Renewable energy has been developing rapidly in the U.S. over the past decades. This thesis first reviewed the status, challenges, and government policies related to the development of bioenergy products from forest-derived woody biomass. Forest management alternatives of loblolly pine (Pinus taeda) plantations for producing both timber and biofuels were then evaluated using economic and biological criteria. The PTAEDA3.1 computerized yield simulator was used to predict growth effects of various site preparation techniques, initial planting densities, and thinning activity. Results indicated that on Site Index 50 to 70 lands, the average annual yields of stem residues ranged from 0.86 to 1.20 tons per acre, from which 39.8 to 47.4 gallons of ethanol could be produced. The rise of relative biomass price would increase wood availability for biofuels. It will also boost intensive management practices, such as intensive site preparation, closer initial planting spacing, earlier thinnings and a shorter harvesting age.

Increased markets for renewable energy feedstocks have led to increased energywood production in the Southeastern United States. Energywood requires additional processing and is often the lowest value product generated, making profitability difficult. Additionally, numerous environmental concerns surround energywood harvesting, such as potential increased erosion, applicability and adequacy of conventional water quality best management practices (BMPs), increased area in road network features due to increased machine trafficking, and reduced quantities of residual woody debris. Energywood harvesting operations have been established in the lower Mid-Atlantic region of the U.S. for several decades, and research examining these operations provides insight into various aspects of the sustainability of the practice in this region and similar locations elsewhere. Therefore, this research provides a literature review on the practice of energywood harvesting, followed by four studies on energywood harvesting operations in the lower Mid-Atlantic region of the U.S. The first study evaluated the productivity and costs of two Appalachian Mountain and three Coastal Plain energywood harvests, providing stakeholders with a comparison of harvesting operations that can be used to make better-informed decisions regarding the efficient and economical harvest of energywood. The second study compared estimated erosion, operational feature areas, BMP implementation rates, ground cover characteristics, and downed woody debris quantities following 10 energywood and 10 conventional harvests in the Mountains of Virginia. The third study detailed a survey conducted among energywood business owners in Virginia designed to characterize harvesting operations and markets, assess business owner opinions related to the current and future state of the industry, and update/expand the results of a previous survey from 2014. The fourth study combined data from the second study with data from two other independent studies, comparing site impact metrics from energywood and conventional harvests across the Mountain, Piedmont, and Coastal Plain regions of Virginia. In the first study, cut and haul costs averaged $32.07/tonne and ranged from $26.19 to $38.28/tonne. Hauling consistently comprised the largest function cost at an average of $12.24/tonne. Harvesting system analysis also highlighted the importance of ensuring a balanced equipment mix to lower costs and ensure efficiency. In the second study, conventional harvests had higher estimated erosion contributions from skid trails (P = 0.089) and averaged more estimated erosion mass overall than energywood harvests, despite being significantly smaller in size (P = 0.054). There was significantly less area in heavy slash (P = 0.076) and lower estimated mass of residual downed woody debris (P = 0.001) on energywood sites than conventional sites (10.98 and 27.95 tons/acre, respectively). Site-wide BMP implementation scores (P = 0.041), as well as those for Streamside Management Zones (SMZs) (P = 0.024), and skidding (P = 0.063) were significantly higher on energywood sites than conventional sites. BMP implementation scores were significant predictors of estimated erosion rates (P < 0.001, R² = 59%), indicating that adequate levels of existing water quality BMPs are effective for erosion control on both conventional and energywood harvests. The third study indicated that energywood harvesting operations in Virginia were generally conventional single-crew roundwood operations utilizing their own residues for energywood. Production levels varied widely with energywood comprising an average 31% of total production. Material was comminuted utilizing large (650 median horsepower) older (13.2 years average) whole-tree chippers fed by a single loader. Coastal Plain operations were larger scale than Piedmont operations, though those in the Piedmont had been in business longer. Businesses had a median of $400,000 USD invested in energywood production equipment, which was double their median investment in the previous survey. Logging businesses that had produced