessed a vine on the main bole of the tree when compared to the treated brush sites. Brush sites showed a significantly less number of total trees compared to clover and soybean covers and a higher percent of autumn olive cover (%) compared to soybeans. No significance was found in the percent of oaks with a vine, the percent of oaks overtopped, E. umbellata density or L. japonica cover (%) across the four previous vegetation categories. One treatment of pre-planting mowing and herbicidal application is not effective on fallow sites that are host to early successional species and money should not be invested on Quercus trees or mowing and herbicidal treatments in these scenarios. The results suggest that it is best to plant Quercus species immediately following clover or soybean harvest on abandoned agricultural lands before early successional species become established.
334

Succession of an Upland Oak/Hickory Forest in the Central Hardwood Region

Hoover, Nathan 01 August 2018 (has links)
For the last 9,000-10,000 years the Central Hardwood Region (CHR) has been primarily composed of a mosaic of mesophytic communities in climax and communities of successional forest types dominated by oak (Quercus Linnaeus) and hickory (Carya Nuttall). Shade intolerant oak/hickory dominated forest types have been maintained by natural disturbance processes in synergy with anthropogenic causes, resulting in a large composition of communities which are neither at climatic nor edaphic climax. Reduction in fire events, thinning, forest grazing, and other disturbance processes over the last 80-100 years have coincided with decreased regeneration of shade intolerant species due to lack of adequate light availability and recruitment of shade tolerant species of communities dominated by American beech (Fagus grandifolia L.) and maple (Acer saccharum L.) into the overstory of forests typically dominated by oak/hickory. Forest inventory data at Trail of Tears State Forest was analyzed across two separate time events (1980 and 2014) to determine compositional and structural changes which have occurred. Density, basal area, and community patterns via ordination were compared across six Ecological Land Types (ELTs) to determine topography’s effect on composition. Community trends were analyzed via NMS Ordination and between ELTs by a Mantel Test. A Multi-Response Permutation Procedures (MRRP) was also used as a nonparametric method for assessing differences between ELTs examined in the NMS. Density and basal area between years for species, ELT, and species*ELT interactions were compared. Across all ELTs, between 1980 and 2014, overstory density decreased from 218 trees/ac in 1980 to 180 trees/ac in 2014 and basal area increased from 98 ft2/ac in 1980 to 106 ft2/ac in 2014. Maple basal area increased from 5 ft2/ac to 12 ft2/ac while beech increased from 1 ft2/ac to 8ft2/ac, signifying progression of these species from the understory up into the canopy. The component of soft masting species within the forest has also decreased sharply in the last 34 years. MRPP analysis of overstory compositional gradients reported distinct species compositions between ELTs, however the trend was weak (MRPP: p < 0.001, A = 0.038). NMDS ordination graphs confirmed MRPP showing little separation among ELTs. The final stress was 18.71146 and instability was < 0.01 after 212 iterations (Table 6). Our research at TTSF is a clear example of oak/hickory succession to beech maple on an upland site among species community types as delineated by topographic moisture gradient (ELTs) within the CHR. Expansion of beech and maple onto xeric ELTs suggests a breakdown of edaphic barriers that have previously been thought to be resistant to encroachment from mesophytic species. Currently oak decline induced by lack of management is likely the number one forest health issue resulting in loss of oak/hickory and other soft masting species.
335

Ecological restoration of an oak woodland in Kansas informed with remote sensing of vegetation dynamics

