The Stability of Mean Wood Specific Gravity across Stand Age in US Forests Despite Species Turnover

Research Highlights: Estimates using measurements from a sample of approximately 132,000 field plots imply that while the species composition of US forests varies substantially across different age groups, the specific gravity of wood in those forests does not. This suggests that models using increasingly accurate spaceborne measurements of tree size to model forest biomass do not need to consider stand age as a covariate, greatly reducing model complexity and calibration data requirements. Background and Objectives: Upcoming lidar and radar platforms will give us unprecedented information about how big the trees around the world are. To estimate biomass from these measurements, one must know if tall trees in young stands have the same biomass density as trees of equal size in older stands. Conventional succession theory suggests that fast-growing pioneers often have lower wood (and biomass) density than the species that eventually dominate older stands. Materials and Methods: We used a nationally consistent database of field measurements to analyze patterns of both wood specific gravity (WSG) across age groups in the United States and changes of species composition that would explain any shifts in WSG. Results: Shifts in species composition were observed across 12 different ecological divisions within the US, reflecting both successional processes and management history impacts. However, steady increases in WSG with age were not observed, and WSG differences were much larger across ecosystems than across within-ecosystem age groups. Conclusions: With no strong evidence that age is important in specifying how much biomass to ascribe to trees of a particular size, field data collection can focus on acquiring reference data in poorly sampled ecosystems instead of expanding existing samples to include a range of ages for each level of canopy height.

The Effect of Site Class, Tree-age and Axial Direction on Adhesion Properties of Teakwood

Teak wood is a well-known prime wood species in Indonesia. The teak forest had been managed well by PERHUTANI, a state forest company for a long time. In the teak forest the site quality has been classified according to land’s capability to grow the teak plant. This site classification had been set up from the beginning of forest management and it has not been reviewed yet. This research’s objectives are to know the effect of teak forest site quality class and axial direction on the adhesion properties of the teak wood. The research conducted using Completely Randomized Design arranged in factorial experiment. The first experiment used site quality and axial direction factors, while the second experiment used tree’s age and axial direction. The site quality factor consisted of three levels of site index III, III/IV and IV. The three levels of axial direction of the teak stem were butt, center and top. The tree’s age consisted of three age class of 25, 35 and 45 years. Three teak trees employed as replication. The adhesion properties parameter were wood specific gravity, adhesion compression shear test and wood failure in both dry and wet condition using block test. The first research result showed that no interaction factor affected in adhesion properties. The teak growing site-class influenced significantly to the wood specific gravity and adhesion shear strength. The more fertile of teak growing site class, the lower wood specific gravity and adhesion strength. The site class of III, III/IV and IV revealed the average wood’s specific gravity of 0.54; 0.50 and 0.47 consecutively. The adhesion strength produced from the three site classes were 41.71; 32.56 and 23.52 kg/cm2 consecutively. The axial direction (from the butt to the top) showed a decreasing trend of wood specific gravity and adhesion strength. The second research showed that tree age affected significantly the wood specific gravity. The wood specific gravity increased from 0.57 to 0.67 and 0.69 produced from tree age of 25, 35 and 45 year old consecutively.

Density of Araucaria angustifolia wood from overstocked stand

The aim of this work was to evaluate the radial and longitudinal variations of wood specific gravity in an overstocked stand of Araucaria angustifolia, with 65 years. The stand was located in the National Forest of Açungui, Campo Largo, Parana State, Brazil, with thinning recorded between 1970 and 1980, without subsequent thinnings. We selected three trees for each diameter class: 10-30 cm, 30-50 cm and 50-70 cm. To the longitudinal analysis, we collected discs from seven heights (0, 20, 40, 60, 80 and 100% of commercial stem and at 1.3 m). The barks were removed and it was obtained opposite wedges until pith and five samples were taken in radial direction from each disk. In general, there was an increase of wood specific gravity in radial direction. The average differed significantly along the stem, with decreasing trend of wood specific gravity in the longitudinal direction. However, average specific gravity at 60% of commercial height was higher than at 40%, than reducing to the top, indicating effect of competition that occurred in the area. The no uniform wood along stem indicates negative effects of the lack of management in the stand.Index terms: Quality of wood; Radial and longitudinal variations; CompetitionMassa específica básica da madeira de Araucaria angustifolia em povoamento superestocadoO objetivo do presente trabalho foi avaliar as variações radiais e longitudinais de massa específica básica da madeira em um plantio superestocado com 65 anos de Araucaria angustifolia. O plantio, localizado na Floresta Nacional de Açungui, Campo Largo, PR, foi desbastado entre 1970 e 1980, não havendo registros de desbastes posteriores a essa data. Foram selecionadas três árvores para cada classe de diâmetro: 10-30 cm, 30-50 cm e 50-70 cm. Para a análise longitudinal, foram seccionados discos em sete alturas (0, 20, 40, 60, 80 e 100% da altura comercial e a 1,3 m do solo), sendo removidas as cascas e retiradas duas cunhas opostas até a medula e cinco corpos de prova no sentido radial de cada disco. Em geral, na direção radial houve aumento da massa específica. As médias da massa específica diferiram estatisticamente ao longo do fuste, com diminuição da massa específica na direção longitudinal. No entanto, a massa específica média a 60% da altura comercial foi maior do que a 40%, com redução a partir dessa altura em direção ao topo, indicando efeito da competição que ocorreu na área. A desuniformidade da madeira ao longo do fuste é um indicativo dos efeitos negativos da falta de manejo na área.