Letteratura scientifica selezionata sul tema "Temperate oaks"
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Articoli di riviste sul tema "Temperate oaks"
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Petersson, Linda K., Magnus Löf, Anna M. Jensen, Daryl R. Chastain e Emile S. Gardiner. "Sprouts of shoot-clipped oak (Quercus alba and Q. robur) germinants show morphological and photosynthetic acclimation to contrasting light environments". New Forests 51, n. 5 (14 novembre 2019): 817–34. http://dx.doi.org/10.1007/s11056-019-09762-5.
Testo completoAbstract (sommario):
AbstractSprouting by woody plants can increase species resilience to disturbance and foster regeneration during periods with little recruitment from seed. Though sprouting often plays a critical role in oak forest regeneration, there is little information available on sprouting capacity and sprout physiology at the seedling stage, particularly for new germinants. This study compared sprouting capacity and sprout photosynthesis of shoot-clipped germinants of two temperate oaks established in contrasting light environments. We studied the North American Quercus alba and the European Q. robur, both are in the section Quercus and appear to share similar biological and ecological requirements. Sprouting capacity for both species was enhanced under high light availability (29% more sprouts per plant), a response not previously noted for oak germinants. Seedling sprouts acclimated to high light with a 34% decrease in leaf area ratio, a 56% increase in leaf mass per area, and a 49% increase in the light-saturated maximum photosynthetic rate. Though both species appeared similarly adapted to shoot loss, a greater sprouting capacity (29% more sprouts per plant) and plant-level net photosynthesis (73% higher) was observed for Q. robur, regardless of light environment. As naturally regenerated oak seedlings in forest understories often experience disturbance or stress resulting in shoot loss or die-back, our results highlight the importance of the light environment during early plant development. Our comparison of temperate oaks from different continents should facilitate exchange of successful stand regeneration practices within the range of temperate oak forests.
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Franc, Niklas. "Standing or downed dead trees — does it matter for saproxylic beetles in temperate oak-rich forest?" Canadian Journal of Forest Research 37, n. 12 (dicembre 2007): 2494–507. http://dx.doi.org/10.1139/x07-096.
Testo completoAbstract (sommario):
For conservation of forest biodiversity, dead wood in the form of logs, snags, or cut high stumps is sometimes left or created when forests are harvested. In Scandinavia, such dead wood usually comes from conifers. For forests in temperate regions, few studies have analysed composition and species richness of beetles using dead wood of oaks ( Quercus spp). In this study in southern Sweden, I examined the occurrence of saproxylic beetles trapped at lying (logs) and standing (snags) dead wood of European oaks ( Quercus robur L. and Quercus petraea (Mattuschka) Liebl.) in 13 oak-rich mixed forests of relatively high conservation value. The assemblage of beetles differed strikingly between the lying and standing dead wood. Traps on lying dead wood, compared to traps on standing dead wood, had more fungivores and fewer primary and secondary wood boring species. Of 94 species tested for individual substrate preferences, 48 showed prevalence for different trap/substrate types. Absolute species richness was significantly higher on logs than snags, but a smaller proportion of the snag substrate or snag beetles may have been sampled. For red-listed beetles, no differences in their species richness were detected among substrates. These results suggest that logs of dead oaks are valuable and that both snags and logs of oak should be retained and, if needed, created in forestry, such that they are continuously available in stands.
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Harrington, Constance. "Oak Forest Ecosystems: Ecology and Management for Wildlife". Forest Science 48, n. 4 (1 novembre 2002): 792–93. http://dx.doi.org/10.1093/forestscience/48.4.792.
Testo completoAbstract (sommario):
Abstract Oaks (Quercus spp.) are important components in many temperate forest ecosystems, and a new book that synthesizes information on their management is always of interest. The intent of this book was to bring together knowledge from a diverse group of people who study oak forests and make that information available to those interested in managing those forests in a sustainable manner for wildlife. I think the authors have done a good job in achieving their objectives.
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Götmark, Frank. "Experiments for alternative management of forest reserves: effects of partial cutting on stem growth and mortality of large oaks". Canadian Journal of Forest Research 39, n. 7 (luglio 2009): 1322–30. http://dx.doi.org/10.1139/x09-045.
Testo completoAbstract (sommario):
Although protected forests are usually kept as free of human disturbance as possible, careful cutting may favour biodiversity in such areas. However, the use of heavy machinery during cutting operations may have a negative impact on protected forests. The large oaks ( Quercus spp.) found in many temperate nature reserves have a rich associated biodiversity. In 25 conservation forests in Sweden, the basal area growth and mortality of 250 large oaks (31–110 cm DBH) were compared between plots that were partially cut to promote the growth and survival of oaks and undisturbed plots. Each forest had one treatment plot (1 ha) and one undisturbed reference plot (1 ha) with similar levels of canopy cover. In 2002–2003, about 25% of the basal area was harvested in treatment plots, thereby increasing canopy openness from 14% to 33%. Cutting increased the mean relative basal area growth of large oaks (49% by plot, 22% by tree) after four seasons (P = 0.026). However, in nine forests, the growth rate was not higher in the treated plot than in the reference plot. Mortality, apparently due to cutting, was recorded only in one forest, where 18 large oaks died. Tree condition (percentage of dead large branches in crown) was the best (negative) predictor of growth rate, and openness around oak crown was also a (positive) predictor. Partial cutting favoured the growth of oaks and may be recommended, but a “hands-off” policy is also effective for these conservation forests.
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Castillo-Mendoza, Elgar, Alejandro Zamilpa, Manasés González-Cortazar, Ever A. Ble-González e Efraín Tovar-Sánchez. "Chemical Constituents and Their Production in Mexican Oaks (Q. Rugosa, Q. Glabrescens and Q. Obtusata)". Plants 11, n. 19 (4 ottobre 2022): 2610. http://dx.doi.org/10.3390/plants11192610.
Testo completoAbstract (sommario):
Mexico is considered one of the main regions of diversification of the genus Quercus (oaks). Oak species are one of the most important tree groups, particularly in temperate forests, due to its diversity and abundance. Some studies have shown that oak contains specialized metabolites with medicinal importance. In this work, the acetonic extract from leaves of three Mexican oaks (Quercus rugosa, Q. glabrescens, and Q. obtusata) was separated using thin-layer chromatography and column chromatography. Chemical identification of the major compounds was determined using high-performance liquid chromatography and nuclear magnetic resonance. Nineteen compounds were identified, three belonging to the terpenoid family (ursolic acid, β−amyrin, and β−sitosterol) and 16 from the phenolic family. Of the isolated compounds, seven are new reports for oak species (scopoletin, ursolic acid, β-amyrin, luteolin−7−O−glucoside, kaempferol−3−O−sophoroside, kaempferol−3−O−glucoside, and kaempferol−3−O−sambubioside). More compounds were identified in Q. rugosa followed by Q. glabrescens and then Q. obtusata. The characterization of specialized metabolites in oak species is relevant, from both phytocentric and anthropocentric perspectives.
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PÉNZES, ZSOLT, CHANG-TI TANG, GRAHAM N. STONE, JAMES A. NICHOLLS, SZABINA SCHWÉGER, MIKLÓS BOZSÓ e GEORGE MELIKA. "Current status of the oak gallwasp (Hymenoptera: Cynipidae: Cynipini) fauna of the Eastern Palaearctic and Oriental Regions". Zootaxa 4433, n. 2 (12 giugno 2018): 245. http://dx.doi.org/10.11646/zootaxa.4433.2.2.
