Technical Abstract: To better understand the effects of fire in the Chihuahuan desert, gas exchange characteristics of two dominant grass species, Bouteloua eriopoda and Aristida purpurea, and soil nitrogen availability were studied in response to prescribed fire at the Jornada Experimental Range in southern New Mexico. Burned and unburned plant individuals were measured before and after fire. Rates of net photosynthesis and stomatal conductance were highest in burned individuals, with those of A. purpurea exceeding B. eriopoda. Water use efficiency of both species was not affected by fire. Soil nitrogen supply rates increased compared to unburned controls. Similar to other grasslands where fire is common, physiological characteristics of vegetation responded positively. These adaptations indicate that fire may be beneficial in the restoration of native grasses.