Thèse de doctorat : Sciences du Bois : Nancy 1 : 2009. / Titre provenant de l'écran-titre.

Decomposition, the process of breaking down organic material into its increasingly finer physical and chemical constituents, is an important component in the cycling of carbon and nutrients through an ecosystem. While ultraviolet (UV) radiation is known to be detrimental to human health, might it also play an important role in decomposition, and consequently soil fertility and land cover, in the arid southwestern US? To address this question, a 4-week field experiment was designed to quantify decomposition under contrasting radiant energy regimes at the Santa Rita Experimental Range near Tucson from July-August 2011. Velvet mesquite (Prosopis velutina) leaves were placed in litterbags constructed with fiberglass mesh and plastic that was either UV transparent or UV-B absorbing. The litterbags were deployed in open areas receiving full sun or in the shaded area beneath a shrub canopy. Leaf mass loss (an indicator of decomposition rates), soil-surface temperature, levels of photosynthetically active radiation, soil moisture, and precipitation were quantified over the 4-week period. UV (present vs. absent) and radiant energy environments (open areas vs. shaded) were compared using a mixed-effect model controlling for temporal autocorrelation. Soil-surface temperatures and decomposition rates in open areas were significantly higher (F1, 64 = 89.4, p < 0.0001; F1, 97 = 4.83, p = 0.0303, respectively) than those in shaded areas, but did not differ between UV treatments (F1, 97 = 0.064, p = 0.8012). These results suggest that over a short time period, radiant energy levels influence decomposition, but via temperature effects rather than via levels of UV.

La première partie de l’étude concerne l’évaluation des propriétés technologiques du bois de Prosopis juliflora poussant dans les régions semi-arides et arides du Kenya. Le duramen est durable vis à vis des champignons et relativement résistant vis à vis des termites. Les extractibles du duramen possèdent des propriétés fongistatiques et antitermites. Le bois de P. Juliflora est dimensionnellement stable et présente des caractéristiques calorifiques, anatomiques et mécaniques normales , mais un taux de cendre élevé. L’imprégnabilité de l'aubier est bonne. La deuxième partie de l'étude concerne la caractérisation chimique des extractibles et l’étude de leurs propriétés antioxydantes et antibactériennes. Le duramen contient une quantité importante (? 8 %) d’un flavonoïde rare, le (-)- mesquitol, alors que l’écorce renferme différents produits tels que de la (+)- épicatéchine, de la (+)-catéchine, de la 4-O-methylgallocatechine, des acides gras et des sucres. Le (-)-mesquitol comme la (+)-catéchine sont capables d’inhiber l'oxydation du linoléate de méthyle induite par l’AIBN ainsi que d’inhiber le radical du DPPH. Les extractibles du duramen obtenus avec différents solvants présentent des propriétés antioxydantes plus élevées comparativement à celles des extractibles contenus dans l'écorce ou l'aubier suggérant que les propriétés antioxydantes de ces derniers soient à l’origine des propriétés fongistatiques. Les extraits brutes acétoniques du duramen sont capables d’inhiber l’activité de E. faecalis (MIC? 2.5mg/ml). Les extractibles du P. juliflora peuvent donc être une source importante de flavanols connus pour leurs propriétés antioxidantes. L’utilisation des extractibles de P. juliflora comme additifs dans les produits où des propriétés antioxydantes et des propriétés antifongiques et antibactériennes douces sont requises telles que des produits de beauté, des savons et des shampoings peut constituer une voie de valorisation supplémentaire en plus de la valorisation du bois de cette essence pouvant limiter la pénurie de bois au Kenya et aux effets négatifs associés à cette essence. / The first part of the study was to evaluate technological wood properties of Prosopis juliflora growing in the semi-arid and arid land of Kenya. Heartwood is durable against all tested fungi and relatively resistant to termites. Heartwood extractives possess fungistatic and antitermitic properties. The wood of P. Juliflora is dimensionally stable with normal calorific, anatomical and mechanical characteristics but relatively high ash content and sapwood treatability. The second part of the study was to identify and characterise the chemical nature, antioxidant and antibacterial properties of extractives. Important amount (? 8 %) and high purity of the rare flavonoid (-)-mesquitol was identified in heartwood extractives, while (+)-epicatechin, (+)-catechin, 4’-O-methylgallocatechins, fatty acids and free sugar are present in the bark. (-)-mesquitol like (+)-catechin is able to slow down oxidation of methyl linoleate induced by AIBN as well as inhibit the activities of DPPH radical. Heartwood extractives by different solvents presented higher antioxidant properties compared to bark and sapwood extractives suggesting that antioxidant properties could be at the origin of fungistatic properties. The crude acetonic heartwood extractives were able to inhibit the activities of E. faecalis (MIC ? 2.5mg/ml). Extractives of P. juliflora could therefore be of valuable interest as potential source of flavanols, which have been described as powerful antioxidants. Utilisation of P. juliflora extractives as additives in products where antioxidant, mild fungicidal and antibacterial properties are required such as cosmetics, soaps and shampoo could offer another way of valorization in addition to the use of wood which can remedy to the shortage of wood resources in Kenya and the negative effects associated with this species.

