I evaluated effects of 5 pine plantation establishment regimes 6 – 8 years postestablishment on loblolly pine (Pinus taeda) growth, vegetation characteristics, nutritional carrying capacity for white-tailed deer, and breeding birds in the Lower Coastal Plain of Mississippi. Treatments combined mechanical site preparation (MSP), chemical site preparation (CSP), and herbaceous weed control (HWC) designed to represent a range of operational intensities. Chemical SP provided greater long-term control of woody competition than MSP, but did not provide significant pine growth advantage. Vegetation richness, diversity, and structure were best maintained with MSP and year 1 banded HWC. Canopy cover appears to be shading out herbaceous understory and altering composition of woody understory toward more shade-tolerant species. Total forage biomass and 3 levels of carrying capacity declined on average 54% each year. Avian metrics decreased as treatment intensity increased. Regionally important species were influenced positively by greater vegetation coverage attained by banded HWC.

Master of Science / Department of Agronomy / Kraig Roozeboom / High soybean [Glycine max.] commodity prices in recent years have led to an increase in use of yield enhancing and protecting products. These products need to be evaluated to determine if the use of multiple inputs has a positive impact on yield and how these inputs interact with agronomic practices. The objectives of this study were to evaluate products individually and collectively in input systems, examine interactions between varieties and input systems (IS), seeding rates (SR) and IS, and row spacing (RS) and IS. Field experiments were conducted at high-yielding locations in Kansas and Minnesota in 2012 to 2014 to meet these objectives. Sixteen treatments consisting of individual inputs and inputs combined in systems were evaluated in one experiment. A second experiment evaluated the variety by IS interaction by constructing 18 treatments from a factorial combination of six glyphosate [N-(phosphonomethyl) glycine] resistant varieties and three IS’s: untreated control (UTC), SOYA (combination of possible yield-enhancing products representative of those currently being marketed), and SOYA minus foliar fungicide (SOYA – foliar F). A third experiment evaluated the SR by IS interaction by constructing 12 treatments from a factorial arrangement of six SR’s and two IS’s: UTC and SOYA. A fourth experiment evaluated the RS by IS interaction by constructing 12 treatments from a factorial arrangement of three RS’s and four IS’s: UTC, fungicide and insecticide seed treatment plus foliar fungicide (STFF), SOYA, and SOYA – foliar F. Very few interactions between IS and agronomic practices were detected in any of the experiments. Varieties had an effect on multiple growth parameters but yield differences were marginal; linear-plateau and non-linear models found that seeding rates that maximized yield in this study were similar to University recommendations; and in general, narrow rows produced the greatest yields. The use of inputs and IS’s typically increased seed mass and yield above the UTC across all experiments. However, given current costs and soybean prices, yield response to IS’s was not great enough to cover the additional costs. Overall, it appears producers would be better served by focusing on agronomic practices rather than implementing input systems.

Northern bobwhites (Colinus virginianus) are an important cultural, ecological, and economical part of the southern Texas landscape. I used radio-telemetry data from 2000?2005, part of a long-term, bobwhite study in southern Texas, to test the nest-concealment hypothesis, develop a stochastic simulation model for bobwhite populations, and evaluate the influence of brush canopy coverage (BCC) on short- and long-term demographic performance of bobwhites. Bobwhite nests tend to be situated in taller and denser vegetation than would be expected if nest-site location was a random process. I compared 4 microhabitat variables between successful (n = 135) and depredated nests (n = 118). I documented similar microhabitat attributes between successful and depredated nests. The discriminant function correctly classified only 48?59% of nest fates into the correct group, but only 18% of the variation in nest fate. Thus, my results did not support the nest-concealment hypothesis. My stochastic simulation model for bobwhite populations is based on difference equations (?t = 3 months) and simulations run for 100 years using STELLA� 9.0.2. The probability of persistence for 100 years for the spring population was 74.2% and 72.5% for the fall population. Simulated population parameters were similar to those observed in the field for 5 of 6 population parameters. Only simulated male adult annual survival differed by 275.0% from field estimates. Despite this difference, my model appears to be a good predictor of bobwhite populations in the Rio Grande Plains of Texas. I estimated bobwhite density, survival, and production (proportion of hens nesting, nesting attempts per hen, and clutch size) in 3 study areas with ~10%, ~25%, and >30% BBC. All demographic parameters were similar among the 3 BCC classes. However, simulation modeling indicated that long-term demographic performance was greater on the ~25% and >30% BCC classes. The probability of fall population persistence was greater in the ~25% (90.8%) and >30% (100.0%) BCC classes than in the ~10% BCC class (54.2%). My study highlights the shortcoming of considering only short-term effects when comparing habitat given that short- and long-term effects of habitat on demographic performance can differ.

