Abstract Quantitative data obtained from native forests is costly and time-consuming. Thus, alternative measurement methods need to be developed to provide reliable information, especially in Atlantic Rain Forests. In this study we evaluated the hypothesis that the combination of an Airborne Laser Scanner (ALS) and an Unmanned Aerial Vehicle (UAV) can provide accurate quantitative information on tree height, volume, and aboveground biomass of the Araucaria angustifolia species. The study was carried out in Atlantic Rain forest fragments in southern Brazil. We tested and evaluated 3 digital canopy height model (CHM) scenarios: 1) CHM derived from ALS models; 2) CHM derived from UAV models; and 3) CHM from a combined ALS digital terrain model and UAV digital surface model. The height value at each tree coordinate was extracted from the pixel in the three evaluated scenarios and compared with the field measured values. ALS and UAV+ALS obtained RMSE% of 6.38 and 12.82 for height estimates, while UAV was 49.91%. Volume and aboveground biomass predictions are more accurate by ALS and UAV+ALS, while the UAV produced biased estimates. Since the ALS is currently used, periodic monitoring can be carried out by a combination of active (ALS) and passive (UAV) sensors.

Abstract Cattle ranching is the primary land-use of deforested areas in the Brazilian Amazon. Deforestation precedes pasture establishment, implying tremendous amounts of greenhouse gas emissions caused by carbon stock losses. Despite several studies addressing carbon storage in forests, there is a lack of data regarding cultivated pastures. Hence, the estimation of greenhouse gas emissions associated with land-use change becomes uncertain. In this study, we assessed the carbon stock of cultivated pastures located in Rondônia, southwestern Brazilian Amazon. A total of 50 squared plots of 1 m² were randomly allocated in cattle ranching farms covered by Oxisols (Dystrophic Yellow and Dystrophic Red-Yellow Latosols). Carbon fraction ranged from 0.36 for belowground biomass to 0.45 gC.g-1 d.m. for aboveground biomass. The average total carbon stock was 5.17 MgC.ha-1, with non-significant differences when stratifying data by soil types. Considering data from the III Brazilian Inventory of Anthropogenic Emissions and Removals of Greenhouse Gases, our results suggested that land-use change from primary forests to cultivated pastures resulted in a loss of 192.54 MgC.ha-1, which corresponds to a net emission of 705.98 MgCO2eq.ha-1 to the atmosphere. This study provides valuable information to improve the Brazilian Inventory of Anthropogenic Emissions and Removals of Greenhouse Gases.

Abstract “Bracatingais” are common forest formations formed by bracatinga (Mimosa scabrella) and secondary species, which have replaced bracatinga over time; these forests are an important source of income for small farmers. The objective of this study was to model the growth and yield volume of firewood per unit of area and to evaluate the dynamics of the stock across the years. Data from 320 plots were used to fit 12 mathematical models separately addressing the data for bracatinga and secondary species and total species. The Clutter model presented better results for bracatinga (IA = 0.954 and Syx% = 8.54) and for total species (IA = 0.917 and Syx% = 11.56). The modified Clutter model was the best for the secondary species, with IA = 0.952 and Syx% = 25.08. The volumetric estimation of these equations was used to compare the estimated volume of the bracatinga with that of the secondary species, identifying the age as between 13 and 14 years when the volume of the bracatinga is supplanted by the volume of the secondary species. Furthermore, 8 years of age was ideal for clearcutting the bracatingais.

Abstract Taper functions and volume equations are essential for estimation of the individual volume, which have consolidated theory. On the other hand, mathematical innovation is dynamic, and may improve the forestry modeling. The objective was analyzing the accuracy of machine learning (ML) techniques in relation to a volumetric model and a taper function for acácia negra. We used cubing data, and fit equations with Schumacher and Hall volumetric model and with Hradetzky taper function, compared to the algorithms: k nearest neighbor (k-NN), Random Forest (RF) and Artificial Neural Networks (ANN) for estimation of total volume and diameter to the relative height. Models were ranked according to error statistics, as well as their dispersion was verified. Schumacher and Hall model and ANN showed the best results for volume estimation as function of dap and height. Machine learning methods were more accurate than the Hradetzky polynomial for tree form estimations. ML models have proven to be appropriate as an alternative to traditional modeling applications in forestry measurement, however, its application must be careful because fit-based overtraining is likely.

