Degradation and deforestation have taken their toll on bottomland hardwood forests in the Lower Mississippi Alluvial Valley (LMAV). To combat this, many managers, both public and private, have sought silvicultural techniques to ensure future generations have the benefits bottomland hardwoods provide. In the first study of this thesis, artificial regeneration and chemical thinning were implemented to evaluate the effects of these treatments on restoration and enrichment of bottomland hardwoods. Very high mortality rates were seen across all species and sites likely due to improper handling and planting, drought, and competition. The second study explored the feasibility of transplanting bottomland oaks via tree spade that were pruned, topped, or cut at stump height for coppice. The initial establishment results are promising. These projects could potentially provide landowners with the tools and knowledge needed to restore and enhance some of the LMAV’s most unique habitats.

How and why species’ ranges shift has long been a focus of ecology but is now becoming increasingly important given the current rate of climatic and environmental change. In response to global warming, species will need to migrate northward or upward to stay within their climatic tolerances. The ability of species to migrate will determine their fate and affect the community compositions of the future. However, to more accurately predict the future extent of species, we must identify and understand their responses to past and current climatic and environmental changes. The first place change is expected to occur is within ecotones where the ranges of many species converge and individuals exist at the limits of their environmental tolerances. In montane regions, these boundaries are compressed, creating a situation in which even relatively small changes in conditions can lead to shifts in the elevational ranges of species. In this dissertation, I examine the responses of forests in the Green Mountains of Vermont to recent climatic and environmental change in an attempt to understand how future climate change will affect their location and composition. I focus on the Boreal-Deciduous Ecotone (BDE), where the high elevation spruce-fir forests converge with the lower elevation northern hardwoods. In addition to investigating adult trees within the BDE, I also examine the responses of understory herbs and tree seedlings to changes in environmental and climatic factors. Factors considered in these investigations include temperature, soil environment, light environment, invasive species, competition, disturbance and many others. I will examine the complex range of responses in forest species that results from prolonged exposure to these forces alone and in combination. I have attempted to identify the responses of forest species to environmental changes by resurveying historic vegetation plots (Chapter 2), experimentally manipulating the growing environment of tree seedlings (Chapter 3) and performing dendrochronological analyses on tree rings (Chapter 4). Through my resurvey of historic vegetation plots, I determined the degree to which understory species have shifted as individuals or as groups. I also identified a set of novel understory communities that have developed since the 1960's in response to recent climate change, acid deposition and invasive species (Chapter 2). By transplanting and artificially warming tree seedlings, I identified factors responsible for limiting the growth and survival of northern hardwood species above the BDE. Temperature was the primary factor limiting sugar maple (Acer saccharum) at high elevations, while yellow birch (Betula alleghaniensis) was limited almost exclusively by light (Chapter 3). Dendrochronological studies of sugar maples indicated that prolonged exposure to acidified soils has only recently caused growth declines and has altered their relationship to climate (Chapter 4). Together, these studies have produced a cohesive picture of how northeastern montane forests have responded to recent climate change and other anthropogenic impacts. These findings can be used to help predict future species' ranges and identify species that may not be capable of migrating fast enough on their own to keep pace with changes in climatic conditions.

Forest management practices emphasizing stand structural complexity are of interest across the northern forest region of the United States because of their potential to enhance carbon storage. Our research is nested within a long-term study evaluating how silvicultural treatments promoting late-successional forest characteristics affect aboveground biomass development in northern hardwood forests. We are testing the hypothesis that biomass development (carbon storage) will be greater in structural complexity enhancement (SCE) treatments when compared to conventional uneven-aged treatments. SCE treatments were compared against selection systems (single-tree and group) modified to retain elevated structure. Manipulations and controls were replicated across 2-hectare treatment units at two study areas in Vermont, USA. Data on aboveground biomass pools (live trees and coarse woody material, standing dead and downed wood) were collected pre- and post-harvest then again a decade later in 2013. Species group-specific allometric equations were used to estimate live and standing dead biomass and downed log biomass was estimated volumetrically. We used Forest Vegetation Simulator to project "no-treatment" baselines specific to treatment units, allowing measured carbon responses to be normalized relative to differences in site-specific characteristics and pre-treatment conditions. Results indicate that 10 years post-harvest biomass development and carbon storage were greatest in SCE treatments compared to conventional treatments, with the greatest increases in coarse woody material (CWM) pools. Structural complexity enhancement treatments contained 12.67 Mg ha-1 carbon in CWM compared to 6.62 Mg ha-1 in conventional treatments and 8.84 Mg ha-1 in areas with no treatment. Percentage differences between post-harvest carbon and baseline values indicate that carbon pool values in SCE treatments returned closest to pre-harvest or untreated levels over conventional treatments. Total carbon storage in SCE aboveground pools was 15.90% below baseline conditions compared to 44.94% less in conventionally treated areas (P = 0.006). Results from CART models indicated treatment as the strongest predictor of aboveground C storage followed by site-specific variables, suggesting a strong influence of both on carbon pools. Structural enhancement treatments have potential to increase carbon storage in managed northern hardwoods based on these results. They offer an alternative for sustainable management integrating carbon, associated climate change mitigation benefits, and late-successional forest structure.

