title: Plant species-specific changes in root-inhabiting fungi in a California annual grassland: responses to elevated CO2and nutrients.
abstract: Five co-occurring plant species from an annual mediterranean grassland were grown in monoculture for 4 months in pots inside open-top chambers at the Jasper Ridge Biological Preserve (San Mateo County, California). The plants were exposed to elevated atmospheric CO2and soil nutrient enrichment in a complete factorial experiment. The response of root-inhabiting non-mycorrhizal and arbuscular mycorrhizal fungi to the altered resource base depended strongly on the plant species. Elevated CO2and fertilization altered the ratio of non-mycorrhizal to mycorrhizal fungal colonization for some plant species, but not for others. Percent root infection by non-mycorrhizal fungi increased by over 500% for Linanthus parviflorus in elevated CO2, but decreased by over 80% for Bromus hordeaceus. By contrast, the mean percent infection by mycorrhizal fungi increased in response to elevated CO2for all species, but significantly only for Avena barbata and B. hordeaceus. Percent infection by mycorrhizal fungi increased, decreased, or remained unchanged for different plant hosts in response to fertilization. There was evidence of a strong interaction between the two treatments for some plant species and non-mycorrhizal and mycorrhizal fungi. This study demonstrated plant species- and soil fertility-dependent shifts in below-ground plant resource allocation to different morpho-groups of fungal symbionts. This may have consequences for plant community responses to elevated CO2in this California grassland ecosystem.
authors.affiliation: Department of Biology, Soil Ecology & Restoration Group, San Diego State University, San Diego, CA 92182, USA Fax: (619)594-5676; e-mail: mrillig@sunstroke.sdsu.edu, , , , , , US.
authors.forename: Matthias C
authors.initials: MC
authors.lastname: Rillig
authors.affiliation: Department of Biology, Soil Ecology & Restoration Group, San Diego State University, San Diego, CA 92182, USA Fax: (619)594-5676; e-mail: mrillig@sunstroke.sdsu.edu, , , , , , US.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Allen
authors.affiliation: Department of Botany, University of Guelph, Guelph, ON, Canada N1G 2W1, , , , , , CA.
authors.forename: John N
authors.initials: JN
authors.lastname: Klironomos
authors.affiliation: Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA, , , , , , US.
authors.forename: Nona R
authors.initials: NR
authors.lastname: Chiariello
authors.affiliation: Department of Plant Biology, Carnegie Institution of Washington, Stanford, CA 94305, USA, , , , , , US.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Field
keywords: Annual grassland; Arbuscular mycorrhiza; Key words Elevated CO2; Saprophytic fungi; Soil nutrients