Testo completoAbstract (sommario):
Cynipid gallwasps comprise 1364 species worldwide, predominantly in temperate regions of the Holarctic. The vast majority of recorded species are from the Nearctic and the Western Palaearctic, both of which are long-standing centers of research on the taxonomy and biology of this group. In contrast, the Eastern Palaearctic and the Oriental Region faunas are much less studied, but potentially extremely rich. Previously recorded species richness of cynipid groups in the Eastern Palaearctic and Oriental regions probably represents a significant underestimate. This is particularly marked for gallwasps associated with oaks (tribe Cynipini), as has been shown by recent works, which describe many new species galling oaks in the subgenera Quercus and Cyclobalanopsis and plants of the other Fagaceae genera (Castanopsis, Lithocarpus and Castanea). In the present paper, we summarise the current knowledge of oak gallwasps in the regions that extend from Pakistan, through Nepal and China to Japan and south to Indonesia, and list a total of 97 species of Cynipini from the area.
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Canadell, Josep, e Ferran Rodà. "Root biomass of Quercusilex in a montane Mediterranean forest". Canadian Journal of Forest Research 21, n. 12 (1 dicembre 1991): 1771–78. http://dx.doi.org/10.1139/x91-245.
Testo completoAbstract (sommario):
Biomass allocation to roots was studied in holm oak (Quercusilex L.), a dominant evergreen tree in broad-leaved sclerophyllous Mediterranean forests. The root systems of 32 single-stemmed holm oaks growing in shallow soils on largely unfissured bedrock were excavated in a mesic site and a xeric site in the Montseny Mountains (northeast Spain). Individual root:shoot biomass ratios (roots with diameter <1 cm not included) of single-stemmed trees were significantly higher in the xeric site (mean 0.45) than in the mesic site (mean 0.37), probably reflecting the lower water availability and higher light availability in the xeric site. It is concluded that single-stemmed holm oaks have higher root:shoot ratios than most temperate forest trees, particularly so when growing on a xeric site. Root:shoot ratios of single-stemmed trees were not linearly correlated with dbh. Allometric regressions of root biomass on dbh did significantly differ between sites. Roots <1 cm in diameter were sampled with soil cores in the mesic site. Holm oaks ≥5 cm dbh in a stand dominated by single-stemmed trees on the mesic site had an aboveground biomass of 160 t/ha and a belowground biomass of 63 t/ha. The belowground biomass was composed of 30 t/ha of root crowns plus roots >5 cm in diameter, 17 t/ha of roots 1–5 cm in diameter, and 16 t/ha of roots <1 cm in diameter. The xeric stand was dominated by multistemmed holm oaks with massive root crowns developed after repeated coppicing. Three multistemmed trees were excavated, yielding a mean root:shoot ratio of 1.2. Through resprouting from root crowns, managed or disturbed holm oak forests can accumulate a belowground biomass greater than that displayed aboveground: 91 t/ha (excluding roots <1 cm in diameter) and 79 t/ha, respectively, in our xeric stand.
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Kremer, A. "Social Broadleaves. EUFORGEN genetic conservation network". Forest Systems 9, n. 4 (1 dicembre 2001): 117–23. http://dx.doi.org/10.5424/699.
Testo completoAbstract (sommario):
The «Social Broadleaves» EUFORGEN network include temperate oaks and beeches, as broadleaved species living in large population in pure or mixed forest. Most important economic Social Broadleaves have a wide distribution (Q. petraea, Q. robur and F. sylvatica). They occupy also a large ecological range, giving many opportunities for natural selection to differentiate populations. Species delineation is imprecise in oaks, and various names and classification are proposed in different countries. The main objective of the network is the development of «joint, long-term, practically oriented gene conservation strategies». Most urgent needs were expressed by each member mainly in the area of in situ conservation methods. Other objectives are to «stimulate collaborative initiatives related to conservation activities». These initiatives concern dissemination of information and research results, and the raising of awareness on conservation issues. A review of the current knowledge on genetic structure and dynamics is summarised in order to define the Genetic Resource Conservation Strategy for Social Broadleaves. There is an important morphological variation that encompasses taxonomic units. There is clearly a need to provide some common methodology for assigning oak trees to taxonomic units. Oak species belonging to the same botanical section intercross naturally. Natural hybridization can be seen as a mechanism to enrich genetic diversity. Oaks and beeches are preferentially outbreeding, with extensive gene flow by pollen. There is a common agreement that practical actions should be taken, even if knowledge on population structure is still lacking. Conservation strategies should be established not only to maintain diversity but also to safeguard the evolutionary potential of the species. In situ conservation measures are implemented in most countries for both Fagus and Quercus (mostly Q. petraea and Q. robur) based mostly on pragmatic rules. Ex situ measures are promoted in a few countries in the case of oaks. No additional measures are requested by the different members in the case of beech, since natural regeneration is widely used to renew the stands.
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Semerikova, S. A., Kh U. Aliev, N. V. Semerikov e V. L. Semerikov. "Phylogeography of Oak Species in the Caucasus Based on the Results of Chloroplast DNA Analysis". Генетика 59, n. 7 (1 luglio 2023): 772–88. http://dx.doi.org/10.31857/s001667582307010x.
Testo completoAbstract (sommario):
In order to study the biogeography and history of the temperate biota of the Caucasian region, one of the centers of biological diversity of Eurasia, the phylogeographic structure of the chloroplast DNA of roburoid oaks (Quercus L. sect. Quercus, Fagaceae) was studied. We analyzed 926 trees of five species (Quercus robur, Q. petraea, Q. pubescens, Q. hartwissiana, Q. macranthera) from 70 populations located in different parts of the Caucasus. Sequencing of five fragments with a total length of more than 10 000 bp revealed eight haplotypes, which were typed using chloroplast microsatellite loci (cpSSR), sequencing, and restriction analysis. The Quercus phylogenetic tree, which includes 34 chloroplast haplotypes of Western Eurasian and East Asian roburoid species, confirmed the monophyly of roburoid oaks, which form several lines that do not have supported topological relationships with each other. The haplotypes identified in the Caucasus belong to two divergent Western Eurasian lineages. These haplotypes are endemic for the Eastern Black Sea and Caucasian region and do not have related haplotypes beyond its borders, which indicates the long-term presence of oaks in the Caucasus and the historical links of the oaks of the Caucasian region with the Eastern Crimea and Eastern Turkey in the absence of chloroplast DNA exchanges with the Eastern European part of the range. The results of the present study indicate that Caucasian populations could not significantly contribute to the colonization of northern territories, and were not influenced by more northern populations, at least through seed transfer. The distribution zones of the Caucasian haplotypes almost do not intersect with each other, occupying certain geographical areas, probably due to the settlement from individual glacial refugia and genetic drift. The geographical structure of chloroplast DNA variability indicates a long-term presence of oak in addition to Western Transcaucasia (Colchis refugium), in the regions of the Northwestern, Central, Eastern Caucasus and the Lesser Caucasus. The coincident composition of the haplotypes of the studied oak species within the geographic regions indicates the long-term coexistence of different species in different parts of the Caucasus.
