THINNING EFFECTS ON DIAMETER GROWTH IN BLACK AND SCARLET OAK AS SHOWN BY TREE-RING ANALYSES

In the period 1953-1954, five levels of thinning were imposed as part of a crop tree release study on a 32-year-old mixed stand of scarlet oak (Quercus coccinea Muench.) and black oak (Quercus velutina Lam.) located in southeastern Missouri. In winter 1985, 162 live trees were felled (90 scarlet oaks and 72 black oaks). A section of 10 cm thickness was cut from the base of each butt log. Dendro-chronological techniques were used to gather and prepare data to compare treatment responses. Although there was a significant differential treatment response attributable to thinning, the timing of this response varied between the two species. Black oaks had a 10 year period of increased differential growth immediately after the thinning whereas the scarlet oaks, with a 12 year differential growth period, lagged 6-7 years behind. This was not apparent using the standard inventory techniques of periodic diameter measurements.