Third-Year Growth and Bole Quality Responses to Thinning in a Red Oak-Sweetgum Stand on a Minor Streambottom Site in West-Central Alabama

Abstract

Four thinning treatments were applied to a red oak-sweetgum (Quercus spp.-Liquidambar styraciflua L.) stand on a minor streambottom site in west-central Alabama in 1994: (1) unthinned control; (2) light thinning to 70-75 percent residual stocking; (3) heavy thinning to 50-55 percent residual stocking; and (4) B-line thinning to desirable residual stocking for bottomland hardwoods, as recommended by Putnam and others (1960). The thinning operation was a combination of low thinning and improvement cutting to remove most of the pulpwood-sized trees as well as sawtimber-sized trees that were damaged, diseased, of poor bole quality, or of an undesirable species. Prior to treatment, the stand averaged 196 trees per acre with a basal area of 121 ft² per acre. Quadratic mean diameter was 10.7 in., while stocking averaged 107 percent across the 24-acre study area. Light thinning reduced stand density to 83 trees and 82 ft² of basal area per acre, increased quadratic mean diameter to 13.5 in., and reduced stocking to 69 percent. Heavy thinning reduced density to 49 trees and 64 ft² of basal area per acre, increased quadratic mean diameter to 15.5 in., and reduced stocking to 52 percent. B-line thinning produced stand characteristics intermediate between those resulting from light and heavy thinning. Thinning increased 3- year diameter growth of residual trees, across all species, but there were no significant differences among the three levels of thinning. Thinning also increased diameter growth of codominant trees, but not dominant trees, when averaged across all species. All levels of thinning, except heavy thinning, increased the production of new epicormic branches on the butt log, across all species, but all levels of thinning resulted in fewer than four new branches after 3 years. All levels of thinning increased epicormic branching on sweetgum, but only B-line thinning Increased epicormic branching on red oak and only light thinning increased epicormic branching on hickory (Carya spp.). In general, the production of new epicormic branches on the butt log was greatest on low-vigor, lower-crown-class trees.

Citation

Meadows, James S.; Goelz, J.C.G. 1999. Third-Year Growth and Bole Quality Responses to Thinning in a Red Oak-Sweetgum Stand on a Minor Streambottom Site in West-Central Alabama. USDA, Paper presented at the Tenth Biennial Southern Silvicultural Research Conference, Shreveport, LA, February 16-18. 1999.