Abstract Floristic surveys and diversity indices are often applied to measure tree species diversity in mixed tropical forest remnants. However, these analyses are frequently limited to the overall results and do not allow to evaluate the spatial variability distributions of tree diversity, leading to develop additional tools. This study aimed to estimate the spatial variability of tree diversity and map their spatial patterns in a Brazilian mixed tropical forest conservation area. We used indices to measure the tree species diversity (dbh ≥ 10 cm) in 400 sampling units (25 m x 25 m) from a continuous forest inventory. Semivariograms were fitted to estimate spatial dependences and punctual kriging was applied to compose maps. Mean diversity values were constant in the continuous inventories, indicating a forest remnant in an advanced stage of ecological succession. On the other hand, tree diversity presented spatial patterns identified by geostatistics, in which the dynamics were composed of heterogeneous mosaics spatially influenced by tree species with different ecological features and densities, gap dynamics, advancement of forest succession, mortality, and Araucaria angustilofia’s cohorts.

ABSTRACT The spatial distribution of tropical tree species can affect the consistency of the estimators in commercial forest inventories, therefore, appropriate sampling procedures are required to survey species with different spatial patterns in the Amazon Forest. For this, the present study aims to evaluate the conventional sampling procedures and introduce the adaptive cluster sampling for volumetric inventories of Amazonian tree species, considering the hypotheses that the density, the spatial distribution and the zero-plots affect the consistency of the estimators, and that the adaptive cluster sampling allows to obtain more accurate volumetric estimation. We use data from a census carried out in Jamari National Forest, Brazil, where trees with diameters equal to or higher than 40 cm were measured in 1,355 plots. Species with different spatial patterns were selected and sampled with simple random sampling, systematic sampling, linear cluster sampling and adaptive cluster sampling, whereby the accuracy of the volumetric estimation and presence of zero-plots were evaluated. The sampling procedures applied to species were affected by the low density of trees and the large number of zero-plots, wherein the adaptive clusters allowed concentrating the sampling effort in plots with trees and, thus, agglutinating more representative samples to estimate the commercial volume.

RESUMOO objetivo é estudar a dinâmica da radiação fotossintética alcançando a superfície do solo em povoamentos de Acacia mearnsii De Wild e sua influência no crescimento em altura em povoamentos. Este fato dá origem à formulação da seguinte hipótese para este estudo: "A redução da incidência de luz no interior do suporte de acácia negra vai fazer com que o ponto de inflexão no seu crescimento quando esta atinge a altura de 4 a 5 m de altura, isto é, quando o povoamento se encontra entre 2 e 3 anos de idade". O estudo foi realizado em povoamentos no Estado do Rio Grande do Sul, Brasil, onde os diâmetros a altura do peito, altura total e radiação fotossinteticamente ativa disponível ao nível do solo foram medidos. A frequência tendeu a ser mais intensa com o aumento da idade dos povoamentos. Ficou evidente que ocorreu redução da incidência de luz no interior da floresta causada pelo fechamento do dossel. Consequentemente, o dossel fechado propiciou a concorrência das plantas. Isso afetou as condições para o crescimento em diâmetro e altura dessa espécie, razão pela qual se torna possível conceber a ocorrência de um ponto de inflexão no crescimento dessas duas variáveis, confirmando a hipótese formulada.

ABSTRACTThe objective is to study the dynamics of photosynthetic radiation reaching the soil surface in stands of Acacia mearnsii De Wild and its influence on height growth in stands. This fact gives rise to the formulation of the following hypothesis for this study: "The reduction of the incidence of light inside the stand of black wattle will cause the inflection point in its height growth when this reaches 4 to 5 m in height, i.e. when the stand is between 2 and 3 years of age". The study was conducted in stands in the state of Rio Grande do Sul, Brazil, where diameters at breast height, total height and photosynthetically active radiation available at ground level were measured. The frequency tended to be more intense when the age of the stands increases. It was evident that a reduction of light incidence inside the forest occurred, caused by canopy closure. Consequently, closed canopy propitiated the competition of plants. This has affected the conditions for growth in diameter and height of this species, reason why it becomes possible to conceive the occurrence of an inflection point in the growth of these two variables, confirming the formulated hypothesis.

