This study has significantly broadened and deepened the understanding of ecological aspects related to the spread and reproduction of Diplodia pinea as an endophyte, latent pathogen and causal agent of serious disease problems in plantations of Pinus spp. Analyses of genetic diversity in populations using microsatellite data has revealed very high levels of genetic diversity of populations of the pathogen at different spatial levels, ranging from within a single asymptomatic tree to within and between plantations over large geographic areas and in different countries where the fungus has been introduced. Analysis of the structure of the distribution of genotypes and the association of alleles within populations, suggest that sexual recombination is occurring in most environments in the Southern Hemisphere D. pinea populations. This indicates the presence of a cryptic sexual state in this fungus. The genetic diversity was structured and differentiated for regions separated by as little as 65 km to a country and continental scale. The diversity and likely sexual reproduction of D. pinea must complicate control strategies such as selection and breeding for resistance. It is thus essential to strengthen quarantine services aimed at minimizing the risk of introducing additional genotypes of D. pinea. In this regard, understanding the infection and spread between regions is essential. Results of this study demonstrate that this fungus infects seeds, but only at low levels, and is not transmitted vertically via seeds to seedlings. Diplodia pinea was also not isolated from seedlings in three commercial nurseries and open fields in South Africa. These results provide strong evidence that neither seeds nor seedlings are the primary sources of inoculum, but that the pathogen is mainly transmitted horizontally from mature trees and debris left in plantations. Finally extensive sampling conducted as part of this study led to the discovery of the sibling species, D. scrobiculata in South Africa and outside the Northern Hemisphere for the first time. / Thesis (PhD)--University of Pretoria, 2011. / Genetics / Unrestricted

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Economics, 1978 / Bibliography: leaves 240-243. / by José Marcio A. Guimaraés de Camargo. / Ph. D. / Ph. D. Massachusetts Institute of Technology, Department of Economics

As one of antebellum Tidewater's most prominent planters, Hill Carter and the world he and his slaves made at Shirley occupy an important place in Virginia history. Few scholars, however, have analyzed their roles adequately. Previous studies' overwhelming concentration on the architectural and material culture history of the plantation has left Carter's role as one of Virginia's preeminent agricultural reformers virtually unexplored. Assuming ownership of Shirley in 1816, Carter quickly established himself as a leading proponent of agricultural improvement, both embracing and building on the ideas of other reformers like John Taylor and Edmund Ruffin. He diversified his crops and changed their rotations, used new equipment and improved methods of cultivation, reclaimed poor or unproductive lands, and employed a variety of fertilizers and manures to resuscitate his soils. Significantly, Carter efforts to improve Shirley transformed not only the physical landscape of the plantation. The changes produced in the work and lives of his slaves also were considerable. This study, then, investigates the relationship between agricultural reform and slavery. Instead of looking at reform in terms of how slavery affected (or inhibited) it, this work argues that reform must also be understood in relation to how it affected slavery, for changes manifested in attempts to improve lands had important ramifications on slave work routines, which, in turn, affected slave life in important ways. / Master of Arts

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No description available.

