The projected exponential growth of the human population necessitates a concomitant increase in food supplies, and by implication an increase in fixed nitrogen for crops and pastures. This can to a large extent be supplied by biological nitrogen fixation (BNF). However, to achieve this goal improved effectivity of the legume-rhizobium symbiosis is required, implicating improvement in the macro- as well as the micro symbiont. Therefore the search for more effective microsymbionts is a sine qua non to provide better matching and tolerance to stress conditions. The aim of this study was to investigate the range of rhizobia associated with the exotic Australian Acacia species (A. meamsii, A. dealbata and A. decurrens) in South Africa and to determine whether these species could be useful to provide rhizobial strains for application in the South African inoculant industry in order to improve local existing biological nitrogen-fixing systems. Although these Acacia species are geographically widespread throughout South Africa, their root nodule bacteria have never been investigated in depth. Their widespread occurrence and presumed promiscuity suggested that they might form nitrogen-fixing symbioses with a wide range of indigenous rhizobial strains with different ecological adaptations. In this study nodulated plants of the three Acacia spp. were collected from diverse geographic areas with diverse climatic conditions and different soil pH's. Isolates were obtained from root nodules, purified and the putative rhizobial isolates characterized with sodium dodecyl-sulphate polyacrylamide gel electrophoresis (SDS-PAGE), supplemented at the genomic level with 16S rDNA sequence data of selected isolates. The majority of the isolates investigated were members of the genus Bradyrhizobium, whilst some isolates showed close relationships to the genera Agrobacterium, Mesorhizobium, Rhizobium and Sinorhizobium. As a result of their predominant association with the slow-growing strains of the genus Bradyrhizobium, the legume spp. A. meamsii, A. dealbata and A. decurrens as trap plants would not playa significant role as a source of diverse rhizobia for application in the South African inoculant industry. / Dissertation (MSc (Microbiology))--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted

Memoria para optar al Título Profesional de Ingeniero Forestal / Un estudio comparativo de concentraciones de algunos elementos traza fue llevado a cabo para dos especies forestales estabilizadoras, Acacia saligna y Eucalyptus camaldulensis, ubicadas sobre un complejo de tranques de relaves. Los tejidos vegetales y los sustratos fueron muestreados tanto en sitios cubiertos por los relaves como sitios aledaños (grupo control) de manera de evaluar las concentraciones y distribución de elementos traza en los tejidos de las plantas (hojas, ramas, frutos, tallos y raíces). Los sustratos de relave fueron muestreados a dos profundidades, determinándose, en cada uno de ellos, las fracciones biodisponibles y totales de los elementos Cu, Mn, Fe y Zn. En términos generales, se presentaron diferencias significativas entre los sitios muestreados, acumulándose una mayor cantidad de elementos traza en los individuos ubicados en el grupo relave tanto para tejidos vegetales como para los sustratos. En el caso de Acacia saligna el elemento que presentó la mayor acumulación fue el Fe, principalmente ubicado en las raíces con un comportamiento similar tanto en el grupo control como en el relave. Las concentraciones de Cu fueron más altas en las raíces de los individuos ubicados en el grupo relave. El Zn presentó mayores concentraciones en el grupo relave pero se distribuyó homogéneamente entre los tejidos. En general, el comportamiento de los elementos trazas en Eucalyptus camaldulensis fue similar al presentado en Acacia saligna salvo las concentraciones de Mo las cuales fueron menores.

