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The increase in the use of energy from forest biomass has increased the demand for knowledge about tree-chipping operations. Therefore, this study aimed to evaluate the effect of different drying times of wood logs and various combinations of knife and anvil configurations in the horizontal chipper on the quality of Eucalyptus dunnii chips produced for energy purposes. The study was conducted in a seven-year-old stand of E. dunnii. A horizontal chipper was used to chip whole trees and obtain nine types of chips, resulting from the interaction between the three drying times of the trees and three configurations of the horizontal chipper. The chips were characterized, followed by an evaluation of energy quality for comparison between the treatments. Among the outcomes discerned, it became evident that the employed wood exhibited a Basic Density (0.506 g.cm-³). The chip dimensions and bulk density presented notable disparities owing to the distinct chipper configurations and tree drying time. The extended drying period (150 days) conferred a lower average moisture content (34.20%) to the study materials. Moreover, the ash content was lower in the treatment with 150 drying days (0.52%). Both the useful calorific value and the Fuel Value Index were also greater in the treatment (150 drying days), measuring 2600.00 kcal kg-1 and 128.06 cal cm-3, respectively. In the analysis of the Fuel Value Index concerning chipper configurations, it was observed that for chips featuring a granulometry of 25 mm, the treatment involving 150 days of drying, four knives, and one shim proved the most efficient (Q = 0.979). Conversely, for chips with a granulometry of 16 mm, the treatment involving 150 days of drying, eight knives, and one shim emerged as the most efficient (Q = 0.970). Consequently, the proposed index is efficacious and underscores the necessity of adapting knife settings in response to moisture content changes to maintain the desired granulometry and apparent density standards.

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Research indicates the use of adsorbent materials to remove pollutants from wastewater and effluents, which can be obtained from renewable materials such as biomass, biopolymers (chitosan) or composites. Thus, the objective of this work was to produce and evaluate activated carbon (AC) and chitosan composite films as adsorbents of neutral red dye. AC films were produced using CO2 and water vapor. The variables of the activation process were time (1 and 2 h) and temperature (600 and 750 °C). Five films were produced, with one pure chitosan (T1) film and four activated carbon with chitosan films (T2, T3, T4 and T5). The T2 film refers to activated carbon produced at 600 °C for 1 h + chitosan, T3 to activated carbon produced at 600 °C for 2 h + chitosan, T4 to activated carbon produced at 750 °C for 1 h + chitosan and T5 to activated carbon produced at 750 °C for 2 h + chitosan. The T5 film increased its adsorption capacity by approximately 87% and its removal efficiency of neutral red dye by 43% compared to T1. The presence of activated carbon in the films provided an increase in the adsorption capacity of the neutral red dye.

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Forest harvest waste is an attractive biomass feedstock for biofuel production. However, for better use it is necessary to understand the physical-energetic characteristics of the biomass which composes the waste. Therefore, this study aimed to evaluate the bark, wood and tree top characteristics from Eucalyptus urophylla × Eucalyptus grandis (called urograndis) and Acacia mangium harvest wastes. These species present fast-growing characteristics. The evaluations were carried out with waste generated in the forest harvest in central Brazilian plantations. Three fractions were studied: the Top, Wood and Bark. The energetic and physical characteristics of wastes and briquettes were determined. The top and bark of these species are not yet recognized for their energy potential. A. mangium presented better energetic and physical characteristics than urograndis, with a higher mean of fixed carbon (20.84%), a high heating value (20.34 MJ kg-1), as well as high bulk and energy density (272.66 kg m-3 and 5599.00 MJ m-3). A. mangium bark and urograndis tree tops were the fractions with the best characteristics for energy purposes. Bark, wood and tree top waste generated after urograndis and A. mangium forest harvesting can be used as byproducts for energy purposes in their fresh form (as collected in field) or as briquettes, presenting an alternative for the waste.

