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Fourth-Year Effects of Thinning on Growth and Epicormic Branching in a Red Oak-Sweetgum Stand on a Minor Streambottom Site in West-Central Alabama

Informally Refereed

Abstract

Abstract - Four thinning treatments were applied to a 60-year-old, red oak-sweetgum (Quercus spp.-Liquidambar styraciflua L.) stand on a minor streambottom site in west-central Alabama in late summer 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 consisted of 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 thinning, stand density averaged 196 trees and 121 square feet of basal area per acre. Average stand diameter was 10.7 inches, while stocking averaged 107 percent across the 24-acre study area. Light thinning reduced stand density to 83 trees and 82 square feet of basal area per acre, increased average stand diameter to 13.5 inches, and reduced stocking to 69 percent. Heavy thinning reduced stand density to 49 trees and 64 square feet of basal area per acre, increased average stand diameter to 15.5 inches, and reduced stocking to 52 percent. Putnam’s B-line thinning reduced stand density to 65 trees and 86 square feet of basal area per acre, increased average stand diameter to 15.6 inches, and reduced stocking to 70 percent. Only small increases in stand-level basal area and average stand diameter were observed in the thinned areas 4 years after thinning. Thinning significantly increased diameter growth of residual trees, across all species, but there were only slight differences among the three levels of thinning. These increases in diameter growth were most pronounced among red oaks. Thinning produced only small increases in the number of new epicormic branches on the butt logs of residual trees, averaged across all species. Epicormic branching varied widely across both species and crown classes. Thinning had little effect on epicormic branching in red oaks, but greatly increased the production of new epicormic branches in sweetgum. Heavy thinning appears to have produced the best combination of stand-level growth and individual-tree diameter growth, with minimal increases in epicormic branching, especially among red oak crop trees.

Citation

Meadows, James S.; Goelz, J.C.G. 2002. Fourth-Year Effects of Thinning on Growth and Epicormic Branching in a Red Oak-Sweetgum Stand on a Minor Streambottom Site in West-Central Alabama. Gen. Tech. Rep. SRS–48. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. pp. 201-208
https://www.fs.usda.gov/research/treesearch/3127