PS 57-25 - Tracking litter derived carbon in terrestrial ecosystems using stable isotopes

Thursday, August 11, 2011
Exhibit Hall 3, Austin Convention Center
Jennifer L. Soong1, Uffe Nielson2, Karolien Denef1, William J. Parton1, Diana H. Wall3 and M. Francesca Cotrufo1, (1)Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, (2)Department of Biology, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, (3)Department of Biology and Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO

Quantitative and mechanistic information on the fate of plant derived carbon (C) during decomposition is crucial to our understanding of the global C cycle.  The biological processes involved in litter respiration, leaching, and fragmentation, determine the net rate of decomposition and loss from terrestrial ecosystems.  Stable isotopes can be used as a powerful tool to trace the fate of plant derived C as litter decomposes and cycles within and out of terrestrial ecosystems.  In September, 2010, we began a three year decomposition experiment in the tallgrass prairie using 13C and 15N enriched Andropogon gerardii leaf litter.  In order to elucidate the effect of soil fauna on litter decomposition, we are continuously treating half of the experimental plots with naphthalene to repel soil fauna.


Here, we will present the first results from this project.  Monthly respiration measurements, along with isotopic analysis, show a clear partitioning between litter and soil respiration.  Using the DayCent ecosystem model, we estimate continuous C loss from litter and soil respiration in the tallgrass prairie ecosystem over the course of the past year.  We will also present the results of our Time-1 destructive soil and litter harvest.  Using 13C abundance we quantify in which pools the litter derived C remains, including remaining surface litter, dissolved organic carbon, particulate organic matter, mineral associated organic matter, microbial biomass and specific phospholipid fatty acids, and different soil fauna groups.   By quantitatively tracking the fate of litter derived C using a 13C label in this project, we hope to shed light on the biological processes and specific microbial and faunal groups responsible for C storage and loss from the tallgrass prairie during litter decomposition.

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