PARENT SESSION
Oral Session #69: Elevated CO₂ and Global Change. Presiding: L. Gough.
Thursday, August 9, 2001. 1:00 PM to 4:45 PM. Hall of Ideas H.

Effects of whole-ecosystem atmospheric CO₂ concentration manipulation on arthropod population dynamics in southern California chaparral.

Anderson, Alison¹, Williams, Kathy¹, ¹

ABSTRACT- This study examined the in situ effects of elevated CO₂ on arthropod abundance in a chaparral community using a series of controlled CO₂, ambient light, controlled temperature (CO₂LT) null-balance chambers and a Free-Atmosphere Carbon dioxide Enrichment (FACE) ring. We found that abundance of most arthropod groups, including parasitic wasps (Hymenoptera), decreased with elevated CO₂, resulting in reduced total arthropod abundance. However, abundance of moths (Lepidoptera) increased. The relationship of springtails (Collembola) abundance vs. CO₂ concentration was curvilinear, with abundance peaking at 450-550 ppmv, and lowest at 750 ppmv. While other studies have shown that plant biomass typically increases increased CO₂ concentrations, our results suggest that arthropod biomass, in fact, may decrease. Furthermore, our data indicate that ecosystem dynamics would be altered by CO₂-mediated reduction in arthropod services, such as nutrient cycling and energy flow to higher trophic levels.

KEY WORDS: arthropods, elevated, CO₂, chaparral