energywood longer were significantly (P = 0.0391) more likely to report profitability. In addition, loggers reported deriving numerous non-market benefits from energywood production (e.g., improved aesthetics and cleaner sites, leading to increased landowner satisfaction), with most business owners planning to continue production in the future. The fourth study revealed that estimated erosion was higher in the Mountains due to steep slopes and operational challenges. BMP implementation varied by region and harvest type, with energywood sites having better implementation than conventional sites, and conventional Mountain sites having lower implementation than other regions. Sufficient woody debris remained for BMPs on both harvest types in all regions, with conventional Mountain sites retaining twice that of Coastal Plain sites. BMPs effectively reduced potential erosion on both site types; therefore, increased implementation could likely lower erosion potential in problematic areas. Collectively, this research provides a wholistic representation of energywood harvesting operations in the lower Mid-Atlantic region of the U.S., allowing stakeholders in the region and other similar locations to make informed decisions regarding its sustainable harvest. / Doctor of Philosophy / Additional markets for renewable energy feedstocks have led to increased energywood (biomass) production in the Southeastern United States. Energywood is wood that is often used in the place of coal for renewable energy production. This includes wood of insufficient size, poor form, or with no other higher market value at the time of harvest. It also includes both residues from logging operations as well as stands planted to be harvested specifically for bioenergy production. Energywood requires additional processing steps and is often the lowest value product on harvesting sites, making profitability difficult to achieve. Additionally, energywood harvests may result in negative environmental impacts, such as increased erosion, increased area in road network features, and reduced quantities of residual woody debris. Finally, Best Management Practices (BMPs) have been created for conventional forest harvesting operations, but their applicability to energywood harvests has not been verified. Therefore, this research provides a literature review on the practice of energywood harvesting, followed by four studies on energywood harvesting operations in the lower Mid-Atlantic region of the U.S. The first study evaluated the productivity and costs of two Appalachian Mountain and three Coastal Plain energywood harvests, providing stakeholders with a comparison of harvesting operations that can be used to make better-informed decisions regarding the efficient and economical harvest of energywood. It also highlighted the importance of ensuring a balanced equipment mix to lower costs and ensure efficiency, and the high costs associated with hauling. The second study compared estimated erosion, operational feature areas, BMP implementation rates, ground cover characteristics, and downed woody debris quantities following 10 energywood and 10 conventional harvests in the Mountains of Virginia. Conventional harvests were more potentially erosive and had lower BMP implementation rates than energywood harvests, despite energywood harvests resulting in lower quantities of residual woody debris. The third study presents a survey conducted among energywood business owners in Virginia designed to characterize harvesting operations and markets, assess business owner opinions related to the current and future state of the industry, and update/expand the results of a previous survey from 2014. Energywood harvesting operations in Virginia were generally conventional single-crew operations utilizing chippers with energywood comprising an average 31% of total production. Loggers reported deriving numerous non-market benefits from energywood production (e.g., improved aesthetics and cleaner sites, leading to increased landowner satisfaction), with most business owners planning to continue production in the future. The fourth study combined data from the second study with data from two other independent studies, comparing site impacts from energywood and conventional harvests across the Mountain, Piedmont, and Coastal Plain regions of Virginia. Estimated erosion was higher in the Mountains due to steep slopes and operational challenges. BMP implementation varied by region and harvest type, with energywood sites having better implementation than conventional sites, and conventional Mountain sites having lower implementation than other regions. Sufficient woody debris remained for BMPs on both harvest types, regardless of region. Finally, BMPs reduced estimated erosion on both site types, suggesting increased implementation could lower erosion potential in problematic areas. Collectively, this research provides a wholistic representation of energywood harvesting operations in the lower Mid-Atlantic region of the U.S., allowing stakeholders in the region and other similar locations to make informed decisions regarding its sustainable harvest.