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Vincent-Barbaroux, Cécile, Daniel Berveiller, Caroline Lelarge-Trouverie, Rodrigo Maia, Cristina Máguas, João Pereira, Manuela M. Chaves e Claire Damesin. "Carbon-use strategies in stem radial growth of two oak species, one Temperate deciduous and one Mediterranean evergreen: what can be inferred from seasonal variations in the δ13C of the current year ring?" Tree Physiology 39, n. 8 (17 maggio 2019): 1329–41. http://dx.doi.org/10.1093/treephys/tpz043.
Testo completoAbstract (sommario):
Abstract Tree ring synthesis is a key process in wood production; however, little is known of the origin and fate of the carbon involved. We used natural 13C abundance to investigate the carbon-use process for the ring development in a temperate deciduous (Quercus petraea (Matt.) Liebl.) and a Mediterranean evergreen (Quercus ilex L.) oak. The sapwood carbon reserves, phloem sucrose contents, stem respired CO2 efflux and their respective carbon isotope compositions (δ13C) were recorded over 1 year, in the native area of each species. The seasonal δ13C variation of the current year ring was determined in the total ring throughout the seasons, as well as in slices from the fully mature ring after the growth season (intra-ring pattern). Although the budburst dates of the two oaks were similar, the growth of Quercus ilex began 50 days later. Both species exhibited growth cessation during the hot and dry summer but only Q. ilex resumed in the autumn. In the deciduous oak, xylem starch storage showed clear variations during the radial growth. The intra-ring δ13C variations of the two species exhibited similar ranges, but contrasting patterns, with an early increase for Q. petraea. Comparison between δ13C of starch and total ring suggested that Q. petraea (but not Q. ilex) builds its rings using reserves during the first month of growth. Shifts in ring and soluble sugars δ13C suggested an interspecific difference in either the phloem unloading or the use of fresh assimilate inside the ring. A decrease in ring δ13C for both oaks between the end of the radial growth and the winter is attributed to a lignification of ring cell walls after stem increment. This study highlighted the differences in carbon-use during ring growth for evergreen and deciduous oaks, as well as the benefits of exploring the process using natural 13C abundance.
Tesi sul tema "Temperate oaks"
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Keurinck, Léa. "Changement climatique et reproduction des plantes pérennes : le rôle clé de la phénologie florale". Electronic Thesis or Diss., Lyon 1, 2024. http://www.theses.fr/2024LYO10323.
Testo completoAbstract (sommario):
La reproduction de nombreuses espèces d’arbres forestiers est caractérisée par le masting, une production de graines fortement variable d’une année à l’autre au niveau individuel et synchronisée au sein d'une population. Cette dynamique de fructification fluctuante a des effets en cascade importants sur la dynamique et la régénération des écosystèmes forestiers. Dans le cas des chênes tempérés (Quercus robur et Q. petraea), la disponibilité annuelle en pollen pour la reproduction (ou la limitation pollinique) joue un rôle clé dans la production de graines. Celle-ci résulte à la fois de l’investissement dans la floraison, à l'échelle de la population, et des conditions météorologiques dans lesquelles se font la maturation et la diffusion du pollen. La phénologie pollinique, c'est-à-dire le moment du développement et de l’émission de pollen, entretient ainsi une relation étroite avec la dynamique des fructifications en contrôlant en grande partie le niveau de limitation pollinique. Pourtant, les mécanismes qui régissent la phénologie pollinique n’ont pas été étudiés, ce qui empêche de prédire l'impact du changement climatique sur celle-ci, et conséquemment sur les patrons de reproduction des chênes et la régénération des chênaies. Cette thèse a pour objectif de combler ce manque en établissant le lien entre la phénologie pollinique et le masting des chênes tempérés. Pour cela, j’ai cherché à identifier les déterminants de leur phénologie pollinique, à caractériser les liens avec la limitation pollinique et à investiguer les influences observées et attendues du changement climatique. J’ai en particulier croisé un jeu de données polliniques conséquent (rassemblant des données collectées par le Réseau National de Surveillance Aérobiologique sur un large réseau déployé dans 79 sites à travers la France métropolitaine depuis 1989 pour l’enregistrement quotidien de la quantité de pollen aéroportée) avec un jeu de données météorologique (SAFRAN) en mobilisant des modèles statistiques et mécanistes. Mon travail montre que (i) dans les conditions climatiques actuelles, le forçage (le cumul de chaleur en fin d’hiver et début de printemps) explique une grande partie (79 %) de la variabilité de la phénologie pollinique, ce qui en fait un mécanisme prioritaire à considérer pour proposer des projections réalistes sur le devenir du masting des chênes tempérés, (ii) les conditions météorologiques autour de la phénologie pollinique déterminent largement le niveau limitation pollinique, (iii) il existe une forte hétérogénéité spatiale en France dans la trajectoire de la limitation pollinique face au changement climatique depuis 1960, (iv) la trajectoire climatique récente a conduit à une avancée de la phénologie pollinique et une diminution de la limitation pollinique dont la diversité entre sites reste à expliquer. Mon travail illustre ainsi l’importance d’intégrer la phénologie florale aux travaux concernant le devenir de la reproduction des plantes pérennes dans le contexte du changement climatiqueThe reproduction of many forest tree species is characterised by masting, a highly variable seed production between years at individual level, and synchronised within a population. This fluctuating fruiting dynamics has major cascading effects on the dynamics and regeneration of forest ecosystems. In the case of temperate oaks (Quercus robur and Q. petraea), the annual availability of pollen for reproduction (or pollen limitation) plays a key role in seed production. This is the result both of investment in flowering, at the population scale, and of the meteorological conditions in which pollen maturation and distribution take place. Pollen phenology, i.e. the timing of pollen development and emission, is therefore closely linked to fruiting dynamics, largely controlling the level of pollen limitation. However, the mechanisms governing pollen phenology have not been studied, which makes it impossible to predict the impact of climate change on pollen phenology, and consequently on oak reproductive patterns and oak forest regeneration. The aim of this thesis is to fill this gap by establishing the link between pollen phenology and the masting of temperate oaks. To do this, I sought to identify the determinants of their pollen phenology, to characterise the links with pollen limitation and to investigate the observed and expected influences of climate change. In particular, I cross-referenced a large pollen dataset (gathering data collected by the Réseau National de Surveillance Aérobiologique on a large network deployed in 79 sites across mainland France since 1989 for daily recording of the quantity of airborne pollen) with a meteorological dataset (SAFRAN) using statistical and mechanistic models. My work shows that (i) under current climatic conditions, forcing (heat accumulation in late winter and early spring) explains a large part (79%) of the variability in pollen phenology, which makes it a priority mechanism to consider when proposing realistic projections for the future of temperate oak masting, (ii) meteorological conditions around pollen phenology largely determine the level of pollen limitation, (iii) there is strong spatial heterogeneity in France in the trajectory of pollen limitation in the face of climate change since 1960, (iv) the recent climate trajectory has led to an advance in pollen phenology and a decrease in pollen limitation, the diversity of which between sites remains to be explained. My work demonstrates the necessity of integrating floral phenology into studies examining the future of perennial plant reproduction in the context of climate change
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Poulos, Helen M., Graeme P. Berlyn e Uromi M. Goodale. "Physiological and Stuctural Mechanisms of Niche Differentiation for Three Sky Island Oaks in Relation to Light and Temperature". University of Arizona (Tucson, AZ), 2008. http://hdl.handle.net/10150/555932.
