ABSTRACT Accurate wood volume predictions are critical in hyperdiverse forests because each species has specific size and shape traits. Although generic models at a multispecies level were widely used in Amazonian managed forests, they are subject to more significant bias due to interspecific variability. We used an extensive database of wood volume collected in managed forests to test the hypothesis that generic models violate the independence assumption due to that predictions vary with species-specific size. Our hypothesis was proved as residuals of the generic model were conditioned to species and specific size. The multilevel models were more accurate both in fitting and validation procedures, and accounted for variance derived from species and specific size, providing a more reliable prediction. However, we found that the size-specific models have a similar predictive ability to species-specific models for new predictions. This implies more practical estimates in hyperdiverse forests where fitting species-specific models can be complex. The findings are crucial for sustainable forest management as they allow for more reliable wood volume estimates, leading to less financial uncertainty and preventing damage to forest stocks through under or over-exploitation.

RESUMO Previsões precisas do volume de madeira são críticas em florestas hiperdiversas, pois cada espécie tem características específicas de tamanho e forma. Embora modelos genéricos em nível multiespécie sejam amplamente utilizados em florestas manejadas na Amazônia, eles estão sujeitos a maiores vieses devido à variabilidade interespecífica. Usamos um extenso banco de dados de volume de madeira coletado em florestas manejadas para testar a hipótese de que modelos genéricos violam a suposição de independência, pois as previsões variam de acordo com o tamanho específico da espécie. Nossa hipótese foi comprovada pois os resíduos do modelo genérico foram condicionados à espécie e ao tamanho específico. Os modelos multiníveis foram mais precisos nos procedimentos de ajuste e de validação e contabilizaram a variância derivada de espécies e do tamanho específico, fornecendo previsões mais confiáveis. Descobrimos que os modelos específicos de tamanho têm capacidade preditiva semelhante aos específicos da espécie para novas previsões. Isto implica em estimativas mais práticas em florestas hiperdiversas, onde pode ser complexo o ajuste de modelos específicos por espécies. As conclusões são cruciais para o manejo florestal sustentável, pois permitem estimativas mais confiáveis do volume de madeira, conduzindo a menor incerteza financeira e evitando danos aos estoques florestais devido à sub ou superexploração.

ABSTRACT Tree-level growth models are being more used in heterogeneous forests, for they can take underlying processes, such as competition, into account. Although it is common in the forest literature to test several indices in order to define the most suitable for each study, the evaluation of plot sizes or competition radii is poorly addressed in competition studies. The objective of this work was to assess the effect of different plot sizes and competitor selection radii on distance-independent and distance-dependent competition indices, as well as test several modifications in previously created indices. We used data of diameter, canopy stratum and crown quality from two stem mapped measurements carried out in a six-year period. Both distance-dependent and independent indices were calculated for different plot sizes and competitor selection radii. The performance of plot sizes and neighborhood radii was evaluated via Spearman’s rank correlation with the annual growth in diameter, and those with the largest correlation coefficient were included in a stepwise regression to estimate diameter growth. For almost all the indices the correlation increased as the plot size or radius increased. A 50 m x 50 m square plot generated the strongest correlation for distance-independent indices. A 20 m radius resulted the largest correlation for the distancedependent indices. Modifications in some of the indices also improved their performance. The stepwise regression selected BAL and Hegyi indices to describe the diameter growth, which means that using only one competition index might not be enough to fully explain the overall competition.

ABSTRACT Necromass play a significant ecological function, including the deposition of organic matter, which is essential for carbon cycling in forest ecosystems. Despite the devoted attention to the role of forest necromass into the global carbon cycle, international organizations such as IPCC and FAO have reported the lack of compatible data concerning the carbon stocks in forest necromass among different regions. This paper reviews the terminologies and sampling methods regarding the quantification of carbon stock in forest necromass. Volume, biomass and carbon content determination methods were examined into the literature and then notably in Brazil. We address the problems associated with sampling methods and spatial distribution in related studies. Conflict in nomenclatures, components and diameter threshold confound the comparison of regional results. Meanwhile, we present a standard terminology for similar studies. Coarse woody and non-woody (litter) necromass are frequently computed, although fine woody necromass stands ignored in most studies and reports. Finally, we provide recommendations on specific sampling and measurement methods, taking into account necromass size and spatial pattern for both necromass and litter.