Forests face an unprecedented range of disturbances from climate change, introduced pests and pathogens, and novel species, which frequently interact causing severe consequences to forest communities and ecosystem function. Understanding the mechanisms by which forests recover from disturbance and maintain stability of function is not only an issue of ecological interest, but one of pressing human need, as forest functioning is involved in maintaining a suite of ecosystem services that provide for humanity, including the global carbon and water cycles. Using an experimental manipulation of tree species diversity within an oak-dominated temperate northeastern deciduous forest, this dissertation broadly asks: how do forest community biomass and diversity influence stability and magnitude of forest community growth and water use? All three chapters are based on data from the same forest, where four treatments had previously been established by trunk girdling, which kills a tree by severing the cambium and sapwood, but leaves it standing, similar to the effect of many pathogens on trees. The treatments represent a range of species richness (2-10 species), biomass (5.5 × 104 kg/ha to 7.1 × 105 kg/ha), and level of disturbance, with experimental plots losing anywhere from zero to 94% of their living biomass. Chapter 1 focuses on competitive release after the loss of a dominant species using an annual census of trees over the last 10 years. Community level growth rates showed that diversity positively influenced biomass recovery rate. Chapter 2 addresses the role of the tree community’s biomass and diversity on soil water content using soil moisture sensors, which have recorded data hourly for two years, as well as the trees’ water stress, by using foliar stable carbon isotope ratios. Here, diverse communities have higher and more stable levels of soil water as well as trees that are less water stressed. Using the same long term data as Chapter 1, Chapter 3 assesses whether growth in the tree communities has been more stable over the past 10 years, and investigates whether this can be explained by shorter term fluctuations in tree growth measured by automated point dendrometers. While more diverse communities are more stable in their growth rates over time, this was strongly dependent on how much of the original community had been mechanically girdled. Species showed complementarity in phenology of tree growth at the seasonal scale, but our models could not directly link this intra-annual complementarity in more diverse communities to the stability seen over 10 years. Taken together, results from these three chapters suggest that diversity plays a role in mediating recovery of function from disturbance, which has implications for both the global carbon and water cycles.

A crescente conscientização da importância dos serviços ambientais que as florestas proporcionam tem gerado cada vez mais esforços para a restauração desses ecossistemas. Com o objetivo de avaliar a estrutura de florestas restauradas, foram realizados levantamentos fitossociologicos, e estimados os valores de biomassa acima do solo (BAS) e estoque de carbono em quatro reflorestamentos mistos com idades de oito, 23, 55 e 94 anos. As áreas estão localizadas no Estado de São Paulo, sudeste do Brasil, nos municípios de Santa Bárbara d´Oeste (BAN), Iracemápolis (IR), Cosmópolis (COS) e Rio Claro (RC). Nas áreas foram instaladas parcelas permanentes de forma sistemática (300 m2 e 360m2) para a medição de todos os indivíduos arbóreos com diâmetro à altura do peito maior ou igual a cinco centímetros (DAP5cm). Como resultado, observou-se que a densidade dos indivíduos (ind.ha-1) e a área basal (m2.ha-1) aumentaram conforme aumenta a idade dos reflorestamentos. Fabaceae, Malvaceae e Rutaceae foram as famílias com maior riqueza de espécies comuns nas quatro áreas, semelhante às Florestas Estacionais Semideciduais (FES) naturais no Estado de São Paulo. A riqueza e a diversidade de espécies nos reflorestamentos estudados foram superiores à maioria das áreas restauradas no Estado e semelhante às FES naturais. Apesar das quatro áreas de estudo terem predomínio de espécies nativas regionais com síndrome de dispersão zoocórica, também foram encontradas espécies nativas (não regionais), exóticas, e exóticas invasoras. Entre as espécies com maior IVI (índice de valor de importância) destacaram-se Inga vera, Albizia lebbeck, Mimosa bimucronata (BAN), Melia azedarach, Leucaena leucocephala, Nectandra megapotamica (IR), Tipuana tipu, Cariniana estrellensis, Trichilia claussenii (COS), Erythroxylum pulchrum, Anadenanthera colubrina, Joannesia princeps (RC). Não houve similaridade florística entre os quatro reflorestamentos, o que era esperado visto que os reflorestamentos possuem idades e foram implantados com modelos de restauração diferentes. A presença de espécies colonizadoras (não-plantadas) no estrato regenerante pode indicar que em IR, COS e RC os processos ecológicos como a dispersão de sementes podem estar se estabelecendo. A média de BAS, estimada com a utilização de duas equações alométricas da literatura, e do estoque de carbono aumentaram conforme idade do plantio, o que foi esperado, pois as equações alométricas utilizadas neste estudo são em função do diâmetro das árvores (DAP). O estoque de carbono nos quatro reflorestamentos variou de 39,56 a 166,55 MgC.ha-1 (equação 1) e 34,43 a 104,05 MgC.ha-1 (equação 2), médias compatíveis com algumas florestas naturais de FES. As taxas de incremento médio anual em biomassa e carbono diminuíram do plantio mais jovem para o mais antigo, que sugere que os reflorestamentos mais recentes podem ser mais eficazes no sequestro de carbono atmosférico. As espécies nativas regionais e pioneiras apresentaram maiores valores de estoque de carbono nas quatro áreas estudadas. A diferença nos resultados entre as duas equações utilizadas para estimativa de BAS e estoque de carbono foi significativa, no entanto sugere-se que a escolha pela equação mais adequada leve em consideração os intervalos de diâmetro para as quais a equação foi ajustada. / The recognition of environmental services provided by forests has increased demands for ecosystem restoration. The aim of this study was to evaluate the structure of reforested areas, by collecting data on phytosociology, as well as assessment of aboveground biomass and carbon stocks of four mixed reforested areas with eight, 23, 55 and 94 years-old. The study areas were located in the State of São Paulo, southeastern Brazil, within the municipalities of Santa Barbara d´Oeste (BAN), Iracemapolis (IR), Cosmopolis (COS) and Rio Claro (RC). Permanent monitoring plots were placed systematically in each area (300 m2 and 360m2) for sampling all individual trees with diameter at breast height 5cm. The density of individuals (ind.ha-1) and the basal area (m2.ha-1) increased with age of reforested areas. The tree families Fabaceae, Malvaceae and Rutaceae presented the highest species richness of the four study areas, which was similar to other semi deciduous forests of São Paulo state. Species richness and diversity in the study areas were higher than the values obtained for other reforested areas in São Paulo state, but similar to native forests of the region. The regional native species with zoochoric syndrome dispersal were predominant in the four study areas. However, exotic species (including invasive species) were also present. The species with higher values of importance were Inga vera, Albizia lebbeck, Mimosa bimucronata (BAN), Melia azedarach, Leucaena leucocephala, Nectandra megapotamica (IR), Tipuana tipu, Cariniana estrellensis, Trichilia claussenii (COS), Erythroxylum pulchrum, Anadenanthera colubrina, Joannesia princeps (RC). There was no floristic similarity among the four study areas, and this result was expected because the study areas have different ages, as well as different models of reforestation. The presence of regenerants that colonized the areas of IR, COS and RC may indicate that ecological processes such as seed dispersal may have been established. The mean of aboveground biomass, assessed through two allometric equations obtained from the literature, and carbon stocks increased with age of reforested areas. This result was expected because the allometric equations used in this study were originally designed for trees with specific diameter intervals. The carbon stocks in the study areas varied between 39,56 and 166,55 MgC.ha-1 (equation 1) and 34,43 to 104,05 MgC.ha- 1 (equation 2), which are similar to the results obtained for some natural semi deciduous forests. The rates of biomass and carbon annual increment decreased with age of reforestation, suggesting that recent reforested areas may be more effective on carbon sequestration than older reforested areas. The native pioneer species presented high value of carbon storage in the four study areas. Because the difference in these results by using both allometric equations was statistically significant, it is suggested to select the more suitable equation by taking into account the diameter intervals originally used to adjust the equation.

