The use of near-infrared scanning for the prediction of pulp yield and chemical properties of<i>Pinus patula</i>in the Mpumalanga escarpment area of South Africa

Kipuputwa, C; Grzeskowiak, V; Louw, Josua

doi:10.2989/20702620.2010.547270

Cited by 5 publications

(1 citation statement)

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“…One tree was randomly selected from the first quartile (small diameter), two trees from the second quartile, three trees from the third quartile and four trees from the fourth quartile (large diameters). These sample trees were also used by other researchers for previous studies related to strength and stiffness variation, structural grading and pulping properties (Kipuputwa et al 2010, Dowse and Wessels 2013, Wessels et al 2014). Five of the ten trees per compartment were randomly selected for the purposes of this study, giving thirty trees for the whole study.…”

Section: Introductionmentioning

confidence: 99%

The variation of microfibril angle in South African grownPinus patulaand its influence on the stiffness of structural lumber

Wessels

Malan

Kidd

et al. 2015

Southern Forests: a Journal of Forest Science

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Reduction in the rotation ages of softwood saw log plantations in South Africa is causing increased proportions of low stiffness sawn lumber at final harvest. It has been shown for some species that the microfibril angle (MFA) of the S2 layer of tracheids is strongly related to the modulus of elasticity (MOE) of wood, even more so than wood density, especially in wood formed during juvenile growth. The objectives of this study were to describe the variation in MFA in young Pinus patula trees and to determine the relationship between MFA and the dynamic MOE of sawn Pinus patula lumber. Thirty 16-20 year old trees from six compartments from the Mpumalanga escarpment were processed into discs and lumber. MFA, density and ring width were measured at two height levels using Silviscan 3. The average annual ring MFA varied between 7 o and 29 o ; the pattern of variation depending mainly on height level and the ring number from the pith. The MFA in P. patula followed the same within-tree variation trends as in New Zealand-grown Pinus radiata but the average MFA was lower in absolute terms and differences between height levels were less pronounced. MFA and density exhibited highly significant Pearson correlations of 0.73 and 0.70 respectively with board dynamic MOE. A multiple regression model, which included MFA, density and ring width, explained 71% of the variation in the dynamic MOE of boards. A sensitivity analysis on the model showed that MFA and density had approximately similar influences on predicting the dynamic MOE of Pinus patula boards.

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Section: Introductionmentioning

confidence: 99%