Document: DAV-3-48-11

Herbivory of vine maple,Acer circinatum(Pursh) in an old-growth Douglas-fir/western hemlock forest.

BRAUN, D.M.* ¹, B.RUNCHENG ², D.C.SHAW ¹ and M.VANSCOY ¹

University of Washington, Carson, Washington 98610 USA ¹
Shanxi Teacher University, Linfen City, P.R. China ²

Abstract:
Herbivory of vine maple and its lepidopteran herbivore guild were studied in an old-growth Douglas-fir/western hemlock forest in the Wind River Experimental Forest, Washington, to gain understanding of the guild's contribution to ecosystem herbivory and food webs. Herbivory was monitored from bud break in May to leaf drop in October, 1999, by weekly assessment of the area lost on tagged leaves and collections of larvae for species identification. The adjusted percentage herbivory (based on the weekly leaf area) produced levels of 1% to 3% per week in May, after which herbivory was approximately 0.5% per week. Total herbivory was 9.4% of leaf area, based on fully expanded leaf outline. The lepidopteran herbivore guild consisted of four groups which occurred sequentially, with little overlap: the first consisted solely of Operophtera bruceata (Geometridae); the second group consisted of two species, Choristoneura rosaceana and an Archips sp (Tortricidae); the third group consisted of Lambdina fiscellaria fiscellaria and Itame plumosata (Geometridae); and the fourth group consisted of microlepidopterans (Gelichiidae). In addition, 3 or fewer individuals of approximately 13 other species were collected. The guild structure has several implications: First, the sequential nature of appearance of these groups may represent adaptations to increasing levels of tannins and leaf toughness over the course of the season; second, the early-season peak in larval abundance may represent a significant component of the high-quality food available to neotropical migrant birds as well as local birds at a critical time in their life histories, and third, because the forest studied typically has very low levels of conifer herbivory, < 1%, this level of herbivory for its dominant understory shrub has implications for nutrient cycling, primary production, and food webs that are not obvious based on conifer herbivory alone.

Keywords: _Acer circinatum_, insect herbivore guild

This abstract is being presented at: 11:30 AM in session:
Oral Session #26: Invertebrate Herbivore - Plant Interactions.