Tree species belonging to the genus Acacia have a significant impact ecologically and economically in southern Africa. Together with the African baobab, these trees are recognized as icons of the African landscape. They are widely distributed in this area and extensively used by local communities as sources of energy, stock feed, medical remedies and building material. There is still a substantial lack of knowledge regarding the ecological association between these plants and other living organisms such as fungi. This is, however, not new to the African continent where fungi are generally poorly studied and collected, and it is envisaged that many new fungal species will be discovered as scientists focus their efforts more on this geographical niche. An example of the lack of knowledge on the fungal biodiversity in Africa is reflected in the limited reports of members of the Botryosphaeriaceae, described to date from Acacia spp.. A review on phytopathogens in South Africa by Crous et al. (2000) indicated no records of the Botryosphaeriaceae associated with native Acacia spp. Despite the importance of many species within the Botryosphaeriaceae as pathogens, knowledge about the true diversity and taxonomy of species in this family is limited, especially where native plant communities are concerned. This dissertation attempts to contribute to knowledge on the associations between members of the Botryosphaeriaceae and indigenous Acacia trees in southern Africa, and the possible role they may play in diseases of these trees. Chapter 1 represents a literature review that focuses on fungi previously associated with Acacia spp. on the African continent. Information provided in this chapter refers to available reports on pathogens and saprophytes occurring on Acacia spp. that are both native and nonnative to Africa. Special reference is made to those occurring in southern Africa. Due to the concern of the introduction of new pathogens in areas where native and non-native plants are co-existing, emphises is also placed on the possibility of pathogen-host jumps between native and non-native Acacia spp. The potential threat they might pose to the future biosecurity of these important trees is discussed. Acacia mellifera, also known as the blackthorn, is one of the native African Acacia spp. that has been extensively studied. This tree is threatened by a serious die-back disease with symptoms similar to the die-back typically caused by members of the Botryosphaeriaceae. In an effort to understand the association of the Botryosphaeriaceae with native Acacia spp. in southern Africa, a study was undertaken to search for the presence of these fungi on especially A. mellifera in Namibia and the Pretoria area in South Africa. Other Acacia spp. were also sampled in cases where they were present in the same areas as A. mellifera. These results are presented in chapter 2. In a previous study, the fungal diversity of native trees and plant species in the Northern Cape Province of South Africa was studied. This resulted in the isolation of a number of fungi that resembled the morphological characteristics of the Botryosphaeriaceae. In chapter 3, these fungi were further identified to species level based on morphological and phylogenetic characteristics. In chapter 4 an attempt was made to compare the Botryosphaeriaceae that are associated with important native trees with those occurring on non-native trees. To accomplish this, a pilot study was done to investigate the presence of the Botryosphaeriaceae on A. mearnsii in the Gauteng Province of South Africa. Results from chapters 2 and 3 on native Acacia spp. from Namibia and South Africa served as the bases of comparison for this chapter. Results of previous studies that investigated diseases of plantation grown A. mearnsii were also included for comparison. Lastly, a summary is included to review the results of this study and also the significance and impact these results made, not only on the taxonomy of the Botryosphaeriaceae, but also understanding the fungal biodiversity of indigenous tree species in southern Africa. To date, this is the most extensive study of the Botryosphaeriaceae associated with native African Acacia spp. and it is also the first study that resulted in the describtion of so many new species in this group of fungi from a single host. Results from this study indicated that there is a significantly greater diversity in the Botryosphaeriaceae associated with native Acacia spp. in southern Africa than was previously thought. This dissertation attempts to form the basis for future studies to finally understand the interactions between the Botryosphaeriaceae and their native hosts as well as their role and threat as pathogens to indigenous and economically important plants. Copyright / Dissertation (MSc)--University of Pretoria, 2009. / Microbiology and Plant Pathology / unrestricted

