Water Relations of Artemisia tridentata ssp. wyomingensis and Sarcobatus vermiculatus in the Steppe of Southeastern Oregon

Groundwater use by native plants in response to changes in precipitation in an intermountain basin

“…Thus, although S. vermiculatus can acquire groundwater, its water status improved in response to rain-recharged soil water. Romo and Haferkamp (1989) observed a similar J response to a rain-driven increase in surface soil moisture for S. vermiculatus in southeastern Oregon, where summer precipitation is uncommon. Seasonal xylem pressure trends for S. vermiculatus in the SLV during two years with different precipitation patterns were similar to those reported for other western U.S. populations of this species, suggesting that it functions similarly in regions with and without monsoon rains (Donovan et al, 1996;Sorenson et al, 1991;Sperry and Hacke, 2002;Trent et al, 1997).…”

Plant drought tolerance assessment for re-vegetation in heterogeneous karst landscapes of southwestern China

“…Consequently, a large number of studies have considered plant predawn water potential as an index of soil water status around the roots or an estimate of soil water potential (Bréda et al, 1995;Correia and Catarino, 1994;Gebrekirstos et al, 2006;Reich and Hinckley, 1989;Saliendra et al, 1995;Sellin, 1996Sellin, , 1998Sperry and Pockman, 1993). The remarkable relationships between leaf predawn water potential and soilto-leaf hydraulic conductance, maximum stomatal conductance, transpiration and growth (Acherar and Rambal, 1992;Mitchell et al, 1993;Reich and Hinckley, 1989;Romo and Haferkamp, 1989) also emphasize the importance of predawn water potential for understanding plant water relations under water stress.…”

Predawn disequilibrium between plant and soil water potentials in two cold-desert shrubs

“…Predawn water potentials are ecologically relevant. For example, dierences in predawn xylem Y p have been used to infer dierences in rooting depth and habitat partitioning, based on the expectation that these values re¯ect equilibration with soil Y w (Grin 1973;Davis and Mooney 1986;Romo and Haferkamp 1989;Donovan and Ehleringer 1994a). Bre da et al (1995) estimated the zone of oak root water uptake from the match of oak predawn Y w with soil Y w in the depth pro®le.…”

“…Models that integrate plant transpiration responses to water stress and estimate hydraulic resistances also commonly assume that soil and plant Y w equilibrate by dawn (Mishio and Yokoi 1991;Rambal 1992;Brisson et al 1993). Predawn xylem Y p has also been correlated with plant physiological processes including maximum stomatal conductance or transpiration (Reich and Hinckley 1989;Romo and Haferkamp 1989;Acherar and Rambal 1992;Ame glio and Archer 1996) and growth (Mitchell et al 1993). Thus, understanding the mechanisms that control plant predawn Y w , knowledge of variation in this character, and assessment of the validity of the equilibrium assumption are critical to realistic interpretations of plant water use, plant adaptation to stress, water resource partitioning, and community water balance.…”