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BACKGROUND: Reliable information about the spatial distribution of aboveground biomass (AGB) in tropical forests is fundamental for climate change mitigation and for maintaining carbon stocks. Recent AGB maps at continental and national scales have shown large uncertainties, particularly in tropical areas with high AGB values. Errors in AGB maps are linked to the quality of plot data used to calibrate remote sensing products, and the ability of radar data to map high AGB forest. Here we suggest an approach to improve the accuracy of AGB maps and test this approach with a case study of the tropical forests of the Yucatan peninsula, where the accuracy of AGB mapping is lower than other forest types in Mexico. To reduce the errors in field data, National Forest Inventory (NFI) plots were corrected to consider small trees. Temporal differences between NFI plots and imagery acquisition were addressed by considering biomass changes over time. To overcome issues related to saturation of radar backscatter, we incorporate radar texture metrics and climate data to improve the accuracy of AGB maps. Finally, we increased the number of sampling plots using biomass estimates derived from LiDAR data to assess if increasing sample size could improve the accuracy of AGB estimates. RESULTS: Correcting NFI plot data for both small trees and temporal differences between field and remotely sensed measurements reduced the relative error of biomass estimates by 12.2%. Using a machine learning algorithm, Random Forest, with corrected field plot data, backscatter and surface texture from the L-band synthetic aperture radar (PALSAR) installed on the on the Advanced Land Observing Satellite-1 (ALOS), and climatic water deficit data improved the accuracy of the maps obtained in this study as compared to previous studies (R2 = 0.44 vs R2 = 0.32). However, using sample plots derived from LiDAR data to increase sample size did not improve accuracy of AGB maps (R2 = 0.26). CONCLUSIONS: This study reveals that the suggested approach has the potential to improve AGB maps of tropical dry forests and shows predictors of AGB that should be considered in future studies. Our results highlight the importance of using ecological knowledge to correct errors associated with both the plot-level biomass estimates and the mismatch between field and remotely sensed data.

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Mixed tree plantings and natural regeneration are the main restoration approaches for recovering tropical forests worldwide. Despite substantial differences in implementation costs between these methods, little is known regarding how they differ in terms of ecological outcomes, which is key information for guiding decision making and cost-effective restoration planning. Here, we compared the early ecological outcomes of natural regeneration and tree plantations for restoring the Brazilian Atlantic Forest in agricultural landscapes. We assessed and compared vegetation structure and composition in young (7-20 yr old) mixed tree plantings (PL), second-growth tropical forests established on former pastures (SGp), on former Eucalyptus spp. plantations (SGe), and in old-growth reference forests (Ref). We sampled trees with diameter at breast height (DBH) 1-5 cm (saplings) and trees at DBH > 5 cm (trees) in a total of 32 20 × 45 m plots established in these landscapes. Overall, the ecological outcomes of natural regeneration and restoration plantations were markedly different. SGe forests showed higher abundance of large (DBH > 20 cm) nonnative species, of which 98% were resprouting Eucalyptus trees, than SGp and PL, and higher total aboveground biomass; however, aboveground biomass of native species was higher in PL than in SGe. PL forests had lower abundance of native saplings and lianas than both naturally established second-growth forests, and lower proportion of animal dispersed saplings than SGe, probably due to higher isolation from native forest remnants. Rarefied species richness of trees was lower in SGp, intermediate in SGe and Ref and higher in PL, whereas rarefied species richness of saplings was higher in SG than in Ref. Species composition differed considerably among regeneration types. Although these forests are inevitably bound to specific landscape contexts and may present varying outcomes as they develop through longer time frames, the ecological particularities of forests established through different restoration approaches indicate that naturally established forests may not show similar outcomes to mixed tree plantings. The results of this study underscore the importance that restoration decisions need to be based on more robust expectations of outcomes that allow for a better analysis of the cost-effectiveness of different restoration approaches before scaling-up forest restoration in the tropics.

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ResumenLos bosques de Pino-Encino se distribuyen desde el centro de México hasta el norte de Nicaragua y representan un ecosistema de importancia para la conservación en Mesoamérica. En Nicaragua, diferentes áreas protegidas fueron creadas para la preservación de este ecosistema tal como la reserva natural Tisey-Estanzuela, pero son considerados susceptibles a la degradación debido a la deforestación y la agricultura, así como presentarse en un nicho ecológico estrecho (700 a 1 500 msnm). En este trabajo, estudiamos la estructura y composición florística en un gradiente de altitud en un bosque mixto de PinusQuercus de tierras altas en Estelí, en el norte de Nicaragua. Un inventario de vegetación en 15 parcelas rectangulares (0.1 ha 20X50 m) fue llevado a cabo para identificar patrones de densidad de árboles, diversidad de especies y almacenamiento de carbono. En cada parcela todos los fustes con diámetro mayor o igual a 2.5 cm fueron identificados a especie y medidos (diámetro a la altura del pecho y altura total). Un total de 1 081 individuos de 24 especies (17 familias y 21 géneros) fueron registrados, siendo Q. sapotifolia, P. maximinoi, C. vicentina, M. coriacea y S. gladulosum las especies más abundantes representando 92 % de los individuos. Tres asociaciones vegetales fueron definidas basadas en la abundancia y dominancia de Q. sapotifolia, P. maximinoi y las otras especies, dos de estas asociaciones fueron dominadas por Pinus (Bosque de Pino y Bosques de Pino-encino) a altitudes entre 1 300 a 1 400 msnm, mientras la tercera asociación por encinos y otras especies (Cletha vicentina, Myrsine coriaceae, Sapium glandulosum) fue encontrada principalmente a altitudes mayores de 1 400 msnm. La composición y diversidad de especies fue influenciada significativamente por la dominancia de Pinus, mostrando una correlación negativa entre la dominancia y la riqueza de especies de árboles latifoliados diferentes de Quercus spp. Sin embargo, la asociación dominada por Pinus presentó un volumen y biomasa de fustes mayor comparado con las otras asociaciones. Los resultados de este estudio sugieren que los bosques dominados por doseles de encinos o pino-encino presentan la diversidad más alta, mientras bosques dominados por Pinus presentan menor diversidad arbórea por mayor biomasa aérea y almacenamiento de carbono. Por tal razón, se sugiere que estrategias de pagos por servicios ambientales como secuestro de carbono o conservación de la biodiversidad tomen en cuenta las diferencias de las asociaciones encontradas.