Testo completoAbstract (sommario):
In an effort to identify the influence of light and temperature on the physiology and leaf structural characteristics of three species of Quercus from Coahuila, Mexico, we measured a comprehensive suite of plant traits as functions of light and temperature intensity. We tested the hypotheses that 1) species' physiological responses to light and temperature were related to their distributions in their native habitats; and 2) that species' physiological responses corresponded to similar variation in leaf anatomical and morphological traits. Quercus sideroxyla was adapted to high elevation forest over stories as evidenced by its high photosynthetic rate, transpiration rate, relative water content (RWC), leaf density (LD), and thick palisade and spongy parenchyma. Quercus rugosa displayed typical characteristics of a forest understory species including a low photosynthetic rate and light saturation point, thick spongy parenchyma tissue and high RWC, leaf density, and leaf mass per unit area. Quercus laceyi was adapted to hot, dry sites based on its lower RWC and LD, intermediate photosynthetic rate, thick cuticle and upper epidermis, and low transpiration rates at high temperatures. Our results suggest that the physiological and structural adaptations of Mexican oaks to changing environmental conditions across resource gradients are key regulators of plant community structure.
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Paul, Carolyn. "Long-term response of a temperate forest community to prescribed burning and thinning". Master's thesis, Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/527651.
Testo completoAbstract (sommario):
BiologyM.S.
Temperate deciduous forests of eastern North America are undergoing a long-term compositional shift from oak/hickory-dominated forests to maple/birch-dominated forests, resulting in decreased species diversity and more homogeneous understory communities. This shift is likely due to secondary regrowth after extensive logging and intensive fire suppression efforts that together allowed shade-tolerant but fire-intolerant species to flourish. Managers have more recently sought to use forest management practices to counteract this shift. Our aim in this study was to improve understanding of how prescribed burning and mechanical tree thinning shape forest communities and the extent to which they favor declining species and communities of temperate eastern deciduous forest. We conducted our study at Fort Indiantown Gap National Guard Training Center in south-central Pennsylvania. Prescribed burning and mechanical thinning have been conducted onsite since 2003. Forestry plots were surveyed in 2003 just prior to management implementation and again about ten years after intensive management began, during 2013-2014. The data collected at forestry plots, including number of stems, tree diameter at breast height, management activities undertaken at the plot, and other environmental characteristics were analyzed using model selection and generalized linear mixed models. A broader community analysis was then conducted using non-metric multidimensional scaling and permutational multivariate analysis of variance (PERMANOVA) analyses. Specifically, we analyzed tree species persistence, changes in tree basal area, changes in the abundance of tree stems, and changes in the the distribution of basal area and stems within 16 tree species targeted for management and throughout the forest community as a whole following management action. Burning and thinning both had significant effects on tree species persistence, basal area, and stem abundance. The interaction of the two management techniques was rarely significant, but since thinning and burning affected different species of trees, the two management practices were complementary. At a whole community level, management by both burning and thinning shifted the forest composition back toward an oak/hickory-dominated forest, and without such management the shift to a maple/birch-dominated forest is likely to continue.
Temple University--Theses
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Franc, Niklas. "Conservation ecology of forest invertebrates, especially saproxylic beetles, in temperate successional oak-rich stands /". Göteborg : Göteborg University, 2007. http://www.loc.gov/catdir/toc/fy0802/2007423867.html.
Testo completo
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Franc, Niklas. "Conservation ecology of forest invertebrates, expecially saproxylic beetles, in temperate successional oak-rich stands /". Göteborg : Göteborg University, Department of Zoology, 2007. http://www.loc.gov/catdir/toc/fy0802/2007423867.html.
Testo completo
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Terrell, Mark A. "Sensitivity of northern red oak (Quercus rubra L.) to variation of temperature and moisture availability along latitudinal and longitudinal climate gradients". Virtual Press, 2002. http://liblink.bsu.edu/uhtbin/catkey/1247896.
Testo completoAbstract (sommario):
Spatial distribution of species and thus the composition of deciduous forests are expected to change in response to global climatic warming. Climate-growth response algorithms in forest simulation models that represent the influence of climate on tree growth are based on the geographic range limits of a species. These models assume that temperature limitations control the latitudinal range boundaries for tree species in the eastern United States, and that water limitations control the western range boundary. This study investigated spatial variation of tree-growth responses to historical variations in climate using tree-ring data for Quercus rubra L. from 71 study sites across latitudinal and longitudinal temperature and precipitation gradients in eastern North America. Correlation analyses were used to identify significant site-specific associations between radial growth indices and 130 climate variables for the common time interval 1930-1980. Geographic information systems (GIS), and Mantel and partial Mantel spatial correlation analyses were used to map, identify, and measure spatial associations between oak sensitivity to climate and regional climate patterns to test the hypothesis that climate controls the spatial distributions of species range limits.Seasonal climate variables exhibited the strongest correlations with radial growth most consistently across the 71 study sites. However, spatial patterns in regional climate were only weakly associated with spatial variation in red oak sensitivity to climate variables. Contrary to expectations, correlations between red oak radial growth indices and temperature variables at northern and southern sites were not significant, failing to support the hypothesis that latitudinal range limits are defined by temperature effects on mature tree growth. High early growing season temperature reduced growth mostly at sites in the southwest region, which concomitantly experienced high inter-annual variability in soil moisture. Increased early growing season site water balance and precipitation was associated with greater radial growth in the western third of red oak's range, partially supporting the hypothesis that the western range limit is defined by limited water availability. These results indicate that climate only partially determines range limit locations; thus model projections may exaggerate forest responses to climate change.Department of Biology
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Lightle, Nicole E. "Effects of Air vs. Air+Soil Heating During a Simulated Heat Wave on White Oak (Quercus alba) and Black Oak (Quercus velutina)". University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1365159241.
Testo completo
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Herdinius, Andreas. "En undersökning av möjliga tillväxtmiljöer vid den tidiga sågverkshanteringen av ek". Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-86212.
Testo completoAbstract (sommario):
Trä är ett biologiskt och organiskt material vars egenskaper möjliggör att det vid rätt förhållanden kan växa mögel på det. Mögeltillväxt på trä som människor hanterar och har i sin närhet kan skapa hälsoproblem då vissa mögelarter kan orsaka respiratoriska problem samt allergisk alveolit.En undersökning av vilken mögelsvamp som växer på brädor vid ett sågverk i södra Sverige har utförts. Utöver detta har möjliga tillväxtmiljöer för mögel undersökts under brädgårdstorkning samt en torkprocess. De undersökta parametrarna var temperatur och relativ luftfuktighet.Mögelsvampen Paecilomyces hittades samt Aspergillus niger och jäst. Klimatet under brädgårdstorkning samt torkprocessen visade att de under stor del av den tidiga hanteringen av virket fanns ett klimat gynnsamt för mögeltillväxt.Wood is a biological and organic material whose properties makes it possible for mold to grow on it under the right conditions. Mold growth on wood that humans handle and get in contact with can create health problems as some mold species can cause respiratory problems and allergic alveolitis.An investigation of which mold that grows on boards at a sawmill in southern Sweden has ben carried out. In addition to this, possible growth environments for mold have been investigated during lumber yard drying and a kiln drying process. The parameters examined were temperature and relative humidity.Mold of Paecilomyces, Aspergillus niger and yeast was found on boards. The climate during lumber yard drying and the kiln drying process showed that a large part of the early handling of the wood had a favourable climate to mold growth.