More than 20 million clonal loblolly pines have been planted throughout the southeastern United States. Fertilizer has been applied to more than 6.5 million hectares of plantations to alleviate deficiencies of nitrogen and phosphorus that limit growth. Because cloning loblolly pine in large numbers has only become possible in the last decade, it is unknown how clones may respond differently to fertilizer application. Growth, growth efficiency, and biomass partitioning responses to fertilizer application were investigated among 25 clones planted in the Virginia Piedmont. Closely related clones varied in their fertilizer stem volume responses, but not enough to be statistically significant (p = 0.11). Clones varied in growth efficiency and partitioning to individual tissues, but clone-by-fertilizer interactions were not observed. Clonal variability was observed in root morphology, and maximum rooting depth showed a significant clone-by-fertilizer interaction. Clones with rapid growth rates can be selected with a range of other desirable traits. Short-term (i.e. weeks) responses to fertilization are often inconsistent with long-term (i.e. years) responses, but are critical to understanding growth responses. We investigated carbon allocation in two full-sibling clones of loblolly pine under two levels of fertilizer application over four months in a greenhouse. Using monthly harvests of some trees and ecophysiological measurements throughout, we determined carbon allocation on a monthly scale. In response to fertilizer application, both clones reduced allocation belowground and increased allocation to foliage to some extent, increasing whole-canopy photosynthetic capacity. However, these changes in allocation were ephemeral. By the end of the experiment, root-shoot ratios were no longer significantly affected by fertilizer application. Clones had allocation patterns distinct from one another, with one allocating more belowground and the other allocating more to stem mass. While their overall growth responses to fertilizer application were similar, the physiological mechanisms that resulted in these responses were different between clones. Results of the two studies indicate that while fertilizer responses may not need to be included when testing clones for deployment, knowledge of the fertilizer responses of widely-deployed clones would offer forest managers opportunities to apply clone-specific precision-silvicultural systems to optimize growth rates and manage for a range of products. / Ph. D.

This study assessed five fertilizer treatments (control – no fertilizer, urea, urea treated with N-(n-butyl) thiophosphoric triamide (NBPT), coated urea + NBPT (CUF), polymer coated urea (PCU) ) during two application seasons (spring, summer) to: 1) compare fertilizer nitrogen (N) losses (see Chapter 2); 2) evaluate temporal N uptake patterns of loblolly pine (see Chapter 3); and 3) evaluate fertilizer N cycling and partitioning in a loblolly pine ecosystem (see Chapter 4). Chapter 2 results showed enhanced efficiency fertilizers (EEFs) significantly reduced ammonia (NH3) volatilization losses compared to urea. Mean NH3 volatilization after spring fertilization ranged from 4% to 26% for EEFs versus 26% to 40% for urea, and 8% to 23% for EEFs versus 29% to 49% for urea in summer. Chapter 3 results showed an increase in timing and development of foliage in fertilized compared to unfertilized plots. In addition, the cumulative N uptake by loblolly pines increased over the entire growing season from N originating from fertilizer and natural sources. Chapter 4 results showed greater fertilizer N recovery for EEFs in both spring and summer (80%, 70-80% respectively) compared to urea (60%, 50% respectively) with most fertilizer N recovered from mineral soil (20% to 50%) and loblolly pines (10% to 50%). Three primary conclusions come from this research: 1) EEFs reduce NH3 volatilization after N fertilization compared to urea regardless of application timing and weather conditions (see Chapter 2); 2) N uptake by loblolly pines increases over the entire growing season after N fertilization (see Chapter 3); more fertilizer N remains in the ecosystem with EEFs compared to urea with most fertilizer N remaining in the soil (see Chapter 4). From these findings, we hypothesize that the EEFs in this study: 1) reduce ammonia volatilization which 2) translates to an increase in fertilizer nitrogen remaining in the loblolly pine plantation system that 3) increases the amount of plant available nitrogen for an extended period into the stand rotation and 4) increases fertilizer nitrogen use efficiency (FNUE) for all enhanced efficiency fertilizers investigated in this study compared to the conventional form of fertilizer N used in forestry, urea. / Ph. D.