Submitted by (edna.saturno@ufrpe.br) on 2016-05-24T16:31:30Z No. of bitstreams: 1 Helia Cavalcanti Correa Teixeira.pdf: 722085 bytes, checksum: 907e5992b3d6cc6b52100960509a0841 (MD5) / Made available in DSpace on 2016-05-24T16:31:31Z (GMT). No. of bitstreams: 1 Helia Cavalcanti Correa Teixeira.pdf: 722085 bytes, checksum: 907e5992b3d6cc6b52100960509a0841 (MD5) Previous issue date: 2014-05-06 / This study goals to analyze the relation of commercialization system with causes of losses of leafy vegetables: lettuce, chive and coriander traded by producers, middlemen, Central Supply and Logistics of Pernambuco (CEASA) and private supermarkets in Recife. We specifically sought to identify the main causes of losses in the commercialization system; To quantify and to value the physical and monetary losses caused in the marketing process; To check the retailer’s and wholesaler’s commercialization margin. A theoretical basis was presented about agricultural market, marketing channels and flows, losses in production and marketing of hardwoods, horticulture, production of leafy vegetables, logistics, market structure, pricing system. In the study data collection was carried out through visits and semi-structured interviews with farmers: the leafy vegetables lettuce, scallions and cilantro in Vitória de Santo Antão in the settlement of Natuba with middlemen, with the permittees of supply structures and supermarkets Grand Reef. We also implemented a research questionnaire to identify the monetary losses, physical losses, causes of losses, among other issues part of the chain of marketing of leafy greenery. The results of this study demonstrate that the losses in trading occur throughout this process and consequences of these losses are reflected in the budget of the end user, due to increase in price. According to the producers, there are physicall loses of 73,13% of the three hardwoods studied, and there is a total loss of 40,22% of hardwoods to the middleman, while for the retailer and wholesaler from CEASA there is a loss of 34.48% of leafy, and at last there is a loss of 25,36% of hardwood on the supermarkets. / O presente estudo tem como premissa analisar a relação entre o sistema de comercialização e as causas de perdas das hortaliças folhosas: alface, cebolinha e coentro, comercializados entre os produtores, os atravessadores, a Central de Abastecimento e Logística de Pernambuco (CEASA) e os supermercados. Especificamente, buscou-se verificar as principais causas das perdas no sistema de comercialização; Quantificar e valorar as perdas físicas e monetárias provocadas no processo de comercialização; Verificar a margem de comercialização do varejista e atacadista. Um aporte teórico sobre: mercado agrícola, canais e fluxos de comercialização, perdas na produção e comercialização de folhosas, olericultura, sistema de produção das hortaliças folhosas, logística, estrutura de mercado, formação de preço foi apresentado. No estudo a coleta de dados, foi realizada por meio de visitas e entrevistas semiestruturadas com os produtores: das hortaliças folhosas da alface, da cebolinha e do coentro no Município de Vitória de Santo Antão no assentamento de Natuba, com os atravessadores, com os permissionários da CEASA e com os supermercados do Grande Recife. Realizou-se também a aplicação do questionário de pesquisa de campo, com o objetivo de fazer um levantamento: das perdas monetárias, perdas físicas, causas das perdas, entre outras questões para cada ator integrante do processo de comercialização das hortaliças folhosas. Os resultados encontrados desse estudo demonstram que as maiores causas das perdas na comercialização estão associadas às doenças relacionadas: ao cultivo, às condições climáticas, aos produtos que machucam durante o transporte, o manuseio do cliente. Em relação aos produtores, perde-se fisicamente 73,13% das três folhosas estudadas, a perda total das folhosas para o atravessador confere 40,22%, já para o varejista e atacadista permissionário do CEASA configura uma perda de 34,48% de folhosas e por último tem-se uma perda de 25,36% das folhosas para o supermercado.

