|Rogers Jr, Hugo|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/28/2001
Publication Date: 11/28/2001
Citation: Davis, M., Rogers Jr, H.H., Gjerstad, D., Schlesinger, W. 2001. Carbon and nutrient flow through multiple trophic levels in co2-enriched plant communities [abstract]. In Southeast Regional Center National Institute for Global Environmental Change Annual Conference, Program and Abstracts, November 28-29, 2001, Durham, North Carolina. p. 11.
Technical Abstract: The ability to predict the consequences of global change is predicated on our understanding of controls of energy and material flows through ecosystems. A significant gap in that understanding lies belowground and at the soil-litter interface. Root growth and exudation are responsible for direct depositions of carbon into these environments, but aboveground carbon must pass through the soil food web before it can enter the belowground carbon pool. Within temperate forests, up to 90% of net primary productivity passes through the food web of the diverse arthropod fauna residing in forest soil and litter. The dietary quality of litter is often reduced by elevated CO2 via changes in leaf chemistry (e.g., increased C:N, increased secondary compound production, and increased lignin content), thus reductions in decomposition and nutrient cycling are predicted by most models. The effects of CO2-enriched leaf litter on soil fungi, bacteria, and microarthropods have begun receiving attention in the past decade; however, macroarthropod detritivores-predator interactions. Arthropod responses to reduced dietary quality (litter or prey) include reduced fitness, increased consumption, and alterations of dietary preferences, all of which would impact nutrient cycling and carbon flow through forest systems. We are currently testing a simple conceptual model that describes environmental controls on leaf litter quality and subsequent effects on macroarthropod detritivores and predators. Litter collected from at least three CO2 experiments in the southeastern United States are being used to conduct feeding assays to garner information of feeding behavior (consumption rates and selectivity) and detritivore performance (relative growth rate, digestibility of litter) both of which impact nutrient cycling and carbon flow. In addition to feeding trials, intensive macroarthopod surveys are being conducted at Duke University FACTS-1 site, a loblolly pine plantation that has received 6 years of CO2 enrichment, and the National Soil Dynamics Laboratory which has a model regenerating longleaf pine system (3 years of CO2 enrichment) and an agricultural system (4 years of CO2 enrichment). Preliminary data indicates that CO2 effects on litter-detritivore interactions will be species specific. Sand post oak (Quercus margaretta) leaf litter derived from plants exposed twice-ambient CO2 for two years had 32% more total phenolic contents than litter from oaks exposed to ambient CO2. When this oak litter was fed to two species of terrestrial isopods, Porcellio sp. performed poorly on a diet of litter from high-CO2 chambers, while Armadillidium sp. was unaffected by the CO2 environs of its litter diet. Thus, assessing the relative importance of plants species that generate litter and detritivore species that consume litter will be critical in evaluating the effects of elevated CO2 on carbon and nutrient flow through soil food webs.