L’épinette blanche (Picea glauca (Moench Voss)) est une des essences les plus importantes pour le reboisement au Canada, permettant d’alimenter l’industrie forestière. L’épinette blanche est ainsi l’objet d’importants programmes d’amélioration génétique dans la majorité des provinces canadiennes. Afin d’optimiser l’utilisation des épinettes améliorées, une meilleure identification des stations de reboisement serait souhaitable. Pour ce faire, nous avons utilisé les données des inventaires de plantation réalisés par le gouvernement du Québec ainsi que des variables environnementales (climatiques, topographiques, édaphiques et hydrologiques) afin de déterminer quelles variables prédisaient le mieux l’indice de qualité de station (IQS). Trois modèles ont été testés pour deux zones d’étude, soit le modèle « général », qui utilise les données dérivées de la cartographie disponible à échelle 1 / 20 000 pour l’ensemble du territoire forestier du Québec, le modèle général « simplifié » qui utilise l’information de la carte écoforestière plus la localisation des parcelles dans la zone générale et le modèle « LiDAR », qui utilise l’information des modèles numériques de terrain issus de survols LiDAR pour la zone du Québec possédant cette information. Bien que présentant un faible pouvoir prédictif, le modèle général présente une capacité de prédiction légèrement meilleure que les modèles déjà publiés. Une méthode est proposée afin de générer une carte de productivité pour la Réserve faunique du Saint-Maurice. Cette carte, superposée à la cartographie des contraintes d’implantation de zones d’intensification, a permis de déterminer que seul 0,18 % de la superficie totale de la réserve correspond à des zones de haute productivité (IQS > 12m) sans contrainte pour la plantation, soit les meilleures stations pour l’établissement de plantations d’épinettes blanches améliorées. Cependant, la majorité des superficies de la réserve (59,85 %) offre tout de même des zones avec une bonne productivité (IQS 8 - 12m) et aucune contrainte pour la plantation. / White spruce (Picea glauca (Moench) Voss) is one of the most important species for reforestation in Canada. Given its importance for Canada’s forest industry, white spruce is therefore the object of important genetic improvement programs in most provinces. To optimize the use of genetically improved spruce trees, better identification of reforestation sites would be desirable. To identify those sites, data from plantation inventories carried out by the government of Quebec were used, along with climatic, topographic, edaphic, and hydrological variables, to determine which variables best predicted site index. Three models were tested, namely the “general” model, which used data derived from the current mapping at a scale of 1 / 20,000 for the entire forest territory of Quebec, a model “simplified” that use the ecoforestry map information and the location of inventory plots and the “LiDAR” model, which used information from digital elevation models generated with LiDAR data for the area in Quebec with available information. Even if the predictive accuracy of the general model is low, it is slightly better than previously published studies. A methodology was proposed to generate a productivity map of the Saint-Maurice wildlife reserve. This map, overlapped with the map of plantation constraints, determined that only 0,18% of the total area of the reserve showed areas of high productivity (Site index > 12 m) without plantation constraints. However, the majority of the areas of the reserve (59,85%) still offer areas with good productivity (Site index of 8 to 12 m) and no constraints for planting.

Dans la province du Haut-Katanga, en République démocratique du Congo (RD Congo), une forte pression anthropique est exercée sur la forêt claire (FC, Miombo) par l’agriculture et la demande accrue en charbon de bois, due à la croissance démographique. La restauration de la FC dégradée est devenue essentielle pour renverser cette régression et gérer durablement la FC. L’objectif principal de cette thèse était d’étudier la croissance de semis et le potentieldes champignons mycorhiziens arbusculaires (CMA). Elle avait pour objectifs spécifiques:(i) d’évaluer la croissance et le statut mycorhizien des espèces forestières de la FC, en lien avec le statut de succession, espèces pionnières (EP) et tardives (ET); (ii) de déterminer le potentiel d’inoculum mycorhizien arbusculaire (PIMA) dans la FC dégradée; et (iii) de décrire la communauté des CMA, associés à un arbre forestier à usage multiple (Pterocarpustinctorius Welw ou Mninga maji en Swahili, Mukula en Bemba).D’abord, la croissance