Made available in DSpace on 2016-06-02T19:31:41Z (GMT). No. of bitstreams: 1 2032.pdf: 1258357 bytes, checksum: 7a656235a713f3885b57759902651544 (MD5) Previous issue date: 2007-10-04 / The purpose of this study was to analyze the specific composition of tree, arboreal structure, infestation by climbers, canopy layer and compare the results with other forest fragments and, from these, to form a data bank for monitoring. The forest studied is located in the geographical coordinates S 22º 17 and W 47º 24 . The soil is red-dark Latosoil type and its topography is irregular. The floristic analysis was made by expeditions and phytosociology by quadrats of 10x10m in three blocks. The canopy analysis was made by digital image and the climbers infest by coverage index. It was found 114 species belonging to 40 families and 74 genres. It was sampled 728 alive plants. The species with greater importance value were Trichilia clausenii, Galesia integrifolia, Trichilia catigua, Metrodora nigra e Cariniana estrelensis. The sample canopy coverture presented 70% of the samples with 70% of coverture e only 14% with minor than 50%. 83% of the trees presented any infestation by climber and 60% with indice 4 e 5, that was considered elevated. The greatest infestation occurred at the tree of the canopy layer. The population of pioneer species, in the sucessional classification, presented little number of young plants and the secondary and shade tolerant great number and a complete series of diametric classes. / Objetivo deste estudo foi analisar um remanescente de floresta estacional semidecidual, sob o aspecto da: composição específica; estrutura arbórea; infestação por lianas; integridade do dossel; comparação com outros remanescentes para formar um banco de dados para futuros monitoramento. A mata, objeto deste estudo, se localiza nas coordenadas 22º 17' S 47º 24' W. O solo é do tipo Latossolo vermelho escuro e a topografia acidentada. A análise florística foi feita de modo expedito e a fitossociológica por parcelas de 10x10m em três blocos. Foram analisadas as coberturas do dossel por imagem digitalizada e a infestação por lianas por meio do índice de cobertura. Foram encontradas 114 espécies, pertencentes a 40 famílias e 80 gêneros. Foram amostrados 728 indivíduos vivos em meio hectare. As espécies que apresentaram maior valor de importância foram Trichilia clausenii, Galesia integrifolia, Trichilia catigua, Metrodora nigra e Cariniana estrelensis. Na maioria das parcelas (70%) ocorreu uma cobertura do dossel acima de 70% e 14 % com cobertura abaixo de 50%. Os índices de infestação por lianas demonstraram que 83% das árvores apresentaram infestação e 60% das árvores apresentaram índices 4 e 5 que foram considerados elevados. Os maiores índices de infestação por lianas ocorreram nos indivíduos cujas alturas correspondem a de dossel. As populações das principais espécies pioneiras mostraram-se em desequilíbrio, com poucos indivíduos nas classes de menores diâmetros. Enquanto que as secundárias tardias e de subosque em equilíbrio, com indivíduos nas diversas classes diamétricas e grande número de indivíduos jovens.

