Great Basin Naturalist


This study examined the effects of alterations in soil nitrogen on the growth of Artemessia tridentata ssp. wyomingensis Nutt. Soil nitrogen content was altered by applying sugar (45 g/m2), nitrate (4.5 g/m2), or ammonium (4.5 g/m2), and the results were compared with a control treatment (no soil amendments). Addition of either form of nitrogen significantly increased leaf nitrogen content, mean maximum length of ephemeral leaves, number of ephemeral leaves per terminal shoot, and current year's vegetative stem length over the control and sugar treatments. Both soil water and predawn xylem potentials during active growth were lower in the nitrogen-treated plots. The higher growth activity and greater leaf mass of A. tridentata in the nitrogen treatments may have been responsible for this result. Higher photosynthetic rates observed in the nitrogen treatments during an early June sampling period also lend support to this observation. This study suggests A. tridentata ssp. wyomingensis would opportunistically take advantage of increased availability of soil nitrogen. The ability of this species to respond positively to increased soil nitrogen may enhance its competitiveness over associated perennial species.