Abstract The aim of this study was to quantify the aboveground biomass and organic carbon of Araucaria angustifolia (Bertol.) Kuntze in a Mixed Ombrophilous Montane Forest in the state of Paraná. The aboveground biomass determination was carried out according to the direct method, using 29 trees with Diameter at Breast Height (DBH) ≥ 40 cm. The trees were felled, cubed and weighed by compartments, which were sampled for determining moisture and carbon content. The average aerial biomass and carbon were 2,126.5 kg ind-1 and 935.8 kg ind-1, respectively. The moisture content resulted in a mean individual accumulation of 2,376.6 liters ind-1 of water. Age did not necessarily result in higher volume production but resulted in higher stem biomass production. Organic carbon accumulation by native A. angustifolia trees should support carbon credits as an incentive for the conservation of araucaria and Mixed Ombrophilous Forest fragments.

ABSTRACT To quantify the surviving trees in a forest stand and estimate the probability of an individual tree to survival are a fundamental task in forest management planning. Therefore, the main goal of this paper was to estimate the tree survival probability in loblolly pine (Pinus taeda L.) plantations based on generalized linear models (GLM). The data set was obtained from forest inventories carried out in the Midwest of Santa Catarina State, Brazil. The data analysis combined strategies for selecting covariates and different specifications of link functions in a Bernoulli GLM. We performed strategies for covariate selection at plot-level along with the standard stepwise procedure, where we considered the elastic net approach, as well as its special cases the lasso and ridge penalization. Our analyses showed that the stepwise procedure combined with the complementary log-log link function provide the best fit. The variables that most contributed to assess tree survival were basal area, number of individuals, maximum diameter, diameter of the average cross-sectional area and the diameter coefficient of variation per plots. This model presents 81.5% of accuracy given by ROC curve. Finally, we evaluated the fitted model by means of the half-Normal plots and randomized quantile residuals, whose results showed evidence of a suitable fit. We suggest the stepwise procedure for selecting covariates for a tree survival probability model, besides a complementary log-log link function.

ABSTRACT The objective of this study was to assess the prediction of partial volumes with nonlinear mixed modeling for Pinus taeda. The volume of 558 trees was measured. The four-parameter logistic model was used in its modified form for the nonlinear mixed approach and, for comparison, the 5th degree polynomial was used. In the mixed modeling, the random effects diameter, age and place were inserted. The statistical criteria used to assess the quality of the adjustment were the Akaike Information Criterion (AIC), the Bayesian Information Criterion (BIC), standard error of the estimate (Syx) and residual graphical analysis. Among the random effects analyzed, age obtained the best adjustment. However, to predict partial volumes, it was noticed that, regardless of the analyzed portion of the trunk, the 5th degree polynomial had the best estimates, with a mean standard error of 20.1% of the estimate compared to 51.8% of the logistic.

ABSTRACT The objective of this study was to test the performance of canopy data obtained from Airborne Laser Scanner (ALS) in generating estimates of above-ground biomass (AGB) of Araucaria angustifolia (Bertol.) Kuntze individuals. A cloud of ALS points located in a fragment of native urban forest in Curitiba, Paraná was used. The procedures consisted of: classifying points; obtaining and smoothing the Canopy Height Model (CHM); detecting peaks and segmenting canopy using eCognition software. Mathematical models were adjusted to estimate the AGB from the crown areas. Two equations were required to estimate the individual AGB, while R2 (%) values of 96.19 and 98.89 were found. The total AGB stock found was 264.333 kg. The LiDAR technology and the methods for obtaining the information used in this work constitute non-destructive and precise tools for quantifying biomass in native forests.

Abstract Considering the importance of the Iguaçu National Park for the conservation of the Atlantic Forest and the absence of scientific or technical studies characterizing the ecology of forest species after seven and a half decades of its existence, a phytosociological survey of the arboreal vegetation was conducted to identify the various existing species and their successional stages. A total of 54 families, 135 genera, and 218 species were found in this survey. Euterpe edulis Mart. was the most frequently occurring species, which together with Aspidosperma polyneuron Müll. Arg., characterize the seasonal forests in the central and south regions of the park. In the north region, located 700 m asl, Araucaria angustifolia (Bertol.) Kuntze and Ilex paraguariensis A. St.-Hil. were observed along with some seasonal species, characterizing a transitional environment between seasonal and ombrophillous forests. In general, forests in the park were classified in advanced stages of ecological succession.

ABSTRACT The aim of this study was to evaluate the effects of age, site, and density factors on the dynamics of eucalyptus diameter distribution. Data were obtained from a continuous forest inventory measured at different occasions, stratified according to the factors evaluated and adjusted by the three-parameter Weibull function using nonthinned clonal plots of eucalyptus stands located in the Central region of the state of Minas Gerais. In order to evaluate the diameter distribution behavior, asymmetry and kurtosis measures and graphical analysis for fitted curves were used. In general, an increase was observed in diameter amplitudes with aging, as well as with improvement of site productivity and higher densities. The number of trees decreased in the lower classes and increased in the upper classes, resulting in diameter distribution curves, being displaced to the right and flattened with aging.