The objective of this study was to fit regression equations that express the gross calorific power (GCV) of wood from four tree species: Acacia mearnsii De Willd., Eucalyptus grandis Hill, Mimosa scabrella Benth. and Ateleia glazioviana Baill. The backward variable selection procedure was used to formulate GCV equations according to the volatile matter content (VMC), ash content (AC), fixed carbon content (FCC) and organic matter content (OMC). Sample collection was performed one year after planting to determine such variables. All equations performed well: fitted values for the coefficient of determination was greater than 82 %, standard error of the estimate was less than 1.1 % and distribution of residuals was adequate. The equations involving only the VMC for A. mearnsii, AC for E. grandis and A. glazioviana, and elements of proximate analysis for M. scabrella are just as effective at estimating GCV as other equations that include a greater number of independent variables.

El objetivo de este trabajo fue ajustar ecuaciones de regresión que expresen el poder calorífico superior (PCS) de la madera de cuatro especies forestales: Acacia mearnsii De Willd., Eucalyptus grandis Hill, Mimosa scabrella Benth.y Ateleia glazioviana Baill. El procedimiento de selección de variables hacia atrás se utilizó para generar ecuaciones de PCS en función de los contenidos de material volátil (CMV), ceniza (CC), carbono fijo (CCF) y materia orgánica (CMO). Las muestras se recolectaron un año después de la plantación para la determinación de dichas variables. Todas las ecuaciones obtenidas tuvieron buena correlación, presentaron coeficientes de determinación ajustados superiores a 82 %, error estándar de estimación inferior de 1.1 % y distribución adecuada de los residuos. Las ecuaciones que implican solamente el CMV para A. mearnsii, CC para E. grandis y A. glazioviana, y los elementos del análisis proximal para M. scabrella, son tan adecuadas para estimar el PCS como las ecuaciones que incluyen más variables independientes.

As florestas são importantes sumidouros de carbono que contribuem para mitigar mudanças climáticas. Quantificar o estoque de carbono é fundamental para dimensionar este potencial de mitigação. Araucaria angustifolia (Bert.) O. Ktze. Araucariaceae é uma espécie florestal chave no sul do Brasil, devido à sua importância ecológica e econômica. Este estudo visou a analisar comparativamente dois procedimentos de estimativa do estoque individual de carbono (C) de A. angustifolia, em povoamentos implantados no sul do Estado do Paraná. Foram determinados os estoques de carbono em trinta árvores, bem como as correlações entre C, variáveis dendrométricas, Fator de Expansão de Biomassa (FEB) e Razão de Raízes (R). Equações de regressão de C, em função do Diâmetro à Altura do Peito (DAP) e altura total (H), foram ajustadas e comparadas com estimativas do volume do fuste (V) combinadas com FEB e R. O DAP e H se correlacionaram significativamente com C, o que não ocorreu com a idade, FEB e R. As equações de regressão de C, em função de DAP e H, se ajustaram bem aos dados e geraram estimativas acuradas. O mesmo ocorreu em relação às equações de volume, que, combinadas com os fatores de expansão, também propiciaram estimativas estatisticamente aceitáveis. Não houve diferença entre os dois procedimentos testados, sendo ambos acurados para estimar o estoque de carbono individual.

Forests are important carbon sinks that contribute to climate change mitigation. Quantifying the carbon stock is critical for measuring such mitigation potential. Araucaria angustifolia (Bert.) O. Ktze. Araucariaceae is a key forest species in southern Brazil, due to its ecological and economic importance. This study aimed at comparing two procedures for estimating individual carbon stock (C) of A. angustifolia, in pure stands established in the southern Paraná State, Brazil. Individual carbon stocks were determined for thirty trees, as well as correlations between C, dendometric variables, Biomass Expansion Factor (BEF) and Root-to-Shoot Ratio (R). Regression equations of C, concerning Diameter Breast Height (DBH) and total height (H), were adjusted and compared to trunk volume (V) estimates combined with BEF and R. DBH and H showed high correlation to C, what did not happen to tree age, BEF and R. The regression equations of C, concerning DBH and H, adjusted well to the data set, providing reliable estimates. The same happened to the volume equations combined with expansion factors, which also provided statistically acceptable estimates. No difference was observed between the two procedures tested, being both reliable for estimating the individual carbon stock.

