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>The prediction of the flexural lumber properties from standing South African-grown Pinus patula trees
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The prediction of the flexural lumber properties from standing South African-grown Pinus patula trees
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机译：从南非种植的pinus patula树上预测弯曲木材的性质
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摘要
Pinus patula is the most intensively plantedconifer in the tropics and subtropics. The increased proportionof corewood that results when rotation ages of pineplantations are shortened has become a wood quality factorof growing concern worldwide. The purpose of this studywas to develop empirically based models for predicting theflexural properties of the wood produced from relativelyyoung P. patula trees. Models were based on the propertiesof standing trees, and their effectiveness was evaluated atboard, tree, and compartment levels. Sample material wasobtained from 170 P. patula trees, 16–20 years old,established in 17 compartments on the Mpumalangaescarpment of South Africa. Multiple regression modelswere developed, which managed to explain 68, 60, and95 % of the variation in the dynamic modulus of elasticity(MOE) on individual boards, trees, and compartmentslevels, respectively. At compartment level, 80 % of thevariation in the 5th percentile MOR value could beexplained by the model. Sensitivity analyses showed thatsite index at base age of 10 years, acoustic time of flight,wood density, and ring width were influential variables inthe MOE models. The models indicated that treeslenderness during early growth seems to play a major rolein determining the dynamic MOE and MOR of lumber.This is in agreement with Euler’s buckling theory and thebending stress theory. The results from this study indicatedthat the MOEdyn and MOR of lumber can be accuratelypredicted on especially a compartment level. The predictivemodels developed can be used as management tools toimprove operational decisions around tree breeding, silviculturalpractices, and rotation ages.
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