Monday, November 13, 2006
92-12
Enrichment of Co2 and N Influence Arbuscular Mycorrhizal Fungi, Soil Nematodes and Microarthropods in a Long-Term Global Change Experiment.
Anita J. Antoninka1, Peter B. Reich2, and Nancy C. Johnson1. (1) Northern Arizona University, Environmental Sciences, PO Box 5694, Flagstaff, AZ 86011-5694, (2) University of Minnesota, St. Paul, MN 55108
Anthropogenic enrichment of atmospheric CO2 and soil N are affecting plant productivity and community composition. Most plants rely on trading partnerships with arbuscular mycorrhizal fungi (AMF) for uptake of mineral nutrients and water. Alteration of plant communities can affect the abundance and community composition of AMF, and consequently affect plant productivity. Soil mesofauna, including soil nematodes and microarthropods, may also be impacted by changes to the plant community or AMF community. These feedbacks can have major consequences for soil food webs and C and N cycling. We investigated the effects of CO2 and N enrichment and host diversity (0, 1 or 16 plant species) on AMF communities after 7 years in a field experiment in MN, USA. Effects of CO2 and N enrichment on soil nematodes and microarthropods were assessed only in the high diversity plots. We found that the species composition of AMF spore communities was altered by enriched CO2 and host diversity, but not by N, while total AMF abundance and richness were not altered by CO2, but were influenced by N and host diversity. Extramatrical hyphal lengths were also affected by CO2, N and host diversity. AMF responses to treatment varied by fungal species and were dependent on host diversity. For example, Gigaspora gigantea proliferated in 16 species plots, whereas Acaulospora laevis was most abundant in single species plots. While overall nematode abundance was not affected by treatments, we found that the abundance of some feeding guilds was affected by CO2 and N enrichment. Microarthropod abundance was also affected by treatments. These results indicate that soil communities of AMF, soil nematodes and microarthropods are sensitive to changes in atmospheric enrichment of CO2 and soil N fertilization. Changes in these communities can alter plant productivity and community composition, food web dynamics, and nutrient cycling.
Handout (.pdf format, 125.0 kb)