Search

A 12-year-old Eucalyptus globulus plantation forest was studied with the aim of assessing and modeling the effect of both pruning and thinning activities on the growth strain. The stand is located in the Andean foothills of Bio Bio region in Chile. Two forest management activities were carried out after 2 and half years from planting, and were evaluated according to different pruning intensities (from 0 to 60 % from total height of the tree) and different thinning densities (800 UPH with thinning and 1.600 UPH without thinning). Furthermore, the effect of the crown classes (dominant, co-dominant and intermediate crown) was studied by the combination of two treatments on the behavior of the growth strain. Each treatment was defined by two levels of pruning and thinning. Data at single-tree level were collected to each sampling unit for estimating the most relevant parameter for the stand. Thirty-three trees in total were sampled. The growth strain was measured at the dbh in each one of them, with an extensometer designed by the CIRAD-Foret. The pruning and thinning did not significantly affect the behavior of the growth strain in Eucalyptus globulus according to the research study; on the other hand, the crown class had a highly significant affect on the variation of strains, showing the highest levels of it in dominant crown class trees that trees belonging to co-dominant and intermediate crown classes, respectively. The logarithmic functions and the variance obtained by measurements of dbh, crown radii, and pruning respectively, were entered into regression models as predictor variables of behavior of growth strain, showing a R 2 0,44 and a SEE 0,132.

Species of the genus Eucalyptus managed for sawlogs in fast-growing plantations show high potential for substitution for valuable native hardwoods. To obtain high quality wood, technical pruning is necessary. The objective of the study is to analyse the development of the branches for the first and second pruning lifts and to quantify the biomass of the pruned branches. For the study two stands of Eucalyptus grandis were selected (age 18 and 36 months) for evaluating a pruning lift from 0 to 3 m and 3 to 6 m. The average branch diameter and length were 18 mm and 2.1 m in the younger stand and 21 mm and 2.3 m in the older one. The relation between branch diameter and branch length could be expressed in a linear model (R² = 0.8). In both stands a higher proportion of branches were already dead. The oven-dry biomass of the pruned branches was 2.2 ton.ha-1 in the first pruning lift and 1.2 ton.ha-1 in the second. The results showed that branch development in wide spaced and early thinned eucalypt plantations is in line with the objective of high quality wood production. Pruning should take place before 18 month to avoid dead branches. The oven-dry branch biomass cut in the two pruning lifts shows a low volume making a commercial utilization difficult.

The objective of this study was to identify eucalyptus clones for the production of sawed timber based on dendrometric variables and longitudinal residual deformation (LRD), analyzing the correlation between these characteristics. 20 Eucalyptus grandis x Eucalyptus urophylla clones with 13 years of age were analyzed. The crown size, diameter at breast height (DBH) and bark thickness were measured. There was a significant difference between the clones for DBH, LRD and bark thickness. There was no significant correlation between DBH and DRL. The correlation was significant between DBH and crown size, its being possible to affirm that crown size affects the diametrical growth of trees. DBH and bark thickness were also significantly correlated, in so far as trees with a wider diameter possess thicker bark. It was possible to select clones with better potential for sawed timber production, that is to say, elevated DBH with a reduced LRD.

The productivity of Eucalyptus at plantations is increasing and has undergone a variety of research studies. Most research is dealing with simple dendrometric variables like the DBH (diameter at breast height) and tree height, or more complex variables including crown parameters or variables concerning photosynthesis. The root systems, however, have not been well analyzed yet. The objective of the study was to analyze the root system with a non-destructive method and to evaluate possible correlations with dendrometric variables of the tree (DBH, height, crown expansion). A small experimental plantation with 39 even-aged, 6-year-old trees of Eucalyptus grandis x urophylla has been investigated within this study. The results of the study show the highest correlation of the root areas with the crown expansion. In general, the root area shows a significantly bigger expansion in the eucalypt plantation than the tree crown, with a more homogeneous development. RESUMO A produtividade de plantios de Eucalyptus está crescendo e tem sido tópico de muitas pesquisas. A grande maioria dos estudos trata das variáveis aéreas como DAP, área de copa ou número de galhos e seus diâmetros. As raízes, entretanto, ainda não foram propriamente estudadas. O presente trabalho apresenta resultados de um método não destrutivo com equipamento técnico que foi utilizado para determinar variáveis de uma árvore (DAP, altura, área de copa) que possivelmente se correlacionam com área radicular Um pequeno plantio equiâneo com 39 indivíduos de Eucalyptus grandis x urophylla aos seis anos de idade foi estudado no trabalho. Os resultados demonstraram que área radicular tem a correlação mais alta com área de copa. No geral, a expansão radicular é muito superior à área de copa para os indivíduos desse povoamento. Além disso, a expansão radicular demonstrou-se muito mais homogênea do que a área de copa.