Thesis (Ph. D.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xv, 175 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Submitted by Francine Silva (francine.silva@unipampa.edu.br) on 2016-10-11T13:17:09Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Análise morfométrica floral em três populações de prosopis affinis Spreng.( mimosoideae – fabaceae) no Bioma Pampa.pdf: 1018563 bytes, checksum: 1a8d86074edab175201cbc1d92e1d5ad (MD5) / Made available in DSpace on 2016-10-11T13:17:09Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Análise morfométrica floral em três populações de prosopis affinis Spreng.( mimosoideae – fabaceae) no Bioma Pampa.pdf: 1018563 bytes, checksum: 1a8d86074edab175201cbc1d92e1d5ad (MD5) Previous issue date: 2016-08-24 / Bioma Pampa, degradada pela exploração intensiva, incluindo Fabaceae como uma das famílias na sua maioria representadas em formações Savanna-Park. Mimosoideae contém espécies características da Pampa e apresenta diversos sistemas sexuais e reprodutivos entre inflorescência com especialização floral em Prosopis. Portanto, o seu papel pesquisa biologia floral e diferenciação entre P. affinis flores através inflorescência e relação entre essas características e Pampa fragmentação. Então, razão pólen / e as variações morfológicas entre base, meio e ápice da inflorescência coletadas em São Vicente do Sul, Cacequi e Quaraí-RS. biologia floral foi acessado com índice de fecundação cruzada (OCI), razão semente / óvulo, flores por inflorescência e peso de 1.000 kernel. Spikes têm em média 117,13 ± 29,50 flores tubulares amareladas, incluindo 23,33% de flores basais com tendência a auto-polinização alheios a posição da flor. Semente rácio / óvulo (0,503 ± 0,189) foi semelhante ao cruzamento embora OCI foi característico para as espécies de autogamia facultativa, nomeando flexibilidade reprodutiva. peso 1.000-kernel obtido foi de 9.98g. Houve redução reprodutiva em flores basais sem diferenciação reprodutiva desde principalmente anteras foram superiores sigma. Sua estratégia contribui para a ascensão da frequência de visitantes "taxas e flexibilidade do sistema reprodutivo facilita a criação de indivíduos em paisagens fragmentadas como Pampa. / Pampa biome, degraded by intensive exploitation, including Fabaceae as one of mostly represented families in Savanna-Park formations. Mimosoideae contains species characteristic of Pampa and presents diverse sexual and reproductive systems among inflorescence with floral specialization in Prosopis species. Therefore, its paper researches floral biology and differentiation between P. affinis flowers through inflorescence and relation between those traits and Pampa fragmentation. Then, pollen/ratio and morphological variations among base, middle and apex of inflorescence collected in São Vicente do Sul, Cacequi and Quaraí-RS. Floral biology was accessed with outcrossing index (OCI), seed/ovule ratio, flowers per inflorescence and 1,000-kernel weight. Spikes have in average 117.13±29.50 yellowish tubular flowers, including 23.33% of basal flowers with tendency to auto-pollination unrelated to flower position. Seed/ovule ratio (0.503±0.189) was similar to outcrossing although OCI was characteristic to facultative autogamy species, appointing reproductive flexibility. 1,000-kernel weight obtained was 9.98g. There was reproductive reduction in basal flowers without reproductive differentiation since mostly anthers were higher than sigma. Its strategy contributes to rise of frequency of visitors‟ rates and flexibility of reproductive system facilitates establishment of individuals in fragmented landscapes as Pampa.

