Paulo Sérgio Pigatto Schneider

DETERMINAÇÃO INDIRETA DO ESTOQUE DE BIOMASSA E CARBONO EM POVOAMENTOS DE ACÁCIA-NEGRA (Acacia mearnsii De Wild.)

This work was carried out to estimate the carbon storage in even-aged stands of Acacia mearnsii De Wild., in the region of the Southeast Lower Hillside, in Rio Grande do Sul, by the method of derivation of volume and carbon. The biomass components and carbon content were measured in stands 4 to 8-year-old. The method of derivation of volume and carbon was efficient to determine the carbon storage, since the average relative difference was only 4.4%, when considering the whole sample, and independent from stands age. The mean wood basic density found was 0.6 g/cm 3 , regardless of stand age. The mean biomass ratio of the barked-volume to the volume of leaves, branches, litter, and roots was found to be 0.59, independent of stand age. The mean carbon concentration, regardless stand age, was 0.40. The estimated carbon storage by the method of volume and carbon derivation, for 7-year-old stands, was 99.46 t ha -1 , in site index 20; 82.89 t ha -1 , in site index 16; and 46.13 t ha -1 , in site index 12.

Análise da mortalidade de Acacia mearnsii De Wild.

The mortality probability of the Acacia mearnsii De Wild. stands was studied in permanent sample stratified at different spacings and site. The results allowed to conclude that the mortality can estimated with a probabilistic function in relation with the inverse of the diameter at breast height (d) and age (t): PM = {1+ EXP (-9,5593 . d -1 + 104,9543 . t -1 )} –1 . By the Pearson correlation of the mortality rate it was verified a high association with age, average diameter, average height, dominant height, basal area, volume and vital spacing. It was verified that the mortality is directly related to age, site quality and vital spacing in some periods of growth of the trees in the stand.

Crescimento do ipê-roxo, Tabebuia impetiginosa Martius ex A. P. de Candolle, na Depressão Central do Estado do Rio Grande do Sul.

In the present study a dendrocronological approach developed by the American archae logist Andrew Douglas in 1920 was used to analyze the species Tabebuia impetiginosa and to evaluate the growth tendencies in diameter, commercial volume, percentual annual current increment in commercial volume as well as the commercial form factor. Backman´s function was adjusted to diameter and commercial volume considering the age, obtaining for both an excellent adjustment. Backman´s function was also adjusted for commercial volume, commercial form factor and the percentual annual current increment due to the diameter, obtaining a comparable excellent adjustment. The percentual annual current increment in commercial volume varied from 54,02 % with 7 years to 11,26 % at the age of 21 years. Commercial form factor was 0,7 between diameters of 5,2 and 30,0 cm at the ages of 7 and 21 years, respectively.

Avaliação da relação densidade e diâmetro em povoamento de Pinus taeda.

This work was developed with the purpose of studying the efficiency of the models which express the density-diameter relationship in stands of Pinus taeda L., handled in full and highly stocked density. For that, Reineke, Yoda, Zeide and Tang models were adjusted. Such models relate the density of trees per hectare, considering the average diameter through data originated from 50 permanent portions, measured every year until the age of 18, implanted in spacing of 1.5x1.0 and 2.0x1.0 meters and kept in full density. Results indicate that all density and diameter models and self-thinning presented good statistical precision; however, the Tang model was more efficient than the others, presenting excellent coefficient of determination (0.99), low standard error of the estimative (0.0948), low variation coefficient (1.17%), low trend (0.0086) and high efficiency (0.8976), in the estimate of the values of density of trees per hectare for medium diameter, with in good residual distribution of the number of trees per hectare in function of the average diameter of the stand.

Implantação de povoamentos de Dodonaea viscosa (L.) Jacq. com mudas e semeadura direta.

In this study was measured emergency and seedling surviving of Dodonaea viscosa (L.) Jacq. direct in the field. The experiment design used was complete block with three replication and two treatments: seedling planting and direct seeding. The results showed no significant difference of emergency between two plant population implantation methods. The plant surviving for seedling planting was 88 % whereas for direct seedling was 76 %, obtaining 12 % of abslute difference between the two implantion methods.

