Effect of stand density on longitudinal variation of wood and bark growth in fast-growing Eucalyptus plantations

Abstract

The influence of tree spacing on the wood/bark ratio is unknown in young fastgrowing Eucalyptus trees. The objective of this study was to evaluate the effect of plant spacing on the wood and bark production along the Eucalyptus stem. Four genetic materials were planted in four spacings: 3×1 m, 3×2 m, 3×3 m and 3×4 m. Three 5-year-old trees from each clone and in each plant spacing were harvested. Cross-sectional discs (thickness: 30 mm) were cut from each tree along the stem (0%, 25%, 50%, 75% and 100% of the total tree height) and at 1.3 m above ground, totaling 288 disks (4 spacings × 4 clones × 3 replicates × 6 axial positions). The wood thickness was measured at six random and equidistant points around the perimeter using a gauge and means were calculated from each disc. Six cross diameters were measured for each debarked disc. After obtaining the averaged bark thickness and wood diameter, the bark content was calculated as the ratio between the surface area occupied by the bark and the total area of the stem in each level. In the narrowed plant spacing (3×1), the trees had a mean diameter of 7.4 cm, while at the spacing 3×4 the diameter of the trees was 91% higher (14.11 cm) at breast height. The increase in plant spacing from 3 to 12 m 2 per tree resulted in an increase in bark thickness (56.7%) from 1.94 mm to 3.04 mm, but caused a reduction of bark content (16%) from 9.66% to 8.11%. Our findings show that trees grown under wider spacing tend to produce thicker bark. The bark thickness and the effect of plant spacing on the bark thickness decreased in the base-top direction. The correlation between bark thickness and wood diameter increases from 0.682 to 0.825 with the increase of spacing between trees. In contrast, the bark thickness to bark content correlation decrease from 0.735 to 0.15 with increased plant spacing. The stand density significantly affected the variation of the stem diameter, bark thickness and bark content of Eucalyptus plantations.

Propriedades da madeira de Eucalyptus urophylla em diferentes locais de plantio no nordeste do Brasil

“…For dendrometric parameters, the average DBH, height and volume are in accordance with what was expected for Eucalyptus urophylla at the age of 8 years, as can be seen in the study of Trugilho et al (2010). Regarding the bark percentage, the results are in harmony with the studies obtained by Ramalho et al (2019) who found values for Eucalyptus urograndis between 10 and 18%. In a general way, according to Neiva et al (2018) bark percentages for Eucalyptus globulus plantations reach about 18% in relation to the commercial volume.…”

“…Despite this, based on Evangelista et al (2010) research, the results are in accordance with the species expectation and there was no influence on the wood classification, whereas in both sites it fits as a light-wood (<0.50 g cm -3 ). Ramalho et al (2019) explain that the basic density of wood can significantly vary depending on age, origin, forestry treatments, spacing and growth rate. As there were no variations in dendrometric and genotypic aspects, the differences observed can be attributed to external factors such as temperature, direction and speed of the winds that causes changes in the tree's cells promoting substantial modification in the density of the wood and production of reaction wood (BRAZ et al, 2014).…”

The Conversion of Abandoned Chestnut Forests to Managed Ones Does Not Affect the Soil Chemical Properties and Improves the Soil Microbial Biomass Activity

“…This high value can be assigned to the lower tree density. Specifically, since chestnut trees are sensitive to the competition with other trees [69,70], the high spacing among the plants could promoted plant growth [71,72] and, therefore, root development. However, we cannot exclude that the low plant density could have also promoted a wider distribution of the root system [73].…”

Evaluation of the Site Form as a Site Productive Indicator in Temperate Uneven-Aged Multispecies Forests in Durango, Mexico

“…Asthon and Kelty [ 15 ] also documented that very high or low density may influence the h growth of species, conditions that were sampled in the current study that may therefore increase the correlation between the SF and the SDI. In addition, the h-dbh ratio (calculated by dividing the h by the dbh) has been described as a measure related to the stand density that increases in closed spaces [ 37 , 38 , 39 ], affecting dominant and codominant trees [ 40 , 41 ]. Therefore, stand density may influence the estimation of the SF.…”