Effects of Canopy Herbivory On Nutrient Cycling In A Northern Hardwood Forest In Western North Carolina.

In May 1998 an outbreak of sawflies, Periclista sp. (Hymenoptera: Symphyta), occurred in a high-elevation hardwood forest in western North Carolina. Estimated defoliation of northern red oak (Quercus rubra) and white oak (Q. alba) removed 40% of leaf area. Weights of frass (insect feces) collected at the site were greater than at a nearby site of lower elevation that was not defoliated. Within a month of the outbreak, elevated levels of nitrate-nitrogen. (NO3-N) were measured in through fall and resin bag samples from the site and in stream water draining the affected watershed. The lower elevation control watershed did not show increased levels of nitrate-nitrogen in through fall, resin bags, or stream chemistry. This study demonstrates that insect defoliators can influence ecosystem-level processes such as nutrient cycling.