The effects of intensive management on the leaf characteristics and growth phenology of young yellow-poplar stems

Yellow-poplar (Liriodendron tulipifera L.) is one of the more commonly regenerated species in upland Piedmont stands following clearcut reproduction methods. Recent studies show that a variety of silvicultural activities affect the growth of yellow-poplar seedlings. However, the factors responsible for these changes in growth have not been documented in detail. Weed control, fertilization and thinning treatments were imposed on rising 1- and 3-year-old naturally regenerated stands. Stem growth and monthly height growth patterns, and leaf physical and chemical parameters were compared by treatment during the third growing season after treatments were initiated. The response of yellow-poplar to fertilization suggests that inherent site resources are not suitable for optimal growth, especially when stem densities are high. Vector analysis of N, P and K responses to fertilization, weeding and thinning treatments demonstrated that yellow-poplar responded to ameliorations of N and P deficiencies. Thinned + weeded yellow-poplar, with or without fertilization, had a greater percentage of height growth later in the summer compared to other treatments. Foliar characteristics like leaf number, leaf size and nitrogen concentration were positively correlated with stem growth. The largest increases in leaf area were coincident with increases in foliar N and P. (C) 2007 Elsevier B.V. All rights reserved.