F. Munalula; T. Seifert; C.B. Wessels A method for the non-destructive determination of the knotty core sizes of standing Pinus patula trees, based on ring width assessments at breast height and the pruning history Afternoon gentleman, As you can see I’m involved in Solid Wood Processing Teaching and Research. F. Munalula; T. Seifert; C.B. Wessels Department of Forest and Wood Science Stellenbosch University South Africa Department of Forest and Wood Science

Department of Forest and Wood Science Background Pruning of plantation pine trees destined for solid wood processing 4 years 7 years 9 years 28 years Cunningham and Price, 1996 Department of Forest and Wood Science

Department of Forest and Wood Science Motivation Why is it important to know the size of the knotty core of the pruned section of a pine plantation tree? ± 65% of log value (1) The most valuable part of the tree stem Department of Forest and Wood Science

Department of Forest and Wood Science Motivation (2) Large variation exist in the knotty core sizes – which affects the value that can be extracted by processors (Park, 2002) Department of Forest and Wood Science

Department of Forest and Wood Science Motivation (3) Information on knotty core sizes can be used by growers and processors to optimise the value extraction from plantations: - Log allocation decisions; - Log pricing decisions; - Production planning and optimisation; - Silviculture planning and research. Department of Forest and Wood Science

Concept to be evaluated Tree ring measurements + Pruning records Increment core 1 2 3 4 5 7 6 8 9 10 12 11 13 14 15 16 Department of Forest and Wood Science

Department of Forest and Wood Science Some previous work Prediction of knotty defect core sizes using plantation records and growth models (Cunningham and Price, 1996); Pruned Log Index – destructive testing of sub-sample of trees, New Zealand (Park, 1989; 2002; 2005); Pre-Harvest Quality Assessment: destructive testing of sub-sample of trees (Price et al., 2002); Measurement of diameter over stub after each pruning operation (Gosnell, 1987). Department of Forest and Wood Science

Department of Forest and Wood Science Objectives To assess the practical applicability of the methodology developed to predict the knotty core sizes of standing Pinus patula trees; To establish a suitable within-tree increment core sampling strategy; To establish the variation of knotty core sizes in a typical pruned Pinus patula resource; To evaluate some applications of knotty core data from standing trees. Department of Forest and Wood Science

Department of Forest and Wood Science Methodology Sample material: 17 pruned Pinus patula compartments, Mpumulanga, South Africa; 10 trees / compartment = 170 trees, stratified sampling; Discs removed at breast height and 6m and sawlog; 1m 2.1m 1.3m 2.3m 6m 7m 11m 0m Pulping log Saw log Department of Forest and Wood Science

Department of Forest and Wood Science Methodology Discs dried and sanded; Scanned on image analysis programme and year-ring widths measured; Department of Forest and Wood Science

Department of Forest and Wood Science Methodology Creation of reconstruction or model of knotty core per tree and compartment; Radius (mm) 74 mm 72 mm 76 mm 101 mm Height (m) Department of Forest and Wood Science

Department of Forest and Wood Science Methodology Sawing of logs; reconstruction of sub-sample of logs from boards (one log per compartment); Determination of knotty core size at specific height of log – comparison with model; Department of Forest and Wood Science

Department of Forest and Wood Science Methodology Statistical analysis of results; Application of results: Sawing simulation studies. Department of Forest and Wood Science

Department of Forest and Wood Science Results Tree ring measurements, dating of rings relatively easy on the species; Department of Forest and Wood Science

Department of Forest and Wood Science Results No difference in mean annual growth results when measuring 2 radii vs. 4 radii at breast height; Cumulative growth at 6m can be accurately predicted from the independent variables cumulative growth at breast height, site index, and cambial age (R2 = 0.96). Department of Forest and Wood Science

Department of Forest and Wood Science Results ANOVA: Far greater variance between compartments than within compartments; ANOVA: Significant within-tree variance. Bottom log = 49.1% knotty core; Top log = 65.4% knotty core. Department of Forest and Wood Science

Department of Forest and Wood Science Results Comparison predicted knotty core size vs. knotty core measured from reconstructed logs (R2 = 0.62): Department of Forest and Wood Science

Department of Forest and Wood Science Results Application of knotty core data by forest growers and processors: Cross-cutting decisions and production planning. Department of Forest and Wood Science

Department of Forest and Wood Science Conclusions Tree ring measurement and dating is easy and efficient with plantation grown Pinus patula; Annual growth for the full pruned section can be predicted from growth at breast height and site index; Two increment cores per tree will be sufficient to predict mean annual growth; Large variation of knotty cores exist within trees and between compartments; Influence of nodal swelling, branch stub length, and occlusion scar size need to be investigated (not part of this study); Knotty core size information per compartment can be used in production planning and bucking decisions. Department of Forest and Wood Science

Department of Forest and Wood Science Acknowledgements NMMU (Jos Louw) and Komatiland Forests for assistance in collection of study material. Department of Forest and Wood Science