Strength Loss in Small Clear Specimens of Beetle-Killed Southern Pine

Beetle-killed shortleaf and loblolly pine trees with known dates of foliage fade, as normal healthy trees, were harvested and processed into lumber. Small clear specimens were prepared from the lumber meeting the current grading specifications for dimension lumber as determined by quality supervisors of the Southern Pine Inspection Bureau. MOR and MOE in bending and ultimate crushing strength were determined for both the dead and the healthy material. Significant reductions in mean MOR and MOE were noted in the material harvested within 12 months of foliage fade as compared to control material from the same stands. A mean reduction of 19 percent in NOR and 11 percent in MOE were noted for wood taken from trees standing for two full warm seasons after foliage fade. The relationship between MOR and MOE of small clear specimens was significantly affected due to a differential reduction in these two properties. Mean ultimate crushing strength was reduced but not to the same degree of severity as MOR and MOE. Examination of the sample lower 5 percent tolerance limits indicated that both mean and variance of MOR and MOE were significantly affected while those of ultimate crushing strength were relatively insensitive.

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