Submitted to: Journal of Arid Environments
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/14/2006
Publication Date: 5/27/2006
Citation: James, J.J., Aanderud, Z.T., Richards, J.H. 2006. Seasonal Timing of N Pulses Influences N Capture in a Saltbush Scrub Community. Journal of Arid Environments. 67(2006):688-700. Interpretive Summary: Limiting resources are supplied as pulses in arid systems. We evaluated if the seasonal timing of N pulses influences N capture and partitioning in a desert shrub community. We found that shrubs captured more N when pulses coincided with periods of high plant growth rate. When shrubs differ in seasonal pattern of growth rate, variation in the seasonal timing of N pulses may influence competitive interactions and promote diversity in arid systems.
Technical Abstract: Limiting resources are generally available in brief temporal pulses in arid systems. We compared the ability of dominant shrubs in a saltbush scrub community to capture N from pulses and evaluated whether N capture and partitioning within this community is influenced by the seasonal timing of N pulses. Based on previous research in agronomic systems we predicted that the ability of a species to capture N following a pulse would depend on when the pulse occurred in relation to plant growth rate and N demand. Supporting this hypothesis, Atriplex confertifolia and Sarcobatus vermiculatus, which had greater growth rates early in the growing season compared to Atriplex parryi, captured more N from early spring pulses relative to A. parryi. Atriplex parryi, which had higher growth rates later in the growing season, captured more N from mid and late spring pulses compared to the other species. These temporal differences in N capture among species, however, also depended on the magnitude of the N pulse. These results suggest that temporal variation in N availability may differentially impact competitive abilities of coexisting species and potentially facilitate species coexistence in arid systems.