Variation in Sapwood Thickness of Douglas-Fir in Relation to Tree and Section Characteristics

Abstract

Abstract Variation in sapwood thickness in 437 discs cut at stump height and from tops of 16-foot logs in 58 Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) trees is analyzed in relation to 10 tree and 11 section characteristics. Dbh, crown class, and crown width are shown to be the most important tree variables. Diameter outside bark, and rate of growth in the last decade, are the most important section variables. Thickness of sapwood bands and number of annual rings contained therein seem to be explained best by Jorgensen's theory describing formation of protection wood in terms of aeration and/or desiccation of sapwood.