Galgamuwe Arachchige, Pabodha Galgamuwa January 1900 (has links)
Doctor of Philosophy / Department of Horticulture, Forestry, and Recreation Resources / Charles J. Barden / Recurrent, landscape-level fires played an integral part in the development and persistence of eastern oak (Quercus spp.) forests of the United States. These periodic surface fires helped secure a competitive position for oaks in the regeneration pool by maintaining a desirable species composition and forest structure. This historical fire regime was altered with the European settlement of North America, and fire suppression within forestlands became a standard practice since 1930s. With decades of fire suppression, mature oak-dominated woodlands have widely converted to shade-tolerant tree species. Prescribed fire has successfully been used to enhance oak regeneration in eastern forests. However, oak woodland restoration within the forest-prairie ecotone of the Central plains has not been systematically studied. Fuel beds under shade-tolerant species are often less conducive to fire. Therefore, monitoring fuel loading (FL) and its changes are essential to inform management decisions in an oak regeneration project. Rapid expansion of eastern redcedar (Juniperus virginiana/ERC) is another ecological issue faced by land managers throughout North America’s midcontinent forest-prairie ecotone. Hence, it is worthy to monitor ERC expansion and effects on deciduous forests, to inform oak ecosystem restoration interventions within this region. Therefore, the main objectives of this dissertation were three-fold: (1) understand the effects of prescribed burning and mechanical thinning to encourage oak regeneration; (2) investigate the initial effects of an oak regeneration effort with prescribed fire and mechanical thinning on FL; and (3) monitor the spatio-temporal dynamics of ERC expansion in the forest-prairie ecotone of Kansas, and understand its effects on deciduous forests. The first two studies were conducted on a 90-acre oak dominated woodland, north of Manhattan, Kansas. The experimental design was a 2 (burn) x 2 (thin) factorial in a repeated measures design. The design structure allowed four treatment combinations: burn only (B), thin only (T), burn and thin combined (BT), and a control (C). Burning and thinning treatments were administered in spring 2015. Changes in the FL estimates after the burn treatment revealed that the BT treatment combination consumed more fuel and burned more intensely compared to the B treatment. This observation was reflected in vegetation responses. The thinning reduced the canopy cover significantly, but under enhanced light environments, both oaks and competitive species thrived when no burn was incorporated. In contrast, burn treatments controlled the competitive vegetation. Hence, the most promising results were obtained when both fire and thinning were utilized. The remote sensing study documented the expansion of ERC in three areas of eastern Kansas over 30 years. The use of multi-seasonal layer-stacks with a Support Vector Machines (SVM) supervised classification was found to be the most effective approach to map ERC distribution. Total ERC cover increased by more than 6000 acres in all three study areas investigated in this study between 1986 and 2017. Much of the ERC expansion was into deciduous woodlands. Therefore, ERC control measures should be incorporated into oak woodland restoration efforts within the forest-prairie ecotone of Kansas.
336

Envelhecimento da cachaça com circulação forçada e aeração

Borragini, Michelle de Caiado Castro [UNESP] 04 March 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:23:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-04Bitstream added on 2014-06-13T19:09:10Z : No. of bitstreams: 1 borragini_mcc_me_arafcf.pdf: 528016 bytes, checksum: cb194bfea30793f9c1000a6a2c361d48 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Ministério da Ciência, Tecnologia e Inovação (Mcti) / O envelhecimento melhora significativamente os atributos de qualidade da cachaça, permitindo obter-se um produto compatível com as crescentes exigências dos mercados externo e interno, como se pode constatar com o aumento do consumo de cachaças com qualidade diferenciada. A redução do tempo necessário para se obter os benefícios do envelhecimento, maior obstáculo à adoção desta etapa na produção da cachaça, tem sido constantemente testada em função da economia que pode representar e também, como uma forma de estimular e difundir a adoção da prática do envelhecimento dessa bebida. Em trabalhos anteriores, amostras de cachaças bidestiladas, oriundas de um mesmo lote, foram postas a envelhecer de forma tradicional, em pequenos ancorotes de carvalho, e também utilizando-se um processo de circulação forçada com 6 ancorotes interligados em série com um reservatório de vidro, sendo então as amostras coletadas de ambos os processos comparadas. Os resultados obtidos, utilizando-se ou não nitrogênio no “headspace” do reservatório de vidro, revelaram um papel crucial da presença de ar no sistema de circulação, efeito que foi avaliado no presente estudo. Nesse sentido, foi introduzida no sistema de circulação forçada da cachaça uma etapa de aeração do sistema, realizada diariamente durante 12 minutos. Os resultados obtidos revelaram que as amostras de cachaças submetidas ao processo de envelhecimento forçado com aeração, apresentaram ao longo de seis meses, menor extração dos componentes da madeira, menor teor de acidez e tendência de melhor aceitação em relação aos atributos analisados (cor, aroma, sabor, impressão global, sabor adocicado, sabor amadeirado e agressividade), quando comparadas com as amostras submetidas ao envelhecimento tradicional, revelando que a injeção de ar no sistema de circulação forçada pode influenciar... / The aging process, improves significatively the quality sensory attributes of “cachaça” resulting final products that attend the growing marketing quality expectatives, as showed by the increasing consume of the better quality “cachaças”. The reduction of the time to obtain to aging benefits has been tried out, as a way to reduce costs and to stimulate the adoption of this practice in the “cachaças” production. In previous studies, bidistilled “cachaça” aged by the traditional way and by forced circulation through 6 small wood casks and a glass vessel, during 6 months, were compared. The results from the circulating samples, having or not nitrogen in the glass vessel headspace, showed an inportant role of the presence of air in the circulating system. In this work, the air presence effect was verified by introducing air into the circulating “cachaça”, during 12 minutes every day and comparing the samples colected during 6 months. The obtained results showed that the air injection into the system, slow down the acidity and the wood extraction, as well indicate a tendency of better acceptability of the circulating samples in relation to the sensory attributes (color, aroma, taste, global impression, sweed taste, wood taste and agressivity) when compared with that aged by the traditional way, pointing out that the air injection into the forced circulating aging system, may represent a positive... (Complete abstract click electronic access below)
337

