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Species of plants and associated arbuscular mycorrhizal fungi mediate mycorrhizal responses to CO 2 enrichment
Author(s) -
Johnson Nancy Collins,
Wolf Julie,
Reyes Melissa A.,
Panter Ashley,
Koch George W.,
Redman Andrea
Publication year - 2005
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2005.00967.x
Subject(s) - biology , nutrient , glomus , botany , arbuscular mycorrhiza , arbuscular mycorrhizal fungi , agronomy , colonisation , soil fertility , symbiosis , colonization , soil water , ecology , horticulture , inoculation , spore , bacteria , genetics
It has been suggested that enrichment of atmospheric CO 2 should alter mycorrhizal function by simultaneously increasing nutrient‐uptake benefits and decreasing net C costs for host plants. However, this hypothesis has not been sufficiently tested. We conducted three experiments to examine the impacts of CO 2 enrichment on the function of different combinations of plants and arbuscular mycorrhizal (AM) fungi grown under high and low soil nutrient availability. Across the three experiments, AM function was measured in 14 plant species, including forbs, C 3 and C 4 grasses, and plant species that are typically nonmycorrhizal. Five different AM fungal communities were used for inoculum, including mixtures of Glomus spp. and mixtures of Gigasporaceae (i.e. Gigaspora and Scutellospora spp.). Our results do not support the hypothesis that CO 2 enrichment should consistently increase plant growth benefits from AM fungi, but rather, we found CO 2 enrichment frequently reduced AM benefits. Furthermore, we did not find consistent evidence that enrichment of soil nutrients increases plant growth responses to CO 2 enrichment and decreases plant growth responses to AM fungi. Our results show that the strength of AM mutualisms vary significantly among fungal and plant taxa, and that CO 2 levels further mediate AM function. In general, when CO 2 enrichment interacted with AM fungal taxa to affect host plant dry weight, it increased the beneficial effects of Gigasporaceae and reduced the benefits of Glomus spp. Future studies are necessary to assess the importance of temperature, irradiance, and ambient soil fertility in this response. We conclude that the affects of CO 2 enrichment on AM function varies with plant and fungal taxa, and when making predictions about mycorrhizal function, it is unwise to generalize findings based on a narrow range of plant hosts, AM fungi, and environmental conditions.