Submitted by PPG Engenharia e Tecnologia de Materiais (engenharia.pg.materiais@pucrs.br) on 2018-06-11T12:25:49Z No. of bitstreams: 1 Investiga??o de atividades biol?gicas e potencial uso de extratos das flores de Acacia mearnsii o.pdf: 2416660 bytes, checksum: d1a24de16c6bbd6f86f46d3c0bb1dbc0 (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-06-21T18:41:36Z (GMT) No. of bitstreams: 1 Investiga??o de atividades biol?gicas e potencial uso de extratos das flores de Acacia mearnsii o.pdf: 2416660 bytes, checksum: d1a24de16c6bbd6f86f46d3c0bb1dbc0 (MD5) / Made available in DSpace on 2018-06-21T18:54:44Z (GMT). No. of bitstreams: 1 Investiga??o de atividades biol?gicas e potencial uso de extratos das flores de Acacia mearnsii o.pdf: 2416660 bytes, checksum: d1a24de16c6bbd6f86f46d3c0bb1dbc0 (MD5) Previous issue date: 2018-03-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Although the Acacia mearnsii tree is widely cultivated and used in the industry, its flowers are seldom researched. Considering the extensive availability of A. mearnsii flowers and the growing interest in natural products, this work aimed at the obtainment of extracts from these flowers and investigation of their composition and biochemistry properties. In this work, essential oil and aqueous extract by steam distillation and extracts were obtained with supercritical fluid. The essential oil was characterized by CG-MS and olfactometry. The main compounds identified in the essential oil were 8-heptadecene, heptadecane, nonadecane e kaurene. The main aroma detected by olfactometric analysis was roast nutty, as well as coffee, sweet, floral, vegetal and spicy. Antioxidant activity was determined and the aqueous extract showed an activity superior to rutin standard. LC-qTOF-MS identified 42 likely phenolic compounds, such as quercitrin, naringenin, myricetin, rutin, and robinetin. The extracts obtained by supercritical extraction and isolated fractions presented activity against S. aureus. The yield of the supercritical extraction was optimized using factorial planning and mass transfer parameters were obtained through mathematical models that represent the extraction curve. Thus, it was concluded that the flowers of A. mearnsii can be exploited by extractive processes used in this study to generate a plant by-product. The results indicate the aromatic and antioxidant potential of the essential oil and aqueous extract, respectively, obtained with 2.0 bar steam distillation, while the supercritical extract has antibacterial action. / A Acacia mearnsii, apesar de ser amplamente cultivada e utilizada industrialmente, n?o tem o potencial de suas flores explorado. Considerando a disponibilidade de flores da A. mearnsii e o crescente interesse por produtos naturais, esse trabalho consistiu na obten??o de extratos destas flores e na investiga??o de suas composi??es e a??es bioqu?micas. A pesquisa compreendeu a extra??o do ?leo essencial e a obten??o do extrato aquoso de flores da planta via destila??o por arraste a vapor, al?m da extra??o com fluido supercr?tico. O ?leo essencial foi analisado por GC-MS e apresentou, entre os 31 compostos identificados, 8-heptadeceno, heptadecano, nonadecano e caureno como compostos majorit?rios. Na an?lise olfatom?trica (GC-O), os principais aromas detectados no ?leo essencial foram caf?, doce, floral, vegetal e refrescante, com destaque para ?castanha/defumado?. O extrato aquoso das flores da A. mearnsii apresentou atividade antioxidante superior ? da rutina. Utilizando cromatografia de alta resolu??o (LC-qTOF/MS), foram verificados 42 prov?veis compostos fen?licos, entre eles, quercitrina, naringenina, miricetina, rutina, robinetina. Os extratos obtidos via extra??o supercr?tica e fra??es isoladas apresentaram atividade frente a S. aureus. O rendimento da extra??o supercr?tica foi otimizado utilizando planejamento fatorial e par?metros da transfer?ncia de massa foram obtidos atrav?s de modelos matem?ticos que representam a curva de extra??o. Assim, concluiu-se que as flores de A. mearnsii podem ser exploradas pelos processos extrativos empregados nesse estudo a fim de gerar um co-produto da cadeia produtiva da planta, uma vez que o ?leo essencial e o extrato aquoso, obtidos pela extra??o por arraste a vapor a 2,0 bar, possuem, respectivamente, potencial arom?tico e poder antioxidante, enquanto o extrato obtido com fluido supercr?tico apresenta a??o antibacteriana.

