Abstract Machine and hand thinnings beginning at age 7 increased height growth and yield in an overly dense loblolly pine (Pinus taeda L.) stand. In order to be most profitable, it appears that precommercial thinning should be done by machine at age 2 or 3 to at least an 8- by 8-foot spacing.
Charles X. Grano (Sat,) studied this question.