The fixed bed drying of western hemlock and Douglas-fir biomass particles at temperatures ranging from 50��C to 200��C and air velocities from 0.3 to 0.9 m/s was investigated. The objectives were to describe the drying characteristics of the particles, fit a model for thin-layer drying, and develop and test a deep bed drying model based on the thin-layer model. The effects of temperature and air velocity were determined in a bed approximately 1.3 cm in depth and a model for the drying curve was developed. The thin-layer model was then used to predict what would happen in a deeper bed. Model results were compared to drying curves measured in a 23-cm-deep bed. The deep bed model predicted both the experimental drying times and the moisture and temperature profiles in the bed. / Graduation date: 2013

Various methods have been used to estimate the amount of above ground forest biomass across landscapes and to create biomass maps for specific stands or pixels across ownership or project areas. Without an accurate estimation method, land managers might end up with incorrect biomass estimate maps, which could lead them to make poorer decisions in their future management plans. Previous research has shown that nearest-neighbor imputation methods can accurately estimate forest volume across a landscape by relating variables of interest to ground data, satellite imagery, and light detection and ranging (LiDAR) data. Alternatively, parametric models, such as linear and non-linear regression and geographic weighted regression (GWR), have been used to estimate net primary production and tree diameter. The goal of this study was to compare various imputation methods to predict forest biomass, at a project planning scale (<20,000 acres) on the Malheur National Forest, located in eastern Oregon, USA. In this study I compared the predictive performance of, 1) linear regression, GWR, gradient nearest neighbor (GNN), most similar neighbor (MSN), random forest imputation, and k-nearest neighbor (k-nn) to estimate biomass (tons/acre) and basal area (sq. feet per acre) across 19,000 acres on the Malheur National Forest and 2) MSN and k-nn when imputing forest biomass at spatial scales ranging from 5,000 to 50,000 acres. To test the imputation methods a combination of ground inventory plots, LiDAR data, satellite imagery, and climate data were analyzed, and their root mean square error (RMSE) and bias were calculated. Results indicate that for biomass prediction, the k-nn (k=5) had the lowest RMSE and least amount of bias. The second most accurate method consisted of the k-nn (k=3), followed by the GWR model, and the random forest imputation. The GNN method was the least accurate. For basal area prediction, the GWR model had the lowest RMSE and least amount of bias. The second most accurate method was k-nn (k=5), followed by k-nn (k=3), and the random forest method. The GNN method, again, was the least accurate. The accuracy of MSN, the current imputation method used by the Malheur Nation Forest, and k-nn (k=5), the most accurate imputation method from the second chapter, were then compared over 6 spatial scales: 5,000, 10,000, 20,000, 30,000, 40,000, and 50,000 acres. The root mean square difference (RMSD) and bias were calculated for each of the spatial scale samples to determine which was more accurate. MSN was found to be more accurate at the 5,000, 10,000, 20,000, 30,000, and 40,000 acre scales. K-nn (k=5) was determined to be more accurate at the 50,000 acre scale. / Graduation date: 2013

Mémoire (M.E.S.R.)-- Université du Québec à Chicoutimi, 1991. / "Mémoire présenté à l'Université du Québec comme exigence partielle de la maîtrise en études régionales" CaQCU Bibliogr.: f. 444-459. Document électronique également accessible en format PDF. CaQCU

Thesis (MScFor)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The study aims at developing models for predicting aboveground biomass for selected drought tolerant Eucalyptus (E) species (E. cladocalyx, E. gomphocephala and E. grandis x camaldulensis) from the dry west coast. Biomass models were fit for each of the species and a cross-species model was parameterised based on pooled data for all the three species. Data was based on destructive sampling of 28 eucalypt trees which were 20 years of age and additional five five-year old E. gomphocephala trees. Preliminary measurements on diameter at breast height (dbh), height (h) and crown height were recorded in the field. The sampled trees were then felled and samples of discs, branches and foliage were collected. Density of the wood discs and the bark was determined by a water displacement method and computer tomography scanning (CT-scanner). Stem biomass was reconstructed using Smalian’s formula for volume determination and the calculated densities. Upscaling of the crown was carried out by regression equations formulated by employing the sampled branches. Further