Ecosystems

, Volume 5, Issue 1, pp 68–79

Sources of Nitrogen to the Riparian Zone of a Desert Stream: Implications for Riparian Vegetation and Nitrogen Retention

  • John D. Schade
  • Eugenia Marti
  • Jill R. Welter
  • Stuart G. Fisher
  • Nancy B. Grimm

DOI: 10.1007/s10021-001-0056-6

Cite this article as:
Schade, J., Marti, E., Welter, J. et al. Ecosystems (2002) 5: 68. doi:10.1007/s10021-001-0056-6
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Abstract

Riparian zones effectively remove nitrogen (N) from water flowing through riparian soils, particularly in agricultural watersheds. The mechanism of N removal is still unclear, especially the role of vegetation. Uptake and denitrification are the two most commonly studied mechanisms. Retention of groundwater N by plant uptake is often inferred from measurements of N in net incremental biomass. However, this assumes other sources of N are not contributing to the N demand of plants. The purpose of this work was to investigate the relative importance of three sources of available N to riparian trees in a desert stream—input in stream water during floods, input during baseflow, and mineralization of N from soil organic matter. Two approaches were used; a mass balance approach in which the mass of available N from each source was estimated, and a correlational approach in which indexes of each source were compared to leaf N for individual willow trees. Total N from all sources was 396 kg ha−1 y−1, with 172 kg ha−1 y−1 from mineralization, 214 kg ha−1 y−1 from the stream during baseflow, and 9.6 kg ha−1 y−1 from floods. Leaf N was significantly related to N mineralization rates and flood inputs; it was not related to baseflow inputs. We conclude that mineralization is a major source of available N for willow trees, subsidized by input of N from floods. Baseflow inputs are most likely removed by rapid denitrification at the stream–riparian edge, while higher rates of flood supply exceed the capacity of this “filter.”

Key words: riparian zone; nitrogen retention; denitrification; plant uptake; N mineralization; desert stream. 

Copyright information

© Springer-Verlag New York Inc. 2002

Authors and Affiliations

  • John D. Schade
    • 1
  • Eugenia Marti
    • 2
  • Jill R. Welter
    • 1
  • Stuart G. Fisher
    • 1
  • Nancy B. Grimm
    • 1
  1. 1.Biology Department, Arizona State University, Tempe, Arizona 85287-1501, USA; andUS
  2. 2.Centre d'Estudis Avançats de Blanes (CSIC), 17300 Blanes, SpainES

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