Get access

Ecophysiological analysis of two arctic sedges under reduced root temperatures

Authors

  • Gregory Starr,

    Corresponding author
    1. Department of Biological Sciences, Florida International University, Miami, FL 33199, USA
    2. 1Current address: School of Forest Resources and Conservation, University of Florida, 134 Newins-Ziegler Hall, Gainesville, FL 32611, USA
      * e-mail: gstarr@ufl.edu
    Search for more papers by this author
  • Dawn S. Neuman,

    1. Department of Biological Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154, USA
    Search for more papers by this author
  • Steven F. Oberbauer

    1. Department of Biological Sciences, Florida International University, Miami, FL 33199, USA
    Search for more papers by this author

  • Edited by J. J. S. van Rensen

* e-mail: gstarr@ufl.edu

Abstract

Shoot physiological activity in arctic vascular plants may be controlled by low soil temperatures. While leaves may be exposed to moderate temperatures during the growing season, root temperatures often remain near freezing. In this study, two tundra sedges, Eriophorum vaginatum and Carex bigellowii, were subjected to reduced soil temperatures, and photosynthetic parameters (light saturated photosynthesis Amax, variable to maximal fluorescence and Fv/Fm stomatal conductance) and abscisic acid concentrations were determined. Stomatal conductance and Amax for both E. vaginatum and C. bigellowii strongly decreased with declining soil temperatures. Decreasing soil temperature, however, impacted Fv/Fm to a much lesser degree. Root and leaf ABA concentrations increased with decreasing root temperature. These observations support the contention that soil temperature is a significant photosynthetic driving factor in arctic sedges exposed to variable root and shoot temperatures. Because these two species comprise approximately 30% of the vascular ground cover of wet tussock tundra, the soil temperature responses of these sedges potentially scale up to significant effects on ecosystem carbon exchange.

Get access to the full text of this article

Ancillary