Helio Tonini

Morfologia da copa para avaliar o espaço vital de quatro espécies nativas da Amazônia

This work aimed at defining guidelines for thinning of four native species in pure stands, in Roraima State: Brazil nut tree (Bertholletia excelsa), Andiroba (Carapa guianensis), Ipe-roxo (Tabebuia avellanedae), and Jatoba (Hymenea courbaril). Analyses were made on the relations between main crown morphometric index, and diameter and height growth of these species. Eighty-seven trees were measured, and data taken are: diameter at breast height, total height, crown insertion height and crown diameter. Crown parameters analysis showed diameter and crown area superiority of Brazil nut, which indicates its need of a proper initial spacing and bigger growing space. However, Brazil nut crown was less efficient to maintain the same mean annual diameter increment.

Dendrometria de espécies nativas em plantios homogêneos no Estado de Roraima - Andiroba (Carapa guianensis Aubl), Castanha-do-Brasil (Bertholletia excelsa Bonpl.), Ipê-roxo (Tabebuia avellanedae Lorentz ex Griseb) e Jatobá (Hymenaea courbaril L.)

The growth and selection of equations for four native forest species was studied aiming to identify promising species for homogeneous stands, and agroflorestry systems in the Roraima state. The growth of andiroba (Carapa guianensis Aubl.), castanha-do-brasil (Bertholletia excelsa Bonpl.), ipe-roxo (Tabebuia avellanedae Lorentz ex Griseb) and jatoba (Hymenaea courbaril L.) to the seven years of age, revealed to be promising, reaching mean annual increments in merchantable volume of 6.3; 14.6; 6.0 and 2.3 m3.ha-1 year-1, respectively. Regarding diameter growth, all the species presented mean annual increments over than 1 cm, being higher than the observed ones for trees growing in natural forests. The statistical analyses indicated the hypsometric Prodan equation as of better adjustment for the analyzed species. However, the graphical analysis indicated that the shape of the h/d curve varied with the species. The fit of merchantable volume and commercial form factor equations demonstrated to be necessarily different equations for each species. The graphical analysis of the merchantable volume and form factor curves showed that the species differed in both the parameters, indicating that the use of an average form factor for all the species must be avoided.

Fitossociologia de uma Floresta Ombrófila Densa na Amazonia Setentrional, Roraima, Brasil

ABSTRACT This study was carried out to characterize species composition and phytosociology of a native forest located at Caracarai, Roraima, Brazil. All trees with breast diameter (DBH) above 10 cm in nine 1-ha-permanent plots (100 x 100 m each) were inventoried. We observed 4,724 individuals (525 trees per hectare) distributed in 42 families, 111 genera and 165 species. The families with greater number of individuals were Fabaceae (1883), Lecythidaceae (609) and Sapotaceae (434), comprising 52% of the total. The higher densities of individuals were observed in the pioneer (219 trees ha -1 ), followed by secondary (193 trees ha -1 ) and climax species (113 trees ha ). However, species of secondary group had the highest species richness (95), followed by the climax (44) and the pioneer (26). The Shannon diversity index (H’ = 3.27) and the value of Pielou equability (J = 0.64) were lower than those obtained in other floristic inventories in the Amazon, because of the high occurrence of

Fenologia da castanheira-do-brasil (Bertholletia excelsa Humb. & Bonpl., Lecythidaceae) no sul do estado de Roraima

