Some effects of soil-moisture availability on above-ground production and reproductive allocation in Larrea tridentata (DC) Cov

Abstract
Data from the US/IBP [United States/International Biological Program] Desert Biome validation studies indicate that aboveground production and biomass allocated to reproduction in L. tridentata vary from one year to another depending upon the timing and extent of soil-moisture availability. To verify these observations and determine to what extent water availability can affect total aboveground production and reproductive allocation in this widely distributed warm desert shrub, a series of soil-moisture augmentation experiments were conducted. High levels of soil moisture had a greater effect on reproductive allocation than on total aboveground production. Enhanced soil moisture during the period of active growth increased total above-ground production and reduced the percentage of biomass allocated to reproduction. Enhanced soil moisture during the normal periods of little or no growth did not increase total above-ground production.