Fungal endophyte infection increases carbon sequestration potential of southeastern USA tall fescue stands

Javed Iqbal, Jacob A. Siegrist, Jim A. Nelson, Rebecca L. McCulley

Research output: Contribution to journalArticlepeer-review

65 Scopus citations

Abstract

Tall fescue (Schedonorus arundinaceous (Schreb.)) is often infected with a common toxic fungal endophyte (Neotyphodium coenophialum) capable of producing alkaloids that affect grazing animal health, insect herbivory, plant production, and litter decomposition. The strength of these endophyte-associated effects is thought to depend on the abiotic and biotic conditions of a specific site. Prior work from Georgia, USA, has demonstrated that fungal endophyte infection can increase soil carbon pools of tall fescue pastures; however, for endophyte infection to contribute substantially to regional carbon sequestration, this result would have to hold true across the broad range of environmental conditions that support tall fescue growth. In this study, we evaluated whether endophyte infection consistently alters various soil parameters, including carbon storage, of tall fescue stands located throughout the southeastern United States. Soil samples were collected from nine sites with established paired high- and low- endophyte-infected tall fescue stands. These samples were analyzed for basic soil parameters, soil organic carbon (SOC), soil total nitrogen (TN), particulate and non-particulate organic matter-C and -N (POM, n-POM), C and N mineralization rates, and microbial biomass and community composition. Averaged across all sites, endophyte-infected tall fescue stands had 6% greater SOC and 5% greater TN pools in surface soil than adjacent endophyte-free stands. The lack of a significant interaction between site and endophyte infection status indicated that this result was relatively consistent across sites, despite differences in stand age, climate, and other environmental conditions. While POM C and POM N tended to be higher in endophyte-infected than endophyte-free stands, this result was not significant. However, greater pools of n-POM C and N were observed in endophyte-infected vs. endophyte-free stands when averaged across all the sites, suggesting increased retention of recalcitrant substrates occurred in response to fungal endophyte infection. Total microbial biomass, measured via phospholipid fatty acid (PLFA) analysis, was greater in endophyte-infected than endophyte-free soils when averaged across sites, reflecting the trends observed with SOC and TN. Microbial community composition shifted somewhat in response to fungal endophyte infection: significantly higher fungal to bacterial ratios were observed in endophyte-free compared to endophyte-infected stands. However, ordinations of the PLFA data demonstrated only slight separation of endophyte-infected and endophyte-free microbial communities at some sites and no clear separation at others. Enhanced SOC, TN, recalcitrant n-POM C and N pools, and altered microbial biomass and communities suggest that this aboveground fungal endophyte symbiosis has widespread effects on soil biology and biochemistry, and that high prevalence of the aboveground endophyte increases C sequestration capacity of tall fescue stands throughout the southeastern USA.

Original languageEnglish
Pages (from-to)81-92
Number of pages12
JournalSoil Biology and Biochemistry
Volume44
Issue number1
DOIs
StatePublished - Jan 2012

Bibliographical note

Funding Information:
This research project was funded by a cooperative agreement between the College of Agriculture at the University of Kentucky and the USDA-ARS Forage Animal Production Research Unit (58-6440-7-135) and the Kentucky Agricultural Experiment Station (KY006045). We thank Mark Bradford and Elisa D’Angelo for providing us with laboratory protocols and expertise. We thank Elizabeth Carlisle for her assistance with the lab work. We thank the site managers and scientists of the various locations sampled in this project for their willingness to let us sample their sites, their assistance in helping us accomplish the sampling, and for their foresight in setting up paired fungal endophyte-infected and endophyte-free tall fescue plots. We also appreciate the various sources of funding that supported the establishment and maintenance of these plots at individual sites.

Keywords

  • Carbon sequestration
  • Fungal endophyte
  • Microbial biomass
  • Neotyphodium
  • Particulate organic matter carbon
  • Phospholipid fatty acid
  • Tall fescue

ASJC Scopus subject areas

  • Microbiology
  • Soil Science

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