A estrutura da comunidade de plantas pteridófitas em um remanescente da Floresta Ombrófila Mista, no município de São João do Triunfo, Paraná, Brasil, foi caracterizada por amostragem de campo e análises dimensionais. Foram avaliados quatro ambientes distintos, com a instalação de 64 parcelas de 2 m x 2 m, onde foi registrada a ocorrência de espécies, aferidas suas medidas e anotado o seu hábito, se terrestre ou epifítico. As epífitas foram observadas quanto à presença ou ausência nos estratos verticais dos forófitos. Foram registrados 810 exemplares, pertencentes a seis famílias botânicas e 12 gêneros. As pteridófitas tenderam a ter maior densidade em ambiente alterado por práticas agrícolas. Não houve diferença marcante de riqueza de espécies entre ambientes. A distribuição de alturas das plantas terrestres apresentou comportamento decrescente, demonstrando que o nicho ecológico destas é predominantemente rente ao solo. A distribuição das espécies epifíticas ao longo do perfil dos forófitos indicou que a maioria das plantas prefere posições superiores a 7 metros. Concluiu-se que a densidade da comunidade de pteridófitas é inferior àquela das plântulas das espécies fanerógamas, o mesmo ocorrendo com a riqueza. Três categorias de espécies foram identificadas: as generalistas, as especialistas e as sem preferência definida.

La structure de la communauté des ptéridophytes renaissant de la Forêt Ombrophyle Mixte, dans la commune de São João do Triunfo, Paraná, Brésil, a été caractérisée par échantillonnage sur le terrain et par analyses dimensionnelles. Quatre environnements distincts ont été évalués, avec l´installation de 64 de 2 m x 2 m, où l'apparition d'essences a été enregistrée, ses dimensions calibrées et son habitat noté, terrestre ou d'épiphyte. Les épiphytes ont été observées en relation à la présence ou à l'absence des strates verticales de phorophytes. 810 exemplaires appartenant à six familles botaniques et 12 genres ont été enregistrés. Les ptéridophytes ont tendance à avoir une plus grande densité en environnement altéré par des pratiques agricoles. A propos de la richesse des espèces, il n'y a pas eu de différences marquantes entre les environnements. La distribution des espèces d'épiphytes le long du profil vertical des phorophytes a indiqué que la majeure partie des plantes préfère des positions supérieures à 7 mètres. Nous avons conclu que la densité est très supérieure aux plantes des espèces arborées, mais la richesse des espèces est inférieure. Trois catégories d'espèces ont été identifiées : les généralistes, les spécialistes et celles sans préférence définie.

A study was undertaken of the fern community within the remnants of a mixed Aurocarian forest at São João do Triunfo municipality, Paraná State, Brazil. Four sites were evaluated, where 64 sample plots of 2 m x 2 m were established to record the species occurence, their size, and habit - either terrestrial or epiphyte. The epiphyte species were also registered in terms of presence or absence in vertical strata of the phorophyts. A herbarium was prepared in order to identify the botanical material. In total, 810 individuals, belonging to six families and 12 genera were recoded in the study area. Most plants recorded showed terrestrial habit. Ferns tended to show greater density in sites disturbed by agriculture. No remarkable difference was noticed among sites in relation to species richness. Height distribution of the whole community was typically J-shaped, indicating that the forest floor is the preferable ecologial niche of ferns. The distribution of epiphyte species along the phorophyts' profile showed that most ferns prefer positions over 7 meters above ground. It was concluded that ferns density and richness are lower than those of the seedlings of flowering species. Three species categories were identified: the generalists, the specialists, and those without preference.