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Berggren, Sofia. "Water holding capacity and viscosity of ingredients from oats : the effect of b-glucan and starch content, particle size, pH and temperature". Thesis, Linnéuniversitetet, Institutionen för kemi och biomedicin (KOB), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-70544.
Testo completoAbstract (sommario):
Oats is a crop that contains a high amount of fiber, protein and fat, but like all other crops it contains mostly starch. In this study the focus has been oat flours and brans with different b-glucan content. The health benefits of b-glucan, a soluble fiber are well documented and a correlation between intake of b-glucan with high molecular weight and a low glycemic response has been observed. Food with a low glycemic index can lower the risk for diseases like type 2 diabetes, cardiovascular diseases and obesity. Also a connection between intake of b-glucan with high molecular weight and a reduction of LDL-cholesterol has been observed. b-glucans from oat absorb water and build a viscous gel, which make them an interesting component when developing new products, as a fat replacer in for example meat products and pastries. To optimize the use of flours and brans with a modified b-glucan content in new applications, the water absorption was measured with a method called Solvent Retention Capacity and the viscosity with a Rapid Viscosity Analyzer (RVA). The results showed that a higher amount of b-glucan in the flour or bran, a higher water holding capacity (WHC) was observed. The WHC for oat flour with a b-glucan content at 2% was calculated to 73±7%, while the WHC for oat bran with a b-glucan content at 28%, was calculated to a WHC of 880±45%. A comparison of different flours and brans indicates that dietary fiber, where b-glucan have the greatest impact on the WHC. The result from the RVA indicates that a flour with a combination of a high b-glucan content (0.24g) and high starch content (3.72g) leads to a high viscosity 12700 cP, compared to other flours or brans with either a lower b-glucan content (0.12g) or lower starch content (0.12g) gives lower final viscosity, 5390 and 780 cP. The result also indicates that other factors such as a smaller particle size and a higher temperature during the heating step (95°C instead of 64°C) might give a higher viscosity.
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Bednarz, Z., e J. Ptak. "The Influence of Temperature and Precipitation on Ring Widths of Oak (Quercus Robur L.) in the Niepolomice Forest Near Cracow, Southern Poland". Tree-Ring Society, 1990. http://hdl.handle.net/10150/261919.
Testo completoAbstract (sommario):
Analysis of the relationship between ring-width indices of pedunculate oaks (Quercus robur L.) in the Niepotomice Forest with average monthly air temperatures (1826-1980) and total monthly precipitation (1881-1985) in Cracow revealed a strict relationship between tree -growth and the precipitation of June-July, May-July, and June-August. These relationships are described by a high percentage of agreement, at or around 70 %, and coefficients of correlation (rx) of 0.40 (June-July), 0.36 (May-July) and 0.30 (June-August). The group of 10 oaks with the highest coefficients between growth and precipitation yielded still higher correlations: 0.50, 0.50, and 0.41, respectively. High total monthly precipitation in June and July favors radial growth, while low precipitation reduces radial growth. The influence of air temperature on oak ring-width indices is less significant. The highest positive correlation occurs for January to April of the preceding year. Correlations for the years of radial growth have values close to or below (June) zero except for August.
Libri sul tema "Temperate oaks"
1
V, Marshall B., e Roth Edward F, a cura di. Thermal measurements in Oak Springs Formation at the Nevada Test Site, southern Nevada. [Menlo Park, CA]: U.S. Geological Survey, 1987.
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2
Lachenbruch, Arthur H. Thermal measurements in Oak Springs Formation at the Nevada Test Site, southern Nevada. [Menlo Park, CA]: U.S. Geological Survey, 1987.
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3
Paltto, Heidi. Oak-rich temperate forests: Conservation ecology of cryptogams and vascular plants at local and landscape level. Göteborg: Göteborg University, 2008.
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Conservation ecology of forest invertebrates, especially saproxylic beetles, in temperate successional oak-rich stands. Göteborg: Göteborg University, 2007.
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Temperature Log Book for People: Body Temperature Tracker and Recorder for Employees, Patients or Visitors - Oak Brown Cover. Independently Published, 2021.
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Daniels, Richard Culver. An internship with the carbon dioxide information analysis and research program at Oak Ridge National Laboratory: The effects of greenhouse induced sea level rise on the South Carolina coast. 1991.
Cerca il testo completoCapitoli di libri sul tema "Temperate oaks"
1
Sork, V. L. "Evolutionary ecology of mast-seeding in temperate and tropical oaks (Quercus spp.)". In Frugivory and seed dispersal: ecological and evolutionary aspects, 133–47. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1749-4_9.
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Leininger, Theodor D. "Effects of Temperature and Drought Stress on Physiological Processes Associated With Oak Decline". In Ecological Studies, 647–61. New York, NY: Springer New York, 1998. http://dx.doi.org/10.1007/978-1-4612-2178-4_35.
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Pintos, Beatriz, José Antonio Manzanera e Arancha Gómez-Garay. "Production of Doubled Haploid Embryos from Cork Oak Anther Cultures by Antimitotic Agents and Temperature Stress". In Methods in Molecular Biology, 199–219. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-1331-3_13.
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Crosby, Donald G. "Poison Oaks, Poison Ivies, And Relatives". In The poisoned weed, 22–38. Oxford University PressNew York, NY, 2004. http://dx.doi.org/10.1093/oso/9780195155488.003.0002.
Testo completoAbstract (sommario):
Abstract To best understand and appreciate plants, one must relate them in some logical order. This is the function of taxonomy (table 2.1). For example, poi- son oak, poison ivy, and poison sumac all belong to the same large group or family of plants related to mango and cashew: the Anacardiaceae. Members of this family, some 70 genera representing 600 species (Mitchell and Mori, 1987), occur in tropical and temperate areas of the world except for New Zealand and the deserts of Asia, Africa, and Australia (Mitchell, 1990). Some of the familiar ornamental and economic species are discussed in chapter 3.
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ur Rahman, Amjad, Esra Gürbüz, Semih Ekercin e Shujaul Mulk Khan. "Spatial Dynamics of Forest Cover and Land Use Changes in the Western Himalayas of Pakistan". In Vegetation Index and Dynamics. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.98401.
Testo completoAbstract (sommario):
The current study deals with the mapping and evaluation of forest and land use cover changes in the western Himalayas, Pakistan. These forest types include i) Moist temperate forests ii) Mixed coniferous forests and iii) Sub-tropical broad leaved forests. Moist temperate forest mostly consists of evergreen conifers with some of oaks and deciduous trees. Subtropical pine forest are mostly dominated by Pinus roxburghii. These forest type are mostly mixed by Pinus roxburghii and other coniferous species like Pinus wallichiana at the upper ranges in Dewal, Angoori, Nambal, Aucha and Khanitak etc. The broad-leaved subtropical forests are recorded on the hills and in the lower slopes of Himalaya near Islamabad and Rawalpindi. The high quantity of vegetation index were observed in winter season as compared to summer. The Landsat satellite images of years 1988, 1998, 2008 and 2018 were classified into land-cover units. Vegetation land decreased in the total area whereas the bare land class increased in the total. Water class further reduced and the built- up class increased up in the Murree area, Pakistan.