Wong, Man Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 149-164). / Abstracts in English and Chinese; appendix in Chinese. / Abstract --- p.i / Abstract (in Chinese) --- p.iii / Acknowledgements --- p.iv / Table of contents --- p.vi / List of tables --- p.x / List of figures --- p.xii / List of plates --- p.xiv / List of appendices --- p.xv / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Study background --- p.1 / Chapter 1.2 --- Conceptual framework of the study --- p.3 / Chapter 1.3 --- Objectives of the study --- p.10 / Chapter 1.4 --- Significance of the study --- p.10 / Chapter Chapter 2 --- Literature Review --- p.12 / Chapter 2.1 --- Overview of world plantations --- p.12 / Chapter 2.2 --- Restoration through the establishment of exotic plantations --- p.13 / Chapter 2.2.1 --- Rationale for restoration --- p.13 / Chapter 2.2.2 --- Restoration principles --- p.14 / Chapter 2.2.3 --- Use of exotic plantations in restoration --- p.15 / Chapter 2.2.4 --- Role of exotic species in plantations --- p.16 / Chapter 2.2.5 --- Problems associated with exotic plantations --- p.18 / Chapter 2.3 --- Transforming exotic woodlands to native forests --- p.21 / Chapter 2.3.1 --- Options of woodland transformation --- p.22 / Chapter 2.3.2 --- Woodland transformation in Hong Kong --- p.26 / Chapter 2.4 --- Summary --- p.28 / Chapter Chapter 3 --- The Study Area --- p.29 / Chapter 3.1 --- Introduction --- p.29 / Chapter 3.2 --- Geological setting of Hong Kong --- p.29 / Chapter 3.2.1 --- Climate --- p.29 / Chapter 3.2.2 --- Geology --- p.30 / Chapter 3.2.3 --- Soils --- p.31 / Chapter 3.2.4 --- Vegetation --- p.32 / Chapter 3.3 --- Study area --- p.33 / Chapter 3.3.1 --- Site selection --- p.33 / Chapter 3.3.2 --- Tai Lam Country Park and characteristics of Acacia confusa plantations --- p.34 / Chapter 3.3.3 --- Site description --- p.35 / Chapter 3.3.4 --- Site management --- p.38 / Chapter 3.3.5 --- Feral cattle disturbance --- p.40 / Chapter Chapter 4 --- Environmental Changes after Clearfelling --- p.41 / Chapter 4.1 --- Introduction --- p.41 / Chapter 4.2 --- Materials and methods --- p.42 / Chapter 4.2.1 --- Instrumentation and microclimatic measurements --- p.42 / Chapter 4.2.2 --- Data processing and statistical analysis --- p.44 / Chapter 4.3 --- Results and discussion --- p.44 / Chapter 4.3.1 --- Solar radiation and temperature after clearfelling --- p.44 / Chapter 4.3.2 --- Relative humidity and wind velocity after clearfelling --- p.48 / Chapter 4.3.3 --- Effect of clearfelling on exotic woodland transformation --- p.52 / Chapter 4.4 --- Summary --- p.53 / Chapter Chapter 5 --- Changes in Soil Properties after Clearfelling --- p.55 / Chapter 5.1 --- Introduction --- p.55 / Chapter 5.2 --- Materials and methods --- p.58 / Chapter 5.2.1 --- Soil sampling --- p.58 / Chapter 5.2.2 --- Laboratory analysis --- p.58 / Chapter 5.2.2.1 --- Texture --- p.59 / Chapter 5.2.2.2 --- Soil reaction pH --- p.59 / Chapter 5.2.2.3 --- Soil organic carbon (SOC) and organic matter (SOM) --- p.59 / Chapter 5.2.2.4 --- Tokal Kjeldahl nitrogen (TKN) --- p.60 / Chapter 5.2.2.5 --- Carbon: nitrogen ratio --- p.60 / Chapter 5.2.2.6 --- Available phosphorus --- p.60 / Chapter 5.2.2.7 --- Exchangeable cations --- p.60 / Chapter 5.2.3 --- Data processing and statistical analysis --- p.61 / Chapter 5.3 --- Results and discussion --- p.61 / Chapter 5.3.1 --- Temporal change of soil texture and reaction pH after clearcutting / Chapter 5.3.2 --- Temporal change of soil organic matter after clearcutting --- p.65 / Chapter 5.3.3 --- Temporal change of Total Kjedahl Nitrogen after clearcutting --- p.69 / Chapter 5.3.4 --- Temporal change of exchangeable cations after clearcutting --- p.71 / Chapter 5.3.5 --- Temporal change of available phosphorus after clearcutting --- p.74 / Chapter 5.3.6 --- Soil nutrient status after clearfelling --- p.76 / Chapter 5.3.7 --- Importance of tree retention on nutrient cycling --- p.78 / Chapter 5.4 --- Summary --- p.80 / Chapter Chapter 6 --- Soil Nitrogen Fluxes after Clearfelling --- p.81 / Chapter 6.1 --- Introduction --- p.81 / Chapter 6.2 --- Materials and methods --- p.83 / Chapter 6.2.1 --- In situ core incubation --- p.84 / Chapter 6.2.2 --- Sampling method --- p.84 / Chapter 6.2.3 --- Laboratory analysis of mineral N --- p.86 / Chapter 6.2.4 --- "Calculation of N mineralization, leaching and uptake" --- p.86 / Chapter 6.2.5 --- Statistical analysis --- p.89 / Chapter 6.3 --- Results and discussion --- p.89 / Chapter 6.3.1 --- Seasonal variation of NH4-N and N03-N --- p.89 / Chapter 6.3.2 --- "Net ammonification, NH4-N leaching and NH4-N uptake" --- p.92 / Chapter 6.3.3 --- "Net nitrification, NO3-N leaching and NO3-N uptake" --- p.94 / Chapter 6.3.4 --- "Net mineralization, leaching and uptake" --- p.95 / Chapter 6.3.5 --- Mineral nitrogen budget --- p.101 / Chapter 6.4 --- Summary --- p.103 / Chapter Chapter 7 --- Growth Performance of Recruited Trees and Restocked Species after Clearfelling --- p.105 / Chapter 7.1 --- Introduction --- p.105 / Chapter 7.2 --- Materials and methods --- p.106 / Chapter 7.2.1 --- Species identification --- p.106 / Chapter 7.2.2 --- Sampling method --- p.106 / Chapter 7.2.3 --- Statistical analysis --- p.107 / Chapter 7.3 --- Results and discussion --- p.107 / Chapter 7.3.1 --- Effect of overstorey removal on the growth of recruited native trees / Chapter 7.3.2 --- Effect of overstorey removal on growth of restocked native seedlings --- p.112 / Chapter 7.3.3 --- Importance of tree retention and seedling restocking in native forest re-establishment --- p.114 / Chapter 