Oecologia

, Volume 151, Issue 4, pp 704–718

Effects of an increase in summer precipitation on leaf, soil, and ecosystem fluxes of CO2 and H2O in a sotol grassland in Big Bend National Park, Texas

  • Lisa Patrick
  • Jessica Cable
  • Daniel Potts
  • Danielle Ignace
  • Greg Barron-Gafford
  • Alden Griffith
  • Holly Alpert
  • Natasja Van Gestel
  • Traesha Robertson
  • Travis E. Huxman
  • John Zak
  • Michael E. Loik
  • David Tissue
Global Change and Conservation Ecology

DOI: 10.1007/s00442-006-0621-y

Cite this article as:
Patrick, L., Cable, J., Potts, D. et al. Oecologia (2007) 151: 704. doi:10.1007/s00442-006-0621-y

Abstract

Global climate models predict that in the next century precipitation in desert regions of the USA will increase, which is anticipated to affect biosphere/atmosphere exchanges of both CO2 and H2O. In a sotol grassland ecosystem in the Chihuahuan Desert at Big Bend National Park, we measured the response of leaf-level fluxes of CO2 and H2O 1 day before and up to 7 days after three supplemental precipitation pulses in the summer (June, July, and August 2004). In addition, the responses of leaf, soil, and ecosystem fluxes of CO2 and H2O to these precipitation pulses were also evaluated in September, 1 month after the final seasonal supplemental watering event. We found that plant carbon fixation responded positively to supplemental precipitation throughout the summer. Both shrubs and grasses in watered plots had increased rates of photosynthesis following pulses in June and July. In September, only grasses in watered plots had higher rates of photosynthesis than plants in the control plots. Soil respiration decreased in supplementally watered plots at the end of the summer. Due to these increased rates of photosynthesis in grasses and decreased rates of daytime soil respiration, watered ecosystems were a sink for carbon in September, assimilating on average 31 mmol CO2 m−2 s−1 ground area day−1. As a result of a 25% increase in summer precipitation, watered plots fixed eightfold more CO2 during a 24-h period than control plots. In June and July, there were greater rates of transpiration for both grasses and shrubs in the watered plots. In September, similar rates of transpiration and soil water evaporation led to no observed treatment differences in ecosystem evapotranspiration, even though grasses transpired significantly more than shrubs. In summary, greater amounts of summer precipitation may lead to short-term increased carbon uptake by this sotol grassland ecosystem.

Keywords

Bouteloua curtipendulaChihuahuan DesertDasylirion leiophyllumEcosystem fluxesPrecipitation manipulation

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • Lisa Patrick
    • 1
  • Jessica Cable
    • 2
  • Daniel Potts
    • 2
  • Danielle Ignace
    • 2
  • Greg Barron-Gafford
    • 2
  • Alden Griffith
    • 3
  • Holly Alpert
    • 3
  • Natasja Van Gestel
    • 1
  • Traesha Robertson
    • 1
  • Travis E. Huxman
    • 2
  • John Zak
    • 1
  • Michael E. Loik
    • 3
  • David Tissue
    • 1
  1. 1.Department of Biological SciencesTexas Tech UniversityLubbockUSA
  2. 2.Ecology and Evolutionary BiologyUniversity of ArizonaTucsonUSA
  3. 3.Department of Environmental StudiesUniversity of CaliforniaSanta CruzUSA