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Desmond, Ray. "The Himalayas". In The European Discovery of the Indian Flora, 123–53. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198546849.003.0011.
Testo completoAbstract (sommario):
Abstract While apathy or, at best, subdued activity prevailed in botanical circles in western India, the Himalayas beckoned the adventurous and the curious, among them surveyors and scientists who observed in a casual note or expansive report the indigenous plant and animal life of this complex mountain range which separates India from Central Asia, extending from Afghanistan for 1700 miles to Assam in the East, and continues into China. A diversity of soils and climates, especially the summer monsoons, support what the plant collector, Frank Kingdon Ward succinctly described as an ‘immense reservoir of hardy plants’. A fertile jungle strip, ten to twenty miles wide-the terai-which skirts its eastern ranges is home to slender evergreens such as the sal (Shorea robusta) and tall bamboos. The abundant sal yields to conifers and oaks in a gradual ascent of four or five vertical miles through a progression of rain forest, temperate vegetation, conifers, and rhododendrons to the alpine zone above the tree-line at about 10 000 feet. Everywhere plants have adapted to their environment, a delicate ecological balance which man’s intervention through cultivation, grazing and logging is swiftly destroying with consequent erosion and lowland flooding. The phytogeographical variations range between the arid zones of the Hindu Kush and the warmer, wetter regions of the east, with Kashmir, Nepal, and Sikkim offering bumper harvests for botanist and plant collector.
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"Restoration of Midwestern Oak Woodlands and Savannas". In Restoration of Boreal and Temperate Forests, 416–43. CRC Press, 2015. http://dx.doi.org/10.1201/b18809-24.
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McCreary, Doug, e Isabel Cañellas. "Restoration of oak woodlands in Mediterranean ecosystems". In Restoration of Boreal and Temperate Forests, 253–66. CRC Press, 2004. http://dx.doi.org/10.1201/9780203497784.ch16.
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"Reaction of Collection Samples of Barley (Hordeum L.) and Oats (Avena L.) on Chloride Salinization". In Temperate Crop Science and Breeding, 359–70. Apple Academic Press, 2016. http://dx.doi.org/10.1201/b19861-28.
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Hardy, Thomas. "Chapter XXXVIII Rain: one solitary meets another". In Far from the Madding Crowd. Oxford University Press, 2008. http://dx.doi.org/10.1093/owc/9780199537013.003.0040.
Testo completoAbstract (sommario):
It was now five o’clock, and the dawn was promising to break in hues of drab and ash. The air changed its temperature and stirred itself more vigorously. Cool breezes coursed in transparent eddies round Oak’s face. The wind shifted yet a point or two...
Atti di convegni sul tema "Temperate oaks"
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Stinner, C. P., J. M. Rakowski e P. Maziasz. "Stainless Steels for High Temperature Heat Exchangers". In CORROSION 2006, 1–17. NACE International, 2006. https://doi.org/10.5006/c2006-06468.
Testo completoAbstract (sommario):
Abstract Stainless steels have been used for high temperature applications since their invention due to their inherent ability to form a protective chromium-rich oxide. As technology has continued to evolve, alloy compositions and processing schemes have been tailored to meet the demands of new applications, acting in synergy to affect the high temperature properties of the alloy. This paper reviews recent work at ATI Allegheny Ludlum on the development of alloys and processing to improve the high temperature properties of stainless steels. A joint project with Oak Ridge National Lab (ORNL) to improve the creep resistance of Type 347 stainless steel is discussed. In addition, the development of a creep and oxidation-resistant 20Cr-25Ni austenitic stainless steel will be reviewed. This alloy, developed in coil form in conjunction with Solar Turbines, has good high temperature strength and phase stability, while maintaining excellent oxidation resistance. The primary goal of this work has been in developing durable stainless steel foils for turbine recuperator applications. The work has since expanded to include other applications and product forms.
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Bagaria, Hitesh, Moshood Adewale, Nimeshkumar Patel, Jennifer Sargent e Trevor Place. "Nucleation Corrosion in Liquid Hydrocarbons". In CONFERENCE 2023, 1–9. AMPP, 2023. https://doi.org/10.5006/c2023-19463.
Testo completoAbstract (sommario):
Abstract Dewpoint corrosion is a well-known phenomenon in refinery overheads, where fine water droplets condense from the vapor upon cooling, and the acid gases in the vapors diffuse into water droplets to form a highly corrosive low pH liquid. We have identified a similar mechanism in hydrocarbon liquids (HLs), which we call as Nucleation Corrosion. HLs leaving warm separators are saturated with dissolved water (DW), which even in the presence of corrosive species such as organic acids (OAs) are not corrosive. Upon cooling, the DW nucleates as sub-micron free water droplets and organic acids present in the HL partition into the water droplets decreasing pH to ~3. These highly acidic water droplets cause aggressive corrosion, called ‘Nucleation Corrosion' (akin to dew point corrosion), where acids diffuse from liquid hydrocarbon to water nuclei. We present a systematic method to study, elicit the effect of OAs and H2S, temperature gradients and hydrocarbon composition as well as ways to mitigate Nucleation Corrosion. Further, our initial data suggests that nucleation corrosion may occur in refinery overhead naphtha reflux lines that have both high levels of OAs and insufficient insulation.
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Romedenne, Marie, Praneeth Bachu, James Smialek, Govindarajan Muralidharan e Rishi Pillai. "Unsupervised Clustering and Supervised Regression Learning to Select High Temperature Oxidation-Resistant Materials". In CONFERENCE 2025, 1–17. AMPP, 2025. https://doi.org/10.5006/c2025-00554.
Testo completoAbstract (sommario):
Abstract High temperature oxidation and corrosion degradation mechanisms dictate the lifetime of materials critical to energy production. The combination of modeling and experimental approaches such as machine learning (ML) and data analytics, with sufficient experimental data, can enable a cost-effective acceleration of the development of new materials. In the present work, ML will be applied to two high temperature oxidation data libraries (Oak Ridge National Laboratory and National Air and Space Administration) that comprised of about 5000 mass change sample datasheets for a variety of materials and temperatures in dry air and air + 10 % H2O. A python code was developed to prepare the data for machine learning by collecting and formatting oxidation rate constants, alloy compositions and environment of exposure into a single data frame. Scikit-learn library and Statistics and Machine Learning Toolbox within MathWorks were then used to perform unsupervised clustering and supervised regression learning. The impact of dataset distribution on the performance of the developed ML models was evaluated. Potential strategies to improve the predictions and enhance extrapolative capability of the previously trained model were investigated.
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Muralidharan, G., D. F. Wilson e J. R. Keiser. "Corrosion Evaluation of Alloys for High Temperature Service in Molten Fluoride Salt Cooled Reactors". In CORROSION 2017, 1–7. NACE International, 2017. https://doi.org/10.5006/c2017-09497.