7.3.4 --- Species selection for clearcut site --- p.115 / Chapter 7.3.5 --- Browsing damage by feral cattle and its prevention --- p.118 / Chapter 7.4 --- Summary --- p.120 / Chapter Chapter 8 --- Effect of Shade and Water on the Growth of Selected Native Species --- p.121 / Chapter 8.1 --- Introduction --- p.121 / Chapter 8.2 --- Materials and methods --- p.124 / Chapter 8.2.1 --- Study sites --- p.124 / Chapter 8.2.2 --- Experimental design --- p.124 / Chapter 8.2.3 --- Light and water treatments --- p.124 / Chapter 8.2.4 --- Growth performance analysis --- p.126 / Chapter 8.2.5 --- Statistical analysis --- p.127 / Chapter 8.3 --- Results and discussion --- p.127 / Chapter 8.3.1 --- Height growth --- p.127 / Chapter 8.3.2 --- Basal diameter growth --- p.132 / Chapter 8.4 --- Summary --- p.135 / Chapter Chapter 9 --- Conclusions --- p.136 / Chapter 9.1 --- Introduction --- p.136 / Chapter 9.2 --- Summary of major findings --- p.137 / Chapter 9.3 --- Implications of the study --- p.141 / Chapter 9.3.1 --- Transformation of Acacia confusa woodland into native forest by clearfelling --- p.141 / Chapter 9.3.2 --- When and where to undertake clearfelling --- p.144 / Chapter 9.4 --- Limitations of the study --- p.146 / Chapter 9.5 --- Suggestions for further study --- p.147 / References --- p.149 / Appendices --- p.165

The gum arabic belt in Sudan plays a significant role in environmental, social and economical aspects. The belt has suffered from deforestation and degradation due to natural hazards and human activities. This research was conducted in North Kordofan State, which is affected by modifications in conditions and composition of vegetation cover trends in the gum arabic belt as in the rest of the Sahelian Sudan zone. The application of remote sensing, geographical information system and satellites imageries with multi-temporal and spatial analysis of land use land cover provides the land managers with current and improved data for the purposes of effective management of natural resources in the gum arabic belt. This research investigated the possibility of identification, monitoring and mapping of the land use land cover changes and dynamics in the gum arabic belt during the last 35 years. Also a newly approach of object-based classification was applied for image classification. Additionally, the study elaborated the integration of conventional forest inventory with satellite imagery for Acacia senegal stands. The study used imageries from different satellites (Landsat and ASTER) and multi-temporal dates (MSS 1972, TM 1985, ETM+ 1999 and ASTER 2007) acquired in dry season (November). The imageries were geo-referenced and radiometrically corrected by using ENVI-FLAASH software. Image classification (pixel-based and object-based), post-classification change detection, 2x2 and 3x3 pixel windows and accuracy assessment were applied. A total of 47 field samples were inventoried for Acacia senegal tree’s variables in Elhemmaria forest. Three areas were selected and distributed along the gum arabic belt. Regression method analysis was applied to study the relationship between forest attributes and the ASTER imagery. Application of multi-temporal remote sensing data in gum arabic belt demonstrated successfully the identification and mapping of land use land cover into five main classes. Also NDVI categorisation provided a consistent method for land use land cover stratification and mapping. Forest dominated by Acacia senegal class was separated covering an area of 21% and 24% in the year 2007 for areas A and B, respectively. The land use land cover structure in the gum arabic belt has obvious changes and reciprocal conversions between the classes indicating the trends and conditions caused by the human interventions as well as ecological impacts on Acacia senegal trees. The study revealed a drastic loss of Acacia senegal cover by 25% during the period of 1972 to 2007.The results of the study revealed to a significant correlation (p ≤ 0.05) between the ASTER bands (VNIR) and vegetation indices (NDVI, SAVI, RVI) with stand density, volume, crown area and basal area of Acacia senegal trees. The derived 2x2 and 3x3 pixel windows methods successfully extracted the spectral reflectance of Acacia senegal trees from ASTER imagery. Four equations were developed and could be widely used and applied for monitoring the stand density, volume, basal area and crown area of Acacia senegal trees in the gum arabic belt considering the similarity between the selected areas. The pixel-based approach performed slightly better than the object-based approach in land use land cover classification in the gum arabic belt. The study come out with some valuable recommendations and comments which could contribute positively in using remotely sensed imagery and GIS techniques to explore management tools of Acacia senegal stands in order to maintain the tree component in the farming and the land use systems in the gum arabic belt.

