A avaliação da floresta, em termos de seu potencial de madeira comercial, fundamenta tanto as licitações das concessões florestais quanto à autorização de exploração por parte dos órgãos ambientais competentes. Portanto, torna-se necessário o desenvolvimento de novas equações volumétricas com bons níveis de precisão para espécies e formações florestais amazônicas. Este trabalho teve como objetivo ajustar e selecionar modelos para estimativa do volume comercial de espécies em uma floresta sob concessão na Amazônia. Modelos volumétricos foram ajustados para obtenção de uma equação genérica, considerando as 32 espécies comerciais, e de equações específicas para as 12 espécies mais exploradas na área. Com a finalidade de reduzir os erros de estimativa, foram testadas estratificações por classe de diâmetro para todas as equações. Os modelos de Schumacher & Hall e de Spurr foram estatisticamente os mais adequados, ao passo que as equações específicas e a estratificação por classes de diâmetro proporcionaram maior precisão nas estimativas de volume, sendo recomendadas principalmente para dados oriundos de florestas naturais.

RESUMOO presente estudo teve como objetivo avaliar os aspectos ecológicos e sucessionais de um fragmento de floresta subtropical via projeção da estrutura diamétrica de diferentes grupos ecológicos com uso da Matriz de Transição. Com base em medições de 2009 e 2012 de todas as árvores acima de 10 cm de DAP, foram realizadas projeções da distribuição diamétrica, bem como análise da dinâmica de três agrupamentos de espécies: Pioneiras; Não Pioneiras; e Floresta como um todo. Simulações da dinâmica dos agrupamentos foram feitas até 2027 após validação do método. O método de projeção se mostrou aderente em todos os casos, apresentando maior precisão quando utilizado o intervalo de classe de 5 cm. As análises indicaram tendência de substituição gradual das espécies pioneiras, sugerindo avanço sucessional no fragmento florestal estudado, bem como eficiência do método para análise da dinâmica dos grupos ecológicos estudados.Palavras-chave: dinâmica florestal, sucessão florestal, cadeia de Markov. Diametric Distribution Projection of Ecological Groups in a Mixed Tropical Forest ABSTRACTThis study aimed to evaluate the ecological and successional aspects of a subtropical forest fragment by projection of the diameter distribution of different ecological groups, using transition matrix model. Based on measurements of 2009 and 2012 of all trees above 10 cm of DBH, projection of the diameter distribution as well as analysis of forest dynamic were made for three species groups: Pioneer; Non Pioneers, and the whole forest. Simulations of the dynamics of the groups were made until 2027 after method validation. The projection method was adherent in all cases, with higher precision when using the 5cm class interval. The analysis made indicated a gradual substitution tendency of the pioneer species, suggesting a successional advance in the forest fragment under study, as well as an efficiency of the projection method for dynamics analysis of the ecological groups studied.

The State of Rio de Janeiro still holds unknown portions of the Atlantic Forest, which represent gaps in the knowledge of this ecosystem. Paracambi and neighbor municipal districts comprise a vast stretch of virtually unknown forest that makes up part of the Serra do Mar biodiversity corridor. The following study describes the tree community structure in a stretch of the ombrophilous Atlantic Forest, in the Parque Natural Municipal do Curió (Curio MNP), Paracambi, Rio de Janeiro, which serves as the basis to evaluate species diversity and conservation status. The altitudes in the area ranges from 100 to 690 m and the climate varies from mild subtropical to tropical hot and humid. Forty plots (10x10m) were randomly placed along the area, where all the stems equal to or greater than five centimeters (5 cm) diameter at breast high from ground level were measured. A total of 749 individuals, pertaining to 128 genera and 210 species were recorded, eight of which are listed as threatened of extinction in the Brazilian flora. The Shannon-Weaver diversity index (H′) was 4.7 nat.ind.-1 and the species with greater importance value was Pseudopiptadenia contorta (1.6460 m2; 18 individuals) while the most common species wereSenefeldera vertcilata (48) and Actinostemon verticilatus (47 individuals). Despite the sample area being a little smaller than that commonly adopted in tropical studies, data pointed to a richness hitherto not registered in any other study for the State of Rio de Janeiro, no matter the inclusion criteria used, and also confirmed by the two estimator indices used, which have revealed very similar results. The vertical forest structure, the values associated to the successional stage of the species and other aspects of community structure indicate that the Curio MNP encompasses forest stretches in advanced stages of ecological succession. Besides its key location for the connectivity of forest fragments in the region, the results emphasize the ecological importance of this forest remnant and the need for its conservation.

