Diversity in land management objectives has led to changes in the character of raw material available to the forest products industries in the US Pacific Northwest. Increasing numbers of logs from small-diameter trees, both plantation grown and those from suppressed or young stands, now constitute a large proportion of logs coming into the mill yard. Wood coming from plantations or young stands has different properties than wood coming from older, suppressed stands. This research examined wood properties of small-diameter plantation-grown Douglas-fir and western hemlock with the goal of a better understanding of utilization of small-diameter, fast-grown trees for use in manufacturing engineered wood composites. Twelve trees of each species were harvested and three bolts cut from each tree. Each bolt provided samples for X-ray densitometry profiles, compression, and tension parallel to grain and flexure tests. Both species were found to have a very high proportion of juvenile wood. Most wood properties decreased with increasing vertical position and increased with increasing distance from pith for both species. Increased competition for wood fiber, which accounts for as much as 25 to 35 percent of total wood composite (such as particleboard, medium-density fiberboard and oriented strand board) manufacturing costs, necessitates an understanding of raw material properties and their variations. This knowledge could assist in optimizing the manufacturing process and maximizing efficiency of wood raw material use, thus increasing profits.
Contributor Notes
The authors are, respectively, Former Graduate Student and Assistant Professor, Dept. of Civil and Environmental Engineering, Washington State Univ., Pullman (clangum@hotmail.com, vyadama@wsu.edu); and Research Forest Products Technologist, USDA Forest Serv., Pacific Northwest Research Sta., Portland, OR (elowell@fs.fed.us). This paper was received for publication in March 2009. Article no. 10593.