Artemisia tridentata has increased dramatically during the past 100 yr throughout the sagebrush steppe at the expense of late-seral perennial grasses. This study was designed to determine the effects of addition or depletion of different nitrogen forms on aboveground vegetative and reproductive growth of Artemisia tridentata ssp. wyomingensis and Stipa thurberiana, a late-seral grass. Treatments included application of sugar (45 g m-2), nitrate (4.5 g N m-2), ammonium (4.5 g N m-2) and a control. Both nitrogen forms significantly increased Stipa aboveground biomass and tiller density. Individual tiller weight was not different among treatments. Added nitrogen also increased aboveground biomass, total shoot density and individual shoot [...]
