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Seedling Survivorship of Mojave Desert Shrubs as Affected by Elevated CO2
Reference
Housman, D.C., Zitzer, S.F., Huxman, T.E. and Smith, S.D.  2003.  Functional ecology of shrub seedlings after a natural recruitment event at the Nevada Desert FACE facility.  Global Change Biology 9: 718-728.

Background
The Nevada Desert FACE Facility (NDFF) was established in an undisturbed Mojave Desert ecosystem during the winter of 1996-97. It consists of three 25-m-diameter FACE arrays maintained at a CO2 concentration of 550 ppm, three similar FACE arrays (blower controls) that receive ambient air (about 370 ppm CO2), and three ambient CO2 plots without blowers.

What was done
CO2 enrichment began in April of 1997; and from 1997 to 2001, the authors seasonally examined survival, growth, gas exchange and water potential responses of seedlings of the evergreen shrub Larrea tridentata D.C. (Cov.) (Zygophyllaceae) and the drought-deciduous shrub Ambrosia dumosa A. Gray (Payne) (Asteraceae) that had germinated in the fall of 1997.

What was learned
The authors report that early survival of both species was greater under elevated CO2 in the initial wetter-than-normal year, but that this advantage disappeared in the following drier years.

What it means
In the words of the authors, "elevated CO2 may have its greatest effect on Mojave Desert shrub recruitment when accompanied by increased rainfall, which is predicted for this region (Taylor and Penner, 1994)."

Reference
Taylor, K.E. and Penner, J.E.  1994.  Response of the climate system to atmospheric aerosols and greenhouse gases.  Nature 369: 734-737.
Reviewed 30 July 2003