Collapse-type shrinkage characteristics in plantation-grown eucalypts： I . Correlations of basic density and some structural indices with shrinkage and collapse properties

Collapse-type shrinkage is one of highly refractory drying defects inlow-medium density plantation-grown eucalypt wood used as solid wood products. Basic density (BD),microfibril angle (MFA), double fibre cell wall thickness (DWT), proportion of ray parenchyma (RP),unit cell wall shrinkage, total shrinkage and residual collapse, which are associated withcollapse-type shrinkage characteristics, were investigated by using simple regression method forthree species of collapse-susceptible Eucalyptus urophyll,, E. grandis and E. urophyllaxE.grandis,planted at Dong-Men Forest Farm in Guangxi autonomous region, China. The results indicated that:unit cell wall shrinkage had a extremely strong positive correlation with BD, moderately strongpositive correlation with DWT, and a weakly or moderately negative correlation with RP and MFA;total shrinkage was positively correlated with BD, DWT and RP and negatively related to MFA, but notable to be predicted ideally by any examined factors alone owing to lower R^2 value (R^2≤0.5712);residual collapse was negatively correlated with BD and DWT, linearly positively correlated withMFA, and had strongly positive linear correlation with RP. It is concluded that BD can be used assingle factor (R^2≥ 0.9412) to predicate unit cell wall shrinkage and RP is the relatively soundindicator for predicting residual collapse

Variation of basic density,calorific value and volumetric shrinkage within tree height and tree age of Ugandan grown Eucalyptus grandis wood

Insufficient knowledge on Ugandan grown Eucalyptus grandis W.Hill ex Maiden wood properties,high demand,and processing challenges led to a study into its physical properties.We obtained the variation of basic density(BD),calorific value(CV)and volumetric shrinkage(VS)within tree height and tree-age of E.grandis,and its appropriate use based on these properties.Trees with good boles were harvested from Kabarole District in western Uganda to produce specimens as prescribed by British Standards and ASTM standard wood testing procedures.Secondary data reviews and statistical analysis using ANOVA,Tukey’s test and multivariate analysis were done to obtain property estimates and their variation within trees and amongst tree ages.The mean BD of E.grandis is 413.6,380.5,471.0,and 501.1 kg m^(−3)at 3,6,9,and 12 years,respectively,showing significant increase with tree age(p=0.003).The pattern of BD with tree height showed a reduction with tree height although with higher values in the middle portion of the tree.The CV increases(p=0.014)with tree age and reduces with tree height with values of 14,560.32,15,447.3,16,079.11,and 16,932.6 kJ kg^(−1)at 3,6,9,and 12 years,respectively.The percentage VS was 11.02,9.84,12.31,and 14.45 for 3-,6-,9-,and 12-year-old trees,respectively,and it did not vary significantly(p=0.088)with tree height.Basing on these property values,E.grandis wood could be used for scaffolding,light constructions and fuel wood production.Its seasoning needs to be longer with well monitored drying schedules to reduce seasoning defects caused by the high VS.Further studies on strength properties,seasoning schedules,panel products properties and tree-age chemical variations would improve the knowledge about its wood quality and would enhance its efficient utilization.

Interclonal and within-tree variation in wood properties of poplar clones

The wood basic density, cellulose content and fiber form were investigated for all sample trees at breast height (1.3 m) in seven poplar clones, and at 0 (butt), 5.6, 9.6, 13.6, 17.6, 19.6 and 21.6 m for clone Nanlin-95 and Nanlin-895, respectively, for providing information on variation patterns of wood density, fiber characteristics and holocellulose content within trees and among clones. The results showed that significant variations about wood density, cellulose content, fiber diameter and the ratio of fiber length to diameter existed among poplar clones examined. Variance analysis indicated that there were significant differences in wood basic density, fiber length, fiber diameter and cellulose content among the growth rings, which had an increasing tendency along the direction from pith to bark. The significant differences also existed in wood basic density, fiber length and fiber diameter at different tree height. The mean wood basic density had a general increase trend with increasing height of trees and the lowest was found at the base, while fiber length and fiber diameter had a general decline pattern with increasing height of trees and the biggest value was observed at the height of 5.6 m. Regression analysis indicated that the relationship between examined wood properties and growth ring number (cambial age), and the relationship between examined wood properties and tree height can be described by polynomial functions.