assessment was carried out on a sub-sample by subjecting the samples to different drying temperatures in a series between 60 and 105ºC. Linear models were parameterised by a simultaneous regression approach based on Seemingly Unrelated Regression (SUR) using the “Systemfit” R statistical package. The predictor variables employed in the study were dbh, d2h and h in which the coefficient of determination (R2), Mean Standard Error (MSE) and Root Mean Standard Error (RMSE) were used to determine the goodness of fit for the models. Akaike Information Criteria (AIC) was also used in the selection of the best fitting model. A system of equations consisting of five models was formulated for each Eucalyptus species. The biomass prediction models had degrees of determination (R2) ranging from 0.65 to 0.98 in which dbh and d2h were the main predictor variable while h improved the model fit. The total biomass models were the best fitting models in most cases while foliage biomass had the least good fit when compared to other models. When the samples were subjected to different drying temperatures, stem wood had the largest percentage change of 6% when drying from 60ºC to 105ºC while foliage had the lowest percentage change of less than 2%. / AFRIKAANSE OPSOMMING: Die doel met hierdie studie is om modelle vir die voorspelling van die bogrondse biomassa van drie droogte-bestande Eucalyptus (E) spesies (E. cladocalyx, E. gomphocephala en E. grandis x camaldulensis), gekweek op die droë kusvlakte in Wes-Kaapland, te ontwikkel. Biomassa modelle vir elk van die spesies is gepas en ’n model gegrond op die gekombineerde data van al drie die spesies, is geparameteriseer. Verder is die biomassa variasie onder verskeie droogingstemperature vasgestel. Die data versameling is uitgevoer gegrond op die destruktiewe mostering van 28 Eucalyptus bome wat 20 jaar oud was en ’n bykomende vyf vyfjarige E. gomphocephala bome. Die aanvanklike mates, naamlik deursnee op borshoogte (dbh), boomhoogte (h) en kroonhoogte is in die veld opgemeet. Die gemonsterde bome is afgesaag en monsters van stamhout skywe, takke en die bas is versamel. Die digtheid van die skywe en die bas is deur die waterverplasing metode, en Rekenaar Tomografie skandering (“CT-scanning”) vasgestel. Stam biomassa is rekonstrukteer deur gebruik te maak van Smalian se formule vir die vasstelling van volume en berekende digtheid. Die opskaal van die kroon biomassa is gedoen met behulp van regressie vergelykings van gekose takmonsters. Submonsters is onderwerp aan ’n reeks van verskillende drogingstemperature tussen 60 en 105ºC. Lineêre modelle is deur ’n gelyktydige regressie benadering gegrond op die Seemingly Unrelated Regression (SUR) wat ’n“Systemfit” R statistiese pakket gebruik, parameteriseer. Die voorspeller veranderlikes wat in hierdie studie gebruik is, is dbh, d2h en h waarin die koëffisient van bepaling (R2), gemiddelde standaardfout (MSE) en vierkantswortel van die gemiddelde standaardfout (RMSE) gebruik is om vas te stel hoe goed die model pas. Akaike Inligting Kriteria is gebruik vir die seleksie van die gepaste model. ’n Reeks vergelykings wat bestaan uit vyf modelle is vir elke Eucalyptus spesie geformuleer. Die biomassa voorspelling model het waardes vir die koëffisiente van bepaling (R2) opgelewer wat strek van 0.65 to 0.98% en waarin dbh en d2h die hoof voorspelling veranderlikes is, terwyl h die pas van die model verbeter. Die totale biomassa model het in die meeste gevalle die beste gepas en die blaarbiomassa die swakste as dit met die ander modelle vergelyk word. Tydens droging vind die grootste persentasie verandering van 6% by stamhout plaas tussen temperature van 60ºC tot 105ºC, en die kleinste persentasie verandering van minder as 2% by blare.

Biomass can be used in several ways to obtain the most diversify forms of energy, either by direct or indirect conversion. The aim of this work was to evaluate the technical viability of the use of different classes of forest residues from pulp and paper industries to produce briquettes. The classes of forest residues were classified as: sawdust and wooden sticks (class 1), litter (class 2), woodchips and chips (class 3), all residues of Eucalyptus spp., and Pinus taeda barks (class 4). The briquettes were manufactured using different classes of forest residues, totalizing 10 treatments: 4 treatments containing 100% of each class of residue and 6 treatments formulated in a 50-50% proportion of each class. The conditions used for the production of briquettes were: 100 bar pressure, temperature of 120º +/- 5ºC, pressing time of 3 minutes and cooling time of 5 minutes. Besides the chemical characterization from the different residues, some other parameters that directly influence the briquettes quality were determinated, such as: superior calorific value, thermogravimetric analysis, compressive strength and apparent, bulk and energetic