Document: KAT-3-59-66

Alteration of soil carbon by communities of mycorrhizal fungi in a chaparral ecosystem exposed to elevated CO₂.

TRESEDER, K.K.*, L.M.EGERTON-WARBURTON and M.F.ALLEN

University of California, Riverside, CA 92521, USA ¹

Abstract:
We examined the potential of arbuscular mycorrhizal (AM) fungi to increase soil carbon storage under elevated atmospheric CO₂ in a chaparral system at the Sky Oaks Field Station in southern California. With antisera labeling, we assessed the community composition and total lengths of live AM hyphae associated with soil macroaggregates under varying CO₂ levels. We then used stable isotopes to calculate C input to these macroaggregates. Carbon concentrations and AM hyphal lengths were correlated (P < 0.06) and rose 30-fold (P < 0.05) and 10-fold (P < 0.01), respectively, between the 250- and 650-ppm treatments. The AM genera Scutellospora and Acaulospora responded strongly and positively to CO₂ concentration, while Glomus and Gigaspora did not. AM fungi appear to increase macroaggregate-C under CO₂ enrichment, possibly due to changes in community structure as well as stimulation of hyphal production. The C content of bulk soil may rise as macroaggregates disintegrate and release C into other soil fractions.

Keywords: mycorrhizal fungi, soil carbon, elevated CO₂, stable isotopes, antisera labeling

This abstract is being presented at: 4:15 PM in session:
Oral Session #30: Effects of Elevated Carbon Dioxide.