Factors limiting the regeneration of large- seeded hardwoods in the Upper Coastal Plain of South Carolina

To test factors limiting regeneration of large-seeded hardwoods in the Upper Coastal Plain of South Carolina, we planted one-year old bare root Quercus alba L. and Cornus florida L. seedlings in pine plantation understories and adjacent clearcuts. We hypothesized that soil moisture, light, and leaf and stem herbivory would have relatively strong effects on growth and survival during the first two years after planting. Next to each seedling, we measured five abiotic factors (soil carbon and moisture, gap light index (GLI), and available nitrogen and phosphorus). We also estimated percent stem and leaf herbivory and harvested seedlings after the second year to measure seedling growth. Survival was not significantly different between clearcut (62.9%) and understory (64.6%) treatments. Biomass growth was significantly greater (P<0.05) in the clearcuts for both species. All abiotic variables measured except soil carbon were greater in the clearcuts (P<0.05). Each seedling growth response was regressed against all variables using forward selection (P=0.15). Soil moisture significantly affected survival in 12.5% and biomass growth in 16.7% of the regressions. Light availability significantly impacted biomass growth in 8.3% of the regressions. Neither leaf nor stem herbivory frequently affected survival, but one or the other or both significantly influenced the biomass growth of seedlings in 41.5% of the regressions. Herbivory had the strongest impact on seedling responses. Neither water nor light was very influential for growth or survival responses. We conclude that hardwood restoration in the uplands of the Upper Coastal Plain is best accomplished by planting in recent clearcuts.