Considerando os desafios do aumento da pressão antrópica, das emissões de gases do efeito estufa, das mudanças climáticas e do crescimento da área de desmatamento acumulado na Amazônia - incentivado pelo avanço da fronteira agropecuária - é necessário encontrar formas alternativas de produção agrícola que apresentem potencial mitigatório. A presente pesquisa coletou dados em sistemas agroflorestais de cacau (Theobroma cacao L.) (SAF-cacau) em 40 parcelas de 20 x 50 metros (1000 m2) amostradas em 20 pequenas propriedades, no município de São Félix do Xingu, no sudeste do Pará, objetivando encontrar a relação entre o estoque de carbono acima do solo de indivíduos arbóreos e a produção de cacau, buscando sua relação ótima. Para melhor compreensão da relação carbono x produção também foram estimadas variáveis que influenciam na produtividade do cacaueiro, como fertilidade do solo, entrada de luz no sistema, e manejo. Para tanto, os métodos utilizados na coleta dos dados foram: (1) estimativa da altura do dossel; (2) medida da circunferência à altura do peito (CAP) dos indivíduos arbóreos de sombreamento; (3) medida da circunferência a 30 cm do solo dos cacaueiros; (4) amostra do solo em duas profundidades - 0-10 cm e 20-30 cm; (5) cálculo do Índice de Cobertura de Dossel (ICD) utilizando densiômetro florestal; (6) estimativa da produção de cacau por contagem de frutos e (7) levantamento por meio de questionário semiestruturado das condições socioeconômicas e percepção dos agricultores sobre seu plantio, além do manejo dado a ele. Os dados referentes ao SAFs-cacau foram analisados com uso de Análise de Componentes Principais e regressões polinomiais, de forma a compreender de que forma as variáveis se relacionavam. Como resultado, constatamos que os SAFs-cacau possuem em média 14,35 ± 4,9 anos de plantio, produzem em média 354,32 ± 335,52 kg de amêndoa seca de cacau.ha-1.ano-1 estocando em média 13,53 ± MgC.ha-1 em cacaueiros, 16,05 ± 23,56 MgC.ha-1 em árvores de sombreamento, compondo um total de 29,58 ± 24,37 MgC.ha-1 de biomassa arbórea acima do solo, sob índice de cobertura de dossel (ICD) acima do cacaueiro médio de 27,85 ± 22,84. Foi averiguado que quando considerada a relação renda por área, a cultura do cacau provê renda até 8 vezes maior que a pecuária. As análises indicam uma grande variedade de formas de manejo, resultando em grande variação dos dados amostrados, inclusive produtividade. A parcela com melhor relação carbono/produtividade, com produtividade acima da média local, apresentou carbono de sombreamento de 17,92 MgC.ha-1, estoques de carbono acima do solo em cacaueiros de 11,53 MgC.ha-1 e carbono total acima do solo de 29,45 MgC.ha-1, com produtividade de 501,28 kg de amêndoa seca/ano e ICD de 48,83%. As análises de solo mostraram pH, fósforo, magnésio e cálcio em média fora do desejável para cultivo do cacaueiro. As regressões polinomiais indicam que há potencial para enriquecer os SAFs-cacau com árvores de sombreamento de uso econômico, compensando a perda de renda advinda da menor produtividade do cacaueiro, além de prover serviços ambientais. / Considering the challenges posed by the increasing anthropogenic pressure, greenhouse gas emissions, climate change and the growth of deforestation in the Amazon - encouraged by the advancement of the agricultural and livestock frontier - it is necessary to find alternative forms of agricultural production that has potential for mitigation. The present study collected data on 20 cocoa (Theobroma cacao L.) agroforestry systems (AFS), 2 plots of 20 x 50 meters (1000 m2) sampled in 20 small farms in the municipality of São Félix do Xingu, in the southeast of the Pará, aiming to find the relation between the aboveground carbon stocks and cocoa production, searching for its optimal relation. For a better understanding of the carbon x production relationship, we also estimated variables that influence cacao yield, such as soil fertility, light input into the system, and management. To do so, the methods used in data collection were: (1) canopy height estimation; (2) measurement of the circumference at the chest height (CAP) of shade trees; (3) measurement of the circumference at 30 cm of the soil of cacao trees; (4) soil sample at two depths: 0-10 cm and 20-30 cm; (5) calculation of the Canopy Coverage Index (DCI) using a forest densitometer; (6) estimation of cocoa yield by fruit counts and (7) semi-structured questionnaire survey of socioeconomic conditions and farmers\' perception of their AFS, in addition to the management given to them. The data concerning cocoa-based AFs were analyzed using Principal Component Analysis and polynomial regressions, in order to understand how the variables were related to each other. As a result, we found that cocoa SAFs have a mean of 14.35 ± 4.9 years of planting, producing on average 354.32 ± 335.52 kg of dry cocoa beans.ha-1.year-1 stocking on average 13.53 ± MgC.ha-1 in cacao trees, 16.05 ± 23.56 MgC.ha-1 in shading trees, composing a total of 29.58 ± 24.37 MgC.ha-1 of aboveground tree biomass , under canopy cover index (ICD) (measured above the cocoa tree) of 27.85 ± 22.84. It was verified that when considering the relation income by area, the cocoa AFS provides income up to 8 times greater than livestock. The analyzes indicate a wide variety of management methods, resulting in a large variation of the data sampled, including yield. The plot with best carbon/yield relation and with yield above the local average, showed shading tree carbon stocks of 17.92 MgC.ha-1, aboveground carbon stocks in cacao trees of 11.53 MgC.ha-1 and total aboveground carbon of 29.45 MgC.ha-1, yielding 501.28 kg of dried cocoa beans/year and ICD of 48.83%. Soil analyzes showed soils with averages of pH, phosphorus, magnesium and calcium below recommended values for cacao cultivation. Polynomial regressions indicate that there is potential to enrich cocoa-based AFS with shading trees for economic use, compensating for the loss of income from lower cocoa yield, as well as providing environmental services.