densities. Through the chemical analysis, it can be observed that the residues class 4 presented the highest content of extractives and lignin when compared to the other studied classes. Evaluating the apparent and energetic densities of briquettes, it can be seen that all the 10 treatments had results without much variation between the values, where the apparent density remained in the average of 1148.20 Kg / m³ and the energy density in 4108,92 MJ / m 3. The superior calorific value analysis results showed a low variation between the treatments, with a higher expression in treatments 4 and 10, with values of 4631.94 Kcal / kg and 4497.07 Kcal / kg, respectively. The briquettes produced by the 10 treatments had a mean burst load of 525.1Kgf, and the treatments 2 and 8 were the most resistant during the mechanical tests, obtaining values of 654Kgf and 610Kgf, respectively. Through the results obtained by the various analysis and evaluations, it can be seen that the briquettes in which formulations had the class of residue 4 were the ones that presented a better quality for energetic power, however, for the purpose of storage and durability of the final product, in a laboratorial scale, the treatments with the most satisfying results were the treatments 2 and 8. / A biomassa pode ser utilizada em diversas formas e estados para obtenção das mais variadas formas de energia seja por conversão direta ou indireta. O objetivo desse estudo foi avaliar a viabilidade técnica do uso de diferentes classes de resíduos florestais, provenientes de empresas de papel e celulose, para a fabricação de briquetes. As classes de resíduos florestais foram classificadas como: serragem e palitos de madeira (classe 1), cascas e folhas(classe 2), cavacos e lascas de madeira (classe 3), todos resíduos de Eucalyptus spp., e cascas de Pinus taeda (classe 4). Os briquetes foram produzidos utilizando diferentes classes de resíduos florestais, totalizando 10 tratamentos: 4 tratamentos contendo 100% de cada classe de resíduos e 6 tratamentos formulados em proporções de 50-50% de cada classe. As condições empregadas para fabricação dos briquetes foram: pressão de 100 bar, temperatura de 120º +/- 5ºC, tempo de prensagem de 3 minutos e tempo de resfriamento de 5 minutos. Além da caracterização química dos diferentes resíduos, foram determinados outros parâmetros que influenciam diretamente na qualidade dos briquetes, tais como: poder calorífico superior, análise termogravimétrica, resistência a compressão e densidades aparente, a granel e energética. A classe de resíduos 4 apresentou os maiores teores de extrativos totais e de lignina quando comparada as demais classes estudadas. Avaliando as densidades aparente e energética dos briquetes, pode-se observar que todos os 10 tratamentos tiveram resultados semelhantes, onde a densidade aparente se manteve na média dos 1148,20 Kg/m³ e a densidade energética em 4108,92 MJ/m³. As análises de poder calorífico superior mostraram resultados de pouca variação entre os tratamentos tendo maior expressão nos tratamentos 4 e 10, com valores de 4631,94 Kcal/Kg e 4497,07 Kcal/Kg, respectivamente. Os briquetes produzidos pelos 10 tratamentos apresentaram carga de ruptura média de 525,1Kgf, sendo os dos tratamentos 2 e 8 os mais resistentes, obtendo valores de 654Kgf e 610Kgf, respectivamente. Através dos resultados obtidos nas diversas análises e avaliações, pode-se constatar que os briquetes em que as formulações continham a Classe 4 de resíduo foram os que apresentaram melhor qualidade para poder energético, porém para fins de armazenamento e durabilidade do produto final, em escala laboratorial, os tratamentos com resultados mais satisfatórios foram os tratamentos 2 e 8.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / This study aimed to quantify and characterize forest biomass by determining the biomass production, the power calorific value, of basic density and energy productivity of species: Acacia mearnsii De Wild, Eucalyptus grandis W. Hill ex Maiden, Mimosa scabrella Benth and Ateleia glazioviana Baill, distributed in different planting space: 2.0x1.0 m; 2.0x1.5 m; 3.0x1.0 m and 3.0x1.5 m, the first and third year after planting. Therefore, it was considered an experiment located in the city of Frederico Westphalen-RS, installed in a randomized complete block design with three replications in a split-plot. After the felling of the trees were removed disks of 2.0 cm thick at positions Tree: 0% (base), 1.30 m (diameter at breast height - DBH), 25%, 50%, 75% and 100% of the total height, for evaluations of wood biomass and bark, power calorific value and higher basic density. To determine the biomass and power calorific value upper branches and leaves, stratified samples were taken and determined its final weight. The determination of power calorific value of the trees was carried out from the weighting of the values obtained in each