Une étude de faisabilité de poutres en bois lamellé-collé a été menée en Guyane Française en utilisant les essences locales. Le but est de déterminer les paramètres de collage assurant la bonne résistance mécanique des assemblages par lamellation et par aboutage, nécessaires à la fabrication de poutres en bois lamellé-collé en climat tropical. Trois essences de bois abondantes de différentes densités ont été sélectionnées. Les adhésifs de types Mélamine-Urée-Formol et Résorcinol-Phénol-Formol ont été utilisées. Les paramètres de collage considérés sont : le grammage, le temps d’assemblage fermé et la pression.En utilisant les normes Européennes, plusieurs campagnes de tests ont été conduites sur des échantillons normalisés. Concernant le collage par lamellation, des tests élémentaires de délamination et de cisaillement des joints de colle ont été réalisés. Le test de délamination consiste en deux cycles d’immersion dans l’eau sous pression et de séchage, il induit de sévères variations d’humidité du bois susceptibles de créer des ouvertures des joints de colles. Le collage par aboutage est réalisé sur des poutres normalisées aboutées. Les entures sont obtenues grâce à un outillage standard communément utilisé pour les résineux. Les résultats ont mis en évidence l’influence des propriétés du bois et des paramètres de collage sur la résistance du joint et la résistance mécanique du produit. En effet, les paramètres du bois, tels que la densité, la rétractibilité et l’imprégnation, ont une forte influence sur le collage, en particulier sur la pression et le grammage nécessaires à la production d’un produit commercialisable. Il apparait qu’un bois de densité moyenne et poreux nécessite un grammage et une pression élevés comparé à un bois de densité élevée qui nécessite des valeurs moindres. Aussi, l’influence d’autres paramètres de fabrication, tels que le rabotage, l’encollage double face et simple face ainsi que l’épaisseur des lamelles, a été établie. Par contre il semblerait que le matériel communément utilisé pour l’aboutage des résineux n’est pas adapté aux feuillus tropicaux. En final, des paramètres de collage ont été validés pour la fabrication de lamellé-collé endémique en Guyane Française et une étude du coût de production d’une poutre lamellé-collé standard a identifié les conditions économiques d’une fabrication en Guyane Française. / A feasibility study of glued-laminated timber beams was carried out in French Guiana using local wood species. The aim of the study was to evaluate the gluing parameters that could ensure good mechanical properties for the manufactured glued-laminated beams in tropical climates. Three abundant wood species with different specific gravity were selected for the study. Melamine-Urea-Formaldehyde and Resorcinol-Phenol-Formaldehyde resins were used for gluing. The three gluing parameters considered are: adhesive spread rate, closing assembly time and gluing pressure.Using European standards, several laboratory tests were performed on normalized samples. The evaluation of a successful lamella’s gluing was done by using elementary tests of delamination and shearing. A delamination test consists of two cycles of water immersion at high pressure and drying which induces severe hygroscopic variation in wood thus causing joints opening. The finger-joints are made using a standard tool usually used for cutting softwoods. The performed tests revealed the influence of wood properties and the gluing parameters on the joint resistance and the mechanical properties of the product. Results show that wood properties such as specific gravity, shrinkage coefficient, and permeation, have a high degree of influence on the gluing step especially on the gluing pressure and on the adhesive spread rate needed to produce a commercial product. Furthermore, wood with medium specific gravity needs more adhesive and more pressure than the one with high specific gravity. Additionally, the effects of other manufacturing parameters, such as planning, double or simple side glue spreading and lamellae thicknesses, on the glue joint resistance were demonstrated. Finally, the common tools used for softwoods are not adapted to making the finger joints with tropical hardwoods.In conclusion, optimal gluing parameters for manufacturing glued-laminated timber beams in French Guiana were established and an economical study using standard glued-laminated timber beams revealed the economic conditions under which a successful manufacturing of these local beams can be implemented in French Guiana.

The health of the northern hardwood forest in the Southern Appalachian Mountains of Tennessee, North Carolina, and Virginia has recently gained attention from the media and environmental stakeholders. This project was designed to examine concentrations of metals, including lead, aluminum, and calcium in growth rings of an important northern hardwood species, American beech (Fagus grandifolia Ehrh.) at Mount Rogers and Whitetop Mountain, Virginia. Dominant and codominant trees were sampled from sixteen research plots located at two different elevations. Samples were crossdated, divided into sections of ten-year periods, and analyzed using atomic absorption spectroscopy. Concentrations of metals were negatively correlated with ring width. Elevation and aspect were significantly associated with the concentration of the cations analyzed. Both lead and calcium concentrations increased during the 1860s and again during the mid-1900s. This increase in lead and calcium may suggest the mobilization of these elements in soil.

