Thursday, August 9, 2007: 1:30 PM-5:00 PM
C1&2, San Jose McEnery Convention Center
OOS 43 - Biodiversity in the litter layer: Mechanisms and applications
We propose this oral session to promote exploration and synthesis of the major ecological drivers of non-additive mixed litter decomposition to improve predictions and applications in the natural world. Empirical investigations and reviews of biodiversity and ecosystem function have focused primarily on the responses of primary productivity, ecosystem stability, and nutrient use; and there is consensus that patterns are complex, but better mechanistic understanding is needed if emergent effects are to be found. A large number of mixed litter decomposition studies have found non-additive effects (both positive and negative) of species mixtures on litter decomposition, but demonstrated mechanistic explanations still elude scientists. Our first aim, then, is to bring together various leading scientists concurrently working on the mechanistic drivers of non-additive mixed litter decomposition. Second, we would like to address potential applications of litter diversity. Leaf litter inputs represent 50 to 80% of the recycled input of nutrients in many forest ecosystems and litter decomposition is the primary link between productivity and ecosystem nutrient recycling. Thus, restoration and replanting efforts must consider the identity and diversity of focal species. For example, applications of mixed-litter mulch on maize fields has been shown to increase seedling performance, though whether this effect would extend toward other crop species or other litter mixtures remains unclear. In this session we propose to explore a variety of application questions that will be complemented by improvements in our mechanistic understanding. For example, speakers will address the following questions: What level of diversity is important to litter mixing? What other trophic levels are important to promote in restoration plans? What is the role of invasive species in litter mixtures? Do different classes of organisms respond differently to litter mixtures (i.e. soil macrofauna and microbial decomposers)? Finally, this session will showcase both established ecologists and researchers new to the field and will thus promote discourse between scientists from disparate backgrounds and places of origin.
Organizer:	Samantha K. Chapman, Smithsonian Environmental Research Center
Co-organizer:	Tracy B. Gartner, The Environmental Science Program, Carthage College
Moderator:	Samantha K. Chapman, Smithsonian Environmental Research Center
1:30 PM	OOS 43-1		Effects of leaf litter species richness and composition on nutrient turnover and decomposer biota Becky A. Ball, University of Georgia, Mark A. Bradford, University of Georgia-Athens, Dave C. Coleman, University of Georgia, Mark D. Hunter, University of Michigan, John S. Kominoski, University of Georgia, Cathy Pringle, University of Georgia
1:50 PM	OOS 43-2		Inter- vs. intraspecific competition among exotic earthworms interacts strongly with leaf litter diversity in driving soil organic matter decomposition rate Jerry L. Burgess, Johns Hopkins University, Katalin Szlavecz, Johns Hopkins University, Christopher M. Swan, University of Maryland, Baltimore County, Lijun Xia, Johns Hopkins University
2:10 PM	OOS 43-3		Unique or important systems I - Mixing litter of plants with different nitrogen economies: Hemiparasites in the sub-Arctic Helen Quested, Stockholm University
2:30 PM	OOS 43-4		Aquatic litter diversity: Directional differences in diversity effects Carri J. LeRoy, The Evergreen State College, Christopher M. Swan, University of Maryland, Baltimore County
2:50 PM	OOS 43-5		Non-additive effects of biotic interactions on litter decomposition Jennifer A. Schweitzer, University of Tennessee, Joe Bailey, University of Tennessee, Carri J. LeRoy, The Evergreen State College, Thomas Whitham, Northern Arizona University, Stephen C. Hart, Northern Arizona University
3:10 PM			Break
3:20 PM	OOS 43-6		Do soil animals control litter diversity effects on decomposition? Stephan Hattenschwiler, Centre of Functional Ecology and Evolution, Patrick Gasser, Centre of Functional Ecology and Evolution, Benjamin Jackson, Centre of Functional Ecology and Evolution, Soraya Rouifed, Centre of Functional Ecology and Evolution, Helene Bracht-Jorgensen, Centre of Functional Ecology and Evolution, I. Tanya Handa, Centre of Functional Ecology and Evolution, Jean-Francois David, Centre of Functional Ecology and Evolution
3:40 PM	OOS 43-7		Slow breakdown: Does microbial functional overlap drive non-additive litter decomposition? Samantha K. Chapman, Smithsonian Environmental Research Center, Ilka C. Feller, Smithsonian Environmental Research Center
4:00 PM	OOS 43-9		The relative role of species richness versus evenness on the decomposition of multi-species leaf litter mixtures in a Piedmont stream Christopher M. Swan, University of Maryland, Baltimore County, Megan A. Gluth, University of Maryland, Baltimore County, Courtney L. Horne, University of Maryland, Baltimore County
4:20 PM	OOS 43-10		Aspen genotypes create patches of ecosystem functioning that influence leaf litter decomposition Michael D. Madritch, University of Wisconsin, Richard L. Lindroth, University of Wisconsin
4:40 PM	OOS 43-8		Synthesizing mechanisms that drive nonadditive decay Tracy B. Gartner, Carthage College

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