Objetivou-se, com a realizacao do presente trabalho, estudar o padrao fenologico da castanheira-do-brasil em floresta natural localizada no sul do estado de Roraima, procurando relacionar a frequencia de ocorrencia das fenofases as condicoes pluviometricas do periodo. Para o levantamento fenologico, foram selecionados 20 individuos adultos localizados em uma parcela permanente de 9 ha. As observacoes fenologicas ocorreram quinzenalmente de fevereiro de 2006 a fevereiro de 2009 tendo-se registrado a presenca ou a ausencia dos eventos de floracao, frutificacao e mudanca foliar para cada arvore. Para estimar a sincronia dos eventos fenologicos, utilizou-se o indice de sincronia da populacao (Z). A floracao da castanheira-do-brasil mostrou-se periodica, anual, longa e sincronica e ocorreu predominantemente durante o periodo de menor precipitacao. A frutificacao mostrou-se periodica e sincronica e a dispersao dos frutos ocorreu predominantemente no periodo chuvoso. O padrao fenologico da emissao de folhas tendeu a variar anualmente, sendo proximo ao continuo em 2007 e bi-modal em 2006 e 2008. Observou-se uma maior proporcao de individuos perdendo folhas entre os meses de agosto e outubro que caracterizam um periodo de transicao entre a epoca seca e a chuvosa com sensivel reducao de precipitacao.

Utilização de variáveis dummy em equações de volume para Acacia mearnsii De Wild.

This work was accomplished with the objective of selecting a volume equation with the use of dummy variables for Acacia mearnsii De Wild, in the area of Central Depression of Rio Grande do Sul. In the study there were sampled 750 trees distributed in three places, in ages varying from 3,5 to 7,5 years. The statistical parameters indicated the Stoate Model as the one with the best precision. The fit of this equation with the use of dummy variables was shown to be efficient because it allowed to identify tree growth differences among places, which suggest that the fit of volume equations should be separate to each place, as a way of minimizing errors of volume estimation.

FENOLOGIA DA ANDIROBA (Carapa guianensis, Aubl., MELIACEAE) NO SUL DO ESTADO DE RORAIMA

O presente estudo foi realizado com o objetivo de estudar o padrao fenologico da especie arborea Carapa guianensis , Aubl., em floresta natural localizada no sul do estado de Roraima, procurando relacionar a frequencia de ocorrencia das fenofases as condicoes pluviometricas do periodo. Para o levantamento fenologico foram selecionados 20 individuos adultos localizados em uma parcela permanente de 9 ha. As observacoes fenologicas ocorreram quinzenalmente de fevereiro de 2006 a fevereiro de 2009, registrando-se a presenca ou ausencia dos eventos de floracao, frutificacao e mudanca foliar para cada arvore. Para analisar a influencia da precipitacao na fenologia da especie foi utilizado o coeficiente de correlacao de Spearman e, para estimar a sincronia dos eventos fenologico utilizou-se o indice de sincronia da populacao (Z). A floracao da andiroba mostrou-se subanual, sincronica e correlacionada negativamente com precipitacao no periodo do evento fenologico. Foram observados dois ciclos de floracao, sendo um longo com inicio em outubro, estendendo-se para o ano seguinte, por um periodo medio de 9 meses, e um curto com duracao de dois meses (julho a agosto). A frutificacao e anual, longa e sincronica, e correlacionou-se positivamente com a precipitacao. A epoca ideal para a coleta dos frutos maduros no local estudado e durante o periodo chuvoso, que compreende abril a julho. A emissao de folhas ocorreu de forma continua e nao se correlacionou com a precipitacao. Observou-se uma maior proporcao de individuos perdendo folhas, entre os meses de agosto a novembro, que caracterizam um periodo de transicao entre a epoca seca e chuvosa, com sensivel reducao de precipitacao.

Repeatability of fruits and seeds production and selection of Brazil nut genotypes in native populations in Roraima