Quociente do diâmetro pela área basal e zonas de competição em povoamento monoclonal de Eucalyptus saligna

The present work was developed in order to study the relation among the diameter and the basal area, the competition zones, the relative density, and the self-tinning in Eucalyptus saligna Smith monoclonal stand, with 238 pair’s data basis of permanent sampling by full density stand distribution, observed from 3 to 18 years old. The results obtained allowed to conclude that Tang’s density model was very precise and efficient. The self-thinning begins when the population reaches an average diameter of 8 cm. The relative density was equal 34.46%, with line gradient of 1.5818 (b). The maximum current annual increment in diameter and between the relative densities was observed between the ages of 14 and 15 years when the relative densities were 12.5% and 25%, characterizing a free growth competition zone among the individuals of the population. The zone of increasing competition between the relative densities of 25 and 50% and the imminent mortality zone occurred between the relative densities of 50 and 100%. The density model allowed detecting five competition zones, in the development of the stands, defined by zones of: excessive space, free growth, increase of competition, complete stock and imminent mortality, in relation to the relative density of the population.

INFLUÊNCIA DO ESPAÇAMENTO NO AUTODESBASTE DE POVOAMENTO MONOCLONAL DE Eucalyptus saligna Smith

In the present study the effect of initial spacing on relationship between the density of trees per hectare and the average diameter in monoclonal stands of Eucalyptus saligna were investigated. The data used were collected from full stocked stands and highly stored annually, monitored until 18 years old using permanent plots. For that, the density model of trees per hectare by diameter was tested and the self-thinning model of Tang was indicated as the most accurate one and provided great performance statistics, with a coefficient of determination equal to 0.85, lower standard error equal to 0.1026, low coefficient of variation equal to 1.39%, a minimal tendency equal to -0.0534 and high-efficiency equal to 0.3903. The self-thinning occurs in a diameter directly proportional to the initial density of trees per hectare of plantation. As great is the initial spacing greater is the mean diameter in the moment of initiation of self-thinning of the population. The slope of the equation of density and diameter was equal to 1.0124 diverging from the value indicated for forest species in the law of self-thinning.

Influence of spacing on self-thinning of a monoclonal stand of Eucalyptus saligna Smith

In the present study the effect of initial spacing on relationship between the density of trees per hectare and the average diameter in monoclonal stands of Eucalyptus saligna were investigated. The data used were collected from full stocked stands and highly stored annually, monitored until 18 years old using permanent plots. For that, the density model of trees per hectare by diameter was tested and the self-thinning model of Tang was indicated as the most accurate one and provided great performance statistics, with a coefficient of determination equal to 0.85, lower standard error equal to 0.1026, low coefficient of variation equal to 1.39%, a minimal tendency equal to -0.0534 and high-efficiency equal to 0.3903. The self-thinning occurs in a diameter directly proportional to the initial density of trees per hectare of plantation. As great is the initial spacing greater is the mean diameter in the moment of initiation of self-thinning of the population.

RELAÇÃO DA RAZÃO DO QUOCIENTE DIÂMETRO E ÁREA BASAL COM O AUTODESBASTE EM POVOAMENTOS EQUIÂNEOS DE Pinus taeda L.

This work aimed to study the relationship of the ratio of mean diameter and basal area at the self-thinning moment; the diameter tree growth; the occurrence and moment of self-thinning using the diameter-area proportion and the rate of self-thinning, comparing it to the law of the -3/2 power in stands of Pinus taeda L.. The data was collected from permanent plots experiment installed into a Pinus taeda L. stand and measured annually until 18 years-old with different spacing managed with complete density. The Tang model was used in order to relate the density of trees with the mean diameter. The self-thinning model showed precision and high efficiency. However, it showed a different slope coefficient of -1.65 that stressed from the self-thinning law of -3/2. At the self-thinning moment, the trees reached a diameter of 14 and 17 cm at the space of 2 x 2 and 3 x 3 with basal area of 38.8 and 47.5 m2/ha, respectively. In all spacing the maximum basal area was 78 m2/ha at 18 years old showing upward trend. In that spacing the diameter and basal area ratio at the moment of occurrence of self-thinning was 0.36 and 0.37, respectively.

Relação do quociente do diâmetro pela área basal com o autodesbaste em povoamento equiâneo de Pinus taeda L.

This work undertakes to study de diameter: the basal area ratio at the moment of occurrence of self-thinning of Pinus taeda L. stand in some spacings, considering its full density. For that, the Tang model was used in order to relate the density of trees with the diameter, with data of permanent plots, measured annually until 18 years-old. The results indicate that self-thinning model for Tang presented excellent precision and high efficiency, however with distinct slope coefficient of the praised one for Tang (-3/2) resulting a value of -1.6523. At the moment of occurrence of self-thinning, trees reached diameter equal to 14 and 17 cm, in the spacing of 2 x 2 or 3 x 2 m, with basal area of 38.8 and 47.5 m2 ha-1, respectively. In these spacings, the maximal basal area was of 78 m2 ha-1, in 18 years-old, rising tendency. In these spacing, the diameter: the basal area ratio at the moment of occurrence of self-thinning was 0.36 and 0.37, respectively.