, Volume 9, Issue 5, pp 740–755 | Cite as

Plasticity in Resource Allocation and Nitrogen-use Efficiency in Riparian Vegetation: Implications for Nitrogen Retention

  • John D. SchadeEmail author
  • David B. Lewis


In this work, we summarize our current understanding of the function of riparian zones and describe an investigation of changes in the production per unit nitrogen (N) taken up, or nitrogen-use efficiency (NUE) and resource allocation of a riparian shrub in response to changes in N availability. Empirical work included measuring leaf %N and root-to-shoot ratios (R:S) of individual riparian shrubs (Baccharis salicifolia, or seepwillow) growing at a range of N availabilities in the field and growing in fertilized and unfertilized plots in a field fertilization experiment. In both observational and experimental work, N availability was related positively to %N of plant tissues and negatively to R:S. We used a simulation model to investigate feedbacks between seepwillow responses to and effects on N availability. In the model, plasticity in resource allocation and NUE in response to changes in N led to lower productivity at low N supply and higher productivity and lower retention at high N supply than was observed in plants constrained to a constant %N and R:S. Furthermore, uptake became relatively more important as a retention mechanism when plants responded to high N supply. These feedbacks could have significant effects on N retention by riparian zones in watersheds receiving large fertilizer inputs of N or on ecosystems exposed to high rates of atmospheric N deposition.


riparian vegetation nitrogen retention denitrification resource allocation nitrogen use efficiency plasticity 



JD Schade was funded during this project by an EPA National Center for Environmental Research (NCER) Science to Achieve Results (STAR) fellowship. We are grateful to Stuart Fisher for his insight and generosity. We thank Cathy Kochert and Tom Collela for help with laboratory analyses. Nancy Grimm and Jill Welter helped with the development of these ideas. We owe a great debt of gratitude to Dr. Don DeAngelis for his patience and willingness to help with the modeling and presentation of equations. Three anonymous reviewers provided many insightful comments and suggestions that significantly improved the manuscript. We are grateful for their hard work.


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Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  1. 1.School of Life SciencesArizona State UniversityTempeUSA
  2. 2.Biology Department, Science CenterSt. Olat CollegeNorthfieldUSA

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