Sintia Valerio Kohler

Evolution of the hypsometric relationship in Araucaria angustifolia plantations in the mid-south region of Paraná state

The aim of this study was to assess and model the evolution of the hypsometric relationship in Araucaria angustifolia plantations grown in the 1940s and 1960s in the Irati National Forest, in the mid-south region of Parana state, Brazil. Using the complete stem analysis method, it was possible to reconstitute the past annual growth of the diameter at 1.3 m (d) and of the total height (h) of a sample of 30 trees, selected so as to cover diametric and age variability. Eleven discs were removed from each tree at 0.1 and 1.3 m and at 15, 25, 35,..., 95% of the total height. Eleven models traditionally used in hypsometric relationships were tested, two of which were considered generic because they involved the age variable. The models were selected based on the Adjusted Coefficient of Determination (R2Adj), Standard Estimate Error (Syx), absolute (m) and relative (%), and on the graphic distribution of residues in percentage. In the models tested by age, no tendencies were observed and erros (Syx) remained below 14.6%, except for ages 5 and 11. However, the coefficients of determination were low, ranging from 0.29 to 0.55. The Curtis generic model (1970), selected to represent the h/d curve for all ages, also presented a satisfactory performance (R2Adj = 0.87 and Syx = 16%), with results similar to those obtained for the models in each age. As age increases, the h/d curve shifts to the right and changes level, remaining steep at the younger ages and more stable and flat as the population nears the end of its cycle.

Efeito da Idade no Afilamento e Sortimento em Povoamentos de Araucaria angustifolia

The objective of this research was to evaluate the effect of age on adjust taper functions and evolution of the assortment of male and female trees of Araucaria angustifolia stands. Sixty trees were sampled in a plantation located in the municipality of Laranjeiras do Sul, Parana state, Brazil. The fifth degree polynomials were adjusted to the whole data set, and they were stratified into age classes. The evolution of the tapering and assortment of trees was analyzed with age. The results showed a slight advantage in the use of equations adjusted for age classes and a significant improvement in the stem form with increasing age. The female trees presented higher growth (0.9975 m3) than the male trees (0.9384 m3) at 30 years of age. Volumes for the noblest assortments are produced only when the stand reaches the age class of 11 to 15 years.

Efeito da Idade no Afilamento e Sortimento em Povoamentos de Araucaria angustifolia / Effect of Age on Tapering and Assortment in Araucaria angustifolia Stands

The objective of this research was to evaluate the effect of age on adjust taper functions and evolution of the assortment of male and female trees of Araucaria angustifolia stands. Sixty trees were sampled in a plantation located in the municipality of Laranjeiras do Sul, Parana state, Brazil. The fifth degree polynomials were adjusted to the whole data set, and they were stratified into age classes. The evolution of the tapering and assortment of trees was analyzed with age. The results showed a slight advantage in the use of equations adjusted for age classes and a significant improvement in the stem form with increasing age. The female trees presented higher growth (0.9975 m3) than the male trees (0.9384 m3) at 30 years of age. Volumes for the noblest assortments are produced only when the stand reaches the age class of 11 to 15 years.

Dinâmica do afilamento do tronco e da produção de madeira em plantios de Araucaria angustifolia

The research aimed to evaluate the evolution of stem taper and wood assortment in plantations of Araucaria angustifolia. The data came from 30 sampled trees in plantations established between the decades of 1940-1960 in Irati National Forest, Parana State, Brazil. The trees were subjected to the technique of complete stem analysis that allows reconstitution of the entire past growth. The data generated allowed the obtaintion of diameter at different heights at various ages. The mean stem profile by age was obtained from taper functions and cubic splines functions were used to evaluate the evolution of wood assortment by age classes. We also conducted studies on the stem taper dynamics with the use of form factors. The results were presented with the mean of all trees and grouping them into two site classes, when the trees are 50 years old they reach an average volume of 1.20 m 3 , of which 14% could be used for lamination, 66.2% for sawmill 2, 15.9% for sawmill 1, 3.7% for pulpwood and only 0.3% would be residuals. In this same age the sites I and II had mean total volume of 1.94 m 3 and 0.57 m³, respectively. The 5 th degree polynomial function adjusted by age classes allowed to infer that stem tapering improves with age, with the stem becoming more cylindrical. This same trend can be established on the form factor, which practically stabilized after the 35 years of age, at a value of about 0.6.