RESUMOO objetivo deste trabalho foi avaliar a influência do espaçamento do plantio da madeira de eucalipto, quanto às suas características dendrométricas e a deformação residual longitudinal (DRL) da madeira e as relações entre essas variáveis. O material utilizado foi o Eucalyptus benthamii aos 5 anos de idade nos espaçamentos 2 × 3, 3 × 3, 3 × 4 e 4 × 4 m, a projeção da copa foi determinada através da medição de oito raios com ângulos variáveis, sendo elaborados mapas da distribuição e projeção da copa. As medições da DRL foram à 1,30 m do solo nas quatro direções cardinais, em árvores vivas, com o auxílio de extensômetro (Growth Strain Gauge), pelo método CIRAD-Fôret. Nos resultados houve grande variabilidade das variáveis de crescimento e dos níveis de tensão de crescimento para os diferentes espaçamentos. Os menores valores médios de DRL foram observados na direção sul, o aumento do espaçamento não alterou significativamente os valores da DRL. As correlações de maiores magnitudes ocorreram entre os valores máximos de DRL e as variáveis de crescimento árvore. ABSTRACTThe aim of this study was to evaluate the influence of planting eucalyptus wood with respect to its dendrometric characteristics and longitudinal residual strain (LRS) of the wood, and the relationships between these variables. The material used was Eucalyptus benthamii at five years of age in 2×3, 3×3, 3×4 and 4×4 m spacing. The projection of the crown was determined by measuring eight spokes with variable angles, and maps of crown distribution and projection were prepared. Measurements of LRS were taken 1.30 m above the ground in the four cardinal directions in living trees, with the aid of strain meters (Growth Strain Gauge) by the CIRAD-Forêt method. There was great variability in the results of the growth variables and levels of growth stresses for different spacing. The lowest average values of LRS were observed in the south direction, and increased spacing did not significantly alter the LRS values. Correlations between LRS and growth variables were only found with maximum LRS values for each tree.

A complexidade dos processos de formacao, estruturacao e orientacao do lenho de reacao origina estudos buscando relacionar implicacoes tecnologicas da madeira. Em coniferas e folhosas, a madeira de reacao e reflexo das diferencas quimicas, fisicas e anatomicas, recebendo denominacoes especificas. As diferentes caracteristicas peculiares ao lenho de reacao influenciam nas propriedades fisicas, quimicas, anatomicas e mecânicas, podendo limitar seu uso, com tais implicacoes ainda sendo ignoradas.

In the construction sector, wood is facing competition with other materials such as concrete, steel or plastics. Therefore, there is a need for more efficiency in the forest–wood chain by improving silvicutural management and wood processing technologies. The objective of the study is to analyse the influence of log diameter and quality to recovery rate, veneer quality and economic benefit. The trees used in the study came from a 30-year-old Pinus taeda L. thinning trial in Southern Brazil. In total, 57 logs (20.7 to 67.0 cm) were peeled following the standard industrial processing methods of the plywood mill. Average recovery rate was 54 % ranging from 35 to 72.6 %, with a linear trend (R 2 = 0.48) of increasing recovery with an increment on the log small-end diameter. Results show that the gap between theoretically possible and real recovery was lower in the logs with bigger diameters, indicating their higher efficiency in industrial processing. Moreover, the economic analysis detected that the current prices for log assortments reflect only the industrial potential of low-quality pruned logs. An optimised pruning strategy would result in higher industrial efficiency, which would allow higher log prices. The results indicate that the recovery rate of bigger logs is higher in terms of volume of peeled veneer. The quality and therefore the value obtained from each log were negatively influenced by inadequate pruning strategies. Management of pines for higher value utilisation requires optimized thinning and pruning strategies in order to meet high growth rates and proportionally bigger dimensions of clear wood.

