One of two planted loblolly pine trees (Pinus taeda L.) and over one of three (36%) planted slash pine trees (Pinus elliottii Engelm.) on non-old-fields in East Texas have a poor quality stem. For both species, o poor quality stem is three times more likely to occur on trees with crowns in the upper canopy then in the lower canopy.
Lenhart, J. David and Hunt, Ellis V. Jr., "Research Report No. 2, Tree Quality" (1985). Informal Project Reports. Paper 52.