Thesis (PhD) -- University of Western Sydney, Nepean, 1998. / Bibliography : p. 164-171.

Les plantations forestières représentent 5% de la surface forestière mondiale mais assurent plus du tiers de l’approvisionnement en bois de la planète. La durabilité de ces systèmes de production repose sur le maintien à long terme de leur fertilité, sans recourir à la fertilisation. L’introduction d’une espèce fixatrice d’azote (N) dans les plantations forestières est une des solutions envisagées pour relever ce défi. L’objectif de la thèse était d’évaluer l’effet de l’introduction de l’Acacia mangium dans une plantation pure d’eucalyptus sur la croissance des arbres, la production de biomasse et la dynamique de N dans le sol. Pour atteindre cet objectif, des inventaires destructifs combinés à une collecte des chutes de litière ainsi qu’un suivi annuel de la minéralisation de N dans le sol, ont été réalisés. Ils ont été associés à l’étude de la fixation symbiotique de N et de l’enrichissement en N de la matière organique particulaire. Cette étude a permis de mettre en évidence un effet positif de l’acacia sur la croissance des eucalyptus à travers une modification des relations interspécifiques. La relation de facilitation engendrée par la fixation symbiotique de N a été à l’origine d’une augmentation de la croissance des eucalyptus et de la production primaire nette aérienne. Cette augmentation de croissance était liée à l’amélioration du contenu azoté du sol, en particulier dans la fraction grossière de la matière organique particulaire. Une augmentation de la production de N par minéralisation a révélé un recyclage beaucoup plus rapide du N du sol. Ces travaux ouvrent des perspectives pour une intensification écologique de la sylviculture des plantations tropicales. / Forest plantations represent 5% of the world forest area but provide more than one third of world wood supply. Sustainability of these systems is based on the long-term maintenance of their fertility without using fertilizers. The introduction of nitrogen (N) fixing species in forest plantations is one of the solutions to take-up this challenge. The aim of this work was to assess the effects of the introduction of Acacia mangium in pure stand of eucalypts on tree growth, biomass production and soil nitrogen dynamics. To achieve this goal, destructive inventories combined with quantification of N fluxes in litter fall and annual monitoring of N mineralization in soil, has been done. They were associated with study of the symbiotic fixation of N and N enrichment in particulate organic matter. The study highlighted a positive effect of acacia on the growth of eucalyptus through a modification of interspecific interactions. Facilitating relationship created by the symbiotic nitrogen fixation has been the source of an increase in the growth of eucalyptus and aboveground net primary production. This increased growth was related to improvement of the nitrogen content of the soil, especially in the coarse fraction of the particulate organic matter. An increase in nitrogen mineralization indicated a much faster soil nitrogen cycling. This work opens perspectives for an ecological intensification of tropical plantation forestry.