ABSTRACT The aim of this study was to develop a mathematical model for the spatial forest planning of harvest activity scheduling. Thirty-eight (38) blocks were formed from stands aged 13 to 17 years considering a total area limit set to 350 hectares. The model was built in Excel ® spreadsheet and solved by CPLEX® optimization software using the Branch and bound method for the linear programming of problems with integer variables. The results of optimization are presented in the form of a map of spatial distribution of the selected blocks. The total harvested area was 5,989 hectares and the volume generated was 2,956,913 m3 in a planning horizon of five years. Higher results compared with those of traditional planning and efficiency to optimize forest harvesting proved to be a viable alternative to the inclusion of space and operational issues associated with forest harvesting.

Resumen El conocimiento de los patrones e interacciones espaciales de las especies arbóreas permite la comprensión de los procesos ecológicos de estructuración espacio-temporal de los bosques tropicales, tornándose imprescindible para el establecimiento de estrategias de conservación y manejo de sus recursos a largo plazo. El objetivo de este estudio fue investigar los patrones y las interacciones espaciales de Astronium lecointei, Dinizia excelsa y Peltogyne paniculata, tres especies arbóreas madereras dominantes en la Selva Nacional del Jamari, Rondônia, Amazonia Brasileña. Para ello, se utilizó el estimador Kernel, con el objetivo de verificar la posible influencia de factores de primer orden en la distribución de las especies. Para el análisis de los patrones e interacciones espaciales de las especies por medio de los factores de segundo orden, se empleó la función K no homogénea. Los análisis univariados revelaron diferentes patrones espaciales dependientes de la escala para las especies. Agregación relacionada a características ecológicas, como preferencia de hábitat y limitación de la dispersión, fue constatada para A. lecointei y P. paniculata. Dinizia excelsa presentó un patrón espacial aleatorio, explicado por características particulares de su establecimiento, como la necesidad de claros debido a sus requisitos lumínicos. Las asociaciones interespecíficas fueron evidenciadas por los análisis bivariados, en que la atracción espacial de las especies resultó de la misma preferencia por micro hábitats y la repulsión fue resultado de la segregación de nichos.

Abstract Knowledge of spatial patterns and interactions of tree species allows for understanding the ecological processes of spatiotemporal structures of tropical forests, becoming essential for the establishment of strategies for the conservation and management of their resources in the long term. The aim of this study was to investigate the spatial patterns and interactions of Astronium lecointei, Dinizia excelsa and Peltogyne paniculata, three dominant timber tree species in the Jamari National Forest, Rondônia, Brazilian Amazon. The Kernel estimator was used aiming to verify the possible influence of first-order factors on species distributions. Inhomogeneous K-functions were applied to analyze species spatial patterns and interactions by means of second-order factors. Univariate analyses revealed different scale-dependent spatial patterns for the species. Aggregation related to ecological characteristics, such as habitat preference and dispersal limitation, was verified for A. lecointei and P. paniculata. D. excelsa presented a random spatial pattern, explained by specific features of its establishment, such as the need for clearings due to light requirements. Interspecific associations were evidenced by bivariate analyses, in which spatial attraction of species resulted from the same preference for microhabitats and the repulsion was a result of niche segregation. Rev. Biol. Trop. 66(3): 1009-1017. Epub 2018 September 01.

ABSTRACT The aims of the present study were to test the hypothesis that data stratification by cluster analysis and the use of other variables, in addition to DBH, can improve the precision of the estimates in diametric increment modeling for Mixed Ombrophilous Forest species. The study was carried out in the Irati National Forest. Data from 25 permanent sample plots of 1 ha each were used with all individuals presenting DBH equal to or greater than 10 cm being identified and measured. The increment modeling was performed for the whole forest (non-stratified data), ecological groups and species subgroups (stratified data) defined by cluster analysis. DBH presented a low correlation with the diametric increment and the use of other independent variables had a positive effect on the fitting, reducing the standard error of estimate and increasing the coefficient of determination. The data stratification did not make the models suitable to estimate the diametric increment; however, it provided improvements by reducing the standard error of estimate, suggesting that this technique can be better applied in the search for improvements to diametric modeling in natural forests.

ABSTRACT We reviewed key studies published so far regarding Eremanthus erythropappus (DC.) MacLeish (Candeia), in order to approach the sustainable management of this species. The objective of this study was to discuss what is already known by the scientific community, presenting the current scenario and outlining the main challenges that still need to be addressed. Candeia is a tree species found in some Brazilian states, being used in the production of fence posts, and essential oils. It aids in the preservation and restoration of natural areas when properly managed, promoting social development through the creation of jobs and economic growth, due to the current high demand and market value for its products. Due to the high value of its timber, there is a strong anthropic pressure on this species, and it has consequently been exploited in an unsustainable manner. However, already published research suggests that well-managed stands of Eremanthus erythropappus can be economically feasible.