AbstractThe pine-oak forest is distributed from Central Mexico to the North of Nicaragua and represent an important ecosystem for conservation in Mesoamerica. In Nicaragua, several protected areas were established for the preservation of this ecosystem, such as the natural reserve Tisey-Estanzuela; however, this forest is considered susceptible to degradation, due to increasing deforestation and agricultural activities, besides being a narrow ecological niche (700 to 1 500 masl). We studied the floristic composition, forest structure and biomass along an altitude gradient dominated by Pinus-Quercus in forest stands on the highlands of Esteli, Northern Nicaragua. A vegetation survey on 15 plots (0.1 ha = 20x50 m) was carried out to identify patterns of tree density and diversity, and carbon stocks. In each plot, all the woody stems with diameter greater or equal to 2.5 cm were identified to species and the diameter at breast height and total height were measured. A total amount of 1 081 individuals of 24 species (17 families and 21 genera) were registered, being Q. sapotifolia, P. maximinoi, C. vicentina, M. coriacea and S. gladulosum the most abundant species representing 92 % of the individuals. Three forest associations were defined based on the abundance and dominance of Q. sapotifolia, P. maximinoi and the other species, two of those associations were dominated by Pinus (pine forest and pine-oak forest) at altitudes between 1 300 to 1 400 masl, while the third association, dominated by oak and other species (Cletha vicentina, Myrsine coriaceae and Sapium glandulosum), was found mainly at altitudes higher than 1 400 masl. Tree composition and species richness was influenced significantly by the dominance of Pinus, showing a negative correlation between the dominance and species richness of broadleaved trees other than Quercus spp. with the dominance of Pinus spp. (P < 0.001). However, the association dominated by Pinus, presented higher stem volume and biomass compared with other associations. The results from this study suggest that stands with both, an oak- or oak-pine-dominated canopy, presented the highest diversity, while Pinus dominated stands presented lower tree diversity, but higher aerial biomass and carbon storage. For this reason, we suggest that the strategies for ecosystem service payments as carbon sequestration or biodiversity conservation, must take into account differences in the type of forest associations found in this work.

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Two different types of typical Brazilian forest biomass were burned in the laboratory in order to compare their combustion characteristics and pollutant emissions. Approximately 2 kg of Amazon biomass (hardwood) and 2 kg of Araucaria biomass (softwood) were burned. Gaseous emissions of CO2, CO, and NOx and particulate matter smaller than 2.5 µm (PM2.5) were evaluated in the flaming and smoldering combustion phases. Temperature, burn rate, modified combustion efficiency, emissions factor, and particle diameter and concentration were studied. A continuous analyzer was used to quantify gas concentrations. A DataRam4 and a Cascade Impactor were used to sample PM2.5. Araucaria biomass (softwood) had a lignin content of 34.9%, higher than the 23.3% of the Amazon biomass (hardwood). CO2 and CO emissions factors seem to be influenced by lignin content. Maximum concentrations of CO2, NOx and PM2.5 were observed in the flaming phase.