Avaliou-se o efeito da densidade inicial de plantio na produção de madeira para serraria em povoamentos de Pinus taeda no sul do Brasil. Cinco espaçamentos foram comparados: (1) 2,5 m x 1,2 m; (2) 2,5 m x 2,0 m; (3) 2,5 m x 2,8 m; (4) 2,5 m x 3,6 m; e (5) 2,5 m x 4,4 m. Os dados foram obtidos de um experimento em blocos casualizados em propriedades de uma empresa florestal brasileira. O experimento foi analisado biometricamente via ANOVA e teste de Tukey. Análise gráfica foi empregada para avaliar o impacto de cinco regimes de desbaste: (1) corte final aos 15 anos, sem desbaste; (2) corte final aos 20 anos, sem desbaste; (3) desbaste sistemático aos 9 anos e corte final aos 20; (4) desbastes selectivos aos 9 e 15 anos e corte final aos 20 anos; e (5) desbaste sistemático combinado com selectivo aos 9 anos, selectivo aos 15 e corte final aos 20. Os resultados indicaram diferenças significativas a 1% entre os espaçamentos. A produção volumétrica para serraria aumentou gradativamente com o aumento do espaçamento, com marcantes diferenças entre as densidades extremas. Na idade de 9 anos, os espaçamentos 2,5 m x 4,4 m e 2,5 m x 4,4 m, não diferentes entre si, foram os de melhor performance. As análises via simulação, entretanto, apontaram que o efeito da densidade inicial pode ser anulado em um período mais longo de tempo, sobretudo pelo efeito de diferentes regimes de desbaste.

Les effets de différentes densités de plantation sur la production de bois destinés à la scierie ont été évalués sur des peuplements de Pinus taeda dans la Région Sud du Brésil. Cinq espacements ont été comparés: (1) 2.5 m x 1.2 m; (2) 2.5 m x 2.0 m; (3) 2.5 m x 2.8 m; (4) 2.5 m x 3.6 m; et (5) 2.5 m x 4.4 m. L'expérience a été analysée à travers ANOVA et l'épreuve de Tukey. L'analyse graphique a aussi été exécutée pour évaluer l'impact des cinq densités de plantation: (1) coupe rase à la 15ème année, sans éclaircie; (2) coupe rase à la 20ème année, sans éclaircie; (3) éclaircie systématique à la 9ème année et coupe rase à la 20ème année; (4) éclaircies sélectives à la 9ème et à la 15ème années et coupe rase à la 20ème année et (5) éclaircie combinée systématique-sélective à la 9ème année, sélective à la 15ème année et coupe rase à la 20ème année. Les résultats ont révélé des différences (p<0,01) parmi les espacements. La production de bois destinée à la scierie croît progressivement avec la décroissance de la densité du peuplement, mais les différences principales ont été remarquées pour les deux derniers traitements. Les espacements 2.5 m x 4.4 m et 2.5 m x 3.6 m, non-considérablement différents l'un de l'autre, ont une meilleure performance. Cependant, l'analyse de la simulation a indiqué que cet effet de la densité peut être minimisé sur une plus longue période de temps, principalement à cause de l'effet des éclaircies.

This paper evaluates the effects of initial plant spacing on the round-wood yield for saw timber in loblolly pine plantations in Southern Brazil. Five initial densities were compared: (1) 2.5 m x 1.2 m; (2) 2.5 m x 2.0 m; (3) 2.5 m x 2.8 m; (4) 2.5 m x 3.6 m; and (5) 2.5 m x 4.4 m. Data came from a randomized blocks experiment established in a Brazilian forestry company. The experiment was analyzed through ANOVA and Tukey's test. Graphical analysis was also performed to evaluate the impact of five thinning regimes: (1): a single final cut at age 15 without thinning; (2) a single final cut age 20 without thinning; (3) systematic thinning at age 9 and final cut at age 20; (4) selective thinning at ages 9 and 15 and final cut at age 20; and (5) systematic cut combined with selective thinning at age 9, selective thinning at age 15 and final cut at age 20. The results revealed differences (p<0.01) among plant densities. Saw timber yield gradually increased with decreasing plant density, but remarkable differences were noticed for the two extreme treatments. The densities 2.5 m x 4.4 m and 2.5 m x 3.6 m, non-significantly different one another, were those of better performance. Simulation analysis, however, indicated that density effect may be minimized for a longer period of time, mainly because of the effect of thinning regimes.