Made available in DSpace on 2016-12-23T13:51:54Z (GMT). No. of bitstreams: 1 Gilson Barbosa Sao Teago.pdf: 1758300 bytes, checksum: bab6d9e38f4b8274b65bb437e2ed506a (MD5) Previous issue date: 2013-08-31 / The pulp and paper sector have great importance in Brazilian economy and their main sources of fiber are the forests of eucalypt and pine. Thus, it is strategic to research alternative fiber sources that might in the future make mixtures with eucalypt or even replace it. Acacia mangium has been used with good yield and quality of pulp and might be used an alternative source of fiber in simple or mixed stands. However, the literature lacks studies about the influence of mixed cultures on the properties of wood. In this way, this study aimed to evaluate the properties of wood of A. mangium and an eucalypt hybrid, both six years old, planted in monoculture and mixed stands in different proportions of the Rio Doce Valley, Minas Gerais state, Brazil. Were evaluated the specific gravity and content of bark, heartwood and sapwood, both along the stem, the radial variability of the vessels and fibers in three positions of DBH and chemical properties in DBH. For the acacia timber the results show a tendency to increase the content of sapwood with increasing proportion of A. mangium in the mixed stand; higher levels of bark at the base and top of the stem, higher specific gravity values at the base of the trunk, decreasing to 25% of commercial height and remaining constant up to the top; basic density of the tree is not influenced by treatments, for chemical properties, only the soluble lignin was influenced by the treatments; medium size vessels, few in number and with increasing diameter from pith to bark, fibers with thin walls and length ranging from very short to short in length and wall thickness increasing and the width and thickness of the heat decreasing from pith to bark. For the wood of the hybrid, results indicated decreasing levels of bark from the base to half the trunk and returning to climb to the top, higher specific gravity values for tree planting in treatments simple and longitudinal variation of this property with no defined pattern; tendency to occur higher lignin content and lower extractives content in the treatments in monoculture, small vessels and few in number with smaller vessel sizes in the treatments in monoculture and increase in vessel diameter from pith to bark, fibers with thick walls and lengths ranging from very short to short, the length, width and wall thickness of the fibers increased from pith to bark / O setor de papel e celulose possui grande importância no cenário brasileiro e suas principais fontes de matéria prima são as florestas de eucalipto e pinus. Portanto, é estratégico a investigação de matérias-primas alternativas que possam no futuro compor misturas com o eucalipto ou até mesmo substituí-lo. A Acacia mangium vem sendo utilizada com bom rendimento e qualidade de polpa e poderá ser alternativa em plantios simples ou mistos. Contudo, a literatura carece de estudos sobre a influência dos cultivos mistos nas propriedades das madeiras. Desta forma, o presente estudo teve como objetivo avaliar as propriedades das madeiras de A. mangium e de um híbrido de eucalipto, com seis anos de idade, plantados em monocultivo, com e sem fertilização nitrogenada, e em diferentes proporções de cultivo misto na região do Vale do Rio Doce, Minas Gerais. Avaliou-se a variabilidade longitudinal da massa específica básica e dos teores de casca, cerne e alburno, a variabilidade radial de vasos e fibras em três posições no DAP e composição química no DAP. Para a madeira de A. mangium os resultados indicaram tendência de elevação no teor de alburno com o aumento da proporção de A. mangium no plantio misto; maiores teores de casca na base e no topo; maiores valores de massa específica básica na base do tronco, diminuindo até 25% da altura comercial e permanecendo constantes até o topo; massa específica básica da árvore não sendo influenciada pelos tratamentos; para as propriedades químicas, apenas a lignina solúvel foi influenciada pelos tratamentos; vasos de tamanho médio, pouco numerosos e com diâmetro aumentando no sentido medula-casca; fibras com paredes delgadas e comprimento variando de muito curto a curto, o comprimento e espessura da parede aumentaram no sentido medula-casca, ao contrário da largura e do diâmetro do lume; menores comprimentos de fibra e maior heterogeneidade das dimensões perpendiculares foram observados no monocultivo. Para a madeira do híbrido de eucalipto os resultados indicam teores de casca decrescendo da base até a metade do fuste e voltando a crescer até o topo; maiores valores de massa específica básica por árvore nos tratamentos em plantio simples e variação longitudinal desta propriedade sem padrão definido; tendência de ocorrerem maiores teores de lignina e menores de extrativos nos tratamentos em cultivo simples; vasos pequenos e pouco numerosos com menores diâmetros de vaso nos tratamentos em monocultivo e aumento do diâmetro dos vasos no sentido medula-casca; fibras com paredes espessas e comprimentos variando de muito curto a curto, o comprimento, a largura e a espessura da parede das fibras aumentaram no sentido medula-casca

