Effects of planting stock quality and browse protection-type on height growth of northern red oak and eastern white pine

The interaction of seedling quality and type of browse protection on height growth of northern red oak and eastern white pine was examined in plots established on abandoned agricultural land and on recent clearcuts with moderate-to-high deer densities (18-21 deer/km(2)). One-year-old seedlings were sorted by size, transplanted, and protected with plastic mesh or fabric sleeves, or tree shelters. Seedling heights were measured in the autumn of each year for 7 years after transplanting. Seven-year northern red oak seedlings in tree shelters were 80% taller than those in other treatments. Tree shelters increased early growth of eastern white pine, but not tree height in the seventh year. Temperature and light transmission was measured for different tree protection devices. Tree shelters increased maximum temperature by up to 10 degrees C and decreased light intensity by 50% or more. The initial rate of height growth was faster in tree shelters, despite the apparent greater environmental stress than in mash or fabric sleeves. Stem length, number of twigs, root collar diameter (RCD), and number of first-order lateral roots (FOLR) were measured prior to planting. When protected by tree shelters, red oaks with greater than or equal to 8 FOLR prior to planting were 55% taller than seedlings with less than or equal to 2 FOLR, and 213% taller than seedlings not protected by tree shelters with less than or equal to 2 FOLR. Seven-year height of unprotected whits pine was significantly correlated with root collar diameter. White pine seedlings with RCD greater than or equal to 8 mm before planting were 75% taller after 7 years than seedlings with RCD less than or equal to 4 mm. Planting higher quality seedlings would permit time previously spent on planting inferior seedlings to be reallocated to vegetation control or browse protection. Therefore, severe grading of seedlings should increase planting efficiency and reforestation success. (C) 2000 Elsevier Science B.V. All rights reserved.