Shelterwood to promote Quercus seedling development via herbicide injection of midstory on the Mid-Cumberland Plateau, Alabama: Status four years after final harvest

by

Callie Schweitzer, Daniel Dey

Research Forester (CJS), USDA Forest Service, Southern Research Station, Huntsville, AL 35801; Research Forester (DCD), USDA Forest Service, Northern Research Station, Columbia, MO 65211. CJS is corresponding author. To contact, call 256-603-0969 or email cschweitzer@fs.fed.us.

Abstract – In 2001, we initiated a study in Jackson County, AL, to examine shelterwood retentions in mixed mesophytic upland hardwood forests located on the escarpment of the mid-Cumberland Plateau. We were particularly interested in testing a shelterwood method that was successfully applied in other upland hardwood systems to recruit Quercus into competitive size classes. We used an herbicide to inject over 380 stems per acre in three stands; average diameter of the killed trees was 3.5 inches. After eight growing seasons, all merchantable timber was removed in a commercial harvest. Prior to treatment, stems per acre (SPA) of trees greater than 1.5 inches dbh were 320 for all species, and included 27 SPA of Quercus spp., 67 SPA of Acer saccharum, and 3 SPA of Liriodendron tulipifera. The herbicide treatment reduced the total SPA to 117, with Quercus and L. tulipifera SPA remaining the same, and A. saccharum reduced to 13 SPA. After the final harvest, there were 18 SPA; no Quercus, no A. saccharum, and no L. tulipifera. After 4 more growing seasons, SPA increased to 35, but there were still no desirable species tallied. The regeneration cohort had 9380 SPA post-final harvest, with 9.8 percent Quercus, 10 percent A. saccharum, and 21.4 percent L. tulipifera. We will further explore the changes in the reproduction cohort, and will compare densities of competitive seedlings to those predicted by the REGEN model.