compartment (wood, bark, twig and leaf). The determination of basic density weighted was performed from the weight of the total shelled with values recorded discs collected at different positions along the stem. Since the energy productivity of biomass was determined from the values of aboveground biomass and power calorific value of each compartment. The results showed that different planting spacing produced different amounts of aboveground biomass and hence the energy productivity of four tree species studied in the first and third year after planting. Minors planting spacing led to an increase in biomass production per unit area in different species, and we found a systematic tendency negative to living space provided, mainly influenced by the number of trees in the different spacing. Thus, species that have excelled in the production of biomass were Eucalyptus grandis and Acacia mearnsii. The basic density weighted of the wood did not show a variation of increase or decrease over time, and the species Acacia mearnsii and Ateleia glazioviana showed the highest values of this property. However, the different levels spacing did not induce the systematic variation of power calorific value and higher basic density in the studied species. The energy yields obtained in the third year, for all species are higher than those of the first year. The species Eucalyptus grandis has the greatest potential for energy productivity, followed by Acacia mearnsii, Mimosa scabrella, Ateleia glazioviana. It is recommended to use the lowest row spacing (2.0 x 1.0 m) for all studied forest species in short rotation plantations with greater production of biomass for energy purposes. / Esse estudo teve como objetivo quantificar e caracterizar a biomassa florestal através da determinação da produção de biomassa, do poder calorífico superior, da massa específica básica e da produtividade energética das espécies: Acacia mearnsii De Wild, Eucalyptus grandis W. Hill ex Maiden, Mimosa scabrella Benth e Ateleia glazioviana Baill, distribuídas em diferentes espaçamentos de plantio: 2,0x1,0 m; 2,0x1,5 m; 3,0x1,0 m e 3,0x1,5 m, no primeiro e terceiro ano após o plantio. Para tanto, foi analisado um experimento situado no município de Frederico Westphalen-RS, instalado em delineamento de blocos completos casualizados com três repetições, no esquema de parcelas subdivididas. Após a derrubada das árvores, foram retirados discos de 2,0 cm de espessura nas posições do tronco: 0% (base), 1,30 m (diâmetro à altura do peito - DAP), 25%, 50%, 75% e 100% da altura total, para as avaliações da biomassa de madeira e casca, poder calorífico superior e massa específica básica. Para a determinação da biomassa e poder calorífico superior dos galhos e folhas, foram retiradas amostras estratificadas e determinadas seu peso final. A determinação do poder calorífico superior das árvores foi realizada a partir da ponderação dos valores obtidos em cada compartimento (madeira, casca, galho e folha). A determinação da massa específica básica ponderada foi realizada a partir da ponderação do volume total sem casca com os valores verificados dos discos coletados em diferentes posições ao longo do tronco. Já a produtividade energética da biomassa foi determinada a partir dos valores de biomassa da parte aérea e do poder calorífico superior de cada compartimento. Os resultados indicaram que os diferentes espaçamentos de plantio proporcionaram diferentes quantidades de biomassa da parte aérea e, consequentemente, na produtividade energética das quatro espécies florestais estudadas, no primeiro e terceiro ano após o plantio. Os menores espaçamentos de plantio conduziram a um aumento na produção de biomassa por unidade de área nas diferentes espécies estudadas, sendo verificada uma tendência sistemática negativa em relação ao espaço vital proporcionado, influenciados principalmente pelo número de árvores presentes nos diferentes espaçamentos. Assim, as espécies que se destacaram na produção de biomassa foram o Eucalyptus grandis e Acacia mearnsii. A massa específica básica ponderada da madeira não apresentou uma variação de acréscimo ou decréscimo ao longo do tempo, sendo que as espécies Acacia mearnsii e Ateleia glazioviana apresentaram os maiores valores dessa propriedade. Todavia, os diferentes níveis de espaçamentos não induziram à variação sistemática do poder calorífico superior e da massa específica básica nas espécies estudadas. As produtividades energéticas obtidas no terceiro ano, para todas as espécies são superiores as do primeiro ano. A espécie Eucalyptus grandis apresentou as maiores potencialidades de produtividade energética, seguida da Acacia mearnsii, Mimosa scabrella e Ateleia glazioviana. Recomenda-se a utilização do menor espaçamento de plantio (2,0 x 1,0 m) para todas as espécies florestais estudadas, em plantios de curta rotação com uma maior produção de biomassa para fins energéticos.