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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #294453
Title: Fungal community responses to past and future atmospheric CO2 differ by soil type

Author
item PROCTER, ANDREW - Duke University
item ELLIS, J. CHRISTOPHER - Duke University
item Fay, Philip
item Polley, Herbert
item JACKSON, ROBERT - Duke University

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2014
Publication Date: 9/19/2014
Publication URL: http://handle.nal.usda.gov/10113/60429
Citation: Procter, A.C., Ellis, J., Fay, P.A., Polley, H.W., Jackson, R.B. 2014. Fungal community responses to past and future atmospheric CO2 differ by soil type. Applied and Environmental Microbiology. 80(23):7364-7377.

Interpretive Summary: The rapid increase in concentration of carbon dioxide (CO2) gas in air is amplifying the “greenhouse” effect that warms Earth. Plants remove CO2 from air during growth and add organic carbon to the soil when plant tissues die, but soil microorganisms release CO2 to the atmosphere when decomposing soil organic material. Potential warming thus depends partly on the balance between effects of rising CO2 on plant carbon input to soil and decomposition of soil organic material. Biological responses of soils to rising CO2, in particular, are poorly understood. We studied responses of soil fungi to the recent and anticipated increase in atmospheric CO2 concentration in grassland growing on two soil types, a clay and sandy soil. The number of fungal species (richness) and relative abundance of one fungal group increased as CO2 rose on the clay soil, whereas a fungal group that facilitates plant uptake of soil phosphorus increased in abundance on the sandy soil. Greater input of easily decomposed plant material likely contributed to the increase in fungal richness at high CO2 on the clay soil. Our results demonstrate that the number and relative abundances of soil fungi adjust rapidly to changes in carbon input from more productive plants at high CO2 to lessen the amount of additional carbon that is retained in soil.

Technical Abstract: Soils sequester and release substantial atmospheric carbon, but the biological responses of soils to rising CO2 are not well understood. We studied fungal communities in a grassland ecosystem exposed to a preindustrial-to-future CO2 gradient (250-500 ppm) on two soil types, a black clay and a sandy loam. Sanger sequencing and pyrosequencing of rDNA revealed that fungal community composition and its response to CO2 differed significantly between soils. Fungal species richness and relative abundance of Chytridiomycota (chytrids) increased linearly with CO2 treatment in the black clay, whereas the relative abundance of Glomeromycota (arbuscular mycorrhizal fungi) increased linearly with elevated CO2 in the sandy loam. Increased labile carbon availability at elevated CO2 may explain the increased fungal species richness and Chytridiomycota abundance in the black clay, whereas increased phosphorus limitation may explain the stimulation of Glomeromycota at elevated CO2 in the sandy loam. Our results demonstrate that soil type is a key variable in soil fungal responses to rising atmospheric CO2.