Document: HEA-3-34-4

Impacts of nitrogen deposition on plant growth and insect herbivory.

THROOP, H.* and M.LERDAU

State University of New York, Stony Brook, NY 11794-5245 ¹

Abstract:
Atmospheric deposition of inorganic nitrogen is leading to increased nitrogen availability in many terrestrial systems. Deposition-induced changes in nitrogen availability can alter plant growth, physiology, and reproduction. In addition, deposition-induced changes in plant tissue chemistry can affect patterns of insect herbivory. We used common ragweed, Ambrosia artemisiifolia (Asteraceae), to examine the influence of simulated nitrogen deposition on the chemical composition of leaf tissue, phloem sap, and xylem sap, and on patterns of photosynthesis, growth, and reproduction. In addition, we investigated the influence of simulated deposition and subsequent changes in plant tissue chemistry on patterns of herbivory by a folivorous beetle (Coleoptera: Ophraella communa) and a phloem-feeding aphid (Hemiptera: Uroleucon ambrosiae). Increased simulated nitrogen deposition led to lower leaf C:N, higher photosynthetic rates, and greater biomass accumulation in the absence of herbivory. Altered nitrogen availability also affected patterns of insect herbivory, although the magnitude to which insects were affected was contingent upon the tissue type upon which herbivores fed.

Keywords: nitrogen deposition, global change, plant growth, herbivory

This abstract is being presented at: 4:30 PM in session:
Oral Session #28: Effects of N Deposition in Ecosystems.