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The purpose of this study was to develop and validate equations to estimate the aboveground phytomass of a 30 years old plot of Atlantic Forest. In two plots of 100 m², a total of 82 trees were cut down at ground level. For each tree, height and diameter were measured. Leaves and woody material were separated in order to determine their fresh weights in field conditions. Samples of each fraction were oven dried at 80 ºC to constant weight to determine their dry weight. Tree data were divided into two random samples. One sample was used for the development of the regression equations, and the other for validation. The models were developed using single linear regression analysis, where the dependent variable was the dry mass, and the independent variables were height (h), diameter (d) and d²h. The validation was carried out using Pearson correlation coefficient, paired t-Student test and standard error of estimation. The best equations to estimate aboveground phytomass were: lnDW = -3.068+2.522lnd (r² = 0.91; s y/x = 0.67) and lnDW = -3.676+0.951ln d²h (r² = 0.94; s y/x = 0.56).

O objetivo deste estudo foi desenvolver e validar modelos preditores para a fitomassa epigéa de uma área de Floresta Atlântica secundária. Em duas parcelas de 100m², 82 árvores foram cortadas, ao nível do solo, e anotadas suas medidas de altura e diâmetro. As folhas foram separadas dos ramos para determinação do massa fresca da porção foliar e lenhosa. Amostras de cada fração foram secas em estufa a 80 ºC, até massa constante, para determinação do massa seca. As árvores foram distribuídas em duas amostras aleatórias, sendo uma utilizada para o desenvolvimento das equações de regressão, e a outra para validá-las. Os modelos foram desenvolvidos através da análise de regressão linear simples, tendo como variável dependente a massa seca (DW) e, como variáveis independentes a altura (h), o diâmetro (d) e o quadrado do diâmetro multiplicado pela altura (d²h). A validação foi analisada através da comparação entre os valores obtidos em campo e os estimados pelas equações, através da análise de correlação intraclasse de Pearson e teste t-Sudent pareado. As melhores equações para estimar o massa seca das árvores foram: lnDW = -3,068+2,522lnd (r² = 0,91; s y/x = 0,67) e lnDW = -3,676+0,951ln d²h (r² = 0,94; s y/x = 0,56).

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Density and biomass of live trees >10 cm DBH and saplings 1-9.9 cm DBH, coarse woody debris (LCG diameter > 10 cm), fine woody debris (LCF diameter 2.5-9.9 cm), and standing dead trees (> 10 cm DBH) were quantified in 56 permanent, 1-ha sample plots. These plots are located in four 1- (4 plots), three 10- (12 plots) and two 100- (14 plots) forest fragments in size and nearby continuous forests (19 plots) as well as in two classes of distance from the edges - 300 m (29 plots) and > 300 m (21 plots). Density and biomass of primary species did not differ significantly among the four size categories and the two edge distance classes. However, forest fragments and distance 300 m from the edges had more biomass and density of pioneer trees and saplings than did continuous forest and distance > 300 m from the edge, respectively. There were no significant differences among the size categories for standing dead trees. Forest fragments, however, had more quantity of LCG and LCF than did continuous forests. Moreover, distances 300 m from the edges had higher quantity of LCG and LCF and total necromass than did distances > 300 m. We performed an ANCOVA to assess whether differences in LCG and LCF in fragments were due to proximity of forest borders. An ANCOVA showed that there was no significant effect of fragment size on necromass, but a significant effect of edge distance on both LCG and LCF. The quantity of LCG and LCF was correlated negatively with edge distance sites close to the edge presented over 40-60% more LCG than sites far from the edges in both forest fragments and continuous forests.

As estimativas de densidade e biomassa de árvores vivas com DAP > 10 cm e arvoretas 1-9,9 cm de DAP, liteira lenhosa grossa caída (LCG diâmetro > 10 cm), árvores mortas em pé (> 10 de DAP) e liteira lenhosa fina caída (LCF - 2,5 9,9 cm de diâmetro) foram quantificadas em 56 parcelas permanentes de 1 ha, distribuídas em quatro categorias de tamanho de fragmento - fragmentos de 1 ha (4 parcelas), fragmentos de 10 ha (12 parcelas) e fragmentos de 100 ha (14 parcelas) e floresta contínua (19 parcelas) e em duas classes de distância da borda - 300 m de distância da borda (29 parcelas) e > 300 m (21 parcelas). A densidade e a biomassa de árvores e arvoretas de espécies de estágios sucessionais mais avançados não diferiram significativamente entre as diferentes categorias de tamanho e entre as duas distâncias da borda. Por outro lado, fragmentos florestais e locais 300 m de distâcia da borda tiveram maior biomassa e densidade de árvores e arvoretas de espécies pioneiras do que floresta contínua e locais > 300 m da borda, respectivamente. Fragmentos florestais apresentaram maior quantidade de LCG e LCF do que a floresta contínua. Houve também diferenças significativas entre ambas as distâncias da borda para a quantidade de LCG e LCF e necromassa total. Uma análise de covariância mostrou que não houve efeito de tamanho do fragmento, mas a distância da borda teve um efeito significativo sobre a quantidade de LCG e LCF. A quantidade de LCG e LCF foi correlacionada negativamente com a distância da borda - locais mais próximos à borda tiveram cerca de 40% e 60% mais LCG do que locais mais distantes.

