Influence of Sawing Patterns on Lumber Quality and Yield in Large Sugi (Cryptomeria japonica) Logs

Abstract Appropriate log sorting and optimal sawing patterns are indispensable for efficient lumber production. It is also important to clarify the relationship between the quality of logs and that of sawn lumber to determine effective sorting and optimal sawing patterns. Although some information on lumber quality has been obtained for medium sugi (Cryptomeria japonica D. Don) logs, little is known about lumber quality in large logs, the supply of which is expected to increase imminently. We investigated the influence of the sawing patterns of large sugi logs on lumber quality. Large sugi logs (30 to 40 cm in diameter) were converted into sawn lumber using different sawing patterns. Sawing yields varied for each sawing pattern. Sorting logs by Young's modulus (Efr) would be useful for the efficient production of reliable sawn lumber from large logs, especially when the dimensions of the main products are large. Conversely, it is important to note the variation of Efr in logs when several main products were sawn. Lumber warp was affected by sawing pattern rather than the log sweep. There is potential to produce reliable lumber by considering sawing patterns based on the variation of Efr within a log and the difference of lumber warp.