Testo completoAbstract (sommario):
Abstract Fluoride Salt Cooled High Temperature Reactors (FHRs) are important to the world as a potential future primary electricity source, with a very high potential that the present fleet of aging Light Water Reactors (LWRs) could be replaced by FHRs. As both the fuel and coolants for FHRs are suitable for very high temperature use (well in excess of 1000 °C), the limiting factor in achieving the highest possible FHR core outlet temperatures and thus thermal efficiency is the availability of compatible structural alloys. Nickel based alloys are candidate materials for high temperature structural applications where they excel in retaining strength, creep and oxidation resistance at high homologous temperatures. There is an extensive body of information on the corrosion of materials in molten fluoride salts as a result of the work performed at the Oak Ridge National Laboratory (ORNL) on fluoride cooled reactors in the 1950s and 1960s. However, very little data is available on alloys for performance in molten fluoride environments at temperatures greater than 750 °C. Furthermore, the effect of alloying elements on the resistance to molten fluoride environments is not known. This study presents preliminary data on the corrosion behavior of selected experimental alloys in 46.5 LiF-11.5 NaF-42.0 KF (FLiNaK).
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Tsukada, T., K. Shiba, G. E. C. Bell e H. Nakajima. "Slow Strain Rate Tensile Tests in High Temperature Water of Spectrally Tailored Irradiated Type 316 Materials for Fusion Reactor Applications". In CORROSION 1992, 1–14. NACE International, 1992. https://doi.org/10.5006/c1992-92104.
Testo completoAbstract (sommario):
Abstract The susceptibility of neutron irradiated type 316 stainless steel to stress corrosion cracking in oxygenated pure water was investigated by Slow Strain Rate Technique(SSRT). The specimens had been irradiated to 8 dpa in the Oak Ridge Research Reactor(ORR) under fusion spectrally tailored condition to simulate radiation environment expected in the near-term water-cooled fusion reactor at temperatures of 60, 200, 330 and 400°C. SSRT tests were conducted at the same temperatures with irradiation for specimens irradiated at 60 and 200°C and at 300°C for specimens irradiated at 330 and 400°C. Intergranular cracking was observed on the specimens irradiated at higher two temperatures, while the specimens irradiated at lower two temperatures showed completely ductile fracture. Crack initiation by transgranular type fracture was observed. On fractured grain facets, apparent slip steps formed. Results of the SSRT were compared with those from specimens irradiated under LWR conditions and discussed.
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Bell, Samuel B. W., Bruce A. Pint, Mackenzie J. Ridley e Sebastien N. Dryepondt. "High Temperature Mechanical Behavior of Refractory Alloys with Digital Image Correlation". In AM-EPRI 2024, 62–73. ASM International, 2024. http://dx.doi.org/10.31399/asm.cp.am-epri-2024p0062.
Testo completoAbstract (sommario):
Abstract Gas turbine efficiency is typically limited by the maximum allowable temperature for components at the inlet side and in the hot gas flow. Refractory alloys and SiC/SiC ceramic-matrix composites (CMCs) are promising candidates for advancing operating temperatures beyond those of Ni-based alloys (>1200 °C). Refractory alloys are more suitable than SiC/SiC CMCs for dynamic components, due to the latter's low toughness and ductility. However, it is well known that refractory alloys suffer from poor oxidation behavior under service lifetimes and conditions, leading to embrittlement concerns. The ARPA-E ULTIMATE program has set out to combine new alloys with advanced coatings to mitigate oxidation/embrittlement effects, while increasing the mechanical performance benefits of refractory materials. Low oxygen (inert gas) or vacuum systems are needed to assess high temperature mechanical performance of developed alloys. To investigate the environmental sensitivity of candidate alloys and develop high temperature testing capabilities, four argon tensile frames were upgraded as well as a single vacuum system at Oak Ridge National Laboratory. Digital image correlation was incorporated into the vacuum frame allowing for surface strain determination and refined insight into thermomechanical response. Creep testing was performed at 1300 °C on two alloys, C-103 and MHC in vacuum and high purity argon environments. The Mo-based alloy showed less sensitivity to oxygen, indicating that testing in well-controlled argon environments may be suitable. The C-103 alloy demonstrated a stronger sensitivity to oxygen in the well-controlled argon environment, illustrating the need for the developed vacuum testing capabilities. “Small” 25 mm and “large” 76 mm MHC specimens showed comparable results in terms of strain rate during creep testing and ultimate tensile strength during tensile testing, suggesting the viability of smaller geometries that use less material of advanced developmental alloys.
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Maziasz, P. J., N. D. Evans e P. D. Jablonski. "High-Temperature Mechanical Properties and Microstructure of Cast Ni-Based Superalloys for Steam Turbine Casing Applications". In AM-EPRI 2010, a cura di D. Gandy, J. Shingledecker e R. Viswanathan, 900–915. ASM International, 2010. http://dx.doi.org/10.31399/asm.cp.am-epri-2010p0900.
Testo completoAbstract (sommario):
Abstract Advanced UltraSupercritical (A-USC) Steam fossil power plants will operate at steam temperatures up to 760°C, which will require the use of Ni-based superalloys for steam boiler/superheater and turbine systems. In 2008, the Oak Ridge National Laboratory (ORNL) and the National Engineering Technology Laboratory/Albany (NETL/Albany) collaborated to make and test castings of Ni-based superalloys, which were previously only commercially available in wrought form. These cast Ni-based based alloys are envisioned for the steam turbine casing, but they may also be applicable to other large components that connect the steam supply to the steam turbine. ORNL and NETL/Albany have produced small vacuum castings of HR 282, Nimonic 105, Inconel 740, and alloy 263, which are precipitation-hardened Ni-based superalloys, as well as solid-solution superalloys such as alloys 625, 617 and 230. The initial alloy screening included tensile and creep-testing at 800°C to determine which alloys are best suited for the steam turbine casing application at 760°C. HR 282 has the best combination of high-temperature strength and ductility, making it a good candidate for the cast-casing application. Cast and wrought versions of HR 282 have similar creep-rupture strength, based on the limited data available to-date. Detailed comparisons to the other alloys and microstructures are included in this paper.
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Yamamoto, Yukinori, Roger Miller, Tim Graening, Arunodaya Bhattacharya e M. Grace Burke. "Development of PWHT-Free, Reduced Activation Creep-Strength Enhanced Bainitic Ferritic Steel for Large-Scale Fusion Reactor Components". In AM-EPRI 2024, 1249–56. ASM International, 2024. http://dx.doi.org/10.31399/asm.cp.am-epri-2024p1249.
Testo completoAbstract (sommario):
Abstract A compositional modification has been proposed to validate an alloy design which potentially eliminates the requirement of post-weld heat treatment (PWHT) while preserving the advantage of mechanical properties in a reduced activation bainitic ferritic steel based on Fe-3Cr-3W-0.2V- 0.1Ta-Mn-Si-C, in weight percent, developed at Oak Ridge National Laboratory in 2007. The alloy design includes reducing the hardness in the as-welded condition for improving toughness, while increasing the hardenability for preserving the high-temperature mechanical performance such as creep-rupture resistance in the original steel. To achieve such a design, a composition range with a reduced C content combining with an increased Mn content has been proposed and investigated. Newly proposed “modified” steel successfully achieved an improved impact toughness in the as- welded condition, while the creep-rupture performance across the weldments without PWHT demonstrated ~50% improvement of the creep strength compared to that of the original steel weldment after PWHT. The obtained results strongly support the validity of the proposed alloy design.
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Keiser, James R., Gavin L. Warrington, Samuel A. Lewis, Raynella M. Connatser, Jiheon Jun, Jun Qu, Kyungjun Lee e Michael P. Brady. "Corrosion and Chemical Characterization of Bio-Oils from Biomass with Varying Ash and Moisture Contents". In CORROSION 2021, 1–10. AMPP, 2021. https://doi.org/10.5006/c2021-16726.