Resumo -Abstract -The goal of this study was to evaluate the performance and select probability density functions to describe the diametric distributions of the forest community and the main three species in a tropical rain forest in southern of Rio de Janeiro State. We tested the functions: Normal, Normal Log, Beta, Gamma, Sb Johnson and Weibull. Adjustments were carried out using Solver tool (MSExcel®) which uses the reduced linear gradient algorithm, optimizing the functions parameters. Value D Kolmogorov-Smirnov and estimation of standard error (Syx%) were evaluate to select the best model. In general, Sb Johnson and Weibull functions presented better statistics adjustment and greater precision in the estimates. Even representing the reality of the distribution, the smaller class intervals did not provide better adjustments, more precise estimates being provided by the larger ranges and smaller classes. ISSN: 1983ISSN: -2605 IntroduçãoAs florestas tropicais são caracterizadas pela alta densidade de plantas e pela grande diversidade de espécies, cujos ritmos de crescimento são, em geral, diferentes (Rangel et al., 2006;Puig, 2008). Em resposta aos ritmos distintos de crescimento e à grande variação de idade das árvores, a estrutura diamétrica apresenta configuração diferenciada entre tipologias florestais, estágios sucessionais e para espécies ou grupos de espécies quando analisadas individualmente.O estudo das distribuições de diâmetros teve início em 1898, quando François De Liocourt estabeleceu seu conceito para florestas naturais multiâneas (Barros et

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.

National Forest Inventories are important primary data sources for large-scale forest resource surveys, in which volume estimates of sampled trees are essential for quantitative analysis. Volume prediction models in natural forests are scarce in Brazil due to legal restrictions for cutting trees, especially in the Atlantic Forest. This study aimed to fit volume models for the main forest types and timber species of the Atlantic Forest in Rio de Janeiro state, considering two hypotheses: (I) generic volume models provide greater generalizability of estimates; however, (II) they may reduce the accuracy of forest typeand species-specific predictions. Four linear models with logarithmic transformation of variables were evaluated to fit volume models for generic and specific datasets, which correspond to the main forest types and timber species. Goodness-of-fit statistics were calculated to compare the accuracy and efficiency of the models, and selected models were validated through leave-oneout cross-validation procedures. The estimates obtained by generic and specific models were compared by non-parametric hypothesis tests. Generic models showed similar predictions to the specific models for forest types and timber species, with similar potential for stem and total volume predictions. Therefore, generic models can be used for Atlantic Forests in Rio de Janeiro state, while specific models are recommended to obtain more detailed local estimates.