des semis a été évaluée, pour deux espèces d’arbres pionnières(Combretum collinum et Pterocarpus tinctorius) et six espèces tardives (Brachystegiaboehmii, B. longifolia, B. spiciformis, B. wangermeana, Julbernardia globiflora et J.paniculata), 1, 2 et 4 ans après la plantation. Ensuite, le PIMA a été évalué par le piégeage des plantules de Crotalaria juncea dans la FC dégradée. La relation entre le PIMA et les indices de végétation a été établie avec les modèles linéaires généralisées mixtes (MLGM)et les régressions linéaires. En dernier lieu, la diversité et la structure de la communauté des CMA des racines de P. tinctorius ont été caractérisées dans les jachères agricoles et forestières de trois sites, par amplification, clonage du gène 28S de la grande sous-unité(LSU) de l’ADN ribosomal et le séquençage Sanger. Les résultats montrent que les espèces forestières pionnières (EP, Chipya) avaient une croissance précoce et une productivité 3 à 40 fois supérieure comparées aux ET (typique du Miombo). Les espèces pionnières étaient colonisées par les CMA, alors que les espèces tardives l’étaient par les ectomycorhizes. Par ailleurs, la densité des arbres des EP influence positivement le PIMA, particulièrement les légumineuses ligneuses agissant en synergie avec l’abondance des herbacées annuelles. Par leur colonisation mycorhizienne élevée, les légumineuses ligneuses seraient les plantes refuges des CMA. Finalement, une diversité moléculaire de 30 unités taxonomiques opérationnelles (UTOs) des CMA était associée à P.tinctorius (une des légumineuses ligneuses mycotrophes), dans les friches agricoles et forestières de trois sites étudiés. La richesse spécifique et la structure de la communauté des CMA étaient influencées par la densité des espèces ligneuses, colonisées par les CMA, équitablement réparties dans les espèces végétales. De plus, la communauté des CMA était dominée par les espèces du genre Rhizophagus et Sclerocystis, qui étaient fortement associées à certaines propriétés chimiques du sol (pH, acidité, Al et Fe total) et à la densité de quelques arbres. Ainsi, les résultats mettent en évidence une variabilité de la croissance et de la biomasse en fonction du statut de succession (groupes écologiques). Aussi, le PIMA et la communauté des CMA étaient contrôlés par la densité des arbres et quelques propriétés du sol. Nous suggérons la reforestation de la forêt claire dégradée avec les espèces indigènes (P.tinctorius, B. spiciformis et C. collinum), en plantations mono spécifiques ou en régie agroforestière avec les cultures vivrières. / In the Katanga province, Democratic Republic of the Congo (DR Congo), the anthropogenic pressure is exerted on the Miombo woodland (MW) with the expansion of the agricultural lands and the increased demand for charcoal, due to the demographic growth. The restorationof agricultural and forest fallows has become essential to reverse this decline and sustainably manage the degraded MW. The main objective of this thesis was to study the development of seedlings and the potential of arbuscular mycorrhizal fungi (AMF) in the MW of UpperKatanga, DRC. Its specific objectives were to: (i) assess the development and mycorrhizalstatus of MW species, with respect to their successional status (early (ES) or late (LS) tree species); (ii) determine the arbuscular mycorrhizal inoculum potential (AMIP) in degradedMW; and (iii) describe the diversity and community structure of AMF associated with amultipurpose forest tree (Pterocarpus tinctorius Welw also named Mninga maji in Swahili,Mukula in Bemba).First, the development of the seedlings was evaluated, for two pioneer tree species(Combretum collinum and P. tinctorius) and six late species (Brachystegia boehmii, B.longifolia, B. spiciformis, B. wangermeana, Julbernardia globiflora and J. paniculata), 1, 2and 4 years after planting. Then, the AMIP was estimated in degraded MW by baitingCrotalaria juncea seedlings. The relationship between AMIP and vegetation indix wase stablished with Generalized Linear Mixed Models (GLMM) and linear regressions. Finally, the diversity and the structure of the AMF community in the roots of P. tinctorius were characterized in the agricultural and forest fallow of three sites, by amplification, cloning of the 28S gene of the large subunit (LSU) of the ribosomal DNA and Sanger sequencing. The results showed that the early successional tree species, ES (Chipya) had early growthand were 3 to 40 times more productive than to LS (tree species characteristic of MW). ESspecies were colonized by AMF, whereas LS species were colonized by ectomycorrhizal fungi. In degraded MW, the density of some trees had