Predicting lumber grade occurrence and volume in sugar maple and yellow birch logs

The North American temperate deciduous forests are an important source of hardwoods sought after by the appearance wood products industries. The purpose of this study was to model the relationships between log characteristics and sawn board attributes in sugar maple (Acer saccharum Marsh.) and yellow birch (Betula alleghaniensis Britt.). We harvested sixty-four sugar maple and thirty-two yellow birch trees from two locations in southern Quebec, Canada, which were then processed into 189 sawlogs and 2,236 boards. We developed statistical models linking log characteristics to the volume recovery of the various lumber grades and color specifications according to the National Hardwood Lumber Association rules. In both species, board grades were strongly related to log length, position of the log in the stem, and small-end diameter and decay of the log. Color classes were related to small-end diameter of the log and red heartwood diameter of the log at both ends for sugar maple, and to log length, diameter of the log at the small-end, and red heartwood diameter at the large-end of the log for yellow birch. These models outperformed a log classification used in practice for predicting lumber volume recovery from different log grades