PARENT SESSION
Poster Session #45: Elevated CO₂ I.
Wednesday, August 7. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Nutrient resorption of naturally occurring desert shrubs exposed to Free-Air CO₂ enrichment.

Housman, David^*,1, Killingbeck, Keith², Evans, R.Dave³, Smith, Stanley¹, ¹ University of Nevada, Las Vegas, Las Vegas, NV² University of Rhode Island, Kingston, RI³ University of Arkansas, Fayetteville, AR

ABSTRACT- Leaf nutrient resorption enables plants to sequester nutrients that might otherwise become unavailable. Resorption could increase if future CO₂ concentrations ([CO₂]) intensify nutrient demands via enhanced growth. We compared resorption efficiency and proficiency of N, P, Cu, Mn and Zn in two deciduous shrubs (Ambrosia dumosa and Lycium pallidum) growing in situ at ambient (~370 mol mol^-1) or elevated (~550 mol mol^-1) [CO₂] at the Nevada Desert FACE Facility. Nitrogen resorption efficiency and proficiency were greater in Ambrosia, regardless of [CO₂]. All treatments completely resorbed P. Both Cu and Mn showed some accretion, while Zn proficiency was highest in Lycium, regardless of [CO₂]. Within-species, resorption proficiency of Cu and Mn were higher in Ambrosia under elevated [CO₂]. Although nutrient resorption patterns did not consistently respond to elevated [CO₂] in a below-average rainfall year, enhanced plant production under elevated [CO₂] during wet years could induce greater resorption in nutrients that are currently incompletely resorbed, but it may also result in greater limitations for nutrients that are completely resorbed at the current atmospheric [CO₂].

KEY WORDS: Ambrosia dumosa, Lycium pallidum, Mojave Desert, nutrient resorption