Envelhecimento da cachaça com circulação forçada e aeração /

Borragini, Michelle de Caiado Castro. January 2009 (has links)
Orientador: João Bosco Faria / Banca: João Bosco Faria / Banca: Fernando Valadares Novaes / Banca: Natália Soares Janzantti / Resumo: O envelhecimento melhora significativamente os atributos de qualidade da cachaça, permitindo obter-se um produto compatível com as crescentes exigências dos mercados externo e interno, como se pode constatar com o aumento do consumo de cachaças com qualidade diferenciada. A redução do tempo necessário para se obter os benefícios do envelhecimento, maior obstáculo à adoção desta etapa na produção da cachaça, tem sido constantemente testada em função da economia que pode representar e também, como uma forma de estimular e difundir a adoção da prática do envelhecimento dessa bebida. Em trabalhos anteriores, amostras de cachaças bidestiladas, oriundas de um mesmo lote, foram postas a envelhecer de forma tradicional, em pequenos ancorotes de carvalho, e também utilizando-se um processo de circulação forçada com 6 ancorotes interligados em série com um reservatório de vidro, sendo então as amostras coletadas de ambos os processos comparadas. Os resultados obtidos, utilizando-se ou não nitrogênio no "headspace" do reservatório de vidro, revelaram um papel crucial da presença de ar no sistema de circulação, efeito que foi avaliado no presente estudo. Nesse sentido, foi introduzida no sistema de circulação forçada da cachaça uma etapa de aeração do sistema, realizada diariamente durante 12 minutos. Os resultados obtidos revelaram que as amostras de cachaças submetidas ao processo de envelhecimento forçado com aeração, apresentaram ao longo de seis meses, menor extração dos componentes da madeira, menor teor de acidez e tendência de melhor aceitação em relação aos atributos analisados (cor, aroma, sabor, impressão global, sabor adocicado, sabor amadeirado e agressividade), quando comparadas com as amostras submetidas ao envelhecimento tradicional, revelando que a injeção de ar no sistema de circulação forçada pode influenciar... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aging process, improves significatively the quality sensory attributes of "cachaça" resulting final products that attend the growing marketing quality expectatives, as showed by the increasing consume of the better quality "cachaças". The reduction of the time to obtain to aging benefits has been tried out, as a way to reduce costs and to stimulate the adoption of this practice in the "cachaças" production. In previous studies, bidistilled "cachaça" aged by the traditional way and by forced circulation through 6 small wood casks and a glass vessel, during 6 months, were compared. The results from the circulating samples, having or not nitrogen in the glass vessel headspace, showed an inportant role of the presence of air in the circulating system. In this work, the air presence effect was verified by introducing air into the circulating "cachaça", during 12 minutes every day and comparing the samples colected during 6 months. The obtained results showed that the air injection into the system, slow down the acidity and the wood extraction, as well indicate a tendency of better acceptability of the circulating samples in relation to the sensory attributes (color, aroma, taste, global impression, sweed taste, wood taste and agressivity) when compared with that aged by the traditional way, pointing out that the air injection into the forced circulating aging system, may represent a positive... (Complete abstract click electronic access below) / Mestre
338

Nonhuman Neighbours: Animals, Community, and Relationships on the West Coast of British Columbia

Gioreva, Viara 29 September 2015 (has links)
This thesis argues that nonhuman animals are constructive of human societies by virtue of the complex relationships they form with humans, both at an individual and at a community level. This thesis also suggests that particular constructions of human/ nonhuman animal relationships fail to account for animal agency, and that the transgressions of liminal animals highlight this agency. Specifically, this thesis uses two case studies – deer in Oak Bay and bears on the Central Coast – to show how nonhuman animals can be seen as actors and as active shapers of our mixed-species social orderings and communities. This thesis argues that, rather than being passive objects who are subject to government policy and human orderings, these nonhuman animals are shaping political processes in their communities through the relationships they have formed with the humans around them. / Graduate
339

Influência da madeira de carvalho na qualidade da cerveja / Influence of oak wood on quality beer