For the substitution of wood from tropical rainforests pruning of for producing valuable hardwoods in short rotation plantations has become important. Existing tools and ergonomic aspects of pruning were not yet well analysed under these conditions. The objective of the study is to evaluate the productivity and ergonomics of three different pruning tools in a pruning lift up to 3 m in height. The trees used in the study came from an 18-month-old clonal stand planted in a 5.0 x 2.8 m spacing. Two manual pruning tools and an electric shear were tested for productivity by using time studies. Ergonomic aspects were evaluated by two test persons using pulse meter equipment. The highest productivity could be shown for the electric shear (236 trees per working day), followed by the manual shear (196 trees/day) and the handsaw (180 trees/day). The heartbeat rate of the two test persons ranged from a level of âvery hard workâ for the manual tools to âmiddle hardâ and âhard workâ for the electric shear. The workload level to achieve the productivity currently reached in practice using purely manual tools is extremely high, exceeding the permanent working capacity of the operators and leading to physical degradation on the long run.EucalyptusEucalyptus grandis

Mimosa scabrella Benth. is an important native species of southern Brazil widely used for energy and promising for reforestation carbon offsets. Quantification of biomass and carbon stock is valuable for both purposes. From a forest inventory conducted in southern Brazil, data of M. scabrella were analyzed. Thirty sample trees were felled, excavated and weighed in the field and brought to laboratory for biomass and carbon determination. The total aboveground biomass represented 85% of the tree biomass, while roots corresponded to 15%. Correlation matrix of diameter at 1.3 m height (D), tree height (H) versus total and compartment biomass (P) indicated strong association between tree dimensions and biomasses. Five regression models were tested and equations were fitted to data of five biomass compartments and total tree biomass. The best fitting model for total biomass was P = –0.49361 + 0.034865 x DH whereas for the partial biomass of the compartments was lnP = β + β x ln(D) + β lnH. Carbon concentration was statistically significantly different in foliage than in other compartments. Three approaches of calculating carbon stocks were evaluated and compared to actual data: 1) Estimated total biomass x weighted mean carbon concentration; 2) Estimated partial (compartment) biomass x compartment average carbon concentration; and 3) Carbon regression equations. No statistical difference was detected among them. It was concluded that biomass equations fitted in this study were accurate and useful for fuelwood and carbon estimations.2012

Eucalypts are renowned for their high growth stress levels. These stresses cause splitting, warping and dimensional instability when cutting, processing and drying the wood. In Chile, large Eucalyptus nitens plantations can be found, which, due to these problems, are scarcely utilised for solid wood products (veneer, sawn wood). This study aims to determine the factors influencing growth stress at different stages of tree’s development, and to identify whether the factors influencing growth stress change over time. In five stands of different ages, growth strain, as an indicator of growth stress, was measured at different tree heights with the single hole drilling method. The tree variables DBH, tree height, slenderness (height/diameter ratio) and crown parameters also were measured. A correlation analysis of tree variables and growth strains was undertaken. The results obtained indicate a high variability in growth strain values. It was concluded that growth strain is not correlated with a single growth parameter, but with a combination of factors that variously influence it at different ages and tree heights.

No presente estudo, foi desenvolvido um programa de desbaste e um modelo para a descricao da dinâmica da base da copa. Para esse fim, 485 arvores foram medidas em parcelas temporarias das empresas Klabin Riocell (Guaiba, hoje Aracruz), Todeschini (Cachoeira do Sul), Universidade Federal de Santa Maria (RS) e Aracruz Celulose (Espirito Santo e Bahia). Foi encontrada uma correlacao linear entre a largura da copa e o diâmetro a altura do peito (DBH), usando-se a metodologia da analise de regressao. A equacao obtida foi largura da copa = e 0.504+0.0307* DBH , com um coeficiente de determinacao de 0.78 e um erro padrao de 0.034. Com esse modelo, foi calculado o espaco da arvore individual necessario para alcancar um determinado crescimento em diâmetro durante todo o ciclo de rotacao, considerando uma cobertura do dossel media de 70%. Assim, o numero de arvores por hectare em diferentes estagios de desenvolvimento foi calculado para diferentes sistemas de manejo com o objetivo de produzir madeira para serraria em ciclos de rotacoes curtas. Tambem foi obtido um modelo multivariado descrevendo a altura da base da copa viva em funcao das variaveis diâmetro a altura do peito (DBH) e altura total. Com base nesses modelos, a dinâmica na insercao da copa viva para diferentes sistemas de manejo em sitios de diferentes qualidades pode ser calculado, possibilitando assim a determinacao do ponto otimo e da intensidade da poda.