Testo completoAbstract (sommario):
ABSTRACT As part of the Feedstock Conversion Interface Consortium four samples of pine chips (all combinations of low and high moisture and ash content) were collected and processed for fast pyrolysis. The prepared biomass samples were liquefied at the National Renewable Energy Laboratory (NREL) using the fast pyrolysis process. Following some characterization of the bio-oils at NREL, the bio-oils were shipped to Oak Ridge National Laboratory (ORNL) for corrosion testing and further characterization. The content and composition of ash in each bio-oil was determined. Corrosion testing consisted of exposing selected metallic and elastomer samples for 1000 hr at 50°C and for longer times at room temperature as well as electrochemical impedance spectroscopy measurements to assess relative corrosivity of the bio-oils. Chemical characterization was conducted to identify the corrosive component of the bio-oils as well as to define the chemical differences among the oils. It was hypothesized that there could be a catalytic effect from the higher ash content in two of the biomass sources. Results of these characterization and corrosion studies will be reported.
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Nedealcov, Maria, Ala Donica e Nicolae Grigoras. "Evaluări privind impactul secetei asupra speciilor de stejari (Quercus Robur, Q. Petraea, Q.Pubescens) în condiții de aridizare a climei". In Starea actuală a componentelor de mediu. Institute of Ecology and Geography, Republic of Moldova, 2019. http://dx.doi.org/10.53380/9789975315593.27.
Testo completoAbstract (sommario):
The growth and survival of forests in the future, especially in the peripheral and transition areas of ecosystems, such as the Moldavian oak forests, depend directly on temperature changes and the amount of atmospheric precipitation. The purpose of this paper is to determine the potential impact of climate aridization on native species - oaks (Quercus robur, Q. petraea, Q.pubescens) in correlation with ecological niche for these species and identifying the vulnerability zones of forests versus the drought (reproduced by various values of the DeMartonne Index). It has been determined that mesophilic oak specie, during the vegetation period, in the central and southern part of the country, under more dry, more arid conditions of development, will feel changes in the sensitivity to water scarcity, changes in the compositional structure of the respective ecosystems and chorological displacements of the species (limiting the growth area of the Quercus robur, Q. petraea and advancing of Q.pubescens to the central part of country).
Rapporti di organizzazioni sul tema "Temperate oaks"
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Blasing, T. J., J. C. Wang e D. A. Lombardi. Temperature inversions in the vicinity of Oak Ridge, Tennessee, as characterized by tethersonde data. Office of Scientific and Technical Information (OSTI), gennaio 1998. http://dx.doi.org/10.2172/666221.
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Taylor, A., V. Allen, M. Burgess e J. Naufal. Wellbore temperature measurements and preliminary interpretation in terms of groundwater movement in the Oak Ridges Moraine, Ontario. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1999. http://dx.doi.org/10.4095/210953.
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Ren, Weiju, Jude Foulds, Roger Miller e Wolfgang Hoffelner. Oak Ridge National Laboratory Technical Input for the Nuclear Regulatory Commission Review of the 2017 Edition of ASME Section III, Division 5, ‘High Temperature Reactors’. Office of Scientific and Technical Information (OSTI), agosto 2020. http://dx.doi.org/10.2172/1661223.
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Hackbarth, Carolyn, e Rebeca Weissinger. Water quality in the Northern Colorado Plateau Network: Water years 2016–2018 (revised with cost estimate). National Park Service, novembre 2023. http://dx.doi.org/10.36967/nrr-2279508.
Testo completoAbstract (sommario):
Water-quality monitoring in National Park Service units of the Northern Colorado Plateau Network (NCPN) is made possible through partnerships between the National Park Service Inventory & Monitoring Division, individual park units, the U.S. Geological Survey, and the Utah Division of Water Quality. This report evaluates data from site visits at 62 different locations on streams, rivers, and reservoirs in or near ten NCPN park units between October 1, 2015 and September 30, 2018. Data are compared to state water-quality standards for the purpose of providing information to park managers about potential water-quality problems. The National Park Service does not determine the regulatory status of surface waters; state water quality agencies determine whether waters comply with the Clean Water Act. Evaluation of water-quality parameters relative to state water-quality standards indicated that 17,997 (96.8%) of the 18,583 total designated beneficial-use evaluations completed for the period covered in this report met state water-quality standards. The most common exceedances or indications of impairment, in order of abundance, were due to elevated nutrients, elevated bacteria (E. coli), elevated water temperature, elevated trace metals, elevated total dissolved solids (and sulfate), elevated pH, and low dissolved oxygen. While some exceedances were recurring and may have been caused by human activities in the watersheds, many were due to naturally occurring conditions characteristic of the geographic setting. This is most apparent with phosphorus, which can be introduced into surface water bodies at elevated levels by natural weathering of the geologic strata found throughout the Colorado Plateau. Higher phosphorus concentrations could also be attributed to anthropogenic activities that can accelerate erosion and transport of phosphorus. Some activities that can increase erosional processes include grazing, logging, mining, pasture irrigation, and off-highway vehicle (OHV) use. Exceedances for total phosphorus were common occurrences at nine out of ten NCPN park units, where at least one site in each of these parks had elevated phosphorus concentrations. At these sites, high levels of nutrients have not led to algal blooms or other signs of eutrophication. Sites monitored in Arches National Park (NP), Black Canyon of the Gunnison NP (BLCA), Bryce Canyon NP (BRCA), Capitol Reef NP (CARE), Curecanti National Recreation Area (CURE), Dinosaur National Monument (DINO), and Zion NP (ZION) all had E. coli ex-ceedances that could be addressed by management actions. While many of these sites already have management actions underway, some of the actions necessary to bring these waters into compliance are beyond the control of the National Park Service. Changes to agricultural practices to improve water quality involves voluntary participation by landowners and/or grazing permittees and their respective states. This could be the case with lands upstream of several parks with E. coli contamination issues, including Red Rock Canyon (BLCA); Sul-phur, Oak, and Pleasant creeks (CARE); Blue Creek and Cimarron River (CURE); Brush and Pot creeks (DINO); and North Fork Virgin River (ZION). Issues with E. coli contamination at Yellow Creek (BRCA) seemed to be resolved after the park boundary fence downstream of the site was repaired, keeping cattle out of the park. At North Fork Virgin River, E. coli exceedances have been less frequent since the State of Utah worked with landowners and grazing permittees to modify agricultural practices. Continued coordination between the National Park Service, state agencies, and local landowners will be necessary to further re-duce E. coli exceedances and, in turn, improve public health and safety in these streams. Selenium concentrations in Red Rock Canyon (BLCA) continued to exceed the state aquat-ic-life standard at both the upstream and downstream sites. Although selenium weathers naturally from bedrock and...
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The High Temperature Materials Laboratory: A research and user facility at the Oak Ridge National Laboratory. Office of Scientific and Technical Information (OSTI), dicembre 1992. http://dx.doi.org/10.2172/10105829.
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The High Temperature Materials Laboratory: A research and user facility at the Oak Ridge National Laboratory. Office of Scientific and Technical Information (OSTI), gennaio 1992. http://dx.doi.org/10.2172/6857486.
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