Effects of Herbivory and Competition on Survival of Carya tomentosa (Juglandaceae) Seedlings

Abstract

We tested the effects of predation, above-ground diffuse competition and below-ground diffuse competition on the survival and growth of Carya tomentosa (Juglandaceae) seedlings in a five year oldfield bordering a mature forest. We planted eighty seedlings under cages, in pots or with surrounding vegetation tied back (in all combinations) to realize the treatments. We found that seedlings unprotected from herbivores suffered great mortality (i.e., survival < 10%). Seedlings planted away from the forest edge suffered significantly less predation than those closer to the forest. Seedlings often resprouted after browsing. Because only a few seedlings survived outside the cages, we focused on the caged seedlings to examine competition effects on seedling growth and survival. No significant differences were found in leaf, stem, root, and total biomass of surviving seedlings under any of the competition treatments. Insect herbivores affected 15% of the seedlings by removing 10% of their leaf area during the first year. In the second year, 30% had 1-10% damage to leaf tissue. No seedlings died due to invertebrate herbivores. Browsing by mammalian herbivores appears to be the primary factor determining woody seeding establishment patterns in seral oldfields.