Characteristics of Compression Wood in Some Native Conifers

It was observed that compression wood is more common in young stems and second-growth species, occurs on the lower sides of branches, and on the lower sides of trees leaning as little as 2 degrees from the vertical. The reaction wood has characteristic growth rings; eccentric, abnormally wide, and less clearly delineated. Microscopically, cells are thick-walled, rounded, with intercellular spaces at the junction of four tracheids, and have excessive spiral checking of the secondary cell wall. In contrast to adjacent normal wood, compression wood has a non-lustrous lifeless appearance on longitudinal surface and is more reddish on the wetted-end. Though traumatic resin canals are not a constant feature of compression wood, these were found in Douglas-fir and white-bark pine. New examinations with an electron microscope indicated fine or incipient spiral checking in the secondary cell wall of compression wood tracheids. The microfibrils of the S layer were found to have a flatter spiral than in normal cells. Abnormal longitudinal shrinkage of compression wood has been attributed to this deviation from normal. Compression wood can be detected, in thin sections of wood, by its relative opacity to light. Importance of recognizing compression wood was emphasized, and elimination from use by the wood industry suggested.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member