Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/30/2004
Publication Date: 8/2/2004
Citation: Patrick, L., Payton, P.R., Lambrecht, S., Zak, J., Loik, M., Tissue, D. 2004. Photosynthetic response of desert plants to a large single precipitation event at big bend national park[abstract]. The Ecological Society of America. Poster No. 74. Interpretive Summary:
Technical Abstract: Changes in the global climate system due to increased levels of CO2 have been linked to an increase in both air and soil temperatures, thereby driving a change in patterns of global air circulation and hydrologic cycling, including regional precipitation regimes. Arid and semi-arid ecosystems are predicted to be particularly sensitive to these future environmental changes since water is the critical limiting factor in these ecosystems. In September 2003, we simulated a large (25mm) rainfall event in a sotol-grassland at Big Bend National Park. Daily measurements of stomatal conductance and photosynthesis (A-Ci and A-Q response curves) were conducted on a native C4 grass (Bouteloua curtipendula) and a native C3 perennial shrub (Dasylirion leiophyllum) one day prior to watering and for three consecutive days after watering. After three days, watered Bouteloua plants exhibited greater rates of net photosynthesis and photosynthetic capacity, while watered Dasylirion plants did not exhibit changes in photosynthesis compared with unwatered controls. Increased stomatal conductance accounted for 60% of the increased photosynthetic rate in Bouteloua, while increased stomatal conductance in Dasylirion did not contribute to an increased photosynthetic rate due to a reduction in biochemical capacity. We suggest that the shallow rooted grass (Bouteloua), has a greater capacity to respond quickly to a precipitation pulse than the more deeply rooted shrub (Dasylirion). Future experiments will evaluate the long-term response of these species to varying magnitude and timing of precipitation pulses, incorporating aspects of water transport and storage capacity.