Savannas comprise over one eighth of the world's land surface with some 50 Mha in North America alone. They are productive systems supporting a high level of both faunal and floral diversity and are of increasing socioeconomic importance. The maintenance and formation of savannas have been attributed to climate, soils, herbivory and fire. However, the reasons for the coexistence of trees and the grass layer have still to be determined. These two contrasting life forms create a complex of intra- and interspecific positive, negative, and neutral interactions, few of which have been quantified. Under lower-than-average rainfall, tree effects on grasses in a Prosopis savanna in northern Texas were largely neutral with few measurable competitive or facultative effects from the tree canopy. However, grasses demonstrated increased productivity where belowground competition with neighboring trees was removed. Similarly, tree growth increased following the removal of grasses under and around individual trees, particularly on shallower soils, but only during a season of significant precipitation. Low intensity burning of grasses enhanced growth of adult trees, but patterns were inconsistent between two different sites. Moderate clipping around individual trees had no apparent effect on tree growth. Intraspecific competition between savanna trees was not evident, but may have been blurred by an extensive, lateral distribution of near-surface roots. Overall, tree intraspecific competition was neutral regardless of soil depth, suggesting lateral tree roots may be only used opportunistically. Although some competitive relationships were verified, the differences in the responses between the two years of study, and at different sites indicated that soil depth and climate may have overriding impacts on tree-grass interactions and savanna dynamics in this system.

Savannas comprise over one eighth of the world's land surface with some 50 Mha in North America alone. They are productive systems supporting a high level of both faunal and floral diversity and are of increasing socioeconomic importance. The maintenance and formation of savannas have been attributed to climate, soils, herbivory and fire. However, the reasons for the coexistence of trees and the grass layer have still to be determined. These two contrasting life forms create a complex of intra- and interspecific positive, negative, and neutral interactions, few of which have been quantified. Under lower-than-average rainfall, tree effects on grasses in a Prosopis savanna in northern Texas were largely neutral with few measurable competitive or facultative effects from the tree canopy. However, grasses demonstrated increased productivity where belowground competition with neighboring trees was removed. Similarly, tree growth increased following the removal of grasses under and around individual trees, particularly on shallower soils, but only during a season of significant precipitation. Low intensity burning of grasses enhanced growth of adult trees, but patterns were inconsistent between two different sites. Moderate clipping around individual trees had no apparent effect on tree growth. Intraspecific competition between savanna trees was not evident, but may have been blurred by an extensive, lateral distribution of near-surface roots. Overall, tree intraspecific competition was neutral regardless of soil depth, suggesting lateral tree roots may be only used opportunistically. Although some competitive relationships were verified, the differences in the responses between the two years of study, and at different sites indicated that soil depth and climate may have overriding impacts on tree-grass interactions and savanna dynamics in this system.

Thèse de doctorat : Sciences physique et de l'ingénieur. Sciences du bois : Bordeaux 1 : 2008. Thèse de doctorat : Sciences physique et de l'ingénieur. Sciences du bois : Université Cheikh Anta Diop de Dakar : 2008. / Titre provenant de l'écran-titre.

Tesis de grado presentado para optar el titulo de Licenciature en Biologia, Universidad Mayor De San Simon, Facultad de Ciencias y Technologia, Carrea Biologia. / Abstract in Spanish and English.

Memoria para optar al Título Profesional de Ingeniero Agrónomo. Mención: Tecnología de los Alimentos / Se estudió la influencia del ión calcio (Ca+2) en el comportamiento reológico de dispersiones de goma de algarrobo (Prosopis chilensis (Mol.) Stuntz) proveniente de extracción ácida a concentraciones de 0,4 y 0,6% p/v. / The influence of calcium ion (Ca+2) in the rheological behavior of algarrobo seed gum dispersions (Prosopis chilensis (Mol.) Stuntz) obtained from acid extraction at 0,4 and 0,6% w/v concentration was studied.