Considerando os desafios do aumento da pressão antrópica, das emissões de gases do efeito estufa, das mudanças climáticas e do crescimento da área de desmatamento acumulado na Amazônia - incentivado pelo avanço da fronteira agropecuária - é necessário encontrar formas alternativas de produção agrícola que apresentem potencial mitigatório. A presente pesquisa coletou dados em sistemas agroflorestais de cacau (Theobroma cacao L.) (SAF-cacau) em 40 parcelas de 20 x 50 metros (1000 m2) amostradas em 20 pequenas propriedades, no município de São Félix do Xingu, no sudeste do Pará, objetivando encontrar a relação entre o estoque de carbono acima do solo de indivíduos arbóreos e a produção de cacau, buscando sua relação ótima. Para melhor compreensão da relação carbono x produção também foram estimadas variáveis que influenciam na produtividade do cacaueiro, como fertilidade do solo, entrada de luz no sistema, e manejo. Para tanto, os métodos utilizados na coleta dos dados foram: (1) estimativa da altura do dossel; (2) medida da circunferência à altura do peito (CAP) dos indivíduos arbóreos de sombreamento; (3) medida da circunferência a 30 cm do solo dos cacaueiros; (4) amostra do solo em duas profundidades - 0-10 cm e 20-30 cm; (5) cálculo do Índice de Cobertura de Dossel (ICD) utilizando densiômetro florestal; (6) estimativa da produção de cacau por contagem de frutos e (7) levantamento por meio de questionário semiestruturado das condições socioeconômicas e percepção dos agricultores sobre seu plantio, além do manejo dado a ele. Os dados referentes ao SAFs-cacau foram analisados com uso de Análise de Componentes Principais e regressões polinomiais, de forma a compreender de que forma as variáveis se relacionavam. Como resultado, constatamos que os SAFs-cacau possuem em média 14,35 ± 4,9 anos de plantio, produzem em média 354,32 ± 335,52 kg de amêndoa seca de cacau.ha-1.ano-1 estocando em média 13,53 ± MgC.ha-1 em cacaueiros, 16,05 ± 23,56 MgC.ha-1 em árvores de sombreamento, compondo um total de 29,58 ± 24,37 MgC.ha-1 de biomassa arbórea acima do solo, sob índice de cobertura de dossel (ICD) acima do cacaueiro médio de 27,85 ± 22,84. Foi averiguado que quando considerada a relação renda por área, a cultura do cacau provê renda até 8 vezes maior que a pecuária. As análises indicam uma grande variedade de formas de manejo, resultando em grande variação dos dados amostrados, inclusive produtividade. A parcela com melhor relação carbono/produtividade, com produtividade acima da média local, apresentou carbono de sombreamento de 17,92 MgC.ha-1, estoques de carbono acima do solo em cacaueiros de 11,53 MgC.ha-1 e carbono total acima do solo de 29,45 MgC.ha-1, com produtividade de 501,28 kg de amêndoa seca/ano e ICD de 48,83%. As análises de solo mostraram pH, fósforo, magnésio e cálcio em média fora do desejável para cultivo do cacaueiro. As regressões polinomiais indicam que há potencial para enriquecer os SAFs-cacau com árvores de sombreamento de uso econômico, compensando a perda de renda advinda da menor produtividade do cacaueiro, além de prover serviços ambientais. / Considering the challenges posed by the increasing anthropogenic pressure, greenhouse gas emissions, climate change and the growth of deforestation in the Amazon - encouraged by the advancement of the agricultural and livestock frontier - it is necessary to find alternative forms of agricultural production that has potential for mitigation. The present study collected data on 20 cocoa (Theobroma cacao L.) agroforestry systems (AFS), 2 plots of 20 x 50 meters (1000 m2) sampled in 20 small farms in the municipality of São Félix do Xingu, in the southeast of the Pará, aiming to find the relation between the aboveground carbon stocks and cocoa production, searching for its optimal relation. For a better understanding of the carbon x production relationship, we also estimated variables that influence cacao yield, such as soil fertility, light input into the system, and management. To do so, the methods used in data collection were: (1) canopy height estimation; (2) measurement of the circumference at the chest height (CAP) of shade trees; (3) measurement of the circumference at 30 cm of the soil of cacao trees; (4) soil sample at two depths: 0-10 cm and 20-30 cm; (5) calculation of the Canopy