RESUMO:Neste trabalho foi caracterizada a florística e a estrutura de um Cerrado sensu stricto localizado no município de Jaborandi, oeste baiano. Para tanto, foram amostrados todos os indivíduos com diâmetro à 30cm da altura da base (D 30cm ≥ 5cm) presentes em área amostral de dois hectares composta por 20 parcelas de 1000 m 2 (20m x 50m). , distribuídos em 58 espécies pertencentes a 42 gêneros e 24 famílias. A família Fabaceae apresentou maior número de espécies (12), seguida de Myrtaceae (8) e Vochysiaceae (5). Os descritores fitossociológicos avaliados revelaram uma comunidade caracterizada pela presença de poucas espécies dominantes, onde a maioria pode ser considerada como pouco comuns e raras. As estruturas diamétrica e da altura evidenciaram uma vegetação equilibrada e composta predominantemente por indivíduos de pequeno porte, onde a riqueza é relevante, assim como a diversidade local, que foi estimada em 2,95 nats . ind -1 pelo índice de Shannon-Wiener. STRUCTURE AND FLORISTIC OF THE CERRADO SENSU STRICTO IN WEST OF BAHIAABSTRACT: In this study it was characterized the structure and floristic of the cerrado sensu stricto located in Jaborandi, a city of western Bahia State. All individuals were sampled based on diameter height (D 30cm ≥ 5cm) present in a sample area of two hectares comprising 20 plots of 1000 m 2 (20m x 50m). Individuals were found in total of 2054 (1027 ind . ha -1 ), on a basal area of 8.24 m 2 . ha -1 and 58 species belonging to 42 genera and 24 families. Fabaceae had the largest number of species (12), followed by Myrtaceae (8) and Vochysiaceae (5). The phytosociological descriptors evaluated, have shown a community characterized by the presence of a few dominant species, where most can be regarded as unusual and rare. The diametrical structure and height presented a balanced vegetation, predominantly composed by small individuals. Here, richness is relevant, as well as local diversity, which was estimated at 2.95 nats . ind -1 by the Shannon-Wiener index.

ABSTRACT:The abundance of tree species in tropical rainforests with different shapes and dimensions, as well as the great structural diversity, makes difficult the employment of form factors or equations to estimate individual volumes. However, the employment of equations at the population level makes possible to predict the volumetric stock per unit of area from forest attributes, excluding the necessity of individual tree volume evaluation. Thereby, the aim of this study was to select variables, fit statistical models and propose stand equations to estimate total and exploitable commercial volumes in an Amazon forest under concession regime. For this, variables commonly measured, like density and basal area, were inserted on traditional commercial volume models; besides the application of variables that considered the diversity and forest structure on models generated by the Stepwise process. After analysis, it was observed that the models obtained through Stepwise propitiated more precise estimation of the volumetric stock, reducing estimation errors and reducing problems with heteroscedasticity of residuals. The insertion of variables that express diversity and forest structure on the equations, like Shannon's and diametric variation indices and the commercial trees ratio, contribute to predictions' improvement, especially for the exploitable commercial volume, being recommended for the precise evaluation of timber potential of areas under Amazon forest concession. MODELAGEM DO ESTOQUE VOLUMÉTRICO COMERCIAL EM UMAFLORESTA OMBRÓFILA NO SUDOESTE DA AMAZÔNIA RESUMO: Nas florestas tropicais, a abundância de espécies arbóreas em diferentes formas e dimensões, bem como a elevada diversidade estrutural, dificulta o emprego de fatores de forma ou de equações para a estimativa de volumes individuais. Contudo, o emprego de equações de povoamento possibilita predizer o estoque volumétrico por unidade de área a partir de atributos da floresta, excluindo a necessidade da avaliação individual do volume das árvores. Com isso, o objetivo deste estudo foi selecionar variáveis, ajustar modelos estatísticos e propor equações de povoamento para a estimativa do volume comercial total e explorável em uma floresta sob regime de concessão na Amazônia. Para isso, medidas comumente mensuradas, como a densidade e a área basal, foram empregadas em modelos tradicionais da literatura; além da aplicação de variáveis que consideraram a diversidade e a estrutura florestal em modelos gerados pelo processo Stepwise. Desse modo, os modelos obtidos por Stepwise propiciaram estimativas mais precisas dos estoques volumétricos, reduzindo os erros de estimativa e reduzindo problemas de heterocedasticidade dos resíduos. Além disso, a inserção de variáveis que expressam a diversidade e a estrutura florestal nas equações, como os índices de Shannon e de variação diamétrica e a razão de indivíduos comerciais, contribuiu para a melhoria das predições, sobretudo para o volume comercial explorável, sendo então recomendadas para a avaliação precisa do pote...