SUMMARY: Forest formations known as bracatingais - bracatinga forest - were initially composed only by the Mimosa scabrella - bracatinga - which, over the years, has been being replaced by several secondary species. The wood produced in these bracatingais is mainly sold for firewood and charcoal, being an important source of income for the small owners of this region. To facilitate the quantification of volumetric wood production, the objective of this work was to model the volume of firewood with bark per unit of area for the other hardwood species of the bracatingais. The data base comes from 320 plots measured in stands with ages varying from 3 to 20 years, measured between 1996 and 2011 in several municipalities of the metropolitan region of Curitiba. In these plots were measured in all the trees, with at least 5 cm in diameter, the variables total height and diameter at breast height. The individual volume of each tree in each plot was estimated using equations adjusted for similar forest formations. Twenty nine forest models selected from the forest literature, plus one arithmetic and one logarithmic, were adjusted by the forward stepwise process. The logarithmic equation adjusted by the forward stepwise process was the one with the best overall performance, with coefficient of determination adjusted of 0.992 and standard error of 10.17 %, which has no correlation among the residues by the Durbin Watson test and which was validated and considered suitable for estimating the volume per hectare of the hardwood species of bracatingais.

RESUMEN: Los bosques de bracatinga o bracatingais, son formaciones forestales que en su inicio se componen exclusivamente por bracatinga (Mimosa scabrella) que a lo largo de los años va siendo reemplazada por otras especies arbóreas secundarias. La madera producida en estos bracatingais es comercializada principalmente para leña y carbón vegetal y es una fuente importante de renta para los pequeños agricultores de la región metropolitana de Curitiba. Con el propósito de facilitar la cuantificación de leña en estos ambientes, el objetivo de este estudio fue ajustar ecuaciones de volumen con corteza en nivel de rodal para especies secundarias allí presentes. La base de datos procede de 320 parcelas temporales en bracatingais con edades comprendidas entre 3 y 20 años, medidas en el periodo de 1996 a 2011 en varios municipios. Para todos los árboles con diámetro mínimo de 5 cm, fueron medidas las variables altura total y diámetro a la altura del pecho. En total fueron ajustados 29 modelos matemáticos provenientes de la literatura forestal, además de uno aritmético y otro logarítmico por medio del proceso de selección de variables hacia adelante paso a paso “forward stepwise”. La ecuación logarítmica ajustada por medio del procedimiento “forward stepwise” fue la de mejor desempeño general, con coeficiente de determinación ajustado de 0,992 y error estándar de 10,17 la cual no tiene correlación entre los residuos por la prueba de Durbin Watson y fue validada estadísticamente para estimar el volumen por hectárea de especies secundarias en rodales de bracatingais.

RESUMO O objetivo deste estudo foi desenvolver uma equação com atributos biológicos e aplicabilidade geral, para representar a relação hipsométrica de povoamentos de Pinus taeda L., com e sem desbaste, na região Meio Oeste do estado de Santa Catarina. Os dados são provenientes de 652 parcelas permanentes, de 428 a 740 m2, localizadas em povoamentos florestais com idades variando de 4,6 a 35,2 anos, em que foram medidas as alturas totais de cerca de 20% das árvores, além das árvores dominantes. As funções de Harrison, Michailoff, Prodan e Stoffels e Van Soest foram ajustadas com seus parâmetros função linear de variáveis do povoamento, baseado no algoritmo Gauss-Newton. De maneira geral, o modelo de Harrison, ajustado com o coeficiente função linear da idade (t), índice de sítio (S), coeficiente de variação dos diâmetros das árvores da parcela (CV d ) e área basal da parcela (G), mostrou o melhor desempenho estatístico para representar a relação hipsométrica, consistência biológica e aplicabilidade geral para povoamentos de Pinus taeda.

ABSTRACT The aim of this study was to develop an equation with biological attributes and general applicability, to represent the height-diameter relationship for Pinus taeda L. stands, with and without thinning, in the Middle West region of Santa Catarina state, Brazil. The data came from 652 permanent plots, with 428 to 740 m2, located in forest stands with ages ranging from 4.6 to 35.2 years, in which the total heights of about 20% of the trees were measured, in addition to the dominant trees. The functions developed by Harrison, Michailoff, Prodan and Stoffels & Van Soest were fitted with their parameters linear function of stand variables, based on the Gauss-Newton algorithm. In general, the Harrison model, fitted with the parameter linear function of age (t), site index (S), coefficient of variation of the tree diameters in the plot (CV d ) and basal area of the plot (G), showed the best statistical performance to represent the height-diameter relationship, biological consistency and general applicability for stands of Pinus taeda.