This study estimates the repeatability coefficients of two production traits in two native populations of Brazil nut trees. It determines the number of years of suitable evaluations for an efficient selection process, determines the permanent phenotypic correlation between production traits and also the selection of promising trees in these populations. Populations, located in the Ita region (ITA) and in the in the Cujubim region (CUJ), are both belonging to the municipality of Caracarai, state of Roraima - Brazil, and consist of 85 and 51 adult trees, respectively. Each tree was evaluated regarding the number of fruits per plant (NFP) and fresh seed weight per plant (SWP), for eight (ITA) and five consecutive years (CUJ). Statistical analyses were performed according to the mixed model methodology, using Software Selegen-REML/BLUP (RESENDE, 2007). The repeatability coefficients were low for NFP (0.3145 and 0.3269 for ITA and CUJ, respectively) and also for SWP (0.2957 and 0.3436 for ITA and CUJ, respectively). It on average takes nine evaluation years to reach coefficients of determination higher than 80%. Permanent phenotypic correlation values higher than 0.95 were obtained for NFP and SWP in both populations. Although trees with a high number of fruits and seed weight were identified, more evaluation years are needed to perform the selection process more efficiently.

Amostragem para a estimativa de produção de sementes de castanheira‑do‑brasil em floresta nativa

The objective of this work was to determine the necessary sample size in order to estimate individual and populational production of Brazil nut trees (Bertholletia excelsa) in a native forest, and to evaluate different sampling systems. Data were obtained from a grove in the Ita region, Caracarai county, RR, Brazil. Fruit and seed production from 239 trees was monitored from 2007 to 2010. Seven sampling procedures were tested based on the relationship of tree characteristics (diameter, morphological type, and canopy traits) with production, allocation type, and sample periodicity. To verify the precision and accuracy, 128 samples were taken from population, then it was calculated the standard error of mean, confidence interval, and the absolute error. To estimate tree production at 1% of probability, it is necessary to sample 97% of fruit, on average. For a 10% error limit, it is necessary to sample 33% of fruit. Continuous sampling, stratified by the diameter at breast height in six strata, and proportional allocation to the number of trees in the diameter class are the most suitable sampling procedures.

Comportamento da castanha-do-brasil (Bertholletia excelsa) e da cupiúba (Goupia glabra) em sistema agrosilvicultural na região da Confiança, Cantá -Roraima

The aim of this present work was to study the behavior of castanha-do-brasil (Bertholletia excelsa) and cupiuba (Goupia glabra) and also set a growing function and an equation for estimating the crown diameter in an agroforestry system model, installed in Confianca Experimental Station, Canta, Roraima, Brazil, in 1995. We measured quantitative data, such as diameter basal height, total height, crown insertion height, crown diameter and qualitative data like survival, bole quality and phytosanitary aspects such as disease or pests. We analyzed the silvicultural behavior and estimated equation at the crown diameter in function of DBH, and adjusted a growing function for the cupiuba and castanha-do-brasil. Of the 71 castanha-do-brasil trees analyzed 20 (27,8%) producing fruits. The cupiuba showed high individual percentage of bifurcation (around 87,5%). The statistical analyses indicated the Backman function as the best adjusted for the observed species; and based on the equations for estimating crown diameter in function of DBH, we could make inferences about the necessary vital space for reaching determinated dimension. Both species have silvicultural potential for restored areas in agroforestry systems or homogeneous plantations.

Atributos do Solo Relacionados com a Produção da Castanheira-do-Brasil (Bertholletia excelsa)

Neste estudo foram analisados os atributos do solo relacionados com variacoes na producao de frutos da castanheira bem como o estado nutricional da especie. As arvores foram selecionadas em parcela permanente (Caracarai, RR) e divididas em quatro classes de producao: alta, media, baixa e muito baixa. Em novembro de 2009, amostras de solo e folhas foram coletadas para se avaliar a fertilidade do solo, o numero de esporos de fungos micorrizicos arbusculares e o estado nutricional das arvores. Arvores com maior producao de frutos ocorreram associadas a maior teor de Al trocavel na camada de 0-20 cm do solo, bem como a menor valor de pH e saturacao por bases. A variavel discriminante resultante deste estudo nao foi considerada como responsavel por interferir no potencial produtivo da castanheira-do-brasil, mas serviu como indicativo de que arvores mais produtivas contribuem na remocao de bases trocaveis, favorecendo a acidificacao do solo.