Marcelo Roveda

GEOSTATISTICAL MODELING OF TIMBER VOLUME SPATIAL VARIABILITY FOR Tectona grandis L. F. PRECISION FORESTRY

Considerando a hipotese de que os volumes de madeira apresentam dependencia espacial, cujo conhecimento contribui para o manejo de precisao, o objetivo deste trabalho foi estimar a variabilidade espacial do volume de sortimentos de madeira e identificar seus padroes espaciais em povoamentos de Tectona grandis. Utilizou-se um conjunto de dados de 1.038 arvores para ajustar funcoes de afilamento e estimar os volumes para fuste total, serraria e lenha em 273 parcelas alocadas em povoamentos de T. grandis ao oitavo ano de idade, o qual representa o segundo desbaste que possibilita volumes comerciais. Modelos de semivariogramas foram aplicados para ajustar a dependencia espacial e a krigagem pontual foi utilizada para compor mapas de volume. A modelagem geoestatistica permitiu estimar a variabilidade espacial de T. grandis e desenvolver mapas de volume de madeira. Assim, tratamentos silviculturais, como desbaste e poda, bem como planejamento de intervencoes espaciais, podem ser recomendados para produtos de madeira almejados.

SPATIAL CONTINUITY IN A MIXED OMBROPHILOUS FOREST WITH DIFFERENT SIZE AND SHAPE OF SAMPLE UNITS

Size and shape of sample units are fundamental for the observation of spatial continuity in native forests and important to characterize patterns structured in space by different scales. Therefore, the objective of this study was to identify the spatial continuity of number of trees and basal area, evaluating the influence of size and shape of sample units in a mixed ombrophilous forest in Parana State, Brazil. An area of 25 hectares was divided in 50 m x 50 m and 25 m x 25 m square sample units, and also in 10 m x 50 m and 20m x 50m rectangular sample units. In these samples, the number of trees (n.ha-1) and the basal area (m².ha-1) were determined in each of them, with the possible spatial continuity analyzed by geostatistics analysis. The influence of size and shape of sample units on the spatial continuity structure was analyzed. Also, adjusted semivariograms were used to observe that the correlation between neighboring sample units for number of trees was stronger than for the basal area. However, due to the similarity of the semiovariograms, both sizes and shapes can be used to describe the spatial structure of number of trees, while the square sample units were more appropriate to describe basal area.

Diameter Increment Modeling in an Araucaria Forest Fragment Using Cluster Analysis

The aims of the present study were to test the hypothesis that data stratification by cluster analysis and the use of other variables, in addition to DBH, can improve the precision of the estimates in diametric increment modeling for Mixed Ombrophilous Forest species. The study was carried out in the Irati National Forest. Data from 25 permanent sample plots of 1 ha each were used with all individuals presenting DBH equal to or greater than 10 cm being identified and measured. The increment modeling was performed for the whole forest (non-stratified data), ecological groups and species subgroups (stratified data) defined by cluster analysis. DBH presented a low correlation with the diametric increment and the use of other independent variables had a positive effect on the fitting, reducing the standard error of estimate and increasing the coefficient of determination. The data stratification did not make the models suitable to estimate the diametric increment; however, it provided improvements by reducing the standard error of estimate, suggesting that this technique can be better applied in the search for improvements to diametric modeling in natural forests.

Testes de identidade de modelos aplicados na construção de curvas de índices de local e na produção de povoamentos de Eucalyptus grandis

This study aimed to apply identity model tests in the construction of site index and on the production of basal area and volume per hectare in stands of Eucalyptus grandis W. Hill. Ex Maiden growing in six farms in Western Sao Paulo State. The Ragazzi test (2003) was applied to analyze the possibility of using a single model for dominant height for all farms. The average production curve in basal area and volume was adjusted by the Clutter (1963) model and projected for the mean local index, and the model identity test was applied through the Chow test (1960). A single equation is not efficient to represent the dominant height growth for the six farms. When applying the test, separately between the farms, we observed that some of the data may be grouped without loss of accuracy. With the projections of the Clutter model (1963), the Chow test (1960) indicated that some farms can be grouped and others should not be grouped for volume and basal area production.

Inventário Florestal Utilizando Técnicas de Silvicultura de Precisão em Povoamentos de Eucalyptus grandis Hill ex Maiden

This study aimed to determine the wood stock through systematic sampling and geoinformation technologies in order to elaborate maps of forest productivity as a forest post-stratification inventory. We positioned 24 plots of 625 m2 each ina distance of 70 m from each other. The yield map was generated after selecting a model for semivariogram adjustment between volumes in the plots. A 3,753.9 m3 total volume was estimated in the forest inventory through systematic sampling, while the yield map produced with precision forestry techniques showed a total volume of 3,768.9 m3. The analysis of variance showed that there is a significant difference between the means of the strata and based on this fact, the estimates were generated per stratum, then the total volume of 3,772.9 m3 was estimated. The precision forestry technique proved to be an efficient tool in the post-stratification of forest inventories.