Growth Response of Young Yellow-Poplar to Release and Fertilization

Release and fertilization treatments were applied to two 10-yr-old yellow-poplar (Liriodendron tulipifera L.) stands of natural origin in southwest Virginia. Seven growing seasons after the first treatment, the released trees had an absolute dbh growth response of 47.4%. Fertilization did not affect any of the growth variables studied, but resulted in a significant interaction with the release treatment for absolute height growth, which was significantly increased. Initially, height growth was slower with the released trees, but they increased their growth in the later years and had significantly greater live crown ratios than the unreleased trees, 53% compared to 46%. The released trees had 311% absolute response in crown volume, significant at the 0.001 level. Release treatments like this may be advantageous in maintaining yellow-poplar on intermediate sites, which may become an important landowner objective, since a component of gypsy moth-immune yellow-poplar can reduce overall stand vulnerability. South. J. Appl. For. 21(4):175-179.