RESUMOA floresta Amazônica apresenta espécies de elevado potencial para exploração sustentável de madeira, entretanto, para que sejam exploradas, há a necessidade de informações para estimativas precisas de seu volume de madeira. Assim, com a hipótese de que volumes estimados por diferentes métodos e os obtidos pela cubagem rigorosa são estatisticamente iguais entre si, este trabalho teve por objetivo comparar estimativas volumétricas obtidas através do fator de forma, modelos volumétricos e modelo de afilamento para cinco espécies comerciais da floresta amazônica. Foram cubadas 449 árvores pelo método de Smalian para desenvolvimento do fator de forma e ajuste das equações volumétricas e de afilamento. Foi utilizado o delineamento blocos ao acaso, onde cada espécie foi considerada como um bloco e cada método de obtenção volumétrica compôs um tratamento. Foi aplicada a análise de variância para verificar a existência de diferença significativa entre os tratamentos e entre os blocos, seguida do teste de Tukey para o nível crítico ≤ 0,05. Entre os modelos ajustados, o de Schumacher-Hall foi o que apresentou maior precisão para estimar o volume. O fator de forma médio estimado é 0,73. Não houve diferenças estatísticas na estimativa do volume utilizando os diferentes métodos, contudo, recomenda-se utilizar o modelo de simples entrada, pois a altura para espécies amazônicas é de difícil obtenção, fazendo deste método o mais prático. PALAVRAS-CHAVE: Fator de forma, Floresta tropical, Volumetria. ABSTRACTThe Amazon rainforest presents species with high potential for sustainable exploitation of timber, however, in order to be exploited, there is a need for information to accurately estimate its volume of wood. Thus, with the hypothesis that volumes estimated by different methods and the real cubic volume are statistically the same, this study aimed to compare volumetric estimates obtained through form factor, volume models and taper function for five commercial species of Amazon rainforest. We scaled 448 trees by Smalian method to develop the form factor and adjust the volume and taper equations. We used the randomized block experimental design, where each species was considered as a block and each method of volume elaboration as a treatment. We applied an analysis of variance to verify the existence of a significant difference between the treatments and between the blocks, followed by the Tukey test for the critical level ≤ 0,05. Among the adjusted models, Schumacher-Hall was the one that presented greater precision to estimate the volume. The estimated mean form factor is 0.73. There were non-statistical differences in the volume estimation using the different methods, however, it is recommended to use the single-entry model, since the height for Amazonian species is difficult to obtain, making this method the most practical.
Land slope contributes to decrease the productivity in the forestry sector activities, including skidding operations. Thus, it is important to study it in order to improve the forest operations planning. Based on this hypothesis, this study aims to analyze the times of the operational cycle and the productivity of the skidder in slope terrain. The study was conducted in Pinus taeda plantations of a forest company located in the CentralWest region of the state of Paraná, Brazil, in three slope classes: flat to moderate, steep and very steep. The data were obtained by the continuous timing method in a time study. Productivity and mean effective cycle time were determined for the three slope classes. The results show that the search and load and the unloading slopes are the ones that consume less time between the activities evaluated in the operational cycle. Considering the slope classes evaluated, flat to moderate and steep require less time to perform all activities of the operational cycle, and their productivities are higher, when compared to the very steep slope class. The productivity of the very steep slope class was 35.3% and 45.0% lower than the flat to moderate and steep classes, respectively. Skidding with skidder on slopes over 26.1º should be avoided because the productivity is negatively influenced in this condition.
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Aim of the study: To develop an index to describe the competition of trees of Eucalyptus spp. clones in different densities; also, to evaluate the productivity of the clones on Nelder wheels (NWs). Area of study: Ten Eucalyptus spp. clones distributed in nine NWs, located in the northern state of Tocantins, Brazil. Material and methods: A new competition index was formulated as the ratio of geometric areas and average cross-sectional areas of sampling units from different locations on the NW referenced to a unit taken in the center of it. Besides, two distance-dependent indices were tested to evaluate their performance in different spacings. The correlation between the competition indices and the variables height, diameter, volume and cross-sectional area, average distance and mortality percentage was evaluated. To check the difference in productivity between the clones we used MANOVA and discriminant analysis. Main results: The Alba-Péllico index provides a better understanding of the competitive relationship between trees, as well as a better explanation of the competitive process in the NWs than the other indices evaluated. The variation in the basal area between the clones in the less dense locations, substantiates the characteristics of each clone or possible interferences of the location since in this condition they are free from the influence of spacing and competition. This shows that competition is more influential than other characteristics of sites and genotypes in the behavior in diameter, basal area and volume in the densest sites. Research highlights: The characteristics of the Alba-Péllico index indicate good interpretation to understand the competitive relationship among trees since the results vary between 0 and 1, and the closer to zero the smaller or non-existence of competition.
Prodan’s sampling method presents relevant characteristics to obtain estimates of the dendrometric variables per hectare in a Nelder systematic design, because it is practical method and maintains the same number of trees sampled in all sample units for the different spacings. The objective of the research was to evaluate the performance of the estimates number of trees, basal area, and volume per hectare in different spacings with the Prodan’s sampling method, under the hypothesis that these estimates show decreasing behavior with increasing spacing. The data used in the study are from an experiment with nine Nelder plots, established with ten clones of Eucalyptus spp., in the state of Tocantins, Brazil. From the center of the sample unit – SU a reference tree was selected, and the eight nearest trees composed the SU. The estimates of number of trees, basal area and volume per hectare were calculated using the Prodan’s method estimators. Statistical differences between the estimates of the clones and between their spacing were evaluated by multivariate profile analysis. The behavior of the dendrometric variables was inversely proportional to spacing, that is, their estimates decreased with the increase of spacing. The number of trees is more influenced by spacing, and additionally with plant genetic material and mortality also influenced estimates of basal area and volume per hectare. Prodan’s sampling method is appropriate and practical to obtain the estimates per hectare in Nelder’s design because it is not necessary to measure all the trees of the experiment. What do you want to do ?New mailCopy
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