The objective of the present work was to analyse diameter growth and the relationship of natural pruning and various morphological characteristics of Parana pine (Araucaria angustifolia (Bert.) O Ktze.) growing on different sites in southern Brazil and to formulate silvicultural strategies for producing high quality timber for this species. Data on four hundreds trees in both natural and planted forests were collected on temporary sample plots each containing 25 Parana pines. The size of the knotty core within Parana pine stems was modeled with the predictor variables height of the lowest dead branch, height to crown base and maximum radial increment of stem at 1.3 m. The results of our study show that crown width is a good estimator of diameter growth and is closely related to stem diameter at 1.3 m above ground. Restricting crown expansion such that average annual radial increment is 4 mm/year at 1.3 m for a stem grown for 63 years compared to one grown for 36 years with less crown restriction such that the average annual radial increment is about 75% greater (7 mm/year) results in a knotty core volume that is about 75% less for the slower growing tree. Managers can use this model to guide silvicultural decisions needed to achieve the production goal of high quality wood of Parana pine., Gérer la croissance en diamètre et l'élagage naturel du pin du Parana (Araucaria angustifolia (Bert.) O Ktze. pour produire un bois de haute valeur. L'objectif de ce travail a été d'analyser la croissance en diamètre et les relations entre l'élagage naturel et différentes caractéristiques du Pin de Parana (Araucaria angustifolia (Bert.) O Ktze) poussant dans différents sites dans le sud du Brésil et de formuler des stratégies sylvicoles pour produire du bois de haute qualité. Quatre cents arbres dans des peuplements naturels et plantés ont été collectés dans des placettes temporaires comprenant chacune 25 arbres. La grosseur des cœurs branchus dans les trouées a été modélisée avec des variables prédictives : hauteur de la plus basse branche morte, hauteur de la base de la couronne et accroissement radial maximum à 1,3 m. Les résultats de l'étude montrent que la largeur de la couronne est un bon estimateur de la croissance en diamètre et qu'elle est étroitement reliée au diamètre du tronc à 1,3 m. La limitation de l'expansion de la couronne de telle manière que l'accroissement annuel moyen atteigne 4 mm/an à 1,3 m pour un arbre ayant poussé depuis 63 ans en comparaison avec un autre qui a poussé depuis 36 ans avec une limitation moindre de la croissance de la couronne tel que l'accroissement en diamètre soit d'environ 75 % plus grand (7 mm/an), a pour résultat un volume de nœud plus faible d'environ 75 % que pour l'arbre ayant poussé plus lentement. Les aménagistes peuvent utiliser ce modèle pour les guider et décider des sylvicultures nécessaires pour atteindre un objectif de production de bois de haute qualité.

Neste trabalho foi analisada a dinâmica e a qualidade da desrama natural de Araucaria angustifolia (Bert.) O. Ktze. em diferentes sítios no Sul do Brasil, dentro de uma estratégia da produção de madeira de alta qualidade. O material usado se constitui de 400 árvores de florestas nativas e plantadas, crescendo sob variadas condições e tratamentos. O método usado foi a análise exploratória dados levantados de parcelas temporárias. Foram feito mapas de distribuição das árvores e das projeções das copas para avaliar a competição e o seu efeito na desrama. O estudo mostra que existe uma relação estreita entre o crescimento em altura e diâmetro, numa idade determinada, e a inserção da copa. O primeiro galho morto está estreitamente ligado com a inserção da copa. Estas variáveis foram usadas para modelar o desenvolvimento da inserção da copa e da altura comercial ao longo do tempo. Além disso, podem ser derivados destes modelos a dimensão do núcleo enodado. Foi mostrado que para o manejo de araucaria em rotações curtas uma poda artificial aumenta significativamente à parte da madeira valiosa sem nós. MODELLING SELF-PRUNING OF ARAUCARIA ANGUSTIFOLIA (BERT.) O. KTZE Abstract In the present study the self-pruning dynamics and quality of Araucaria angustifolia (Bert.) O Ktze. on different sites in Southern Brazil was analyzed in the framework of a strategy of high quality wood production. The material consisted of 400 trees from native forests and plantations growing under varying site conditions and treatments in the Brazilian states of Santa Catarina, Parana and Rio Grande do Sul. The research method applied was an explorative analysis of data taken from temporary sample plots. For each plot stem distribution and crown projection map was established in order to determine the competition status and its impact on self-pruning. The study shows that diameter and height at a certain age are good estimators for predicting height of crown base. The lowest dead branch is closely related to crown base. These parameters are used to model the dynamics of self-pruning depending on radial increment and height growth. Moreover, the dimension of the knotty core was calculated. It could be shown that Araucaria angustifolia has a retarded self-pruning because of its tendency of maintaining dead branches at the stem. Especially for target diameters of 40 to 50 cm within short rotation periods an artificial pruning is recommended in order to reduce the knotty core.