Made available in DSpace on 2014-08-20T13:25:40Z (GMT). No. of bitstreams: 1 Dissertacao_Alexandre_Terracciano_ Villela.pdf: 861318 bytes, checksum: 7eafbc8d87375d8a142a2b051afb0002 (MD5) Previous issue date: 2007-09-21 / The present work had as objective to evaluate the production of seedlings of black wattle (Acacia mearnsii of Wild), in substrata gotten from agro-industrial residues, composted and vermicomposted. After the search and the acquisition of the different residues used in the work, it was proceeded the disposal from these isolated materials and in not aromatical combination in boxes wooden (cedrinho) in order to carry through the composting process later and the vermcomposting. After the vermicomposting to be concluded preceded it mixture from the materials including itself it carbonized rind of rice (CAC). The treatments were: T1 (bovine manure (EB) 50%+ rind of parboilizado rice (CAC) 50%); T2 (ovine manure (EO) 50%+CAC 50%); T3 (agroindustrial residues (FROG) 50%+CAC 50%); T4 (mud of parborizado rice (LP) 50%+CAC 50%); T5 (bovine manure(EB) 25%+LP 25%+CAC 50%); T6 (EO 25%+LP 25%+CAC 50%); T7 (EB 25%+RA 25%+CAC 50%; T8- EO 25%+RA 25%+CAC 50%); T9 (EB 25%+RF 25%+CAC 50%); T10 (EO 25%+RF 25%+CAC 50%) and T11 (Plantmax®). The evaluated variable had been: number of plants, col diameter, height of plants, aboveground biomass (wet and dry), root fitomass (wet and dry), total foliar area, chemistry composition od seedlings and chemistry composition of the substrata before and after the research. The sowing occurred in rigid the first day of June of 2006 in tubetes (1320 units) with capacity conditioning 50 approximately cm3 of substratum. The seeds was concluded the germinative process in day 25 of the same month. When the changes had reached the height of two centimeters, proceded the looping, leaving itselves only one seedlings one for container. During the experiment the changes had been irrigated with the frequency of 6L m-2 day-1, until the 45 days of the plantation. From the 46 days 12L was changed for two irrigations totalizing m-2 day-1, due to rise of the local temperature remaining this frequency until the end of the evaluations in greenhouse. To the twenty and three days of the month of September of 2006 (115 days to count of the sowing), the ending of the evaluations in greenhouse was given and all the changes had been removed and directed to the laboratory to be carried through the too much evaluations. The gotten results had been submitted to the variance analysis, test of averages (Tukey 5%), where it was possible to evidence that the T11 treatment with commercial substratum Plantmax®, presented the best answers for seedlings of black wattle (acácia mearnsii of Wild). / O presente trabalho teve como objetivo avaliar a produção de mudas de acácia negra (Acacia mearnsii De Wild), em substratos obtidos a partir de resíduos agroindustriais, compostados e vermicompostados. Após a busca e a aquisição dos diferentes resíduos utilizados no trabalho, procedeu-se à disposição desses materiais isolados e em combinação em caixas de madeira não aromática (cedrinho) a fim de realizar o processo de compostagem e posteriormente a vermicompostagem. Após a vermicompostagem estar concluída procedeu-se a mistura dos materiais incluindo-se a casca de arroz carbonizada (CAC) que compuseram os seguintes tratamentos: T1(esterco bovino (EB) 50%+ casca de arroz parboilizado (CAC) 50%); T2(esterco ovino (EO) 50%+CAC 50%); T3(restos da agroindustria (RA) 50%+CAC 50%); T4(lodo de arroz parborizado (LP) 50%+CAC 50%); T5(esterco bovino (EB) 25%+LP 25%+CAC 50%); T6(EO 25%+LP 25%+CAC 50%); T7(EB 25%+RA 25%+CAC 50%; T8- EO 25%+RA 25%+CAC 50%); T9(EB 25%+RF 25%+CAC 50%); T10(EO 25%+RF 25%+CAC 50%) e T11(Plantmax®). As variáveis avaliadas foram: diâmetro de colo, altura de plantas, fitomassa fresca da parte aérea, fitomassa fresca da raiz, fitomassa seca da parte aérea, fitomassa seca da raiz, área foliar total, composição química das mudas e dos diferentes substratos antes e após a retirada das mesmas. A semeadura ocorreu no dia primeiro de junho de 2006 em tubetes rígidos (1320 unidades) com capacidade de acondicionar aproximadamente 50 cm3 de substrato. O processo germinativo foi concluído no dia 25 do mesmo mês. Quando as mudas atingiram a altura de dois centímetros, procedeu-se o desbaste, deixando-se apenas uma muda por recipiente. Durante o experimento as mudas foram irrigadas com a freqüência de 6L m-2 dia-1, até os 45 dias do plantio. A partir dos 46 dias mudou-se para duas irrigações totalizando 12L m-2 dia-1, devido à elevação da temperatura local mantendo-se essa freqüência até o final das avaliações em estufa. Aos vinte e três dias do mês de setembro de 2006 (115 dias a contar da semeadura), deu-se o término das avaliações em estufa e todas as mudas foram retiradas e encaminhadas ao laboratório para serem realizadas as demais avaliações. Os resultados obtidos foram submetidos à análise de variância, teste de médias (Tukey 5%), onde foi possível constatar que o tratamento T11 com substrato comercial Plantmax®, apresentou as melhores respostas agronômicas para mudas de acácia negra (acácia mearnsii de Wild).