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Estimates of terrestrial biomass depend critically on reliable information about the specific gravity of the wood of forest trees. The study reported on here was carried out in the southern Peruvian Amazon and involved collection of wood samples from trees (70 spp.) in intact forest stands. Results demonstrate the high degree of variability in specific gravity (ovendry weight/green volume) in trees at single locations. Three forest types (swamp, high terrace forest with alluvial soil, and sandy-soil forest) had values close to the average reported for tropical forest woods (.69). Two early successional forest types, which make up as much as 12% of the total vegetated area in this part of the Amazon, had values significantly lower (.40). An increase in specific gravity with increasing age of the tree, which has been reported in some spe cies of tropical-forest woods, is seen in a positive relationship between specific gravity and di ameter for a species prevalent in one plot. Increases in specific gravity with tree and forest age may be significant in estimating changes in carbon stores over time.

Estimativas de biomassa em ecossistemas terrestres dependem de informações confiáveis sobre a densidade da madeira das árvores. Neste estudo, realizado no sul da Amazônia peruana, foram coletadas amostras de madeira de árvores (70 spp.) em florestas intactas. Os resultados demonstram a grande variabilidade na densidade específica (peso seco / volume fresco) entre as árvores de um único sítio. Três tipos de floresta (baixio de terraço alto, floresta sobre terraço aluvial alto argiloso, e floresta de terra firme sobre solo arenoso) tiveram valores de densidade específica próximos à média reportada para madeiras de floresta tropical (0,69). Duas florestas em fase sucessional, que constituem até 12% da área vegetada nesta parte da Amazônia, tiveram valores significativamente menores (média de 0,40). Um incremento da densidade específica com a idade da árvore, reportada anteriormente para algumas espécies de árvores de floresta tropical, foi também encontrado para uma espécie avaliada neste estudo, com uma relação positiva entre sua densidade específica e seu diâmetro. Os aumentos de densidade específica com a idade, tanto das espécies como das florestas, podem ser importantes para estimativas de mudanças temporais nos estoques de carbono.

RESUMO

Estimates of terrestrial biomass depend critically on reliable information about the specific gravity of the wood of forest trees. The study reported on here was carried out in the southern Peruvian Amazon and involved collection of wood samples from trees (70 spp.) in intact forest stands. Results demonstrate the high degree of variability in specific gravity (ovendry weight/green volume) in trees at single locations. Three forest types (swamp, high terrace forest with alluvial soil, and sandy-soil forest) had values close to the average reported for tropical forest woods (.69). Two early successional forest types, which make up as much as 12% of the total vegetated area in this part of the Amazon, had values significantly lower (.40). An increase in specific gravity with increasing age of the tree, which has been reported in some spe cies of tropical-forest woods, is seen in a positive relationship between specific gravity and di ameter for a species prevalent in one plot. Increases in specific gravity with tree and forest age may be significant in estimating changes in carbon stores over time.

Estimativas de biomassa em ecossistemas terrestres dependem de informações confiáveis sobre a densidade da madeira das árvores. Neste estudo, realizado no sul da Amazônia peruana, foram coletadas amostras de madeira de árvores (70 spp.) em florestas intactas. Os resultados demonstram a grande variabilidade na densidade específica (peso seco / volume fresco) entre as árvores de um único sítio. Três tipos de floresta (baixio de terraço alto, floresta sobre terraço aluvial alto argiloso, e floresta de terra firme sobre solo arenoso) tiveram valores de densidade específica próximos à média reportada para madeiras de floresta tropical (0,69). Duas florestas em fase sucessional, que constituem até 12% da área vegetada nesta parte da Amazônia, tiveram valores significativamente menores (média de 0,40). Um incremento da densidade específica com a idade da árvore, reportada anteriormente para algumas espécies de árvores de floresta tropical, foi também encontrado para uma espécie avaliada neste estudo, com uma relação positiva entre sua densidade específica e seu diâmetro. Os aumentos de densidade específica com a idade, tanto das espécies como das florestas, podem ser importantes para estimativas de mudanças temporais nos estoques de carbono.