Short-term patterns in water and nitrogen acquisition by two desert shrubs following a simulated summer rain

TitleShort-term patterns in water and nitrogen acquisition by two desert shrubs following a simulated summer rain
Publication TypeJournal Article
Year of Publication1999
AuthorsBassiriRad H., Tremmel D.C, Virginia R.A, Reynolds J.F., de Soyza A.G., Brunell M.H
JournalPlant Ecology
Date Published1999
Accession NumberJRN00286
Call Number00733
Keywordsarticle, articles, isotopes, nitrogen, journal, journals, nitrogen, isotopes, nitrogen, shrub acquisition, rainfall simulation, shrubs, shrub, rainfall simulation, water, shrub acquisition

A field experiment was conducted to compare the rapidity with which the shrubs Larrea tridentata and Prosopis glandulosa utilized water, CO2 and nitrogen (N) following a simulated summer rainfall event. Selected plants growing in a roughly 50-m2 area were assigned to treatment and control groups. Xylem water potential (Øx) and net assimilation rate (Anet) were evaluated one day before and one and three days after watering. To monitor short-term N uptake, soils around each plant were labeled with eight equally distant patches of enriched 15N before watering. Nitrogen uptake, measured as leaf ä15N, was evaluated at smaller time intervals and for a longer period than those used for Øx and Anet. Both Øx and Anet exhibited a significant recovery in watered vs. control Larrea plants within 3 days after the imposition of treatment, but no such recovery was observed in Prosopis in that period. Larrea also exhibited a greater capacity for N uptake following the rain. Leaf ä15N was 5-fold greater in watered compared to unwatered Larrea plants within 2 days after watering, while foliar ä15N was not significantly different between the watered and unwatered Prosopis plants during the same period. Lack of a significant change in root 15NO3 uptake kinetics of Larrea, even 3 days after watering, indicated that the response of Larrea to a wetting pulse may have been due to a greater capacity to produce new roots. The differential ability of these potential competitors in rapidly acquiring pulses of improved soil resources following individual summer rainfall events may have significant implications for the dynamic nature of resource use in desert ecosystems.

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