Hurricane Katrina had a devastating impact on bottomland hardwood forests in 2005 resulting in damage to nearly 1.2 billion cubic meters of timber. Following such a natural disaster, natural regeneration is typically not a viable option because the seed source has been destroyed on site. Therefore, an economically efficient method of artificial regeneration is considered the most appropriate technique for reforesting these damaged areas. However, few studies have evaluated comparative research that examined early survival and growth performance of various oak species and stock types in such planting settings. This project was implemented in an effort to expand upon what is already known from previous artificial regeneration attempts on Hurricane Katrina damaged lands. Bareroot, conventional containerized, and large potted EKOgrownTM seedlings of cherrybark oak (Quercus pagoda Raf.) and willow oak (Quercus phellos L.) were planted on two sites located in south Mississippi. Survival was assessed monthly and at the end of each growing season, whereas height and groundline diameter (GLD) were measured immediately post planting and at the end of each growing season. Analysis of variance (ANOVA) and Tukey-Kramer multiple comparisons procedure (MCP), where appropriate, were performed to determine any significant differences. After the first growing season, cherrybark oak did not exhibit a substantial difference regarding survival performance when compared to willow oak (75.5 percent and 76.5 percent, respectively). After two growing seasons, willow oak exhibited considerably greater survival (74.0 percent) overall when compared to cherrybark oak (70.5 percent). Bareroot seedlings had the highest survival (87.2 percent). Conventional containerized seedlings had unacceptable survival (47.5 percent) and EKOgrownTM seedlings had acceptable survival (82.0 percent). EKOgrownTM seedlings demonstrated the best overall GLD growth of all planting stocks (3.9 mm respectively). Bareroot seedlings had the second best overall GLD growth (1.5 mm) and conventional containerized had the least amount of overall GLD growth (0.8 mm). Overall height growth when comparing all three planting stocks bareroot, conventional containerized, and EKOgrownTM were similar to one another (-3.5cm, -0.8cm, and -3.6cm respectively). Therefore, based on an overall consideration of cost and performance, bareroot seedlings are considered the most effective option of the two species considered for artificial regeneration utilized in this study.

No description available.