Biomass production of hybrid aspen growing on former farm land in Sweden

We construct dry weight equations for hybrid aspen growing on former farmland in Sweden. Dry weight equations for fractions of hybrid aspen trees were also made. We estimated biomass production in 24 stands. The stands were located in Sweden at latitudes ranging from 55 to 60o N. The mean age was 18 years （range 15-23）, the mean stand density 1090 stems·ha-1 （range 378 2374）, and the mean diameter at breast height （over bark） 178 mm （range 85 244 mm）. Soil types in the hybrid aspen stands were mainly clay （21 stands）, tills （2 stands） and other （1 stand）. The mean total standing dry weight above stump level （≈ 200 mm） for the hybrid aspen stands was 135±53 t·ha-1 with a range of 42 219 t·ha-1 . In addition to estimating conventional dry weights of trees and tree components, basic density, specific leaf area （SLA）, projected leaf area （PLA） and leaf area index （LAI） were estimated and were in agreement with published figures.

Longitudinal growth strains in five clones of Eucalyptus tereticornis Sm

We studied the variability in longitudinal growth strains and wood basic density in five-year old trees from five clones （one tree per clone） of Eucalyptus tereticornis. Mean longitudinal growth strain in clones ranged from 466 to 876 μm. There was a significant difference between clones in growth strains and wood basic density. Clone 10 exhibited maximum growth strains and basic density, whereas clone 3 and clone 7 exhibited minimum growth strains and basic density, respectively. Within a tree, the growth strain variation with tree height was high but statistically insignificant while within tree variation in basic density was very small. There was no specific trend in variation in either strain or density within a tree. There was 5% 200% difference in growth strain on opposite sides of the logs. However two strains showed a strong positive correlation. There was a moderate positive association of wood basic density and mean growth strains in logs. The variation around the periphery emphasize the need to measure strain more than one, preferably on opposite sides at the same height, on a tree to know the mean strain level for the purpose of selection of clones.

Variations in productivity and wood properties of Amazonian tachi-branco trees planted at diff erent spacings for bioenergy purposes

Marilene Olga dos Santos Silva 1·Marcela Gomes da Silva 1·LTachi-branco(Tachigali vulgaris,L.F.Gomes da Silva&H.C.Lima)is a leguminous tree species native to the Amazon rainforest that has drawn attention for its remarkably fast growth,a required trait for biomass/bioenergy plantations.In evaluations of biomass production and wood properties of T.vulgaris planted in homogeneous plantations at diff erent spacings in the Amazonian state of Pará,Brazil,biomass of 7-year-old trees was quantifi ed for individual trees and the entire population.Wood was also sampled to assess properties relevant to bioenergy applications.The choice for spacing dimension for planting nonclonal T.vulgaris should consider whether the priority is greater productivity per tree,achieved with greater spacings(9.0 m 2 and 12.0 m 2),or productivity per area,achieved with closerina Bufalino 1·Maíra Reis de Assis 2·Delman de Almeida Goncalves 3·Paulo Fernando Trugilho 2·Thiago de Paula Protásio 4 spacings(6.0 m 2 and 7.5 m 2).Genetic variability of the T.vulgaris seed stand and/or high heritability of wood traits overcame the eff ect of diff erent spacing on all morphological,physical,chemical and energetic properties of T.vulgaris wood.This species has moderate basic density when cultivated at spacings larger than 6 m 2 and net heating value above 7.95 MJ/kg,which is suitable for bioenergy purposes.The high variation in wood properties within tree spacing is strongly indicative of great potential for genetic breeding.The fast growth and the suitable moderate wood basic density confi rm the outstanding potential of homogeneous plantations of T.vulgaris for providing wood for bioenergy.

Measuring and Modeling of Density for Selected CaO-MgO-Al_2O_3-SiO_2 Slag With Low Silica

The densities of the selected quaternary CaO-MgO-Al2O3-SiO2 slag with low silica were measured by the Archimedean method in a wide temperature range from 1773 to 1 873 K. Nine different slag compositions were chosen based on three diffel：ent levels of CaO content and three different levels of SiO2 content. WM,O was equal to 7. 0%. Wcao were varied from 40.04% to 50.64%, for wsO2 =10.25%-20. 70%. The effects of temperature, SiOz content and optical basicity were studied. It is shown that density decreases approximately linearly with an increase in temperature. Under the same CaO content, the density decreases with increasing of SiOz content, and increases with optical basicity increasing. Based on the experimental data as the boundary of the homogenous phase region predicated by FACTSAGE software, the mass triangle model is used to calculate the density of selected limited homogenous phase region. The results showed that the mass triangle model works well.