How Much Older are Appalachian Oaks Below- Ground than Above-Ground?

Abstract

Young oaks (Quercus spp.) are known to invest more in early root growth than shoot growth, enabling seedlings to tolerate stem die-back and resprouting. The resulting disparity in age between above- and below-ground tissues has been previously demonstrated for seedling-sized stems, but not for successful canopy-ascending trees. We compared the age of stem cross sections taken at 1.0 ft above the ground and those taken at the rootcollar of northern red (Q. rubra) and chestnut oaks (Q. montana) and measured growth rates over the first five years of development. Of 51 sampled stumps, 88% had root systems that were an average of 2.3 to 3.6 yrs older than the aboveground stem. The early height growth rate averaged 19 in./yr supported the supposition that most sampled oaks had been advance regeneration that resprouted following harvest. These results indicate that at least a single topkill does not necessarily pose an impediment to oak regeneration success and may, in fact, provide a competitive advantage and reiterate long-standing assertions that oak reproduction must be well-established before the final harvest.