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

Abstract

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°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 mesh 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 ≥8 FOLR prior to planting were 55% taller than seedlings with ≤2 FOLR, and 213% taller than seedlings not protected by tree shelters with ≤2 FOLR. Seven-year height of unprotected white pine was significantly correlated with root collar diameter. White pine seedlings with RCD ≥8 mm before planting were 75% taller after 7 years than seedlings with RCD ≤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.