© 2004 Heron Publishing—Victoria, Canada
Stomatal sensitivity to vapor pressure deficit and its relationship to hydraulic conductance in Pinus palustris
Robert N. Addington (1, 2, 3), Robert J. Mitchell (2), Ram Oren (4) and Lisa A. Donovan (1)
1. Department of Plant Biology, University of Georgia, Athens, GA 30602, USA / 2. Joseph W. Jones Ecological Research Center, Rt. 2, Box 2324, Newton, GA 31770, USA / 3. The Nature Conservancy, P.O. Box 52452, Fort Benning, GA 31995, USA (raddington@tnc.org) / 4. School of the Environment, Duke University, Durham, NC 27708, USA / Received April 29, 2003; accepted November 15, 2003; published online March 1, 2004
Summary
We studied the response of stomatal conductance at leaf (gS) and canopy (GS) scales to increasing vapor pressure deficit (D) in mature Pinus palustris Mill. (longleaf pine) growing in a sandhill habitat in the coastal plain of the southeastern USA. Specifically, we determined
if variation in the stomatal response to D was related to variation in hydraulic conductance along the soil-to-leaf pathway (KL) over the course of a growing season. Reductions in KL were associated with a severe growing season drought that significantly reduced soil water content (θ) in the upper 90-cm
soil profile. Although KL recovered partially following the drought, it never reached pre-drought values. Stomatal sensitivity to D was well correlated with maximum gS at low D at both leaf and canopy scales, and KL appeared to influence this response by controlling maximum gS. Our results are consistent with the hypothesis that stomatal response to D occurs to regulate minimum leaf water potential, and that the sensitivity of this response is related to changes in whole-plant
hydraulics.
Keywords:
drought, longleaf pine, soil water, stomatal conductance, water potential.
