Get access

Linking above- and belowground responses to global change at community and ecosystem scales

Authors

  • ANITA ANTONINKA,

    1. Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5694, USA
    Search for more papers by this author
  • JULIE E. WOLF,

    1. Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5694, USA
    2. Department of Mycology and Microbiology Laboratory, United States Department of Agriculture, Beltsville, MD 20705, USA
    Search for more papers by this author
  • MATTHEW BOWKER,

    1. Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5694, USA
    Search for more papers by this author
  • AIMÉE T. CLASSEN,

    1. Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5694, USA
    2. Environmental Sciences Division, Oak Ridge Laboratories, Oak Ridge, TN 37831-6422, USA
    3. Department of Ecology and Evolutionary Biology, University of Tennessee, 569 Dabney Hall, Knoxville, TN 37996, USA
    Search for more papers by this author
  • NANCY COLLINS JOHNSON

    1. Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5694, USA
    Search for more papers by this author

Anita Antoninka, tel. +1 928 523 0913, fax +1 928 523 7423, e-mail: aja6@nau.edu

Abstract

Cryptic belowground organisms are difficult to observe and their responses to global changes are not well understood. Nevertheless, there is reason to believe that interactions among above- and belowground communities may mediate ecosystem responses to global change. We used grassland mesocosms to manipulate the abundance of one important group of soil organisms, arbuscular mycorrhizal (AM) fungi, and to study community and ecosystem responses to CO2 and N enrichment. Responses of plants, AM fungi, phospholipid fatty acids and community-level physiological profiles were measured after two growing seasons. Ecosystem responses were examined by measuring net primary production (NPP), evapotranspiration, total soil organic matter (SOM), and extractable mineral N. Structural equation modeling was used to examine the causal relationships among treatments and response variables. We found that while CO2 and N tended to directly impact ecosystem functions (evapotranspiration and NPP, respectively), AM fungi indirectly impacted ecosystem functions by influencing the community composition of plants and other root fungi, soil fungi and soil bacteria. We found that the mycotrophic status of the dominant plant species in the mesocosms determined whether the presence of AM fungi increased or decreased NPP. Mycotrophic grasses dominated the mesocosm communities during the first growing season, and the mycorrhizal treatments had the highest NPP. In contrast, nonmycotrophic forbs were dominant during the second growing season and the mycorrhizal treatments had the lowest NPP. The composition of the plant community strongly influenced soil N, and the community composition of soil organisms strongly influenced SOM accumulation in the mesocosms. These results show how linkages between above- and belowground communities can determine ecosystem responses to global change.

Get access to the full text of this article

Ancillary