Date of Award
Master of Science
G. Ray Wells
Harold A. Core. John Rennie
The objectives of the study were: (1) to quantify the relative loss in crop-tree lumber value resulting from increased epicormic branching brought on by stand density reduction, and (2) to quantify the time frame required for this loss to attain economic importance. The study was carried out in West Tennessee and examined the effect of a 13-year-old thinning in a seventy-six-year old hardwood stand dominated by Southern red oak (Quercus falcata Michx). Four sample trees were taken from a stand which had developed at a high level of stocking (127 sq. ft. basal area per acre) and compared to four sample trees from a contiguous part of the same forest stand which had been reduced from 85 to 60 sq. ft. of basal area in 1959. Data were collected regarding site characteristics and the density of surrounding stems, using sample trees as quarter-acre plot centers. Sample trees were logged and sawed, and lumber was graded and indexed to quadrants and log sequence including slab and board position; also, knots were examined to determine the character of their origin.
The first boards sawed from the four quadrants of the lower 34 feet of sample trees were used in the lumber degrade comparison. Total firstboard volume was 665 board feet (321 bd. ft. and 344 bd. ft. from the low- and high-density areas, respectively), which was about one-fourth of the total scaled log volume of sample trees.
Epicormic branch knots in sample trees showed a significant; (0.05 level) inverse relationship to understory density in all plot quadrants except the southeast. Epicormic branching in all logs above 8-1/2 feet also showed a definite inverse relationship to density of the understory. There were little differences in epicormic branching in the lower 8-1/2- ft. log between stand density areas, but differences began to appear in the second 8-1/2-ft. log and became greater with increasing height in the sample tree.
The value difference per thousand board feet of first-board lumber between the two stand density areas was found to be about $50.00 at current prices, and to have been about one-fourth the market price of No. 1 Common red oak lumber for consecutive five-year periods during the past 25 years.
The number of epicormic knots in lumber from the low-density area (average 111 per tree or nine times as many as in trees from the high stand density area) was felt to be more a result of early low stocking levels than attributable to the 1959 thinning. Because of the already high number of epicormics, devaluation attributable to the thinning was negligible. However, a similar thinning in the high stand density area probably would have resulted in potentially serious devaluation of subsequent wood production, up to $50.00 per MBF. Degrade of this magnitude would take at least 13 years to form, however, and would vary by the diameter growth rate and form of the individual tree, and by current lumber price levels.
Wolcott, Benjamin Hall, "Epicormic branching in Southern red oak (Quercus falcata Michx)--a measure of maximum degrade associated with reduced stocking in older stands. " Master's Thesis, University of Tennessee, 1973.