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Long-term silvicultural trials contribute to sustainable forest management by providing a better scientific understanding of how forest ecosystems respond to periodic timber harvesting. In this study, species composition, diversity, and net periodic growth of tree species in a mixed mesophytic forest in the central Appalachians were evaluated after about a half century of management. Three partial cutting practices on 18 research compartments and on 3 unmanaged reference compartments were evaluated on 280 ha. Single-tree selection, diameter-limit harvesting, and timber harvesting in 0.162-ha patches were assessed on three northern red oak site index 50 (SI) classes: 24, 21, and 18. Shannon-Weiner's diversity index (H′) declined from the first (1951-1959) to last (1987-2001) measurements and was related to both SI (P = 0.004) and treatment (P = 0.009). Sugar maple (Acer saccharum Marsh.) and red maple (Acer rubrum L.) were the two most abundant species in recent years (1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001); in contrast, in initial inventories (1951)(1952)(1953)(1954)(1955)(1956)(1957)(1958)(1959), northern red oak (Quercus rubra L.) and chestnut oak (Quercus prinus L.) were most abundant. Net periodic annual increment (PAI) of merchantable trees (DBH ≥12.7 cm) was related to both SI (P = 0.004) and treatment (P = 0.003). Mean PAI ranged from 4.6 m 3 ·ha -1 ·year -1 for single-tree selection to 2.5 m 3 ·ha -1 ·year -1 for unmanaged reference areas across all SI classes. The decline of oak species suggests that only intensive and specific forest management focused on maintaining oak species can obtain historical levels of diversity.Résumé : Les expériences sylvicoles à long terme contribuent à l'aménagement forestier durable en procurant une meilleure compréhension scientifique de la façon dont les écosystèmes forestiers réagissent à une récolte périodique de matière ligneuse. Dans cet article, la composition en espèces, la diversité et la croissance périodique nette des espèces arborescentes dans une forêt mésique mixte de la zone centrale des Appalaches ont été évaluées après un demi-siècle d'aménagement. Trois méthodes de coupe partielle dans 18 compartiments expérimentaux et trois compartiments té-moins non aménagés ont été évalués sur une superficie de 280 ha. La coupe de jardinage par pied d'arbre, la coupe à diamètre limite et la coupe par trouées de 0,162 ha ont été évaluées pour trois classes d'indice 50 de station du chêne rouge : 24, 21 et 18. L'indice de diversité de Shannon-Weiner (H′) a diminué du premier (1951-1959) au dernier (1987-2001) inventaire et était relié à la fois à l'indice de station (P = 0,004) et au traitement (P = 0,009). L'érable à sucre (Acer saccharum Marsh.) et l'érable rouge (Acer rubrum L.) étaient les deux espèces les plus abondantes au cours des dernières années (1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001), alors que le chêne rouge (Quercu rubra L.) et le chêne châtai-gnier (Que...

This work investigates solute transport due to self-interstitial defects and radiation induced segregation tendencies in dilute ferritic alloys, by computing the transport coefficients of each system based on ab initio calculations of binding energies and migration rates. The implementation of the self-consistent mean field method in the KineCluE code allows to extend the calculation of transport coefficients to arbitrary interaction ranges, crystal structures, and diffusion mechanisms. The results show that the diffusivity of P, Mn, and Cr solute atoms is dominated by the dumbbell mechanism, that of Cu by vacancies, while the two mechanisms might be in competition for Ni and Si, despite the fact that the corresponding mixed dumbbells are not stable. Systematic enrichment at defect sinks is expected for P and Mn solutes due to dumbbell diffusion, and for Si due mainly to vacancy drag. Vacancy drag is also responsible for Cu and Ni enrichment below 1085 K. The RIS behavior of Cr is the outcome of a fine balance between dumbbell enrichment and vacancy depletion. Therefore, for dilute Cr concentrations global enrichment occurs below 540 K, and depletion above. This threshold temperature grows with solute concentration. The findings are in agreement with experimental observations of RIS and clustering phenomena, and confirm that solutedefect kinetic coupling plays an important role in the formation of solute clusters in reactor pressure vessel steels and other alloys.However, the capability of PDs (vacancies and self-interstitials) to carry solute atoms to the nucleation sites, although often inferred in simple terms from the solute-PD binding energies, is yet not fully characterized. Nowadays, precise analytical models based on the Self-Consistent Mean Field (SCMF) theory [25] or the Green-function approach [26], in combination with ab initio calculations of defect jump rates, allow for a highly accurate analysis of the intrinsic atomic-transport properties by calculation of the transport (Onsager) matrix [27]. By the latter methods, it has been proven that solute drag by vacancies is a widespread phenomenon arising below a given temperature threshold in body-centered cubic (bcc) [28,29], face-centered cubic (fcc) [30,31,32], and hexagonal close-packed (hcp) metals [33], provided that the vacancy-solute interaction is sufficiently strong.In dilute ferritic alloys, the threshold temperature has been systematically determined for all transition-metal impurities [34,29]. This threshold is near or above 1000 K for Cu, Mn, Ni, P, and Si, whereas it lies near 300 K for Cr. Therefore, vacancies are indeed capable of transporting all solutes to sinks (including nucleation sites), with the exception of Cr for which depletion at sinks is expected.On the other hand, the transport efficiency of self-interstitial atoms (SIA) has been only superficially investigated. Speculations based on ab initio evaluations of the stability of mixed dumbbells (MD) [35,36,37], and the interpretation of resistivity-recovery (RR) experiments [38,...