Midstory Shelterwood to Promote Natural Quercus Reproduction on the Mid-cumberland Plateau, Alabama: Status 4 Years after Final Harvest

—In 2001, we initiated a study in Jackson County, AL, to examine shelterwood prescriptions 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. In the midstory herbicide shelterwood (MSW) we used an herbicide to inject more than 380 stems per acre (SPA) in three stands; average diameter of killed trees was 3.5 inches diameter at breast height (d.b.h.). After 8 growing seasons, all merchantable trees were removed in a commercial harvest. Control stands were left untreated for 8 years and then underwent the same final harvest. Before treatment, densities of trees ≥1.5 inches d.b.h. were 320 SPA for all species and included 27 SPA of Quercus spp., 67 SPA of Acer saccharum Marsh., and 3 SPA of Liriodendron tulipifera L. The MSW reduced the total SPA to 117. Quercus and L. tulipifera SPA were unchanged compared to pretreatment densities, and A. saccharum was reduced to 13 SPA. The MSW also increased the amount of full sun reaching the seedling layer for 3 years compared to the control. After the final harvest, there were only 19 SPA in the MSW, with no stems of Quercus, A. saccharum, or L. tulipifera. Control stands after final harvest had 104 SPA, with no stems of Quercus. The reproduction cohort in both control and MSW treatments shifted from 5 percent of stems in the smallest size class to 56 percent in the largest size class 4 years after the final harvest. Large Quercus seedling stems increased by 33 percent in the MSW and by 9 percent in the control. Survival and growth of tagged Quercus seedlings did not differ at any time between treatments. Competitor species of L. tulipifera, A. saccharum, Fraxinus spp., Viburnum spp., and Cercis canadensis L. may need additional treatment to maintain Quercus in these stands.