a positive influence on AMIP,particularly woody legumes acting synergistically with the abundance of annual grasses.Woody legumes were more colonized and would act as AMF plant refuges. Molecular diversity of 30 operational taxonomic units (UTOs) of AMF was associated with P. tinctorius (one of the mycotrophic woody legumes), in the agricultural and forest fallows of three sites studied. The community richness and structure of the AMF were driven by the density ofwoody species colonized by AMF evenly distributed in plant species. The AMF communitywas dominated by species of the genera Rhizophagus and Sclerocystis, and were strongly associated with some chemical properties of the soil (pH, acidity, total aluminium and totaliron) and the density of some trees. Thus, the results highlight a variability of growth and biomass depending on the successional status (ecological groups). Also, the AMIP and the AMF communities were mainly driven by tree density and soil properties. We suggest there forestation of degraded MW with the native species (P. tinctorius, B. spiciformis and C.collinum) in mono-specific plantations or under agroforestry management with food crops.

<p>Even in our contemporary moment, the word plantation evokes a distinctly Southern and rural image in which slavery is well hidden within an idyllic botanical scene. And yet, from the very beginning of industrialization in the United States, plantation agriculture and enslavement were thoroughly embedded in the circuits of Northern capital and urbanization. "Shackled in the Garden" begins from the premise that the plantation is not an archaic institution that withered away in the nineteenth century, but rather is an enduring site of production and reproduction in the U.S. and throughout the Global South. Historically, the plantation has played a central role in organizing racialized bodies, technologies and environments in the South. In the wake of widespread ecological and social disaster across global Southern geographies, I insist that it behooves us to take another view of the plantation.</p><p>"Shackled in the Garden" rethinks the plantation as an ecological space: a space of dynamic relations in which racialized bodies and technologies are aggregated and disaggregated by a powerfully tropical environment. In the midst of ongoing crises over the sustainability of the plantation complex in the mid-eighteenth century, the plantation metamorphosized from an idyllic geography of botanical bounty and pure soil to a "toxic paradise": a tainted space that enclosed usable bodies and usable lands to be put in the service of increasingly experimental purposes. This peculiar conjoining of racialized subjects and the environment transformed the plantation into a privileged site for investigations into natural history, which sought to catalog and organize the natural world. Understandings of natural history as an innocent and feminine pursuit based on non-intervention and simple observation of the environment hid rampant experimentation on all kinds of "specimen" on the plantation including botanical species, agricultural crops, livestock, and enslaved persons. </p><p>While emergent biological models in the mid-nineteenth century began to understand race and identity as being rooted in the body, climatic or environmental determinations of identity continued to hold rhetorical power. Biology may have achieved a hegemonic position with the increasingly legitimated theories of Darwinian evolution, but natural history did not wither into oblivion. While individuation, mechanization, and biology flourished in the North, the plantation South continued to be figured as a natural ecology, a geography where identity refused its disentanglement from a dangerously miasmic and tropical environment. This project emerges out of both literary studies and science studies. Moving from James Grainger and Thomas Jefferson through Thomas Wentworth Higginson to Booker T. Washington, I explore how a literary imaginary of the plantation pastoral, which continued to represent the plantation as an unenclosed, pre-industrial and green geography in the face of extensive industrialization and environmental degradation, contributed to an understanding of the plantation as a "natural" space of scientific experimentation. The second half of the project considers a perhaps surprising genealogy of plantation fiction from authors such as Martin Delany and Jean Toomer who defamiliarized pastoral naturalizations of plantation space at the same time as they played on the heterotopic spatiality of the plantation to imagine a different, more global plantation South.</p> / Dissertation