Plant N capture from pulses: effects of pulse size,growth rate,and other soil resources |
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Authors: | Email author" target="_blank">J?J?JamesEmail author J?H?Richards |
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Institution: | (1) Department of Land, Air, and Water Resources, University of California, One Shields Avenue, Davis, CA 95616-8627, USA;(2) USDA – Agricultural Research Service, Eastern Oregon Agricultural Research Center, 67826-A Hwy 205, Burns, OR 97720, USA |
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Abstract: | In arid ecosystems, the ability to rapidly capture nitrogen (N) from brief pulses is expected to influence plant growth, survival,
and competitive ability. Theory and data suggest that N capture from pulses should depend on plant growth rate and availability
of other limiting resources. Theory also predicts trade-offs in plant stress tolerance and ability to capture N from different
size pulses. We injected K15NO3, to simulate small and large N pulses at three different times during the growing season into soil around the co-dominant
Great Basin species Sarcobatus vermiculatus, Chrysothamnus nauseosus ssp. consimilis, and Distichlis spicata. Soils were amended with water and P in a partial factorial design. As predicted, all study species showed a comparable decline
in N capture from large pulses through the season as growth rates slowed. Surprisingly, however, water and P availability
differentially influenced the ability of these species to capture N from pulses. Distichlis N capture increased up to tenfold with water addition while Chrysothamnus N capture increased up to threefold with P addition. Sarcobatus N capture was not affected by water or P availability. Opposite to our prediction, Sarcobatus, the most stress tolerant species, captured less N from small pulses but more N from large pulses relative to the other species.
These observations suggest that variation in N pulse timing and size can interact with variable soil water and P supply to
determine how N is partitioned among co-existing Great Basin species. |
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Keywords: | Arid ecosystems Great Basin desert Nitrogen isotopes Plant N demand Soil resource pulses |
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