OOS 22
Dead Roots: The Dark Side of the Carbon Cycle

Tuesday, August 11, 2015: 8:00 AM-11:30 AM
341, Baltimore Convention Center
Organizer:
Caryl Ann Becerra, University of California, Santa Barbara
Co-organizer:
Jennie R. McLaren, University of Texas at El Paso
Moderator:
Jennie R. McLaren, University of Texas at El Paso
Soil is the largest reservoir of terrestrial organic carbon and as such represents a major carbon sink. Contributors to soil carbon include decomposition byproducts of litter, microbes, fungi and animals. Despite likely being a major contributor to soil carbon, a largely unexplored source is dead roots buried in the soil. In this sense, the reference of root decomposition as the ‘dark side’ of the carbon cycle is two-fold: the roots are in the dark, given that they decompose below ground, and ecologists are also ‘in the dark’ with our lack of knowledge of this important process. 50% of primary production in many ecosystems is belowground and as such roots represent both a major source of soil carbon and a potential carbon sink. Although there has been much study on species variation in and environmental effects on leaf litter decomposition, root decomposition may not be parallel to these patterns. Environmental controls over decomposition may be different for roots than for leaves because of the vastly different environment in which this litter decomposes. Roots grow in direct contact with the soil where they die, unlike leaf litter, which experiences ultraviolet radiation and rapid temperature and moisture fluctuations. As most of our information on environmental effects on litter turnover comes from leaf decomposition studies, the effects of global change on root carbon turnover are greatly unknown. This session aims to present our current understanding of root decomposition and identify knowledge gaps. The presentations will offer how root decomposition and soil carbon are linked and present findings from studies that test the effect of different environmental factors and root traits on decomposition. Presenters will include novel methods to study root decomposition and identify key factors that affect root carbon turnover. This session is appealing to ecosystem ecologists, biogeochemists, and microbial ecologists alike.
8:00 AM
 A salute to roots: Microbes, rhizodeposits and soil physical processes drive preferential stabilization of root carbon
A. Stuart Grandy, University of New Hampshire; Emily E. Austin, University of New Hampshire
8:20 AM
 Root decomposition and their mediation of soil C stability under warming and elevated CO2
Yolima Carrillo, University of Wyoming; Elise Pendall, University of Western Sydney; Feike Dijkstra, University of Sydney; Daniel LeCain, USDA-ARS
8:40 AM
 Cascading effects of different root C ages in forests and grasslands
Susan Trumbore, Max Planck Institute for Biogeochemistry; Emily Solly, Swiss Federal Research Institute WSL; Ingo Schöning, Max Plank Institute for Biogeochemistry Jena; Marion Schrumpf, Max Plank Institute for Biogeochemistry Jena
9:00 AM
 What controls fine root C turnover and stabilization in temperate ecosystems?
Emily Solly, Max Planck Institute for Biogeochemistry Jena; Ingo Schöning, Max Plank Institute for Biogeochemistry Jena; Susan Trumbore, Max Planck Institute for Biogeochemistry; Beate Michalzik, Friedrich Schiller University Jena; Marion Schrumpf, Max Plank Institute for Biogeochemistry Jena
9:20 AM
 Fine root morphology as a driver of root and soil organic carbon decay rates
Marie-Anne de Graaff, Boise State University; Johan Six, ETH; Julie D. Jastrow, Argonne National Laboratory; Chris Schadt, Oak Ridge National Laboratory; Stan D. Wullschleger, Oak Ridge National Laboratory
9:40 AM
9:50 AM
 Microbial decomposition of dead grassland roots and its influence on the carbon cycle under changing precipitation patterns
Caryl Ann Becerra, University of California, Santa Barbara; Joshua P. Schimel, University of California, Santa Barbara
10:10 AM
 3 m up, >1.3 m under: Tracking carbon fluxes of a change from Midwestern row crops to perennial grasses
Christopher K. Black, Energy Biosciences Institute; Michael Masters, University of Illinois; Kristina J. Anderson-Teixeira, Smithsonian Conservation Biology Institute; Evan H. DeLucia, Institute for Genomic Biology
10:30 AM
 Molecular-level phenolic composition of fine roots is modulated by soil resource environment and is decoupled from morphological and macro-elemental root traits
Nishanth Tharayil, Clemson University; Jun-Jian Wang, Clemson University; Colleen M. Iversen, Oak Ridge National Laboratory; Vidya Suseela, Clemson University; Joanne Childs, Oak Ridge National Laboratory; Alex T. Chow, Clemson University; Hui Zeng, Peking University; Richard J. Norby, Oak Ridge National Laboratory
10:50 AM
 Tracing the activity of extracellular enzymes in dead roots during summer drought
Eric Slessarev, University of California, Santa Barbara; Joshua P. Schimel, University of California, Santa Barbara