The Southern Appalachian hardwood forests contain a wide diversity of flora and fauna. Understanding processes that affect nutrient availability in these forests is essential for sound forest management. Three interconnected research projects regarding soil resource heterogeneity were designed to increase our understanding of this ecosystem. The objective of these projects were as follows: 1) to examine and quantify the role of decaying stumps in regards to total carbon (C) and nitrogen (N) pools and fine-root dynamics, 2) compare and contrast the use of ground-penetrating radar (GPR) vs. a soil auger for estimating soil depth and site quality and 3) to evaluate how eastern red-backed salamanders (Plethodon cinereus) affect N-availability. For the stump study, results show that decomposing stumps occupy approximately 1.2% of the total soil volume and constitute 4% and 10% of total soil N and C pools. Significant differences in N (p = 0.0114), C (p = 0.0172), microbial biomass C (p = 0.0004), potentially mineralizable N (p = 0.0042), and extractable NH4+ (p = 0.0312) concentrations were observed when compared to mineral soil horizons. In particular, potentially mineralizable N was 2.5 times greater in stump soil than the A-horizon (103 vs. 39 mg kg-1), 2.7 times greater for extractable NH4+ (16 vs. 6 mg kg-1) and almost 4 times greater for MBC (1528 vs. 397 mg kg-1). These measured properties suggest higher N-availability, organic matter turnover and N uptake in stump soil versus the bulk soil. 19% of the total fine root length and 14% of fine root surface area also occurred in the stump soil. The increased fine root length suggests higher concentrations of labile nutrient in the stumps since roots often proliferate in areas with higher nutrient availability. Significant differences occurred in N and C concentrations between all four decay classes and the A-horizon, which validated the use of this system and the need to calculate weighted averages based on the frequency and soil volume influenced by each decay class. In the GPR Study, depth estimations were shallower using a soil auger compared to estimates obtained using GPR across all plots (p = 0.0002; Figure 3.4). On a soil volume basis, this was equivalent to about 3500 m3 of soil per hectare unaccounted for using traditional methods. In regards to using soil depth as a predictor for site quality, no significant relationships were observed with soil depth estimations obtained from the auger (Table 3.3). On the other hand, depth measurements from GPR explained significant amounts of variation across all sites and by physiographic region. Across all sites, soil depth estimates from GPR explained 45.5% of the residual variation (p = 0.001; Table 3.3). When the data were stratified by physiographic region, a higher amount of variation was explained by the regression equations; 85% for the Cumberland Plateau (p = 0.009), 86.7% for the Allegheny Plateau (0.007) and 66.7% for the Ridge and Valley (p = 0.013), respectively (Table 4.2). Results from this study demonstrate how inaccurate current methods can be for estimating soil depth rocky forests soils. Furthermore, depth estimations from GPR can be used to increase the accuracy of site quality in the southern Appalachians. In the salamander study, no significant salamander density treatment or treatment by time effects were observed over the entire study period (p < 0.05). However, when the data were separated by individual sampling periods a few significant treatment by time interactions occurred: 1) during August 2006 for available NH4+ under the forest floor (i.e. horizontal cation membranes; p = 0.001), 2) August and 3) September 2006 for available NH4+ in the A-horizon (p = 0.026), and 4) May 2007 for available NO3- under the forest floor (p = 0.011). As a result of these trends, an index of cumulative N-availability (i.e. NH4+ and NO3-) under the forest floor and in the A-horizon was examined through the entire study period. Cumulative N-availability under the forest floor was consistently higher in the low- and medium-density salamander treatments compared to the high-density treatment. For cumulative N-availability in the A-horizon, a gradient of high to low N-availability existed as salamander density increased. Factors such as a prolonged drought in 2007 may have affected our ability to accurately assess the effects of salamanders on N-availability. We concluded that higher salamander densities do not increase N-availability. Implementing methodologies that accurately account for soil nutrient pools such as stump soil, physical properties such as depth and fauna such as salamanders, increase our understanding of factors that regulate site productivity in these ecosystems. As a result, landscape-level and stand-level management decisions can be conducted more effectively. / Ph. D.

Thermally modified wood (TMW) contains no toxic components and is recommended for its durability, levels of equilibrium of moisture content, and dimensional stability performance. A limitation of TMW is the lack of market acceptance and products due to insufficient information regarding the performance of commercially available products. The goal of this project was to improve the market penetration and industrial processes of TMW. The first objective was to study the perception of TMW products from architects in North America using a survey instrument. Results revealed that information regarding TMW is not reaching the audience for TMW, and that providing knowledge regarding technical and marketing aspects of TMW is essential to increase the market share. The second objective consisted of the evaluation of the variability of the physical and mechanical properties of three thermally treated species manufactured in North America. Results showed that the performance of the commercially produced material was similar among the three companies, where only in seven out of 24 properties had statistical differences. Properties that were significantly different, did not have large enough differences in means to be realistically noticed by customers and all were highly different from untreated wood. The final objective involved the implementation of Lean thinking to the manufacturing process of TMW with the goal of improving the process with a direct impact on cost and waste reductions. Three companies were used as case studies for the production process. The implementation of Lean thinking in the process proposed a reduction in lead times from 55.47 days to 23.20 days, with an increase in value-added activities from 1% to 6%. Most of these gains were obtained through a reduction in inventory levels. / Master of Science / Thermally modified wood (TMW) contains no toxic components and is recommended for its durability, levels of equilibrium of moisture content, and dimensional stability performance. The current market for TMW encounters a lack market acceptance, due to insufficient information and performance measures. The main goal of this study was to increase market penetration and study the industrial processes for manufacturing TMW, using three specifics objectives. For the first objective, a survey was conducted to study the perception of TMW among architects. The results showed a that there was a lack of information regarding the technical and marketing aspects of TMW products, which needs to be addressed by distributors and producers. The second objective consisted of the evaluation of the variability of mechanical and physical properties of three thermally treated species manufactured in North America. The results showed that the performance from the commercial processes were similar, where only seven out of 24 cases showed statistical differences based on the Analysis of Variance (ANOVA). The final objective consisted of a Lean process strategy to produce TMW, improving the process with a direct impact on cost and waste reduction. To study the production process, three case study companies were used. The proposed Lean process reduced the lead times and value-added activities increased. The primary gain was seen in reducing inventory levels.