Recovery of 1-year-old loblolly pine seedlings from simulated browse damage
Loblolly pine (Pinus taeda L.) seedlings are frequently browsed by a wide variety of animals during the first few years of their development. Although anecdotal observations indicate that the potential for seedling recovery is good, there is little quantitative information on the factors affecting the recovery process. Thus, we conducted a study to evaluate the effects of the extent and season of simulated browse damage on the recovery of 1-year-old loblolly pine seedlings under controlled conditions. Seedlings were clipped at five positions: at the midpoint between the root collar and cotyledons and so that 25, 50, 75, and 100% of the height between the cotyledons and the terminal remained after clipping. Clipping treatments were applied in two seasons: winter and spring. All seedlings clipped below the cotyledons died, confirming that dormant buds or lateral shoots are required for recovery. Survival of seedlings clipped above the cotyledons was 97% for winter clipping and 96% for spring clipping. Most of the seedling mortality (73%) was for seedlings with only 25% of their height remaining. Regression analysis revealed that second-year seedling size was positively affected by first-year size and percentage of remaining height after clipping and that seedlings clipped in winter were larger at 2 years than those clipped during spring. Logistic regression indicated a higher probability of multiple stems resulting from the more severe clipping treatments. Clipping season and severity also significantly affected the probability for tip moth (Rhyacionia spp.) damage, which occurred more frequently in the larger seedlings. Results suggest that planting seedlings deep, with the cotyledons just below ground level, may be an advantage in areas where browse damage is common.