Plant species-specific changes in root-inhabiting fungi in a California annual grassland: responses to elevated CO 2 and 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 CO and 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 CO and 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 CO, but decreased by over 80% for Bromus hordeaceus. By contrast, the mean percent infection by mycorrhizal fungi increased in response to elevated CO for 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 CO in this California grassland ecosystem.

Extracellular Enzyme Activity Beneath Temperate Trees Growing Under Elevated Carbon Dioxide and Ozone

“…Although we presently do not have data on specific fungal communities in our experiment, an increase in N-acetylglucosaminidase activity under elevated CO 2 may result from a greater production of fungal cell wall litter (Miller et al, 1998). This would be consistent with other studies that have observed greater mycorrhizal infection (%), and higher levels of mycorrhizal and saprophytic fungal biomass under elevated CO 2 (Rillig et al, 1998;Klironomos et al, 1996). N-acetylglucosaminidase in our study displayed a nearly twofold increase with elevated CO 2 (Fig.…”

Ecological Effects of Nitrogen Deposition in the Western United States

“…rubens and Schismus barbatus, have recently invaded portions of the Mojave and Sonoran Deserts (Pake et al 1995, Brooks 1999, Holzapfel and Mahall 1999, Brooks 2003. Field experiments have shown that these grasses are highly responsive to elevated soil N, more so than most native species (Rillig et al 1998, DeFalco et al 2001, Brooks 2003. The recent increases in N deposition are correlated with the increased productivity of these grasses.…”

Climate change goes underground: effects of elevated atmospheric CO2 on microbial community structure and activities in the rhizosphere

“…It is generally assumed that the CO 2 -induced increases in soil C availability will increase fungal biomass more than bacterial biomass (Klironomos et al 1996;Rillig et al 1998). Indeed, Jones et al (1998) observed increases in fungal abundance in response to elevated CO 2 .…”