Patricia Wyler 28 August 2013 (has links)
Cerveja é uma bebida alcoólica mundialmente popular e a mais consumida no Brasil. Existem diversos estilos de cerveja no mundo, os quais são produzidos por modificações no processo de produção, no uso de diferentes ingredientes, na maturação utilizando barris de madeira e/ou adição de fragmentos de madeira, entre outros. A maturação em madeira pode proporcionar complexidade aromática às bebidas, sendo a madeira de carvalho amplamente utilizada para a maturação de bebidas alcoólicas. O uso dessa madeira na maturação da cerveja é o foco desse trabalho, que maturou cervejas a 0°C, durante três meses, em garrafas de vidro de 600 mL, barris de carvalho e recipientes plásticos com cubos de carvalho, na dose de 3g/L, provenientes de três níveis diferentes de tosta (leve, média, e alta). Das cervejas oriundas dos diferentes tratamentos, foram analisadas graduação alcoólica, pH, acidez total, turbidez, fenólicos totais, cor e amargor; os compostos voláteis (aldeídos, ésteres e álcoois superiores) foram analisados por Cromatografia gasosa (FID) e os compostos fenólicos de baixo peso molecular (ácido gálico, 5-hidroximetil-furfural, furfural, ácido vanílico, ácido siríngico, vanilina, siringaldeído, coniferaldeído e sinapaldeído) por Cromatografia líquida de alta eficiência (HPLC). As cervejas também foram analisadas sensorialmente mediante teste de preferência. A análise dos resultados mostrou que não houve alterações na qualidade da cerveja que pudessem ser atribuídas ao armazenamento com madeira. Os compostos voláteis tiveram pequenas alterações, por outro lado, os compostos fenólicos de baixo peso molecular foram os que apresentaram maiores incrementos no período de três meses de maturação. Não houve diferença na aceitação sensorial entre as cervejas maturadas com cubos de madeira, barril e em garrafas de vidro. Futuros estudos são necessários para que seja possível obter um produto de qualidade que possa satisfazer o consumidor e seja acessível à indústria. / Beer is a very popular alcoholic beverage in the world and the most widely consumed in Brazil. There are many styles of beer in the world that can be produced by changes in the production process, use of various ingredients, maturation using wood barrels and / or addition of wood fragments, and others. Wood maturation can provide aromatic complexity to alcoholic beverages, and the oak wood is widely used. The use of oak in the maturation of beer is the focus of this work. The beers matured at 0 °C for three months in glass bottles of 600 mL, oak barrels and plastic containers with oak cubes at a dose of 3g/L, with three different levels of toasting (light, medium, and high). Beers resulting from the different treatments were analyzed physico-chemically (alcohol content, pH, total acidity, turbidity, total phenolics, color and bitterness), the volatile compounds (aldehydes, esters and higher alcohols) by gas chromatography (FID), the low molecular weight phenolic compounds (gallic acid, 5-hydroxymethylfurfural, furfural, vanillic acid, syringic acid, vanillin, syringaldehyde, coniferaldehyde and sinapaldehyde) by High Performance Liquid Chromatography (HPLC), and sensory. The analysis shows that there were no qualities changes in beer that could be attributed to the storage in contact with oak wood. The volatile compounds had minor changes; the low molecular weight phenolic compounds were those with the greatest increases within three months of maturation. There was no difference in sensory acceptance between beers matured in oak barrel, oak cubes and glass bottles. This work suggests that wood influences sensory beer, but more studies are needed to be able to get a quality product that can satisfy the consumer and is accessible to the industry.
340

Changes in the landscape and vegetation of southeastern Vancouver Island and Saltspring Island, Canada since European settlement

Bjorkman, Anne Donahey 05 1900 (has links)
Early land survey records can be used to reconstruct the historical distribution and abundance of tree species prior to the large-scale impact of industrialized societies. Comparing these records to current vegetation patterns enables an examination of the shifts that have occurred in plant communities since the arrival of European settlers in North America. I used presettlement (1859-1874) land survey records from southeastern Vancouver Island and Saltspring Island, British Columbia, Canada to reconstruct the relative abundance and density of tree species in these areas. I then collected equivalent vegetation data from the same points in the modern landscape, which enabled me to compare the two points in time and identify the changes in large-scale vegetation patterns that have occurred since European settlement. My results show a significant increase in the relative abundance of maple (Acer macrophyllum) and cedar (Thuja plicata), and a corresponding decrease in Douglas-fir (Pseudotsuga menzeisii). Furthermore, there has been a considerable increase in tree density in undeveloped areas. The 1859 records indicate that at least one third of the land surveyed was made up of prairies or open “plains,” while a combination of open woods and forests made up the remaining two thirds. Based on comparable density measures from 2007, prairies and plains now represent less than 5% of the undeveloped landscape, while forests comprise nearly 90%. These changes are likely due to a combination of factors that have been influenced by European settlement, most notably logging and fire suppression. The suppression of fire has led to an infilling of trees into previously open areas and has led to the rapid decline of the open prairie and savanna habitat types once common in this area. The results of this study can inform conservation efforts throughout the study area, particularly those involving the restoration of prairie or savanna habitats. / Science, Faculty of / Botany, Department of / Graduate

Page generated in 0.0416 seconds