Coverage Index (DCI) using a forest densitometer; (6) estimation of cocoa yield by fruit counts and (7) semi-structured questionnaire survey of socioeconomic conditions and farmers\' perception of their AFS, in addition to the management given to them. The data concerning cocoa-based AFs were analyzed using Principal Component Analysis and polynomial regressions, in order to understand how the variables were related to each other. As a result, we found that cocoa SAFs have a mean of 14.35 ± 4.9 years of planting, producing on average 354.32 ± 335.52 kg of dry cocoa beans.ha-1.year-1 stocking on average 13.53 ± MgC.ha-1 in cacao trees, 16.05 ± 23.56 MgC.ha-1 in shading trees, composing a total of 29.58 ± 24.37 MgC.ha-1 of aboveground tree biomass , under canopy cover index (ICD) (measured above the cocoa tree) of 27.85 ± 22.84. It was verified that when considering the relation income by area, the cocoa AFS provides income up to 8 times greater than livestock. The analyzes indicate a wide variety of management methods, resulting in a large variation of the data sampled, including yield. The plot with best carbon/yield relation and with yield above the local average, showed shading tree carbon stocks of 17.92 MgC.ha-1, aboveground carbon stocks in cacao trees of 11.53 MgC.ha-1 and total aboveground carbon of 29.45 MgC.ha-1, yielding 501.28 kg of dried cocoa beans/year and ICD of 48.83%. Soil analyzes showed soils with averages of pH, phosphorus, magnesium and calcium below recommended values for cacao cultivation. Polynomial regressions indicate that there is potential to enrich cocoa-based AFS with shading trees for economic use, compensating for the loss of income from lower cocoa yield, as well as providing environmental services.

<p> Despite the continuous breeding efforts towards improving yield, seed quality, and yield-related traits, there is still little understanding of several aspects of soybean breeding; however, crop breeding is ever-evolving, and plant breeding technologies offer immense potential for accelerating genetic improvement in soybeans. This thesis explores different frameworks to further characterize tradeoffs among seed quality traits, soybean maturity's genetic architecture, and selections for yield. We explored the interactions of carbohydrate traits with other seed traits, flowering, and maturity using data from a large panel of <em>G. max </em>accessions from the USDA soybean germplasm collection. We found a negative correlation between sucrose and protein and a negative correlation between protein and oil, representing a significant challenge for improving seed quality. In contrast to other well-documented correlations, such as protein and oil, correlations between raffinose and oil content seem more specific to populations and environments and are unlikely to generalize to the whole specie; however, the correlations of sucrose with protein and seed size appears to be more stable. In addition, we performed a genome-wide association analysis (GWA) to detect novel QTLs for flowering (R1) time, maturity (R8) time, and reproductive length (RL) using a soybean panel with the same genotype for major <em>E </em>genes (<em>e1-as/E2/E3). </em>While major maturity <em>E</em> genes are known to have pleiotropic effects on R1 and R8, we found two QTLs associated with R8 and RL that do not control R1, suggesting minor-effect, trait-specific loci are also involved in controlling R1 and R8. In addition, w<em>e identified six genes that may play essential roles in regulating R1, R8, and RL; however, further validation of the QTLs and f</em>ine mapping and map-based cloning studies of the candidate genes are necessary before they can be used in breeding programs. Lastly, we conducted a selection experiment in progeny row (PR) populations of four breeding programs to compare the agronomic performance of lines selected by breeders using their usual selection methods to lines selected through prediction of yield performance using new sources of data and information. Our results suggest that aerial average canopy coverage (ACC) used as a secondary trait in combination with field spatial variation adjustment is an efficient high throughput methodology to effectively select high-yielding lines from non-replicated experiments at the PR stage. </p>