John P. Dwyer

A dendrochronological study of black and scarlet oak decline in the Missouri Ozarks

Abstract Examination of tree-ring data revealed important relationships regarding red oak decline in the Missouri Ozarks. Red oaks, mainly black and scarlet oak, exhibiting greater than 30% crown dieback had significantly lower present-day growth rates compared with trees with less than 30% dieback. Red oaks with declining crowns first showed significantly lower radial growth than trees that are healthy at present in the 10 years following years of severe drought in southeastern Missouri. These dates for initiation of radial growth decline varied by tree age, and were 1936 for 60–79-year-old trees and 1952 for 40–59-year-old trees.

Thinning effects on diameter growth in black and scarlet oak as shown by tree ring analyses

Abstract 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. Dendrochronological 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.